bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Field Studies by Voyager 2: Preliminary Results at Saturn
Authors: Ness Norman F. , Acuña Mario H. , Behannon Kenneth W. , Burlaga Leonard F. , Connerney John E. P. , Lepping Ronald P. , Neubauer Fritz M.
Published: October 2006

Further studies of the Saturnian magnetosphere and planetary magnetic field by Voyager 2 have substantiated the earlier results derived from Voyager 1 observations in 1980. The magnetic field is primarily that of a centered dipole (moment = 0.21 gauss-
R
S
3
; where one Saturn radius,
R
S
, is 60,330 kilometers) tilted approximately 0.8° from the rotation axis. Near closest approach to Saturn, Voyager 2 traversed a kronographic longitude and latitude range that was complementary to that of Voyager 1. Somewhat surprisingly, no evidence was found in the data or the analysis for any large-scale magnetic anomaly in the northern hemisphere which could be associated with the periodic modulation of Saturnian kilometric radiation radio emissions. Voyager 2 crossed the magnetopause of a relatively compressed Saturnian magnetosphere at 18.5
R
S
while inbound near the noon meridian. Outbound, near the dawn meridian, the magnetosphere had expanded considerably and the magnetopause boundary was not observed until the spacecraft reached 48.4 to 50.9
R
S
and possibly beyond. Throughout the outbound magnetosphere passage, a period of 46 hours (4.5 Saturn rotations), the field was relatively steady and smooth showing no evidence for any azimuthal asymmetry or magnetic anomaly in the planetary field. We are thus left with a rather enigmatic situation to understand the basic source of Saturnian kilometric radiation modulation, other than the small dipole tilt.
Planetary Radio Astronomy Observations from Voyager 2 Near Saturn
Authors: Warwick J. W. , Evans D. R. , Romig J. H. , Alexander J. K. , Desch M. D. , Kaiser M. L. , Aubier M. , Leblanc Y. , Lecacheux A. , Pedersen B. M.
Published: October 2006

Planetary radio astronomy measurements obtained by Voyager 2 near Saturn have added further evidence that Saturnian kilometric radiation is emitted by a strong dayside source at auroral latitudes in the northern hemisphere and by a weaker source at complementary latitudes in the southern hemisphere. These emissions are variable because of Saturn's rotation and, on longer time scales, probably because of influences of the solar wind and Dione. The electrostatic discharge bursts first discovered by Voyager 1 and attributed to emissions from the B ring were again observed with the same broadband spectral properties and an episodic recurrence period of about 10 hours, but their occurrence frequency was only about 30 percent of that detected by Voyager 1. While crossing the ring plane at a distance of 2.88 Saturn radii, the spacecraft detected an intense noise event extending to above 1 megahertz and lasting about 150 seconds. The event is interpreted to be a consequence of the impact, vaporization, and ionization of charged, micrometer-size G ring particles distributed over a vertical thickness of about 1500 kilometers.
Role of Natural Colloids in the Transport of Hydrophobic Pollutants
Authors: Means J. C. , Wuayaratne R.
Published: October 2006

The sorptive properties of natural estuarine colloids were investigated, with the herbicides atrazine and linuron used as model pollutants. Linear Freundlich adsorption constants for atrazine and linuron were 1850 and 6750, respectively. These high values indicate that natural colloids have the potential to be important substrates in the transport of hydrophobic contaminants in aquatic environments.
Scent Organ Development in
Creatonotos
Moths: Regulation by Pyrrolizidine Alkaloids
Authors: Schneider Dietrich , Boppré Michael , Zweig Jonathan , Horsley Stephen B. , Bell Thomas W. , Meinwald Jerrold , Hansen Kurt , Diehl Eduard W.
Published: October 2006

7-Hydroxy-6,7-dihydro-5
H
-pyrolizine-1-carboxaldehyde is the major volatile component of the scent organs in males of two species of
Creatonotos
(Lepidoptera, Arctiidae). The biosynthesis of this presumed pheromone depends on the presence of pyrrolizidine alkaloids in plants that are ingested by the larvae. In addition, these secondary plant substances control the morphogenesis of the scent organs. This morphogenetic effect of an alkaloid has not been observed previously.
Maceral, Total Organic Carbon, and Palynological Analyses of Ross Ice Shelf Project Site J9 Cores
Authors: Wrenn John H. , Beckman Scott W.
Published: October 2006

Analyses of macerals and total organic carbon indicate that the low organic content of core sediments from Ross Ice Shelf Project site J9 has been selectively reduced further, probably by postdepositional submarine oxidation. Palynological analysis revealed a reworked Paleogene dinocyst flora of low diversity (the transantarctic flora). This constitutes the most southerly dinocyst flora reported thus far. The antarctic distribution of the transantarctic flora supports the existence of a transantarctic strait during the Paleogene. The J9 sporomorph assemblage also is reworked and Paleogene in age.
Blade Technology in the Egyptian-Nile Valley: Some New Evidence
Authors: Vermeersch P. M. , Otte M. , Gilot E. , Paulissen E. , Guselings G. , Drappier D.
Published: October 2006

An Upper Paleolithic site with blade technology was excavated at Nazlet Khater, Egypt. Radiocarbon dates center around 31,500 years ago, indicating that the Egyptian Nile Valley was not an isolated enclave where blade technology appeared late in comparison with other eastern Mediterranean areas. This site fills a gap in the record of human history in Egypt between 40,000 and 20,000 years ago.
Bismuth Vanadate: A High-Pressure, High-Temperature Crystallographic Study of the Ferroelastic-Paraelastic Transition
Authors: Hazen R. M. , Mariathasan J. W. E.
Published: October 2006

Lattice dimensions of bismuth vanadate have been determined under 37 different high-pressure or high-temperature conditions or a combination of these conditions. New high-pressure, high-temperature, single-crystal x-ray techniques were used to bracket the reversible monoclinic (ferroelastic) to tetragonal (paraelastic) transition.
The International Breeder's Rights System and Crop Plant Innovation
Authors: Barton John H.
Published: October 2006

Legal arrangements governing a plant breeder's intellectual property rights to his inventions are likely to affect the future of crop research. Such systems, although controversial, are probably currently desirable for the developed world. The new genetic technologies may change this judgment, and certainly require redefinition of the lines between plant patents and regular patents. Several safeguards, present in the United States breeder's rights law, should be applied more broadly. A new safeguard—of ensuring that material be entered into germplasm banks—should be applied everywhere. For the developing world, the desirability of a plant patent system is much less clear; new agreements may be desirable to ensure the free flow and collection of germplasm.
Transmembrane Protein Structure: Spin Labeling of Bacteriorhodopsin Mutants
Authors: Altenbach Christian , Marti Thomas , Khorana H. Gobind , Hubbell Wayne L.
Published: October 2006

Transmembrane proteins serve important biological functions, yet precise information on their secondary and tertiary structure is very limited. The boundaries and structures of membrane-embedded domains in integral membrane proteins can be determined by a method based on a combination of site-specific mutagenesis and nitroxide spin labeling. The application to one polypeptide segment in bacteriorhodopsin, a transmembrane chromoprotein that functions as a light-driven proton pump is described. Single cysteine residues were introduced at 18 consecutive positions (residues 125 to 142). Each mutant was reacted with a specific spin label and reconstituted into vesicles that were shown to be functional. The relative collision frequency of each spin label with freely diffusing oxygen and membrane-impermeant chromium oxalate was estimated with power saturation EPR (electron paramagnetic resonance) spectroscopy. The results indicate that residues 129 to 131 form a short water-exposed loop, while residues 132 to 142 are membrane-embedded. The oxygen accessibility for positions 131 to 138 varies with a periodicity of 3.6 residues, thereby providing a striking demonstration of an α helix. The orientation of this helical segment with respect to the remainder of the protein was determined.
Intracellular Calcium Release Mediated by Sphingosine Derivatives Generated in Cells
Authors: Ghosh Tarun K. , Bian Junhui , Gill Donald L.
Published: October 2006

Soluble and hydrophobic lipid breakdown products have a variety of important signaling roles in cells. Here sphingoid bases derived in cells from sphingolipid breakdown are shown to have a potent and direct effect in mediating calcium release from intracellular stores. Sphingosine must be enzymically converted within the cell to a product believed to be sphingosine-1-phosphate, which thereafter effects calcium release from a pool including the inositol 1,4,5-trisphosphate-sensitive calcium pool. The sensitivity, molecular specificity, and reversibility of the effect on calcium movements closely parallel sphingoid base-mediated inhibition of protein kinase C. Generation of sphingoid bases in cells may activate a dual signaling pathway involving regulation of calcium and protein kinase C, comparable perhaps to the phosphatidylinositol and calcium signaling pathway.
Diversity of
Conus
Neuropeptides
Authors: Olivera Baldomero M. , Rivier Jean , Clark Craig , Ramilo Cecilia A. , Corpuz Gloria P. , Abogadie Fe C. , Mena E. Edward , Woodward Scott R. , Hillyard David R. , Cruz Lourdes J.
Published: October 2006

Conus
venoms contain a remarkable diversity of pharmacologically active small peptides. Their targets are ion channels and receptors in the neuromuscular system. The venom of
Conus geographus
contains high-affinity peptides that act on voltage-sensitive calcium channels, sodium channels,
N
-methyl-D-aspartate (NMDA) receptors, acetylcholine receptors, and vasopressin receptors; many more peptides with still uncharacterized receptor targets are present in this venom. It now seems that the
Conus
species (approximately 500 in number) will each use a distinctive assortment of peptides and that the pharmacological diversity in
Conus
venoms may be ultimately comparable to that of plant alkaloids or secondary metabolites of microorganisms. The cone snails may generate this diverse spectrum of venom peptides by a "fold-lock-cut" synthetic pathway. These peptides are specific enough to discriminate effectively between closely related receptor subtypes and can be used for structure-function correlations.
Identification of a Sequence in the PEPCK Gene That Mediates a Negative Effect of Insulin on Transcription
Authors: O'Brien Richard M. , Lucas Peter C. , Forest Claude D. , Magnuson Mark A. , Granner Daryl K.
Published: October 2006

Phosphoenolpyruvate carboxykinase (PEPCK) governs the rate-limiting step in gluconeogenesis. Glucocorticoids and adenosine 3′,5′-monophosphate (cAMP) increase PEPCK gene transcription and gluconeogenesis, whereas insulin has the opposite effect. Insulin is dominant, since it prevents cAMP and glucocorticoid-stimulated transcription. Glucocorticoid and cAMP response elements have been located in the PEPCK gene and now a 15-base pair insulin-responsive sequence (IRS) is described. Evidence for a binding activity that recognizes this sequence is presented.
Magmatic Resurgence in Long Valley Caldera, California: Possible Cause of the 1980 Mammoth Lakes Earthquakes
Authors: Savage J. C. , Clark M. M.
Published: October 2006

Changes in elevation between 1975 and October 1980 along a leveling line across the Long Valley caldera indicate a broad (half-width, 15 kilometers) uplift (maximum, 0.25 meter) centered on the old resurgent dome. This uplift is consistent with reinflation of a magma reservoir at a depth of about 10 kilometers. Stresses generated by this magmatic resurgence may have caused the sequence of four magnitude 6 earthquakes near Mammoth Lakes in May 1980.
Increased Activity of Calcium Leak Channels in Myotubes of Duchenne Human and
mdx
Mouse Origin
Authors: Fong Peying , Turner Paul R. , Denetclaw Wilfred F. , Steinhardt Richard A.
Published: October 2006

Elevated free Ca
2+
concentrations found in adult dystrophic muscle fibers result in enhanced protein degradation. Since the difference in concentrations may reflect differences in entry, Ca
2+
leak channels in cultures of normal and Duchenne human myotubes, and normal and
mdx
murine myotubes, have been identified and characterized. The open probability of leak channels is markedly increased in dystrophic myotubes. Other channel properties, such as mean open times, single channel conductance, ion selectivity, and behavior in the presence of pharmacological agents, were similar among myotube types. Compared to the Ca
2+
concentrations in normal human and normal mouse myotubes, intracellular resting free Ca
2+
concentrations ([Ca
2+
]
i
) in myotubes of Duchenne and
mdx
origin were significantly higher at a time when dystrophin is first expressed in normal tissue. Taken together, these findings suggest that the increased open probability of Ca
2+
leak channels contributes to the elevated free intracellular Ca
2+
concentration in Duchenne human and
mdx
mouse myotubes.
Cell Cycle Control of DNA Replication by a Homologue from Human Cells of the p34

cdc2

Protein Kinase
Authors: D'Urso Gennaro , Marraccino Robert L. , Marshak Daniel R. , Roberts James M.
Published: October 2006

The regulation of DNA replication during the eukaryotic cell cycle was studied in a system where cell free replication of simian virus 40 (SV40) DNA was used as a model for chromosome replication. A factor, RF-S, was partially purified from human S phase cells based on its ability to activate DNA replication in extracts from G
1
cells. RF-S contained a human homologue of the
Schizosaccharomyces pombe
p34

cdc2

kinase, and this kinase was necessary for RF-S activity. The limiting step in activation of the p34 kinase at the G
1
to S transition may be its association with a cyclin since addition of cyclin A to a G
1
extract was sufficient to start DNA replication. These observations suggest that the role of p34

cdc2

in controlling the start of DNA synthesis has been conserved in evolution.
Pathfinding by Peripheral Pioneer Neurons in Grasshoppers
Authors: Bentley David , Keshishian Haig
Published: October 2006

Grasshopper neurons accurately project axons across long distances between peripheral structures and the central nervous system. Nerve-trunk pathways followed by these axons are established early in embryogenesis by pioneer neurons. Growth cones from the first pioneers navigate along a chain of cells to the CNS. The placement of these cells may constitute the initial guidance mechanism underlying long-distance pathfinding.
Drug Prevention in Junior High: A Multi-Site Longitudinal Test
Authors: Ellickson Phyllis L. , Bell Robert M.
Published: October 2006

Results from a longitudinal experiment to curb drug use during junior high indicate that education programs based on a social-influence model can prevent or reduce young adolescents' use of cigarettes and marijuana. This multi-site experiment involved the entire seventh-grade cohort of 30 junior high schools drawn from eight urban, suburban, and rural communities in California and Oregon. Implemented between 1984 and 1986, the curriculum's impact was assessed at 3-, 12-, and 15-month follow-ups. The program, which had positive results for both low- and high-risk students, was equally successful in schools with high and low minority enrollment. However, the program did not help previously confirmed smokers and its effects on adolescent drinking were short-lived.
Psychological Responses After Abortion
Authors: Adler Nancy E. , David Henry P. , Major Brenda N. , Roth Susan H. , Russo Nancy F. , Wyatt Gail E.
Published: October 2006

A review of methodologically sound studies of the psychological responses of U.S. women after they obtained legal, nonrestrictive abortions indicates that distress is generally greatest before the abortion and that the incidence of severe negative responses is low. Factors associated with increased risk of negative response are consistent with those reported in research on other stressful life events.
Orchestrating the Human Genome Project
Authors: Cantor Charles R.
Published: October 2006

The Human Genome Project is under way. The Department of Energy and the National Institutes of Health are cooperating effectively to develop organizational structures and scientific priorities that should keep the project on schedule and within its budget.
A Mn
2+
-Dependent Ribozyme
Authors: Dange V. , Van Atta Reuel B. , Hecht Sidney M.
Published: October 2006

An RNA hairpin identical in sequence with the one formed during autocyclization of the 414-nucleotide
Tetrahymena
intervening sequence undergoes strand scission at a specific site in the presence of Mn
2+
. In addition to representing one of the smallest and simplest ribozymes possible, strand scission occurs readily under physiological conditions, is unaffected by the presence of Mg
2+
, and displays salt, pH, and temperature optima of potential use in exploiting Mn
2+
as a regulatory switch in intact cells. The chemistry of strand scission of the RNA hairpin is described, as is the Mn
2+
-dependent solvolysis of a 231-nucleotide RNA transcript containing this structural motif.
Spider Web Protection Through Visual Advertisement: Role of the Stabilimentum
Authors: Eisner Thomas , Nowicki Stephen
Published: October 2006

The conspicuous white silken adornments known as stabilimenta, which are commonly found in the orb webs of some spiders, appear to be protective devices that warn birds of the presence of webs in their flight path. Webs endowed with artificial equivalents of stabilimenta tended to survive intact the early morning period when birds are on the wing; unmarked webs showed a high incidence of destruction.
Adaptation of Fruit Morphology to Dispersal Agents in a Neotropical Forest
Authors: Janson Charles H.
Published: October 2006

Two-thirds of 258 fruit species from Peruvian tropical forest belong to one of two classes: large orange, yellow, brown, or green fruits with a husk; or small red, black, white, blue, purple, or mixed-color fruits without a husk. The characteristics of the two fruit classes match the size, visual ability, and jaw morphology of mammals and birds, respectively, and the animals also prefer to eat one class of fruits. Thus, most plants in this forest seem to be adapted to seed dispersal by either of two distinct broad arrays of animal taxa.
Autotrophic Picoplankton in the Tropical Ocean
Authors: Li W. K. W. , Rao D. V. SUBBA , Harrison W. G. , Smith J. C. , Cullen J. J. , Irwin B. , Platt T.
Published: October 2006

In phytoplankton of the eastern tropical Pacific Ocean from 25 to 90 percent of the biomass (measured as chlorophyll
a
) and 20 to 80 percent of the inorganic carbon fixation were attributable to particles that could pass a screen with a 1-micrometer pore diameter. Evidence is presented that these are indeed autotrophic cells and not cell fragments.
Computed Tomographic Analysis of Meteorite Inclusions
Authors: Arnold J. R. , Testa J. P. , Friedman P. J. , Kambic G. X.
Published: October 2006

The discovery of isotopic anomalies in the calcium- and aluminum-rich inclusions of the Allende meteorite has improved our knowledge of the origin of the solar system. Inability to find more inclusions without destroying the meteorite has hampered further study. By using a fourth-generation computed tomographic scanner with modifications to the software only, the interior of heterogeneous materials such as Allende can be nondestructively probed. The regions of material with high and low atomic numbers are displayed quickly. The object can then be cut to obtain for analysis just the areas of interest.
Recruitment and Population Dynamics of a Coral Reef Fish
Authors: Victor Benjamin C.
Published: October 2006

Daily otolith increments were used to determine the daily pattern of settlement of the bluehead wrasse (
Thalassoma bifasciatum
), a Caribbean coral reef fish. Recruitment occurs in brief and sporadic episodes even though bluehead wrasses spawn every day. Patterns of recruitment do not correspond to patterns of mortality on the reef. The composition of the adult population directly reflects the relative rates of recruitment of juveniles the year before. The population dynamics of this species may therefore be determined by the supply of recruits and not by the supply of space or some other resource on the reef.
Primitive Helium in Diamonds
Authors: Ozima Minoru , Zashu Shigeo
Published: October 2006

Thirteen diamond stones from various unspecified mines in South Africa were analyzed for the isotopic ratio of helium-3 to helium-4. Values of the ratio ranged from less than 10
–7
to (3.2 ± 0.25) × 10
–4
. The latter value is higher than the primordial helium-3/helium-4 ratio in meteorites and close to the ratio for solar-type helium. Such extremely high values may represent primitive helium that evolved very little (that is, showed very little increase in radiogenic helium-4) since the formation of the earth.
Lithium, Compression and High-Pressure Structure
Authors: Olinger Bart , Shaner J. W.
Published: October 2006

Lithium is found to transform from a body-centered cubic (bcc) to a face-centered cubic (fcc) structure at 6.9 gigapascals (69 kilobars) and 296 kelvin. The relative volume of the bcc structured lithium at 6.9 gigapascals is 0.718, and the fcc structure is 0.25 percent denser. The bulk modulus and its pressure derivative for the bcc structure are 11.57 gigapascals and 3.4, and for the fcc structure are 13.1 gigapascals and 2.8. Extrapolation of the bcc-fcc phase boundary and the melting curve indicate a triple point around 15 gigapascals and 500 kelvin.
Dwarf Males in the Teredinidae (Bivalvia, Pholadacea)
Authors: Turner Ruth D. , Yakovlev Yuri
Published: October 2006

Extreme sexual dimorphism in the Bivalvia is rare. The occurrence of dwarf males inZachsiaappears to be the first case in the Teredinidae and the first outside the Leptonacea. FemaleZachsiarelease straight-hinge larvae that develop in the plankton and settle on living rhizomes ofPhyllospadix. Larvae entering mantle pouches of females become males. Evolution of this life history pattern is tied to problems of living in a fragile, patchy habitat—that is, the rhizomes ofPhyllospadix.
Plant Cover and Biomass Response to Clear-Cutting, Site Preparation, and Planting inPinus elliottiiFlatwoods
Authors: Swindel Benee F. , Conde Louis F. , Smith Joel E.
Published: October 2006

Pine plantation management did not initially convert natural forests to monocultures; rather it increased plant species richness and diversity. During a 5-year study of two natural watersheds in Florida that were converted to plantations, woody species diminished, but herbaceous species increased. Number of plant species on permanent transects and plots increased. Diversity of cover, frequency, and biomass did not diminish or else increased after harvest.
Biological Control of Yellow Nutsedge with the Indigenous Rust Fungus
Puccinia canaliculata
Authors: Phatak Sharad C. , Sumner Donald R. , Wells Homer D. , Bell Durham K. , Glaze Norman C.
Published: October 2006

Yellow nutsedge (
Cyperus esculentus
L.) is a serious weed problem in the United States and other countries. An indigenous rust fungus [
Puccinia canaliculata
(Schw.) Lagerh.], pathogenic on yellow nutsedge, was released in early spring as a potential biological control agent. The fungus inhibited nutsedge flowering and new tuber formation. The fungus also dehydrated and killed nutsedge plants. The successful control of yellow nutsedge by a rust epiphytotic under experimental conditions demonstrates the potential use of the rust in an integrated weed management system.
Genetic Mapping of the Ecotropic Murine Leukemia Virus-Inducing Locus of BALB/c Mouse to Chromosome 5
Authors: Kozak Christine A. , Rowe Wallace P.
Published: October 2006

By means of an approach that combined the techniques of somatic cell genetics and Mendelian breeding studies, the inducibility locus, designated
Cv
, for ecotropic murine leukemia virus in BALB/c mice, was mapped to chromosome 5, 23 units from the locus for phosphoglucomutase-1, with gene order
Cv-Pgm-1-Gus
. This low-efficiency inducibility locus is therefore not allelic with the chromosome 7 loci previously described for two other mouse strains with high virus inducibility. These studies provide further evidence that endogenous ecotropic viruses represent viral genomes inserted at different chromosomal sites in the various mouse strains.
A Source of Nonshivering Thermogenesis in Fur Seal Skeletal Muscle
Authors: Grav Hans J. , Blix Arnoldus S.
Published: October 2006

The mitochondria from the subscapular muscle of naturally cold-stressed 10- to 15-year-old northern fur seals (
Callorhinus ursinus
) were loosely coupled upon isolation, whereas the mitochondria from the same muscle of warm-acclimated pups of the same age were tightly coupled. Thus, loose-coupled muscle mitochondria might provide an important vehicle for nonshivering thermogenesis in this species.
Taste-Aversion Conditioning of Crows to Control Predation on Eggs
Authors: Nicolaus Lowell K. , Cassel J. Frank , Carlson Robert B. , Gustavson Carl R.
Published: October 2006

Free-ranging crows (
Corvus brachyrhynchos
) that ate chicken eggs that were painted green and contained a nonlethal toxin subsequently avoided green eggs at various locations, whether or not they contained toxin. The crows also continued to eat unpainted and nontoxic chicken eggs. Illness-induced aversions among predators in nature may be a powerful determiner of the evolution of Batesian mimicry and, in human hands, serve as a practical tool for wildlife ecologists.
Female Moorhens Compete for Small Fat Males
Authors: Petrie Marion
Published: October 2006

Female moorhens in flocks competed with each other to obtain mates. The heaviest females won most of the agonistic encounters, and these females paired with males that had large fat reserves. Fat males tended to be small, possibly because of energetic constraints on birds of large body size. Females paired with fat males initiated more nesting attempts in a season.
Soot Carbon and Excess Fine Potassium: Long-Range Transport of Combustion-Derived Aerosols
Authors: Andreae Meinrat O.
Published: October 2006

During a cruise from Hamburg to Montevideo, aerosol samples representing air masses from Europe, the Sahara, tropical Africa, South America, and open oceanic regions were collected. They showed significant amounts of soot carbon over large areas of the remote Atlantic, often similar to concentrations in rural continental areas. Back-trajectories and the ratios of soot carbon to total fine (less than 1.7 micrometers in diameter) carbon and of excess fine potassium (the portion not attributable to soil dust or sea salt) to soot carbon indicate that biomass burning in tropical regions is an important source of soot carbon to the world atmosphere. The ratio of excess potassium to soot carbon in the fine fraction of aerosols is proposed as an indicator of the relative contributions of biomass and fossil-fuel burning to soot carbon aerosols. The ratio of soot carbon to fine carbon suggests that most of the particulate organic carbon over the Atlantic is of continental origin.
The Rotation of Spiral Galaxies
Authors: Rubin Vera C.
Published: October 2006

There is accumulating evidence that as much as 90 percent of the mass of the universe is nonluminous and is clumped, halo-like, around individual galaxies. The gravitational force of this dark matter is presumed to be responsible for the high rotational velocities of stars and gas in the disks of spiral galaxies. At present, the form of the dark matter is unknown. Possible candidates span a range in mass of 10
70
, from non-zero-mass neutrinos to massive black holes.
Titan: Discovery of Carbon Monoxide in Its Atmosphere
Authors: Lutz Barry L. , de Bergh Catherine , Owen Tobias
Published: October 2006

The 3-0 rotation-vibration band of carbon monoxide in the near-infrared spectrum of Titan has been identified, and a reflecting layer model mixing ratio of carbon monoxide to molecular nitrogen of 6 × 10
–5
has been determined. This result supports the probable detection of carbon dioxide by Samuelson and his co-workers and strengthens possible analogies between the atmosphere of Titan and conditions on primitive Earth.
Reversible Loss of Gravitropic Sensitivity in Maize Roots After Tip Application of Calcium Chelators
Authors: Lee June S. , Mulkey Timothy J. , Evans Michael L.
Published: October 2006

The application of calcium chelating agents (EDTA or EGTA) to the tips of maize roots caused a loss of gravitropic sensitivity. When the chelator was replaced with calcium chloride, gravitropic sensitivity was restored. Asymmetric application of calcium chloride near the tip of a vertical root caused curvature toward the calcium source. When the calcium was applied to the upper surface of the tip of a root oriented horizontally, the root curved upward even though control roots exhibited strong downward curvature. Application of calcium chloride to the tips of decapped roots, which are known to be gravitropically insensitive, did not restore gravitropic sensitivity. However, asymmetric application of calcium chloride near the tips of decapped roots caused curvature toward the calcium source. Calcium may play a key role in linking gravity detection to gravitropic curvature in roots.
Fragments of the HIV-1 Tat Protein Specifically Biand TAR RNA
Authors: Weeks Kevin M. , Ampe Christophe , Schultz Steve C. , Steitz Thomas A. , Crothers Donald M.
Published: October 2006

Proteolytically produced carboxyl-terminal fragments of the human immunodeficiency virus type-1 (HIV-1) Tat protein that include a conserved region rich in arginine and lysine bind specifically to transactivation response RNA sequences (TAR). A chemically synthesized 14-residue peptide spanning the basic subdomain also recognizes TAR, identifying this subdomain as central for RNA interaction. TAR RNA forms a stable hairpin that includes a six-residue loop, a trinucleotide pyrimidine bulge, and extensive duplex structure. Competition and interference experiments show that the Tat-derived fragments bind to double-stranded RNA and interact specifically at the pyrimidine bulge and adjacent duplex of TAR.
Macroevolutionary Trends: New Perspectives on the Roles of Adaptation and Incidental Effect
Authors: Vrba Elisabeth S.
Published: October 2006

Trends, long-term directional tendencies in evolution, are traditionally interpreted as selected for and adaptive. Alternatively, trends may be unselected effects of characters and processes within species: the effect hypothesis. Thus adaptations of organisms, varying among species, were selected for immediate fitness, but they may also incidentally determine different speciation and extinction rates and trends.
Tobermorites: A New Family of Cation Exchangers
Authors: Komarneni Sridhar , Roy Della M.
Published: October 2006

Tobermorites have cation-exchange and selectivity properties intermediate between those of clay minerals and zeolites. Aluminum-substituted tobermorites in particular show high selectivity for cesium. This new group of cation exchangers may find applications in catalysis and in nuclear and hazardous waste disposal.
Dimethyl Sulfide in the Surface Ocean and the Marine Atmosphere: A Global View
Authors: Andreae Meinrat O. , Raemdonck Hans
Published: October 2006

Dimethyl sulfide (DMS) has been identified as the major volatile sulfur compound in 628 samples of surface seawater representing most of the major oceanic ecozones. In at least three respects, its vertical distribution, its local patchiness, and its distribution in oceanic ecozones, the concentration of DMS in the sea exhibits a pattern similar to that of primary production. The global weighted-average concentration of DMS in surface seawater is 102 nanograms of sulfur (DMS) per liter, corresponding to a global sea-to-air flux of 39 × 10
12
grams of sulfur per year. When the biogenic sulfur contributions from the land surface are added, the biogenic sulfur gas flux is approximately equal to the anthropogenic flux of sulfur dioxide. The DMS concentration in air over the equatorial Pacific varies diurnally between 120 and 200 nanograms of sulfur (DMS) per cubic meter, in agreement with the predictions of photochemical models. The estimated source flux of DMS from the oceans to the marine atmosphere is in agreement with independently obtained estimates of the removal fluxes of DMS and its oxidation products from the atmosphere.
Isolation of Halimedatrial: Chemical Defense Adaptation in the Calcareous Reef-Building AlgaHalimeda
Authors: Paul Valerie J. , Fenical William
Published: October 2006

Halimedatrial, a structurally unprecedented diterpenoid trialdehyde, has been identified as the major secondary metabolite in six species of the calcareous reef-building algaHalimeda. In laboratory bioassays, halimedatrial is toxic toward reef fishes, significantly reduces feeding in herbivorous fishes, and has cytotoxic and antimicrobial activities. The widespread occurrence of halimedatrial and its potent biological activities suggest that this metabolite represents a chemical defense adaptation in this pantropical marine alga.
Waves and Turbulence in a Tokamak Fusion Plasma
Authors: Surko C. M. , Slusher R. E.
Published: October 2006

The tokamak is a prototype fusion device in which a toroidal magnetic field is used to confine a hot plasma. Coherent waves, excited near the plasma edge, can be used to transport energy into the plasma in order to heat it to the temperatures required for thermonuclear fusion. In addition, tokamak plasmas are known to exhibit high levels of turbulent density fluctuations, which can transport particles and energy out of the plasma. Recently, experiments have been conducted to elucidate the nature of both the coherent waves and the turbulence. The experiments provide insight into a broad range of interesting linear and nonlinear plasma phenomena and into many of the processes that determine such practical things as plasma heating and confinement.
Single Gene Mutations in Tomato Plants Regenerated from Tissue Culture
Authors: Evans David A. , Sharp William R.
Published: October 2006

Plants were regenerated from cultured leaf explants of an inbred variety of
Lycopersicon esculentum
. Seeds were collected from the regenerated plants and sown in the greenhouse. The resultant plants were then evaluated in the field. Several monogenic mutations segregated in the progeny of regenerated plants. The recovery of single gene mutations is evidence that plant tissue culture can be mutagenic. Complementation tests revealed that one mutation was located on the long arm of chromosome 10.
On Seeing Reddish Green and Yellowish Blue
Authors: Crane Hewitt D. , Piantanida Thomas P.
Published: October 2006

Four color names—red, yellow, green, and blue—can be used singly or combined in pairs to describe all other colors. Orange, for example, can be described as a reddish yellow, cyan as a bluish green, and purple as a reddish blue. Some dyadic color names (such as reddish green and bluish yellow) describe colors that are not normally realizable. By stabilizing the retinal image of the boundary between a pair of red and green stripes (or a pair of yellow and blue stripes) but not their outer edges, however, the entire region can be perceived simultaneously as both red and green (or yellow and blue).
Allometry and Reorganization in Horse Skull Proportions
Authors: Radinsky Leonard
Published: October 2006

Allometric analysis of skull proportions in 25 species of fossil equids indicates that both scaling effects (allometry) and reorganization were factors in the evolutionary transformation of horse skulls. A relatively longer preorbital portion of the skull resulted from the ventral and forward displacement of the tooth row relative to the jaw joint and the orbit when high-crowned teeth evolved. Correlated with the increased distance between jaw joint and tooth row is an increase in the relative size of the attachment areas of masseter and internal pterygoid muscles.
Sexual Dimorphism: The Horns of African Antelopes
Authors: Packer Craig
Published: October 2006

Comparisons of the horns of males and females across genera of African antelopes indicate that male horns are better adapted for clashing or pushing against another pair of horns during intrasexual combat. The horns of females are relatively more specialized as stabbing weapons. Horns in females are found in only half the genera and in those genera where females have horns, the genera are heavier than genera with hornless females.
Rangeland Productivity and Exploitation in the Sahel
Authors: Breman H. , de Wit C. T.
Published: October 2006

Results of a Malian-Dutch research project on the Sahelian pastures and their utilization suggest reasons why some efforts to develop traditional livestock farming in this area have been unsuccessful. Failure to appreciate the effects of low soil fertility as well as low rainfall on pasture production has resulted in underestimation of the productivity of the nomadic and seminomadic livestock farming system and overestimation of the possibilities for increasing production by better management and by modernization.
Chromosomal Region of the Cystic Fibrosis Gene in Yeast Artificial Chromosomes: A Model for Human Genome Mapping
Authors: Green Eric D. , Olson Maynard V.
Published: October 2006

A general strategy for cloning and mapping large regions of human DNA with yeast artificial chromosomes (YAC's) is described. It relies on the use of the polymerase chain reaction to detect DNA landmarks called sequence-tagged sites (STS's) within YAC clones. The method was applied to the region of human chromosome 7 containing the cystic fibrosis (CF) gene. Thirty YAC clones from this region were analyzed, and a contig map that spans more than 1,500,000 base pairs was assembled. Individual YAC's as large as 790 kilobase pairs and containing the entire CF gene were constructed in vivo by meiotic recombination in yeast between pairs of overlapping YAC's.
The Primate Hippocampal Formation: Evidence for a Time-Limited Role in Memory Storage
Authors: Zola-Morgan Stuart M. , Squire Larry R.
Published: October 2006

Clinical and experimental studies have shown that the hippocampal formation and related structures in the medial temporal lobe are important for learning and memory. Retrograde amnesia was studied prospectively in monkeys to understand the contribution of the hippocampal formation to memory function. Monkeys learned to discriminate 100 pairs of objects beginning 16, 12, 8, 4, and 2 weeks before the hippocampal formation was removed (20 different pairs at each time period). Two weeks after surgery, memory was assessed by presenting each of the 100 object pairs again for a single-choice trial. Normal monkeys exhibited forgetting; that is, they remembered recently learned objects better than objects learned many weeks earlier. Monkeys with hippocampal damage were severely impaired at remembering recently learned objects. In addition, they remembered objects learned long ago as well as normal monkeys did and significantly better than they remembered objects learned recently. These results show that the hippocampal formation is required for memory storage for only a limited period of time after learning. As time passes, its role in memory diminishes, and a more permanent memory gradually develops independently of the hippocampal formation, probably in neocortex.
Mineralogic Information from a New Airborne Thermal Infrared Multispectral Scanner
Authors: Kahle Anne B. , Goetz Alexander F. H.
Published: October 2006

A new six-channel aircraft multispectral scanner has been developed to exploit mineral signature information at wavelengths between 8 and 12 micrometers. Preliminary results show that igneous rock units can be identified from their free silica content, and that carbonate as well as clay-bearing units are readily separable on the digitally processed images.
Oceanographic Events During El Niño
Authors: Cane Mark A.
Published: October 2006

El Niño events, the most spectacular instances of interannual variability in the ocean, have profound consequences for climate and the ocean ecosystem. The 1982-1983 El Niño is perhaps the strongest in this century. El Niño events usually have followed a predictable pattern, but the recent event differs markedly. The physical oceanography of this El Niño is described and compared with that of earlier events.
Theodore von Kármán and Applied Mathematics in America
Authors: Greenberg John L. , Goodstein Judith R.
Published: October 2006

The emergence of applied mathematics as a discipline in the United States is traditionally associated with World War II. Hungarian-born Theodore von Kármán was among those who had waged a long and vigorous campaign well before the war to make applied mathematics respectable to engineers and mathematicians. While advocating the use of mathematics and physics to solve applied problems, he challenged the prevailing philosophy of engineering programs, locked horns with recalcitrant journal editors, and generally encountered the obstacles to building a discipline that cuts across conventional boundaries.
Late Miocene Vegetational and Climatic Variations Inferred from a Pollen Record in Northwest Wyoming
Authors: Barnosky Cathy W.
Published: October 2006

A pollen stratigraphy from late Miocene lacustrine strata (Teewinot Formation) in Jackson Hole, Wyoming, permits analysis of vegetation and climate history over a time interval of less than 300,000 years with better temporal resolution of data than has been reported from terrestrial Tertiary deposits. The flora was essentially modern, and six successive pollen assemblages indicate alternating dry and wet conditions. The frequency of climatic change in this record is similar to that inferred from marine isotope records for both late Tertiary and Quaternary time.
Dynamics of Molecular Motion at Single-Crystal Surfaces
Authors: Tully J. C. , Cardillo M. J.
Published: October 2006

Dramatic advances in our understanding of the motion of individual atoms and molecules at single-crystal surfaces have been made within the past 5 years. Recent experimental and theoretical studies of the interaction of nitric oxide with metal surfaces illustrate the depth of understanding now obtainable. General principles, applicable to a broader range of molecule-surface encounters, have begun to emerge out of the systematic and in-depth analyses of these and related studies.
Male Crickets Feed Females to Ensure Complete Sperm Transfer
Authors: Sakaluk Scott K.
Published: October 2006

The spermatophore transferred by the male decorated cricket
Gryllodes supplicans
to the female during copulation includes a large gelatinous portion (spermatophylax), which the female removes and feeds on immediately after mating. Females usually removed and ate the smaller sperm-containing portion (ampulla) within 1 to 7 minutes after fully consuming or losing the spermatophylax. Complete sperm transfer requires that the ampulla remain attached for a minimum of 50 minutes; this corresponds to the average time at which females actually removed ampullae, 52.0 ± 2.2 minutes after mating. These results indicate that nuptial feeding of the female cricket functions to deter females from removing the sperm ampulla before sperm transfer is complete.
Incompatibility Between the Dimorphic Flowers of
Collomia grandiflora
, a Cleistogamous Species
Authors: Lord E. M. , Eckard K. J.
Published: October 2006

The cleistogamous species
Collomia grandiflora
produces dimorphic cross-incompatible flowers on a single plant. The open or chasmogamous flower has smaller, flask-shaped stigmatic papillae, larger pollen grains, longer styles, and faster pollen tube growth rates down the style than the closed or cleistogamous flower. In intermorph crosses, pollen tube growth rates are greatly decreased and fertilization does not occur.
People with Absolute Pitch Process Tones Without Producing a P300
Authors: Klein Mark , Coles Michael G. H. , Donchin Emanuel
Published: October 2006

The P300 is a positive-going component of the event-related potential. In subjects with absolute, or "perfect," pitch, the P300 elicited by the less frequent of two auditory probes is small or absent. In these subjects, visual probes elicit a normal P300. These results support the view of P300 as a manifestation of the updating of working memory.
DNA Looping and Unlooping by AraC Protein
Authors: Lobell Robert B. , Schleif Robert F.
Published: October 2006

Expression of the L-arabinose BAD operon in
Escherichia coli
is regulated by AraC protein which acts both positively in the presence of arabinose to induce transcription and negatively in the absence of arabinose to repress transcription. The repression of the
araBAD
promoter is mediated by DNA looping between AraC protein bound at two sites near the promoter separated by 210 base pairs,
araI
and
araO
2
. In vivo and in vitro experiments presented here show that an AraC dimer, with binding to half of
araI
and to
araO
2
, maintains the repressed state of the operon. The addition of arabinose, which induces the operon, breaks the loop, and shifts the interactions from the distal
araO
2
site to the previously unoccupied half of the
araI
site. The conversion between the two states does not require additional binding of AraC protein and appears to be driven largely by properties of the protein rather than being specified by the slightly different DNA sequences of the binding sites. Slight reorientation of the subunits of AraC could specify looping or unlooping by the protein. Such a mechanism could account for regulation of DNA looping in other systems.
Underexpression of β Cell High
K
m
Glucose Transporters in Noninsulin-Dependent Diabetes
Authors: Johnson John H. , Ogawa Atsushi , Chen Ling , Orci Lelio , Newgard Christopher B. , Alam Tausif , Unger Roger H.
Published: October 2006

The role of defective glucose transport in the pathogenesis of noninsulin-dependent diabetes (NIDDM) was examined in Zucker diabetic fatty rats, a model of NIDDM. As in human NIDDM, insulin secretion was unresponsive to 20 mM glucose. Uptake of 3-
O
-methylglucose by islet cells was less than 19% of controls. The β cell glucose transporter (GLUT-2) immunoreactivity and amount of GLUT-2 messenger RNA were profoundly reduced. Whenever fewer than 60% of β cells were GLUT-2-positive, the response to glucose was absent and hyperglycemia exceeded 11 mM plasma glucose. We conclude that in NIDDM underexpression of GLUT-2 messenger RNA lowers high
K
m
glucose transport in β cells, and thereby impairs glucose-stimulated insulin secretion and prevents correction of hyperglycemia.
Detection of
bcr
-
abl
Fusion in Chronic Myelogeneous Leukemia by in Situ Hybridization
Authors: Tkachuk D. C. , Westbrook C. A. , Andreeff M. , Donlon T. A. , Cleary M. L. , Suryanarayan K. , Homge M. , Redner A. , Gray J. , Pinkel D.
Published: October 2006

Chronic myelogeneous leukemia (CML) is genetically characterized by fusion of the
bcr
and
abl
genes on chromosomes 22 and 9, respectively. In most cases, the fusion involves a reciprocal translocation t(9;22)(q34;q11), which produces the cytogenetically distinctive Philadelphia chromosome (Ph
1
). Fusion can be detected by Southern (DNA) analysis or by in vitro amplification of the messenger RNA from the fusion gene with polymerase chain reaction (PCR). These techniques are sensitive but cannot be applied to single cells. Two-color fluorescence in situ hybridization (FISH) was used with probes from portions of the
bcr
and
abl
genes to detect the
bcr
-
abl
fusion in individual blood and bone marrow cells from six patients. The fusion event was detected in all samples analyzed, of which three were cytogenetically Ph
1
-negative. One of the Ph
1
-negative samples was also PCR-negative. This approach is fast and sensitive, and provides potential for determining the frequency of the abnormality in different cell lineages.