bluuebunny/crossref_metadata_2025 huggingface dataset:
Continental Breakup by a Leaky Transform: The Gulf of Elat (Aqaba)
Authors: Ben-Avraham Zvi , Garfunkel Zvi , Almagor Gideon , Hall John K.
Published: October 2006

The floor of the Gulf of Elat consists of five distinct deeps. Its structure is controlled by faulting which has produced rhomb-shaped grabens. The gulf is a newly formed plate boundary between Arabia and Sinai.
A Unique Solar Marking Construct
Authors: Sofaer Anna , Zinser Volker , Sinclair Rolf M.
Published: October 2006

An assembly of stone slabs on an isolated butte in New Mexico collimates sunlight onto spiral petroglyphs carved on a cliff face. The light illuminates the spirals in a changing pattern throughout the year and marks the solstices and equinoxes with particular images. The assembly can also be used to observe lunar phenomena. It is unique in archeoastronomy in utilizing the changing height of the midday sun throughout the year rather than its rising and setting points. The construct appears to be the result of deliberate work of the Anasazi Indians, the builders of the great pueblos in the area.
Fate of Fossil Fuel Carbon Dioxide and the Global Carbon Budget
Authors: Broecker W. S. , Takahashi T. , Simpson H. J. , Peng T. -H.
Published: October 2006

The fate of fossil fuel carbon dioxide released into the atmosphere depends on the exchange rates of carbon between the atmosphere and three major carbon reservoirs, namely, the oceans, shallow-water sediments, and the terrestrial biosphere. Various assumptions and models used to estimate the global carbon budget for the last 20 years are reviewed and evaluated. Several versions of recent atmosphere-ocean models appear to give reliable and mutually consistent estimates for carbon dioxide uptake by the oceans. On the other hand, there is no compelling evidence which establishes that the terrestrial biomass has decreased at a rate comparable to that of fossil fuel combustion over the last two decades, as has been recently claimed.
Gasohol: Does It or Doesn't It Produce Positive Net Energy?
Authors: Chambers R. S. , Herendeen R. A. , Joyce J. J. , Penner P. S.
Published: October 2006

A detailed analysis of energy inputs and outputs is performed on grain-based gasohol (10 percent grain-based ethanol, 90 percent gasoline). Existing differences of opinion on the energy balance derive mainly from variations in interpretation which are several examples of inherent methodological problems in energy analysis. The result is strongly dependent on assumptions about use of crop residues for fuel and the miles-per-gallon rating of gasohol. In terms of total nonrenewable energy, gasohol is close to the energy break-even point. On the other hand, in terms of petroleum or petroleum-substitutable energy, gasohol is an unambiguous energy producer, since most energy inputs to the process can be supplied by nonpetroleum sources such as coal.
The Galilean Satellites and Jupiter: Voyager 2 Imaging Science Results
Authors: Smith Bradford A. , Soderblom Laurence A. , Beebe Reta , Boyce Joseph , Briggs Geoffrey , Carr Michael , Collins Stewart A. , Cook Allan F. , Danielson G. Edward , Davies Merton E. , Hunt Garry E. , Ingersoll Andrew , Johnson Torrence V. , Masursky Harold , McCauley John , Morrison David , Owen Tobias , Sagan Carl , Shoemaker Eugene M. , Strom Robert , Suomi Verner E. , Veverka Joseph
Published: October 2006

Voyager 2, during its encounter with the Jupiter system, provided images that both complement and supplement in important ways the Voyager 1 images. While many changes have been observed in Jupiter's visual appearance, few, yet significant, changes have been detected in the principal atmospheric currents. Jupiter's ring system is strongly forward scattering at visual wavelengths and consists of a narrow annulus of highest particle density, within which is a broader region in which the density is lower. On Io, changes are observed in eruptive activity, plume structure, and surface albedo patterns. Europa's surface retains little or no record of intense meteorite bombardment, but does reveal a complex and, as yet, little-understood system of overlapping bright and dark linear features. Ganymede is found to have at least one unit of heavily cratered terrain on a surface that otherwise suggests widespread tectonism. Except for two large ringed basins, Callisto's entire surface is heavily cratered.
Anthropogenic Albedo Changes and the Earth's Climate
Authors: Sagan Carl , Toon Owen B. , Pollack James B.
Published: October 2006

The human species has been altering the environment over large geographic areas since the domestication of fire, plants, and animals. The progression from hunter to farmer to technologist has increased the variety and pace more than the geographic extent of human impact on the environment. A number of regions of the earth have experienced significant climatic changes closely related in time to anthropogenic environmental changes. Plausible physical models suggest a causal connection. The magnitudes of probable anthropogenic global albedo changes over the past millennia (and particularly over the past 25 years) are estimated. The results suggest that humans have made substantial contributions to global climate changes during the past several millennia, and perhaps over the past million years; further such changes are now under way.
Fish Culture in the United States
Authors: Lovell Richard T.
Published: October 2006

The culture of channel catfish, trout, and crayfish is a well-established, profitable enterprise, but aquaculture provides only a fraction of the protein consumed by Americans, who prefer red meat. This situation could change, since pond-raised fish require less energy for protein synthesis than land animals, the supply of ocean food fish no longer appears inexhaustible, and fish culture can utilize resources unsuitable for other agriculture.
Visual Instruction of the Neural Map of Auditory Space in the Developing Optic Tectum
Authors: Knudsen Eric I. , Brainard Michael S.
Published: October 2006

Neural maps of visual and auditory space are aligned in the adult optic tectum. In barn owls, this alignment of sensory maps was found to be controlled during ontogeny by visual instruction of the auditory spatial tuning of neurons. Large adaptive changes in auditory spatial tuning were induced by raising owls with displacing prisms mounted in spectacle frames in front of the eyes; neurons became tuned to sound source locations corresponding to their optically displaced, rather than their normal, visual receptive field locations. The results demonstrate that visual experience during development calibrates the tectal auditory space map in a site-specific manner, dictating its topography and alignment with the visual space map.
Absence of Adenosine Deaminase Activity in a Mammalian Cell Line Transformed by Rous Sarcoma Virus
Authors: Shipman Charles , Drach John C.
Published: October 2006

No detectable adenosine deaminase activity was found in whole cells or 105,000g cytosol preparations of B-mix K-44/6 cells when either [
3
H]adenosine or [
3
H]arabinosyladenine was used as substrate. When grown in tissue culture medium supplemented with horse serum these cells provide a deaminase-free system not requiring the use of an adenosine deaminase inhibitor.
Adrenocorticotropin in Rat Brain: Immunocytochemical Localization in Cells and Axons
Authors: Watson Stanley J. , Richard Charles W. , Barchas Jack D.
Published: October 2006

By means of antiserum (purified by affinity chromatography) directed against adrenocorticotropin (ACTH) 11-24, cell bodies and beaded axons were visualized in rat brain. The ACTH-like immunoreactivity (ACTH-LI) was primarily located in the hypothalamus (cells and axons). Fibers were scattered throughout thalamus, amygdala, periaqueductal gray area, and reticular formation. There was no change in the distribution of ACTH-LI in rats that had been subjected to hypophysectomy. This distribution of ACTH-LI parallels that of β-lipotropin and is altered by specific lesions in a similar fashion. The presence of ACTH-LI in cells and beaded axons in brain raises the possibility that it is a neuroregulator functioning as a neurotransmitter, neuromodulator, or neurohormone.
Vertical Distribution and Isotopic Composition of Living Planktonic Foraminifera in the Western North Atlantic
Authors: Fairbanks Richard G. , Wiebe Peter H. , Bé Allan W. H.
Published: October 2006

Thirteen species of planktonic foraminifera collected with vertically stratified zooplankton tows in the slope water, Gulf Stream cold core ring, and northern Sargasso Sea show significant differences in their vertical distributions in the upper 200 meters of these different hydrographic regimes. Gulf Stream cold core rings may be responsible for a southern displacement of the faunal boundary associated with the Gulf Stream when reconstructed from the deep-sea sediment record. Oxygen isotope analyses of seven species reveal that nonspinose species (algal symbiont-barren) apparently calcify in oxygen isotope equilibrium, whereas spinose species usually calcify out of oxygen isotope equilibrium by approximately –0.3 to –0.4 per mil in δ
18
O values. The isotope data indicate that foraminifera shells calcify in depth zones that are significantly narrower than the overall vertical distribution of a species would imply.
The Agulhas Current During the Late Pleistocene: Analysis of Modern Faunal Analogs
Authors: Hutson William H.
Published: October 2006

Analysis of micropaleontologic evidence in a deep-sea core in the southwest Indian Ocean indicates that the Agulhas Current was not a dominant feature of this region during glacial intervals. Interpretation of the fossil record, based on the analysis of modern faunal analogs, indicates that during glacial intervals the Agulhas Current was not the strong, year-round current that it is today. Evidence shows that during summer months a weak tropical current was present. During winter months the current was replaced by cool, high-salinity waters. This interpretation suggests that seasonal changes in circulation may have been more pronounced in the southwest Indian Ocean during glacial intervals than today.
Saturnian Trapped Radiation and Its Absorption by Satellites and Rings: The First Results from Pioneer 11
Authors: Simpson J. A. , Bastian T. S. , Chenette D. L. , Lentz G. A. , McKibben R. B. , Pyle K. R. , Tuzzolino A. J.
Published: October 2006

Electrons and protons accelerated and trapped in a Saturnian magnetic field have been found by the University of Chicago experiments on Pioneer 11 within 20 Saturn radii (
R
s
) of the planet. In the innermost regions, strong absorption effects due to satellites and ring material were observed, and from ∼ 4
R
s
inwards to the outer edge of the A ring at 2.30
R
s
(where the radiation is absorbed), the intensity distributions of protons (≥ 0.5 million electron volts) and electrons (2 to 20 million electron volts) were axially symmetric, consistent with a centered dipole aligned with the planetary rotation axis. The maximum fluxes observed for protons (> 35 million electron volts and for electrons > 3.4 million electron volts) were 3 x 10
4
and 3 x 10
6
per square centimeter per second, respectively. Absorption of radiation by Mimas provides a means of estimating the radial diffusion coefficient for charged particle transport. However, the rapid flux increases observed between absorption features raise new questions concerning the physics of charged particle transport and acceleration. An absorption feature near 2.5
R
s
has led to the discovery of a previously unknown satellite with a diameter of ≳ 200 kilometers, semimajor axis of 2.51
R
s
, and eccentricity of 0.013. Radiation absorption features that suggest a nonuniform distribution of matter around Saturn have also been found from 2.34 to 2.36
R
s
, near the position of the F ring discovered by the Pioneer imaging experiment. Beneath the A, B, and C rings we continued to observe a low flux of high-energy electrons. We conclude that the inner Saturn magnetosphere, because of its near-axial symmetry and the many discrete radiation absorption regions, offers a unique opportunity to study the acceleration and transport of charged particles in a planetary magnetic field.
Environmental Applications of Magnetic Measurements
Authors: Thompson R. , Stober J. C. , Turner G. M. , Oldfield F. , Bloemendal J. , Dearing J. A. , Rummery T. A.
Published: October 2006

A wide range of examples of the application of magnetic measurements to environmental studies illustrate the advantages of magnetic techniques over conventional methods. Magnetic measurements, in both the field and the laboratory, are particularly useful for reconnaissance work because of their speed and flexibility, Quantification as well as simple diagnosis of the transformation and movement of magnetic minerals within and between the atmosphere, lithosphere, and hydrosphere is practical. Techniques of investigating intrinsic and mineral magnetic properties, in addition to paleomagnetic remanence, are described in subjects as diverse as meteorology, hydrology, sedimentology, geophysics, and ecology.
Lipid Barrier to Water Exchange in Reptile Epidermis
Authors: Roberts Johnna B. , Lillywhite Harvey B.
Published: October 2006

Extraction of lipids from the shed epidermis of the terrestrial snake
Elaphe obsoleta obsoleta
increases cutaneous water loss in vitro as much as 15-fold. Partial denaturation of epidermal keratin without lipid extraction increases cutaneous water loss only twofold. Histological observations and thin-layer and gas-liquid chromatography of the lipid extracts indicate a complex mixture of polar and neutral lipids predominantly in the mesos layer of the cornified epidermis. Comparative measurements of cutaneous water loss in other species of snakes and a lizard show that permeabilities differ naturally but are essentially identical after lipid extraction. These findings establish the importance of lipids in the permeability barrier of reptilian skin and suggest that keratin or scale morphology are of nominal importance in limiting water exchange.
Serotonin and Octopamine Produce Opposite Postures in Lobsters
Authors: Livingstone Margaret S. , Harris-Warrick Ronald M. , Kravitz Edward A.
Published: October 2006

Serotonin and octopamine, injected into the circulation of freely moving lobsters and crayfish, produce opposite behavioral effects. Octopamine injection produces sustained extension of the limbs and abdomen; serotonin injection produces sustained flexion. Neurophysiological analyses show that these postures can be accounted for by opposing, coordinated effects of these amines on patterns of motoneuron activity recorded from the ventral nerve cord.
Extraterrestrial Cause for the Cretaceous-Tertiary Extinction
Authors: Alvarez Luis W. , Alvarez Walter , Asaro Frank , Michel Helen V.
Published: October 2006

Platinum metals are depleted in the earth's crust relative to their cosmic abundance; concentrations of these elements in deep-sea sediments may thus indicate influxes of extraterrestrial material. Deep-sea limestones exposed in Italy, Denmark, and New Zealand show iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given to indicate that this iridium is of extraterrestrial origin, but did not come from a nearby supernova. A hypothesis is suggested which accounts for the extinctions and the iridium observations. Impact of a large earth-crossing asteroid would inject about 60 times the object's mass into the atmosphere as pulverized rock; a fraction of this dust would stay in the stratosphere for several years and be distributed worldwide. The resulting darkness would suppress photosynthesis, and the expected biological consequences match quite closely the extinctions observed in the paleontological record. One prediction of this hypothesis has been verified: the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the Cretaceous and Tertiary limestones, which are chemically similar to each other. Four different independent estimates of the diameter of the asteroid give values that lie in the range 10 ± 4 kilometers.
Locomotion: The Cost of Gastropod Crawling
Authors: Denny Mark
Published: October 2006

The power of locomotion of a terrestrial slug rises linearly with crawling speed. The metabolic cost of movement is 904 joules per kilogram per meter, considerably more than that reported for other forms of locomotion. This high cost is primarily attributable to the production of the pedal mucus by which the slug adheres to the substratum.
Sensors, Controls, and Man-Machine Interface for Advanced Teleoperation
Authors: Bejczy Antal K.
Published: October 2006

Some advances have been made in teleoperator technology through the introduction of various sensors, computers, automation, and new man-machine interface devices and techniques for remote manipulator control. The development of dexterous articulated mechanisms, smart sensors, flexible computer controls, intelligent man-machine interfaces, and innovative system designs for advanced teleoperation is, however, far from complete, and poses many interdisciplinary challenges. This article summarizes the state of the art, gives a brief outline of the basic problems, and presents the results of teleoperator research and development at the Jet Propulsion Laboratory.
Commissural Transmission: Maturational Changes in Humans
Authors: Salamy A.
Published: October 2006

Latency differences between ipsilateral and contralateral somatosensory evoked potentials show maturational trends in keeping with the myelogenic timetable and development of the corpus callosum. The distribution and modality-specific projection of early ipsilateral activity suggests an origin in the contralateral posterior-parietal area.
Enzyme-Linked Immunosorbent Assay for Identification of Rotaviruses from Different Animal Species
Authors: Yolken Robert H. , Barbour Barbara , Wyatt Richard G. , Kalica Anthony R. , Kapikian Albert Z. , Chanock Robert M.
Published: October 2006

Rotaviruses cause gastroenteritis in man and a wide variety of animal species. They cross-react in many immunologic tests and have a similar appearance by electron microscopy, making differentiation among them difficult. Rotaviruses derived from different host species were distinguished by postinfection serum blocking virus activity in an enzyme-linked immunosorbent assay (ELISA). Thirty-three rotavirus isolates from children living in three different parts of the world could not be differentiated by this technique, but they were distinct from four strains recovered from calves, and a series of strains isolated from piglets, foals, monkeys, and infant mice. The four bovine strains were similar, but they could be differentiated from the other animal strains, each of which exhibited a distinct pattern when tested by the ELISA blocking technique.
Oscillatory Zoning in Plagioclase Feldspar
Authors: Haase C. S. , Chadam J. , Feinn D. , Ortoleva P.
Published: October 2006

A kinetic mathematical model of crystal growth from the melt is used to describe quantitatively the phenomenon of oscillatory zoning in plagioclase feldspar. In this model, the functional dependence of crystal growth rate on both melt and crystal surface composition and the transport of material within the melt are explicitly considered. Oscillatory zoning is found to develop for a wide variety of such functional dependence and to be sensitive to the initial composition of the melt.
IDRC's Approach to Science and Technology for Development
Authors: Hibler Michelle
Published: October 2006

Canada's International Development Research Centre (IDRC) is an independent public corporation established to aid scientific research in developing countries. In supporting 849 projects in 100 countries, it has earned an enviable international reputation and has been used as a model for other aid agencies. Now entering its tenth year, IDRC is reaffirming its policies of responsiveness to the stated needs of developing countries and of strengthening their scientific and technological capabilities. It also seeks to encourage the application of Canadian R & D expertise to the solution of Third World problems.
Associative Behavioral Modification in
Hermissenda
: Cellular Correlates
Authors: Crow Terry J. , Alkon Daniel L.
Published: October 2006

Three days of training consisting of trials of light paired with rotation produces a long-term modification of photopositive behavior in
Hermissenda crassicornis
. The behavioral modification depends on the temporal association of light and rotation. For animals that received light paired with rotation, significant increases in the spontaneous activity of type B photoreceptors were correlated with changes in photopositive behavior after training. A persistent tonic depolarization of type B photoreceptors can explain the cellular changes correlated with the long-term behavioral modification produced by the temporal association of light and rotation.
Foraminifera and Chlorophyll Maximum: Vertical Distribution, Seasonal Succession, and Paleoceanographic Significance
Authors: Fairbanks Richard G. , Wiebe Peter H.
Published: October 2006

Many planktonic foraminiferal species deposit their shells at the chlorophyll maximum zone, and it is the temperature range here that is relevant to oceanographic models which use ratios of oxygen-18 to oxygen-16 in fossil foraminifera and foraminiferal fossil assemblages to ascertain past climates. During periods of stratification of the upper water column, the temperature at the chlorophyll maximum may differ from the sea surface temperature by 10°C in the western North Atlantic.
Atmospheric Carbon Dioxide, the Southern Oscillation, and the Weak 1975 El Niño
Authors: Bacastow R. B. , Adams J. A. , Keeling C. D. , Moss D. J. , Whorf T. P. , Wong C. S.
Published: October 2006

The observed rate of change of the atmospheric carbon dioxide concentration at the South Pole, Fanning Island, Hawaii, and ocean weather station P correlates with an index of the southern oscillation and with El Niño occurrences. There are changes at all four stations that seem to be in response to the weak 1975 El Niño. Thus, even poorly developed El Niño events may affect the atmospheric carbon dioxide concentration.
Photochemical Production of Formaldehyde in Earth's Primitive Atmosphere
Authors: Pinto Joseph P. , Gladstone G. Randall , Yung Yuk Ling
Published: October 2006

Formaldehyde could have been produced by photochemical reactions in Earth's primitive atmosphere, at a time when it consisted mainly of molecular nitrogen, water vapor, carbon dioxide, and trace amounts of molecular hydrogen and carbon monoxide. Removal of formaldehyde from the atmosphere by precipitation can provide a source of organic carbon to the oceans at the rate of 10
11
moles per year. Subsequent reactions of formaldehyde in primeval aquatic environments would have implications for the abiotic synthesis of complex organic molecules and the origin of life.
Hydrogen Release: New Indicator of Fault Activity
Authors: Wakita Hiroshi , Nakamura Yuji , Kita Itsuro , Fujii Naoyuki , Notsu Kenji
Published: October 2006

The hydrogen concentration in soil gas has been measured in the area around the Yamasaki Fault, one of the active faults in southwestern Japan. Degassing of a significant amount of hydrogen (up to more than 3 percent by volume) has been observed for sites along the fault zone. The hydrogen concentration in soil gas at sites away from the fault zone was about 0.5 part per million, almost the same as that found in the atmosphere. The spatial distribution of sites with high hydrogen concentrations is quite systematic. A hypothesis on the production of hydrogen by fault movements is postulated.
Saline Culture of Crops: A Genetic Approach
Authors: Epstein Emanuel , Norlyn Jack D. , Rush Dale W. , Kingsbury Ralph W. , Kelley David B. , Cunningham Glen A. , Wrona Anne F.
Published: October 2006

Increasing salinity of soil and water threatens agriculture in arid and semiarid regions. By itself, the traditional engineering approach to the problem is no longer adequate. Genetic science offers the possibility of developing salt-tolerant crops, which, in conjunction with environmental manipulation, could improve agricultural production in saline regions and extend agriculture to previously unsuited regions.
Flight Activity Initiated via Giant Interneurons of the Cockroach: Evidence for Bifunctional Trigger Interneurons
Authors: Ritzmann Roy E. , Tobias Martha L. , Fourtner Charles R.
Published: October 2006

Activity in dorsal giant interneurons of the cockroach initiates flight movements if leg contact with a substrate is prevented. The same interneurons initiate activity associated with running when leg contact is maintained. Thus, which one of two completely different behaviors the giant interneurons evoke depends on the presence or absence of leg contact.
Internal Winds in Water Lilies: An Adaptation for Life in Anaerobic Sediments
Authors: Dacey John W. H.
Published: October 2006

The network of internal gas spaces in the yellow water lily constitutes a pressurized flow-through system which forces oxygen to the roots and rhizome buried in the anaerobic sediment. By the purely physical processes of thermal transpiration and hygrometric pressure, several liters of air per day enter the young, newly emerged leaves of
Nuphar luteum
against a small pressure gradient. This air moves en masse down the petioles of the young leaves (at rates up to 50 centimeters per minute) to the rhizome, forcing a simultaneous flow of gas (rich in carbon dioxide) from the rhizome up the petioles of the older emergent leaves to the atmosphere. The ventilation system has important physiological and ecological consequences
A Temperature and Precipitation Record of the Past 16,000 Years in Southern Chile
Authors: Heusser Calvin J. , Streeter S. Stephen
Published: October 2006

Regression equations relating pollen taxa from surface samples to temperature and precipitation are applied to a radiocarbon-dated pollen sequence in a lake core from Alerce. The resulting curves are a measure of the fluctuations of these climatic variables and show similarities to other late Quaternary records from the Southern Hemisphere.
Activin-Binding Protein from Rat Ovary Is Follistatin
Authors: Nakamura Takanori , Takio Koji , Eto Yuzuru , Shibai Hiroshiro , Titani Koiti , Sugino Hiromu
Published: October 2006

Activin, a member of the transforming growth factor β protein family, was originally isolated from gonadal fluids and stimulates the release of pituitary follicle-stimulating hormone (FSH). Activin has numerous functions in both normal and neoplastic cells. Various cells synthesize activin and have a specific binding site for this peptide. However, the molecular basis for its actions is unknown. A binding protein for activin was purified from rat ovary and was identical to follistatin, a specific inhibitor of FSH release. It is likely that the binding protein participates in the diverse regulatory actions of activin.
Quaternary Climates and Sea Levels of the U.S. Atlantic Coastal Plain
Authors: Cronin Thomas M. , Szabo Barney J. , Ager Thomas A. , Hazel Joseph E. , Owens James P.
Published: October 2006

Uranium-series dating of corals from marine deposits of the U.S. Atlantic Coastal Plain coupled with paleoclimatic reconstructions based on ostracode (marine) and pollen (continent) data document at least five relatively warm intervals during the last 500,000 years. On the basis of multiple paleoenvironmental criteria, we determined relative sea level positions during the warm intervals, relative to present mean sea level, were 7 ± 5 meters at 188,000 years ago, 7.5 ± 1.5 meters at 120,000 years ago, 6.5 ± 3.5 meters at 94,000 years ago, and 7 ± 3 meters at 72,000 years ago. The composite sea level chronology for the Atlantic Coastal Plain is inconsistent with independent estimates of eustatic sea level positions during interglacial intervals of the last 200,000 years. Hydroisostatic adjustment from glacial-interglacial sea level fluctuations, lithospheric flexure, and isostatic uplift from sediment unloading due to erosion provide possible mechanisms to account for the discrepancies. Alternatively, current eustatic sea level estimates for the middle and late Quaternary may require revision.
Sex Ratio Manipulation and Selection for Attractiveness
Authors: Burley Nancy
Published: October 2006

Laboratory experiments performed on a monogamous estrildid, the zebra finch (
Poephila guttata
), indicate that sex ratio of offspring is affected by nongenetic markers (colored plastic leg bands) that vary in attractiveness to birds. Results suggest that natural selection favors individuals that produce offspring of the sex of the more attractive parent within a breeding pair.
Pelagic Sedimentation of Aragonite: Its Geochemical Significance
Authors: Berner Robert A. , Honjo Susumu
Published: October 2006

The relative importance of the pelagic flux of aragonite, as compared to calcite, to the deep-sea floor has been evaluated by means of a quantitative x-ray diffraction study of samples collected from sediment traps and from an unusually shallow portion of the open Atlantic Ocean (the Rio Grande Rise). The results suggest that the aragonite flux constitutes at least 12 percent of the total flux of calcium carbonate on a worldwide basis. The presence of high-magnesium calcite in several samples suggests that some of the calcareous material falling to the deep-sea floor may be derived from the long-distance transport of debris from shallow-water benthic organisms as well as from the settling of planktonic remains. This observation supports the contention that 12 percent represents a minimum value. Aragonite and high-magnesium calcite transported laterally from shallow-water regions, upon dissolution during settling into deeper water, may contribute to the neutralization of excess anthropogenic carbon dioxide added to the oceans.
Phosphorylation of the Polymeric Immunoglobulin Receptor Required for Its Efficient Transcytosis
Authors: Casanova James E. , Breitfeld Philip P. , Ross Stuart A. , Mostov Keith E.
Published: October 2006

The endosomal compartment of polarized epithelial cells is a major crossroads for membrane traffic. Proteins entering this compartment from the cell surface are sorted for transport to one of several destinations: recycling to the original cell surface, targeting to lysosomes for degradation, or transcytosis to the opposite surface. The polymeric immunoglobulin receptor (pIgR), which is normally transcytosed from the basolateral to the apical surface, was used as a model to dissect the signals that mediate this sorting event. When exogenous receptor was expressed in Madin-Darby Canine Kidney (MDCK) cells, it was shown that phosphorylation of pIgR at the serine residue at position 664 is required for efficient transcytosis. Replacement of this serine with alanine generated a receptor that is transcytosed only slowly, and appears to be recycled. Conversely, substitution with aspartic acid (which mimics the negative charge of the phosphate group) results in rapid transcytosis. It was concluded that phosphorylation is the signal that directs the pIgR from the endosome into the transcytotic pathway.
Relation of Neuronal APP-751/APP-695 mRNA Ratio and Neuritic Plaque Density in Alzheimer's Disease
Authors: Johnson Steven A. , McNeill Thomas , Cordell Barbara , Finch Caleb E.
Published: October 2006

An ongoing controversy concerns the cellular distribution of the differentially spliced forms of the amyloid protein precursor (APP) mRNAs and changes in prevalence of these transcripts during Alzheimer's disease. In situ hybridization on serial sections was used to prove that most hippocampal pyramidal neurons contain both APP-751 and APP-695 mRNA species. The APP-751/APP-695 mRNA ratio is generally increased during Alzheimer's disease, as shown by RNA gel blot analysis. Moreover, there was a strong linear relation between the increase in APP-751/APP-695 mRNA ratio in pyramidal neurons and the density of senile plaques within the hippocampus and entorhinal cortex. Thus, the increase in APP-751/APP-695 mRNA provides a molecular marker for regional variations in plaque density between individuals diagnosed with Alzheimer's disease by the commonly used composite criteria.
A Novel Nucleoprotein Complex at a Replication Origin
Authors: Serrano Manuel , Salas Margarita , Hermoso José M.
Published: October 2006

The viral protein p6, required for the protein-primed initiation of replication of
Bacillus subtilis
phage φ29, forms a nucleoprotein complex at the viral replication origins that shows novel features. Deoxyribonuclease I and hydroxyl radical footprinting data, as well as the induction of positive supercoiling, support a model in which a DNA right-handed superhelix tightly wraps around a multimeric p6 core. The interaction occurs through the DNA minor groove. The activity of p6 not only requires the formation of the complex but also its correct positioning, indicating that the other proteins involved in the initiation of replication recognize, at a precise position, either the p6 core or the DNA conformational change induced by p6.
A New Redox Cofactor in Eukaryotic Enzymes: 6-Hydroxydopa at the Active Site of Bovine Serum Amine Oxidase
Authors: Janes Susan M. , Mu David , Wemmer David , Smith Alan J. , Kaur Surinder , Maltby David , Burlingame Alma L. , Klinman Judith P.
Published: October 2006

An active site, cofactor-containing peptide has been obtained in high yield from bovine serum amine oxidase. Sequencing of this pentapeptide indicates: Leu-Asn-X-Asp-Tyr. Analysis of the peptide by mass spectrometry, ultraviolet-visible spectroscopy, and proton nuclear magnetic resonance leads to the identification of X as 6-hydroxydopa. This result indicates that, contrary to previous proposals, pyrroloquinoline quinone is not the active site cofactor in mammalian copper amine oxidases. Although 6-hydroxydopa has been implicated in neurotoxicity, the data presented suggest that this compound has a functional role at an enzyme active site.
Site-Specific Gene Expression in Vivo by Direct Gene Transfer into the Arterial Wall
Authors: Nabel Elizabeth G. , Plautz Gregory , Nabel Gary J.
Published: October 2006

A recombinant β-galactosidase gene has been expressed in a specific arterial segment in vivo by direct infection with a murine amphotropic retroviral vector or by DNA transfection with the use of liposomes. Several cell types in the vessel wall were transduced, including endothelial and vascular smooth muscle cells. After retroviral infection, a recombinant reporter gene was expressed for at least 5 months, and no helper virus was detected. Recombinant gene expression achieved by direct retroviral infection or liposome-mediated DNA transfection was limited to the site of infection and was absent from liver, lung, kidney, and spleen. These results demonstrate that site-specific gene expression can be achieved by direct gene transfer in vivo and could be applied to the treatment of such human diseases as atherosclerosis or cancer.
Radio Science Investigations of the Saturn System with Voyager 1: Preliminary Results
Authors: Tyler G. L. , Eshleman V. R. , Anderson J. D. , Levy G. S. , Lindal G. F. , Wood G. E. , Croft T. A.
Published: October 2006

Voyager 1 radio occultation measurements of Titan's equatorial atmosphere successfully probed to the surface, which is provisionally placed at a radius of 2570 kilometers. Derived scale heights plus other experimental and theoretical results indicate that molecular nitrogen is the predominant atmospheric constituent. The surface pressure and temperature appear to be about 1.6 bars and 93 K, respectively. The main clouds are probably methane ice, although some condensation of nitrogen cannot be ruled out. Solar abundance arguments suggest and the measurements allow large quantities of surface methane near its triple-point temperature, so that the three phases of methane could play roles in the atmosphere and on the surface of Titan similar to those of water on Earth. Radio occultation measurements of Saturn's atmosphere near 75° south latitude reached a maximum pressure of 1.4 bars, where the temperature is about 156 K. The minimum temperature is about 91 K near the 60-millibar pressure level. The measured part of the polar ionosphere of Saturn has a peak electron concentration of 2.3 × 10
4
per cubic centimeter at an altitude of 2500 kilometers above the 1-bar level in the atmosphere, and a plasma scale height at the top of the ionosphere of 560 kilometers. Attenuation of monochromatic radiation at a wavelength of 3.6 centimeters propagating obliquely through Saturn's rings is consistent with traditional values for the normal optical depth of the rings, but the near-forward scattering of this radiation by the rings indicates effective scattering particles with larger than expected diameters of 10, 8, and 2 meters in the A ring, the outer Cassini division, and the C ring, respectively. Preliminary analysis of the radio tracking data yields new values for the masses of Rhea and Titan of 4.4 ± 0.3 × 10
–6
and 236.64 ± 0.08 × 10
–6
times the mass of Saturn. Corresponding values for the mean densities of these objects are 1.33 ± 0.10 and about 1.89 grams per cubic centimeter. The density of Rhea is consistent with a solar-composition mix of anhydrous rock and volatiles, while Titan is apparently enriched in silicates relative to the solar composition.
Extreme Ultraviolet Observations from Voyager 1 Encounter with Saturn
Authors: Broadfoot A. L. , Sandel B. R. , Shemansky D. E. , Holberg J. B. , Smith G. R. , Strobel D. F. , McConnell J. C. , Kumar S. , Hunten D. M. , Atreya S. K. , Donahue T. M. , Moos H. W. , Bertaux J. L. , Blamont J. E. , Pomphrey R. B. , Linick S.
Published: October 2006

The global hydrogen Lyman α, helium (584 angstroms), and molecular hydrogen band emissions from Saturn are qualitatively similar to those of Jupiter, but the Saturn observations emphasize that the H
2
band excitation mechanism is closely related to the solar flux. Auroras occur near 80° latitude, suggesting Earth-like magnetotail activity, quite different from the dominant Io plasma torus mechanism at Jupiter. No ion emissions have been detected from the magnetosphere of Saturn, but the rings have a hydrogen atmosphere; atomic hydrogen is also present in a torus between 8 and 25 Saturn radii. Nitrogen emission excited by particles has been detected in the Titan dayglow and bright limb scans. Enhancement of the nitrogen emission is observed in the region of interaction between Titan's atmosphere and the corotating plasma in Saturn's plasmasphere. No particle-excited emission has been detected from the dark atmosphere of Titan. The absorption profile of the atmosphere determined by the solar occultation experiment, combined with constraints from the dayglow observations and temperature information, indicate that N
2
is the dominant species. A double layer structure has been detected above Titan's limb. One of the layers may be related to visible layers in the images of Titan.
Plasma Observations Near Saturn: Initial Results from Voyager 1
Authors: Bridge H. S. , Belcher J. W. , Lazarus A. J. , Olbert S. , Sullivan J. D. , Bagenal F. , Gazis P. R. , Hartle R. E. , Ogilvie K. W. , Scudder J. D. , Sittler E. C. , Eviatar A. , Siscoe G. L. , Goertz C. K. , Vasyliunas V. M.
Published: October 2006

Extensive measurements of low-energy plasma electrons and positive ions were made during the Voyager 1 encounter with Saturn and its satellites. The magnetospheric plasma contains light and heavy ions, probably hydrogen and nitrogen or oxygen; at radial distances between 15 and 7 Saturn-radii (
R
S
) on the inbound trajectory, the plasma appears to corotate with a velocity within 20 percent of that expected for rigid corotation. The general morphology of Saturn's magnetosphere is well represented by a plasma sheet that extends from at least 5 to 17
R
S
, is symmetrical with respect to Saturn's equatorial plane and rotation axis, and appears to be well ordered by the magnetic shell parameter
L
(which represents the equatorial distance of a magnetic field line measured in units of
R
S
). Within this general configuration, two distinct structures can be identified: a central plasma sheet observed from
L
= 5 to
L
= 8 in which the density decreases rapidly away from the equatorial plane, and a more extended structure from
L
= 7 to beyond 18
R
S
in which the density profile is nearly flat for a distance ± 1.8
R
S
off the plane and falls rapidly thereafter. The encounter with Titan took place inside the magnetosphere. The data show a clear signature characteristic of the interaction between a subsonic corotating magnetospheric plasma and the atmospheric or ionospheric exosphere of Titan. Titan appears to be a significant source of ions for the outer magnetosphere. The locations of bow shock crossings observed inbound and outbound indicate that the shape of the Saturnian magnetosphere is similar to that of Earth and that the position of the stagnation point scales approximately as the inverse one-sixth power of the ram pressure.
Genetic Evidence That Protein Synthesis Is Required for the Circadian Clock of
Neurospora
Authors: Nakashima Hideaki , Perlman Janine , Feldman Jerry F.
Published: October 2006

Small doses of cycloheximide given at intervals (pulses) cause phase shifts of the circadian clock of
Neurospora
. The effects of this drug on the clock are mediated through its inhibition of protein synthesis, since two cycloheximide-resistant mutants whose 80
S
ribosomes are resistant to cycloheximide showed no phase shift after exposure to the drug.
Energetics of Honeybee Swarm Thermoregulation
Authors: Heinrich Bernd
Published: October 2006

Honeybee swarms regulate their core temperature at a high set point (near 36°C) and the mantle at a low set point (near 15°C). The temperature gradient from core to mantle permits considerable energy economy, and it is abolished only shortly before swarm takeoff.
Sludge Decomposition and Stabilization
Authors: Hartenstein Roy
Published: October 2006

Sludges are labile putrescible materials which must undergo a heterotrophic decomposition process and be subject to humification before becoming stabilized substances. An understanding of the principles underlying these processes may give rise to better management plans for the application of sludge to land. Procedures are suggested for the evaluation of sludge stabilization rates.
Tsukuba Science City: Japan Tries Planned Innovation
Authors: Bloom Justin L. , Asano Shinsuke
Published: October 2006

Tsukuba Science City is Japan's new municipal complex of research laboratories and educational facilities. About 30 percent of the nation's government research laboratories and more than 40 percent of its government research manpower are concentrated in the community. A brief history of the monumental project is presented and problems confronting the city are discussed.
Deep-Seated Gas Emission Induced by the Earth Tide: A Basic Observation for Geochemical Earthquake Prediction
Authors: Sugisaki Ryuichi
Published: October 2006

Variations of the helium/argon ratio of gas bubbles in a mineral spring along a fault zone coincide with fluctuations of areal dilation induced by the earth tide. This observation suggests that deep-seated gases characterized by higher helium/argon ratios are squeezed out by stress preceding an earthquake.
Hydrovolcanic Explosions: The Systematics of Water-Pyroclast Equilibration
Authors: Sheridan Michael F. , Wohletz Kenneth H.
Published: October 2006

The initial contact of external water with erupting magma and the mass ratio of water to magma govern the development of hydrovolcanic phenomena. The phase relations of water within the runout system and the separation of vapor or liquid from the pyroclasts explain gradational transitions between some pyroclastic flows, base surges, mud hurricanes, mudflows, and sheetfloods.
Peptidal Sex Hormones Inducing Conjugation Tube Formation in Compatible Mating-Type Cells of
Tremella mesenterica
Authors: Sakagami Youji , Yoshida Mitsuru , Isogai Akira , Suzuki Akinoiu
Published: October 2006

The pair of peptidal sex hormones (tremerogen A-10 and tremerogen a-13) that induce conjugation tube formation in compatible type cells (A and a types) of
Tremella mesenterica
were isolated. Tremerogen A-10 is a dodecapeptide and tremerogen a-13, a tridecapeptide. In both peptides, the sulfhydryl group of the cysteines at the carboxyl terminus was blocked by farnesyl moieties.
Restoration of Inactivation in Mutants of
Shaker
Potassium Channels by a Peptide Derived from ShB
Authors: Zagotta William N. , Hoshi Toshinori , Aldrich Richard W.
Published: October 2006

Site-directed mutagenesis experiments have suggested a model for the inactivation mechanism of
Shaker
potassium channels from
Drosophila melanogaster
. In this model, the first 20 amino acids form a cytoplasmic domain that interacts with the open channel to cause inactivation. The model was tested by the internal application of a synthetic peptide, with the sequence of the first 20 residues of the ShB alternatively spliced variant, to noninactivating mutant channels expressed in
Xenopus
oocytes. The peptide restored inactivation in a concentration-dependent manner. Like normal inactivation, peptide-induced inactivation was not noticeably voltage-dependent. Trypsin-treated peptide and peptides with sequences derived from the first 20 residues of noninactivating mutants did not restore inactivation. These results support the proposal that inactivation occurs by a cytoplasmic domain that occludes the ion-conducting pore of the channel.
Mount St. Helens Eruption of 18 May 1980: Air Waves and Explosive Yield
Authors: Donn William L. , Balachandran Nambath K.
Published: October 2006

Strong atmospheric acoustic-gravity waves were recorded by sensitive microbarographs and seismographs at large distances from the Mount St. Helens eruption of 18 May 1980. Wave signatures were similar to those of waves from large nuclear explosions. Independent theoretical and empirical analyses indicate that the explosive yield of the eruption was approximately 35 megatons.
Demineralization of Porous Solids
Authors: Cussler E. L. , Featherstone John D. B.
Published: October 2006

When a porous ionic solid is placed in acid, the acid will dissolve surface material. When this dissolved material and the acid diffuse into the solid's pores, they can precipitate more solid. If the acid is buffered, the diffusing species can bring about precipitation in some regions and dissolution in others. When the porous solid contains several chemical species, the diffusion can precipitate one species and dissolve another. The results have implications for the demineralization of teeth.
Feedback Inhibition of Brain Noradrenaline Neurons by Tricyclic Antidepressants: α-Receptor Mediation
Authors: Svensson Torgny H. , Usdin Ted
Published: October 2006

The use of different receptor blocking agents and single-unit recording techniques indicates that feedback inhibition of brain noradrenaline neurons by tricyclic antidepressants is mediated by presynaptic α-receptors. After chronic imipramine treatment, noradrenaline neurons in the locus coeruleus of rat brain remained partly depressed, in agreement with clinical data. They were, however, resistant to further inhibition by imipramine or clonidine.