bluuebunny/crossref_metadata_2025 huggingface dataset:
Corotation Lag in Jupiter's Magnetosphere: Comparison of Observation and Theory
Authors: Hill T. W.
Published: October 2006

Voyager 1 plasma flow data are compared with a recent theory that predicted measurable departures from rigid corotation in Jupiter's magnetosphere as a consequence of rapid plasma production and weak atmosphere-magnetosphere coupling. The comparison indicates that the theory can account for the observed corotation lag, provided that the plasma mass production rate during the Voyager 1 encounter was rather larger than expected, namely ∼10
30
atomic mass units per second.
Free-Radical Oxidants in Natural Waters
Authors: Mill Theodore , Hendry Dale G. , Richardson Harold
Published: October 2006

Photooxidation of cumene (isopropylbenzene) and pyridine in dilute solution in natural waters gives products characteristic of reactions with alkylperoxy (RO
2
⋅) and hydroxyl (HO⋅) radicals. On the basis of the rates of formation of the products, the average concentrations of RO
2
⋅ and HO⋅ are estimated to be about 10
-9
and 10
-17
mole per liter, respectively. The concentration of RO
2
⋅ is large enough that, for some classes of reactive chemicals, oxidation can be an important process in natural waters.
Modeling the Climatic Response to Orbital Variations
Authors: Imbrie John , Imbrie John Z.
Published: October 2006

According to the astronomical theory of climate, variations in the earth's orbit are the fundamental cause of the succession of Pleistocene ice ages. This article summarizes how the theory has evolved since the pioneer studies of James Croll and Milutin Milankovitch, reviews recent evidence that supports the theory, and argues that a major opportunity is at hand to investigate the physical mechanisms by which the climate system responds to orbital forcing. After a survey of the kinds of models that have been applied to this problem, a strategy is suggested for building simple, physically motivated models, and a time-dependent model is developed that simulates the history of planetary glaciation for the past 500,000 years. Ignoring anthropogenic and other possible sources of variation acting at frequencies higher than one cycle per 19,000 years, this model predicts that the long-term cooling trend which began some 6000 years ago will continue for the next 23,000 years.
Isotopic Disequilibrium of Uranium: Alpha-Recoil Damage and Preferential Solution Effects
Authors: Fleischer Robert L.
Published: October 2006

Preferential loss of uranium-234 relative to uranium-238 from rocks into solutions has long been attributed to recoiling alpha-emitting nuclei. Direct evidence has been obtained for two mechanisms, first, recoil ejection from grains, and now release by natural etching of alpha-recoil tracks. The observations have implications for radon emanation and for the storage of alpha-emitting radioactive waste.
East Pacific Rise: Hot Springs and Geophysical Experiments
Authors: Spiess F. N. , Macdonald Ken C. , Atwater T. , Ballard R. , Carranza A. , Cordoba D. , Cox C. , Garcia V. M. Diaz , Francheteau J. , Guerrero J. , Hawkins J. , Haymon R. , Hessler R. , Juteau T. , Kastner M. , Larson R. , Luyendyk B. , Macdougall J. D. , Miller S. , Normark W. , Orcutt J. , Rangin C.
Published: October 2006

Hydrothermal vents jetting out water at 380° ± 30°C have been discovered on the axis of the East Pacific Rise. The hottest waters issue from mineralized chimneys and are blackened by sulfide precipitates. These hydrothermal springs are the sites of actively forming massive sulfide mineral deposits. Cooler springs are clear to milky and support exotic benthic communities of giant tube worms, clams, and crabs similar to those found at the Galápagos spreading center. Four prototype geophysical experiments were successfully conducted in and near the vent area: seismic refraction measurements with both source (thumper) and receivers on the sea floor, on-bottom gravity measurements, in situ magnetic gradiometer measurements from the submersible
Alvin
over a sea-floor magnetic reversal boundary, and an active electrical sounding experiment. These high-resolution determinations of crustal properties along the spreading center were made to gain knowledge of the source of new oceanic crust and marine magnetic anomalies, the nature of the axial magma chamber, and the depth of hydrothermal circulation.
Late Miocene Origin of the Benguela Upswelling System off Northern Namibia
Authors: Siesser William G.
Published: October 2006

Deep Sea Drilling Project cores collected at site 362/362A suggest the time of initiation of the Benguela upwelling system off northern Namibia. Studies of sediment accumulation rates, diatom abundances, microfossil temperature preferences (for planktic foraminifers, calcareous nannoplankton, and silicoflagellates), productivity (expressed as the organic carbon content), and phosphorus incorporation in calcareous skeletons all suggest that major, sustained upwelling began in the early late Miocene. Upwelling brought cold, nutrient-rich waters to the surface, and the modern Benguela system dates from this time (about 10 million years before the present).
Devonian Gametophytes with Anatomically Preserved Gametangia
Authors: Remy Winfried , Remy Renate
Published: October 2006

The oldest anatomically preserved and physiologically apparently independent gametophytes are described from the Lower Devonian of Scotland. These gametophytes have upright, leafless axes with terminally borne, bowl-shaped gametangiophores. The antheridia are stalked and their walls are multicellular. The archegonia are clustered in groups on common bases.
Seasonal Movements in a Salt Glacier in Iran
Authors: Talbot Christopher J. , Rogers Eric A.
Published: October 2006

The philosophy of the storage of high-grade radioactive wastes in salt seems to be based on the assumption that the salt glaciers of Iran are no longer moving. Monitoring the movements of markers painted onto one of the salt glaciers suggests that the glacier deforms elastically as a result of temperature changes most of the time but flows plastically when it is sufficiently wet during each annual rainy season.
Animals as an Energy Source in Third World Agriculture
Authors: Ward Gerald M. , Sutherland Thomas M. , Sutherland Jean M.
Published: October 2006

Agricultural development programs have so far been largely unable to meet the food needs of the world's poorest. Increased food production can be achieved only from more intensive agriculture, which requires greater energy inputs per farm worker. Problems of technological infrastructure and escalating oil prices appear to preclude the spread of mechanization to Third World agriculture at this time. Efficient utilization of grazing animals in specific integrated farming systems could not only increase energy inputs through draft and transportation but also increase the yield of high-grade products and by-products from the renewable energy of biomass. An approach to development based on animal agriculture systems is suggested that might initiate a self-sustaining, more productive agriculture requiring only small inputs of fossil-fuel energy.
Acid Precipitation and Sulfate Deposition in Florida
Authors: Brezonik Patrick L. , Edgerton Eric S. , Hendry Charles D.
Published: October 2006

The acidity of rainfall in Florida has increased markedly in the past 25 years, and the average sulfate and nitrate concentrations have increased by factors of 1.6 and 4.5, respectively, over the period. Annual average
p
H values below 4.7 now occur over the northern three quarters of the state. Summer rainfall has average
p
H values 0.2 to 0.3 unit lower than winter rainfall, and sulfate concentrations at most sites are higher in summer. The annual deposition of H
+
(about 300 to 500 equivalents per hectare) in northern Florida is a third to a half of the deposition in the heavily impacted northeastern United States; comparable figures for excess sulfate (derived from sulfur dioxide) are 7 to 11 kilograms of sulfur per hectare or 50 to 90 percent of the sulfate deposition rates at Hubbard Brook, New Hampshire.
No-Tillage Agriculture
Authors: Phillips Ronald E. , Thomas Grant W. , Blevins Robert L. , Frye Wilbur W. , Phillips Shirley H.
Published: October 2006

The no-tillage cropping system, a combination of ancient and modern agricultural practices, has been rapidly increasing in use. By the year 2000, as much as 65 percent of the acreage of crops grown in the United States may be grown by the no-tillage practice. Soil erosion, the major source of pollutants in rural streams, is virtually eliminated when no-tillage agriculture is practiced. The no-tillage system reduces the energy input into corn and soybean production by 7 and 18 percent, respectively, when compared to the conventional tillage system of moldboard plowing followed by disking. In addition, crop yields are as high as or higher than those obtained with traditional tillage practices on large areas of agricultural land.
Contact Metamorphism by an Ophiolite Peridotite from Neyriz, Iran
Authors: Hall Robert
Published: October 2006

Ophiolites are conventionally regarded as fragments of former oceanic lithosphere. Mineralogical and field evidence indicates that peridotite of the Neyriz ophiolite was intruded at high temperature into folded crystalline limestones, forming skarns. This excludes the formation of the ophiolite at a mid-ocean ridge but is consistent with its origin by intrusion during continental rifting.
Expert and Novice Performance in Solving Physics Problems
Authors: Larkin Jill , McDermott John , Simon Dorothea P. , Simon Herbert A.
Published: October 2006

Although a sizable body of knowledge is prerequisite to expert skill, that knowledge must be indexed by large numbers of patterns that, on recognition, guide the expert in a fraction of a second to relevant parts of the knowledge store. The knowledge forms complex schemata that can guide a problem's interpretation and solution and that constitute a large part of what we call physical intuition.
Platinum Metals Magmatic Sulfide Ores
Authors: Naldrett A. J. , Duke J. M.
Published: October 2006

Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example.
Mathematics
Authors: Mac Lane Saunders
Published: October 2006

Current research in mathematics involves a wide variety of interlocking ideas, old and new. For example, results about the curves and surfaces defined by polynomial equations, as in algebraic geometry, appear in the study of solitary waves and also in the gauge theories in physics. Centuries-old problems in number theory have been solved, while others have been revealed as insoluble. The classification of all finite simple groups is nearly achieved (and the full treatment will be voluminous); the representation of groups aids in their application to the study of symmetry. These developments, and many others, attest to the vitality of mathematics.
Quantum Nondemolition Measurements
Authors: Braginsky Vladimir B. , Vorontsov Yuri I. , Thorne Kip S.
Published: October 2006

Some future gravitational-wave antennas will be cylinders of mass ∼100 kilograms, whose end-to-end vibrations must be measured so accurately (10
–19
centimeter) that they behave quantum mechanically. Moreover, the vibration amplitude must be measured over and over again without perturbing it (quantum nondemolition measurement). This contrasts with quantum chemistry, quantum optics, or atomic, nuclear, and elementary particle physics, where one usually makes measurements on an ensemble of identical objects and does not care whether any single object is perturbed or destroyed by the measurement. This article describes the new electronic techniques required for quantum nondemolition measurements and the theory underlying them. Quantum nondemolition measurements may find application elsewhere in science and technology.
Tracing Food Webs with Stable Hydrogen Isotopes
Authors: Estep Marilyn F. , Dabrowski Halina
Published: October 2006

The hydrogen isotopic content of an animal's food, not water, determines that animal's hydrogen isotopic content. Liver and muscle tissue from mice reared on a diet such that the ratio of deuterium to hydrogen (D/H) of their food and water was kept constant, have the same average D/H ratio as the food source. In a simple, natural population of snails and their possible algal diets,
Littorina obtusata
(northern Atlantic intertidal snails that feed almost exclusively on the brown alga (
Fucus vesiculosus
) has the same D/H ratio as
Fucus vesiculosis
and not that of the other algae available to the snails.
Embodied Energy and Economic Valuation
Authors: Costanza Robert
Published: October 2006

Input-output analysis has been adapted to calculate the total (direct plus indirect) energy required to produce goods and services in the U.S. economy; this quantity has been termed the embodied energy. Usually, the energy required to produce labor and government services and the solar energy input to the economy are ignored by analysts. The former omission can be traced to the assumption that traditional primary factors of economic production—land, labor, and capital—are independent. A strong case can be made that these input factors are not independent and that energy is required for their production. Embodied energies can be calculated in this case by using input-output data. The results of such an analysis show that there is a strong relation between embodied energy and dollar value for a 92-sector U.S. economy if the energy required to produce labor and government services is included.
The Biology of Oxygen Radicals
Authors: Fridovich Irwin
Published: October 2006

The reactive superoxide radical, O
2
-
, formerly of concern only to radiation chemists and radiobiologists, is now understood to be a normal product of the biological reduction of molecular oxygen. An unusual family of enzymes, the superoxide dismutases, protect against the deleterious actions of this radical by catalyzing its dismutation to hydrogen peroxide plus oxygen.
Ribozymes as Potential Anti-HIV-1 Therapeutic Agents
Authors: Sarver Nava , Cantin Edouard M. , Chang Pairoj S. , Zaia John A. , Ladne Paula A. , Stephens Delilah A. , Rossi John J.
Published: October 2006

Certain RNA molecules, called ribozymes, possess enzymatic, self-cleaving activity. The cleavage reaction is catalytic and no energy source is required. Ribozymes of the "hammerhead" motif were identified in plant RNA pathogens. These ribozymes possess unique secondary (and possibly tertiary) structures critical for their cleavage ability. The present study shows precise cleavage of human immunodeficiency virus type 1 (HIV-1) sequences in a cell-free system by hammerhead ribozymes. In addition to the cell-free studies, human cells stably expressing a hammerhead ribozyme targeted to HIV-1
gag
transcripts have been constructed. When these cells were challenged with HIV-1, a substantial reduction in the level of HIV-1
gag
RNA relative to that in nonribozyme-expressing cells, was observed. The reduction in
gag
RNA was reflected in a reduction in antigen p24 levels. These results suggest the feasibility of developing ribozymes as therapeutic agents against human pathogens such as HIV-1.
Global Transport of Organic Pollutants: Ambient Concentrations in the Remote Marine Atmosphere
Authors: Atlas E. , Giam C. S.
Published: October 2006

Concentrations of organic pollutants in the air and in precipitation have been measured at Enewetak Atoll in the North Pacific Ocean. These data from a site removed from industrial and human activity indicate the present concentrations of synthetic organic pollutants in the atmosphere and establish the long-range atmospheric transport of organic pollutants to remote marine areas. Hexachlorobenzene and hexachlorocyclohexane isomers are present in the remote marine atmosphere. Polychlorobiphenyls, total DDT, dieldrin, chlordane, and two phthalate ester plasticizers were also found in the samples. The concentrations of pollutants in the atmosphere remote from continental sources are good measures of the minimum concentrations of air pollutants on Earth.
Stable Lead Isotopes as a Tracer in Coastal Waters
Authors: Stukas V. J. , Wong C. S.
Published: October 2006

The natural abundances of the stable isotopes of lead are used to identify natural and industrial sources of lead in the coastal waters of British Columbia, Canada. The
206
Pb/
207
Pb ratios, used to characterize the lead source, had values of ∼ 1.24 for coastal oceanic water, ∼ 1.22 for fjord waters receiving lead from mine tailings, and ∼ 1.163 for waters near urban centers. The lead concentration data are in agreement with presently accepted seawater values.
Mutation of the Alzheimer's Disease Amyloid Gene in Hereditary Cerebral Hemorrhage, Dutch Type
Authors: Levy Efrat , Carman Mark D. , Fernandez-Madrid Ivan J. , Power Michael D. , Lieberburg Ivan , van Duinen Sjoerd G. , Bots Gerard Th. A. M. , Luyendijk Willem , Frangione Blas
Published: October 2006

An amyloid protein that precipitates in the cerebral vessel walls of Dutch patients with hereditary cerebral hemorrhage with amyloidosis is similar to the amyloid protein in vessel walls and senile plaques in brains of patients with Alzheimer's disease, Down syndrome, and sporadic cerebral amyloid angiopathy. Cloning and sequencing of the two exons that encode the amyloid protein from two patients with this amyloidosis revealed a cytosine-to-guanine transversion, a mutation that caused a single amino acid substitution (glutamine instead of glutamic acid) at position 22 of the amyloid protein. The mutation may account for the deposition of this amyloid protein in the cerebral vessel walls of these patients, leading to cerebral hemorrhages and premature death.
Vitamin D
3
-Induced Calcium Binding Protein in Bone Tissue
Authors: Christakos Sylvia , Norman Anthony W.
Published: October 2006

As detected by radioimmunoassay with antiserums against chick intestinal calcium binding protein (CaBP), administration of vitamin
3
to rachitic chicks causes a 25- to 100-fold increase in immunoreactive CaBP in chick bone. The bone CaBP has a higher molecular weight (approximately 34,000 daltons) than intestinal CaBP (28,000 daltons), is concentrated principally in the spongiosa and cartilage plate regions of tibia, and responds adaptively to reflect the level of dietary calcium.
Polarity of the Blood-Brain Barrier: Neutral Amino Acid Transport into Isolated Brain Capillaries
Authors: Betz A. Lorris , Goldstein Gary W.
Published: October 2006

Capillary endothelial cells isolated from rat brain exhibit Na
+
-dependent uptake of the neutral amino acid analog α-(methylamino)isobutyric acid. Since studies in vivo demonstrate that this transport system is not present on the blood side of brain capillaries we conclude that Na
+
-dependent neutral amino acid transport is located on the brain side. Therefore, the luminal plasma membrane and the antiluminal plasma membrane appear to be functionally distinct. This polarity should permit brain capillary endothelial cells to actively regulate the internal milieu of the brain.
Redox Regulation of Fos and Jun DNA-Binding Activity in Vitro
Authors: Abate Cory , Patel Lekha , Rauscher Frank J. , Curran Tom
Published: October 2006

The proto-oncogenes c-
fos
and c-
jun
function cooperatively as inducible transcription factors in signal transduction processes. Their protein products, Fos and Jun, form a heterodimeric complex that interacts with the DNA regulatory element known as the activator protein-1 (AP-1) binding site. Dimerization occurs via interaction between leucine zipper domains and serves to bring into proper juxtaposition a region in each protein that is rich in basic amino acids and that forms a DNA-binding domain. DNA binding of the Fos-Jun heterodimer was modulated by reduction-oxidation (redox) of a single conserved cysteine residue in the DNA-binding domains of the two proteins. Furthermore, a nuclear protein was identified that reduced Fos and Jun and stimulated DNA-binding activity in vitro. These results suggest that transcriptional activity mediated by AP-1 binding factors may be regulated by a redox mechanism.
First Radioisotope (Potassium-Argon) Age of Marine Neogene Rionegro Beds in Northeastern Patagonia, Argentina
Authors: Zinsmeister William J. , Marshall Larry G. , Drake Robert E. , Curtis Garniss H.
Published: October 2006

An average age of 9.41 million years was obtained from radioisotope (potassium-argon) age determinations of three glass concentrates of a tuff from the upper part of the marine Rionegrense at Punta Cracker in Golfo Nuevo, Argentina. This age correlates with the Tortonian marine stage of Europe and the Chasicoan Land Mammal Age of South America.
Beans for Valdivia
Authors: Damp Jonathan E. , Pearsall Deborah M. , Kaplan Lawrence T.
Published: October 2006

Carbonized remains of
Canavalia
beans were recovered from archaeological deposits excavated at Real Alto (OGCh-12), southwestern Ecuador. The identification, context and dating of the earliest beans from Real Alto demonstrate their use from the beginning of Valdivia (about 3300 B.C.) and the Early Formative in coastal Ecuador.
Polyphenolic Substance of
Mytilus edulis
: Novel Adhesive Containing L-Dopa and Hydroxyproline
Authors: Waite J. Herbert , Tanzer Marvin L.
Published: October 2006

The fouling marine mussel
Mytilus edulis
attaches itself to various substrates by spinning byssal threads, the adhesive discs of which are rich in the amino acid 3,4-dihydroxyphenylalanine (dopa). An acid-soluble protein was extracted and purified from the phenol gland located in the byssus-secreting foot of the animal. This protein is highly basic and contains large amounts of lysine, dopa, and 3- and 4-hydroxyproline. The composition of this protein and its sticky tendencies in vitro strongly suggest that it contributes to byssal adhesion.
Distal Regeneration and Symmetry
Authors: Bryant Susan V. , French Vernon , Bryant Peter J.
Published: October 2006

A revision of the "polar coordinate model" shows how pattern formation in diverse regenerating systems can be understood in terms of strictly local cell interactions.
Ocean Crustal Dynamics
Authors: Talwani Manik , Langseth Marcus
Published: October 2006

The study of oceanic crust continues to be important because of the presence of economic resources in oceanic areas and because many fundamental problems of geologic evolution are best solved from studies of the ocean. Although modeling and syntheses of existing data remain important, key breakthroughs in the future will come from the application of new technology such as multichannel towed seismic arrays, deep-towed side scan sonars, improved thermal probes, deep drilling, and satellite altimeters.
Calcium Dependence of the Inactivation of Calcium Currents in Skeletal Muscle Fibers of an Insect
Authors: Ashcroft Frances M. , Stanfield P. R.
Published: October 2006

Calcium currents in skeletal muscle fibers of an insect,
Carausius morosus
, inactivate under depolarization. This inactivation depends on the current being carried across the membrane by calcium ions, rather than strontium or barium ions.
Sexual Difference Theory: Mormon Crickets Show Role Reversal in Mate Choice
Authors: Gwynne Darryl T.
Published: October 2006

Male Mormon crickets produce a large spermatophore that the female eats. Spermatophore proteins are important to female reproduction, and females compete for access to singing males. Males reject most receptive females as mates, and those accepted are more fecund than rejected individuals. This role reversal in courtship is in contrast to the behavior of the sexes in katydid species in which the males produce small spermatophores.
Radar Detection of Cloud-Seeding Effects
Authors: Hobbs Peter V. , Lyons Jamie H. , Locatelli John D. , Biswas Kumud R. , Radke Lawrence F. , Weiss Richard R. , Rangno Arthur L.
Published: October 2006

The effects on precipitation of artificially seeding clouds with Dry Ice have been monitored from cloud to ground with a radar that has a wavelength of 8.6 millimeters.
A Major Helium-3 Source at 15°S on the East Pacific Rise
Authors: Lupton John E. , Craig Harmon
Published: October 2006

An extensive plume of water enriched with helium-3 has been discovered in the deep Pacific Ocean at latitude 15°S on the East Pacific Rise. In the core of the plume, at a depth of 2500 meters over the ridge crest, the helium-3/helium-4 ratio is 50 percent higher than the ratio in atmospheric helium, indicating a strong injection of mantle or primordial helium at the spreading center axis through local hydrothermal systems. The helium-3 plume is completely absent east of the rise, but it can be traced over 2000 kilometers to the west above a newly observed physical feature: a density discontinuity here called the "ridge-crest front." The injected plume provides a unique deep-sea tracer with an asymmetric distribution which shows that the deep circulation across the rise is from east to west. The striking intensity and lateral extent of this helium-3 anomaly, compared to observations at known oceanic hydrothermal sites, suggest that the largest hydrothermal fields in the ocean are yet to be discovered and that they will be found near 15°S on the East Pacific Rise.
Colonization Lessons from a Tropical Forest
Authors: Smith Nigel J. H.
Published: October 2006

The decade-old Transamazon Highway provides a useful stage for examining some of the major issues related to frontier conquest and the impact of pioneer settlement on one of the world's richest biomes. The highway project is an ambitious colonization scheme and the lessons that can be drawn from it, ranging from the environmental effects of stripping back the tree cover to the spread of diseases, will be useful in guiding development policy in other tropical regions.
Canopy Roots: Convergent Evolution in Rainforest Nutrient Cycles
Authors: Nadkarni Nalini M.
Published: October 2006

Accumulations of living and dead epiphytes in the canopy of rainforest trees provide an aboveground nutrient resource. A wide range of host tree species in both temperate and tropical rainforests gain access to these nutrients by putting forth extensive networks of adventitious roots beneath the epiphyte mats they support.
Induction of a Neuronal Proteoglycan by the NMDA Receptor in the Developing Spinal Cord
Authors: Kalb Robert G. , Hockfield Susan
Published: October 2006

Activation of the
N
-methyl-D-aspartate (NMDA) subclass of glutamate receptors is a critical step in the selection of appropriate synaptic connections in the developing visual systems of cat and frog. Activity-dependent development of mammalian motor neurons was shown to be similarly mediated by activation of the NMDA receptor. The expression of the Cat-301 proteoglycan on motor neurons was developmentally regulated and could be specifically inhibited by blockade of the NMDA receptor at the spinal segmental level. In the adult, Cat-301 immunoreactivity on motor neurons was not diminished by NMDA receptor blockade. The NMDA receptor may regulate the expression of a class of neuronal proteins (of which Cat-301 is one example) that underlie the morphological and physiological features of activity-dependent development.
Carbon-14 Dates at Grande Pile: Correlation of Land and Sea Chronologies
Authors: Woillard Geneviéve M. , Mook Willem G.
Published: October 2006

Sixteen radiocarbon dates extending back to 70,000 years provide a chronology for the continuous continental pollen record of Grande Pile. This record reflects climatic changes over the last 140,000 years in northeastern France. The cold period initiating the Middle Weichselian, dated previously at 55,000 years, is dated at 70,000 years before the present (B.P.) at Grande Pile. This event is marked by the disappearance of deciduous forests at this site. The Early Weichselian is placed before 70,000 years B.P. A correlation with the oxygen isotope stages from oceanic records is demonstrated until 70,000 years B.P. and attempted beyond.
Tax Policy and Innovation
Authors: Mansfield Edwin
Published: October 2006

Tax policy should be formulated with recognition of its effects on research and development and innovation. Many changes in tax policy designed to stimulate innovation have been proposed in recent years. Some of these changes were embodied in the 1981 tax bill. Basic economic analysis and rudimentary statistics enable economists to make some useful statements about the effects of recent and proposed tax changes but, because practically no studies have been conducted in this area, there is little or no dependable information concerning the quantitative impact of particular changes of this sort on the rate of innovation.
Global Sea Level Trend in the Past Century
Authors: Gornitz V. , Lebedeff S. , Hansen J.
Published: October 2006

Data derived from tide-gauge stations throughout the world indicate that the mean sea level rose by about 12 centimeters in the past century. The sea level change has a high correlation with the trend of global surface air temperature. A large part of the sea level rise can be accounted for in terms of the thermal expansion of the upper layers of the ocean. The results also represent weak indirect evidence for a net melting of the continental ice sheets.
Microinjection of a Conserved Peptide Sequence of p34

cdc2

Induces a Ca
2+
Transient in Oocytes
Authors: Picard André , Cavadore Jean-Claude , Lory Philippe , Bernengo Jean-Claude , Ojeda Carlos , Dorée Marcel
Published: October 2006

The product of the yeast cell cycle control gene
cdc2
, and its homologs in higher eukaryotes (p34

cdc2

), all contain a perfectly conserved sequence of 16 amino acids that has not been found in any other protein sequence. Microinjection of this peptide triggers a specific increase in the concentration of intracellular free Ca
2+
that originates from intracellular stores in both starfish and
Xenopus
oocytes. Thus, p34

cdc2

might interact through its conserved peptide domain with some component of the Ca
2+
-regulatory system.
Steady-State Coupling of Ion-Channel Conformations to a Transmembrane Ion Gradient
Authors: Richard Edwin A. , Miller Christopher
Published: October 2006

Under stationary conditions, opening and closing of single
Torpedo
electroplax chloride channels show that the number of transitions per unit time between inactivated and conducting states are unequal in opposite directions. This asymmetry, which increases with transmembrane electrochemical gradient for the chloride ion, violates the principle of microscopic reversibility and thus demonstrates that the channel-gating process is not at thermodynamic equilibrium. The results imply that the channel's conformational states are coupled to the transmembrane electrochemical gradient of the chloride ion.
Dominance in Fishes: The Relation Between Environment and Abundance
Authors: Skud Bernard Einar
Published: October 2006

Changes in abundance of dominant species of fish were positively correlated with environmental factors that improved survival, and abundance of the subordinate species was negatively correlated with the same factors. When dominance changed, the responses of both the dominant and subordinate species also changed. Implicit in this inverse relation is the conclusion that the abundance of the subordinate depends on the density of the dominant species, and this hierarchy must be recognized in the interpretation of the correlations. Changes in dominance not only explained why the response of a species changed from positive to negative, but also why different stocks did not respond in the same way to temperature. The findings support the thesis that climatic factors can affect the abundance of a species but do not govern its absolute population density. The results have important implications for fishery management.
Mass Mortality and Its Environmental and Evolutionary Consequences
Authors: Hsü Kenneth J. , He Q. , McKenzie Judith A. , Weissert Helmut , Perch-Nielsen Katharina , Oberhänsli Hedy , Kelts Kerry , LaBrecque John , Tauxe Lisa , Krähenbühl Urs , Percival Stephen F. , Wright Ramil , Karpoff Anne Marie , Petersen Nikolai , Tucker Peter , Poore Richard Z. , Gombos Andrew M. , Pisciotto Kenneth , Carman Max F. , Schreiber Edward
Published: October 2006

The latest Mesozoic and earliest Tertiary sediments at Deep Sea Drilling Project site 524 provide an amplified record of environmental and biostratographic changes at the end of Cretaceous. Closely spaced samples, representing time intervals as short as 10
2
or 10
3
years, were analyzed for their bulk carbonate and trace-metal compositions, and for oxygen and carbon isotopic compositions. The data indicate that at the end of Cretaceous, when a high proportion of the ocean's planktic organisms were eliminated, an associated reduction in productivity led to a partial transfer of dissolved carbon dioxide from the oceans to the atmosphere. This resulted in a large increase of the atmospheric carbon dioxide during the next 50,000 years, which is believed to have caused a temperature rise revealed by the oxygen-isotope data. The lowermost Tertiary sediments at site 524 include fossils with Cretaceous affinities, which may include both reworked individuals and some forms that survived for a while after the catastrophe. Our data indicate that many of the Cretaceous pelagic organisms became extinct over a period of a few tens of thousands of years, and do not contradict the scenario of cometary impact as a cause of mass mortality in the oceans, as suggested by an iridium anomaly at the Cretaceous-Tertiary boundary.
Venus Was Wet: A Measurement of the Ratio of Deuterium to Hydrogen
Authors: Donahue T. M. , Hoffman J. H. , Hodges R. R. , Watson A. J.
Published: October 2006

The deuterium-hydrogen abundance ratio in the Venus atmosphere was measured while the inlets to the Pioneer Venus large probe mass spectrometer were coated with sulfuric acid from Venus' clouds. The ratio is (1.6 ± 0.2) × 10
–2
. The hundredfold enrichment of deuterium means that at least 0.3 percent of a terrestrial ocean was outgassed on Venus, but is consistent with a much greater production.
Curiosities in Periodic Precipitation Patterns
Authors: Müller Stefan C. , Kai Shoichi , Ross John
Published: October 2006

Observations have been made of several types of Liesegang patterns that are more complex than the usual concentric rings or parallel bands of precipitate. The structures observed show radial gaps, segmentation, irregular patterns within concentric rings, and the formation of spiral precipitation bands instead of sets of parallel Liesegang bands.
Evidence for a Major Meteorite Impact on the Earth 34 Million Years Ago: Implication for Eocene Extinctions
Authors: Ganapathy R.
Published: October 2006

A deep-sea core from the Caribbean contains a layer of sediment highly enriched in meteoritic iridium. This layer underlies a layer of North American microtektites dated at 34.4 million years ago and coincides with the extinction of five major species of Radiolaria. It is suggested that a massive, chemically undifferentiated meteorite collided with the earth, producing the tektites and leading to extinctions 34 million years ago.
Spherical Crystallization: Direct Spherical Agglomeration of Salicylic Acid Crystals During Crystallization
Authors: Kawashima Yoshiaki , Okumura Motonari , Takenaka Hideo
Published: October 2006

Direct spherical agglomeration of salicylic acid crystals during crystallization is described. The needle-like salicylic acid crystals simultaneously form and agglomerate in a mixture of three partially miscible liquids, such as water, ethanol, and chloroform, with agitation. The agglomerates can be made directly into tablets because of their excellent flowability. Spherical crystallization could eliminate the usual separate agglomeration step after crystallization and may be adaptable to other pharmaceutical and chemical systems.
Induction of AIDS in Rhesus Monkeys by Molecularly Cloned Simian Immunodeficiency Virus
Authors: Kestler Harry , Kodama Toshiaki , Ringler Douglas , Marthas Marta , Pedersen Niels , Lackner Andrew , Regier Dean , Sehgal Prabhat , Daniel Muthiah , King Norval , Desrosiers Ronald
Published: October 2006

Better understanding of the pathogenesis of acquired immunodeficiency syndrome (AIDS) would be greatly facilitated by a relevant animal model that uses molecularly cloned virus of defined sequence to induce the disease. Such a system would also be of great value for AIDS vaccine research. An infectious molecular clone of simian immunodeficiency virus (SIV) was identified that induces AIDS in common rhesus monkeys in a time frame suitable for laboratory investigation. These results provide another strong link in the chain of evidence for the viral etiology of AIDS. More importantly, they define a system for molecular dissection of the determinants of AIDS pathogenesis.
Mediation of Wound-Related Rous Sarcoma Virus Tumorigenesis by TGF-β
Authors: Sieweke Michael H. , Thompson Nancy L. , Sporn Michael B. , Bissell Mina J.
Published: October 2006

In Rous sarcoma virus (RSV)-infected chickens, wounding leads to tumor formation with nearly 100% frequency in tissues that would otherwise remain tumor-free. Identifying molecular mediators of this phenomenon should yield important clues to the mechanisms involved in RSV tumorigenesis. Immunohistochemical staining showed that TGF-β is present locally shortly after wounding, but not in unwounded controls. In addition, subcutaneous administration of recombinant transforming growth factor-β1 (TGF-β1) could substitute completely for wounding in tumor induction. A treatment protocol of four doses of 800 nanograms of TGF-β resulted in v-
src
-expressing tumors with 100% frequency; four doses of only 10 nanograms still led to tumor formation in 80% of the animals. This effect was specific, as other growth factors with suggested roles in wound healing did not elicit the same response. Epidermal growth factor (EGF) or TGF-α had no effect, and platelet-derived growth factor (PDGF) or insulin-like growth factor-1 (IGF-1) yielded only occasional tumors after longer latency. TGF-β release during the wound-healing response may thus be a critical event that creates a conducive environment for RSV tumorigenesis and may act as a cofactor for transformation in this system.
Isotopic Paleoceanography of the Caribbean and East Pacific: Role of Panama Uplift in Late Neogene Time
Authors: Keigwin Lloyd
Published: October 2006

Comparisons of carbon isotopic data on benthic foraminifera from Deep Sea Drilling Project sites 502 (western Caribbean) and 503 (eastern Pacific) indicate that the difference between the Atlantic and the Pacific in the per mil enrichment in carbon-13 of total dissolved carbon dioxide increased about 6 million years ago and again 3 million years ago, when the difference reached the modern level (1 per mil). Comparisons of planktonic foraminiferal oxygen isotopic data for the Caribbean and the Pacific suggest that the salinity of Caribbean surface waters began increasing 4 million years ago, possibly in response to shoaling of the Panama isthmus. These results suggest that modern circulation patterns in the Caribbean and eastern Pacific developed by 3 million years ago in concert with changing tectonic, climatic, and biogeographic patterns.
Computer-Assisted Mapping of Pyroclastic Surges
Authors: Malin Michael C. , Sheridan Michael F.
Published: October 2006

Volcanic hazard maps of surge boundaries and deposit thickness can be created by using a simplified eruption model based on an "energy line" concept of pyroclastic surge and flow emplacement. Computer image-processing techniques may be used to combine three-dimensional representations of the energy relations of pyroclasts moving under the influence of gravity (defined by an "energy cone") with digital topographic models of volcanoes to generate theoretical hazard maps. The deposit boundary and thickness calculated for the 18 May 1980 eruption of Mount St. Helens are qualitatively similar to those actually observed.
Trace Fossils from the Athabasca Oil Sands, Alberta, Canada
Authors: Pemberton S. George , Flach Peter D. , Mossop Grant D.
Published: October 2006

A diverse and well-preserved ichnofossil suite has been identified from surface exposures of the middle and upper parts of the Lower Cretaceous McMurray Formation. The suite, consisting of representatives of at least ten ichnogenera, is one of the few clues to the original biotic component of the deposit. The distribution and abundance of these biogenic structures present strong evidence that the deep channel complex in which the sediments were deposited was closely associated with a nearby marine shoreline.
Repopulating the Countryside: A 1980 Census Trend
Authors: Long Larry , DeAre Diana
Published: October 2006

Census data confirm that in the 1970's population grew more rapidly outside than inside metropolitan territory, reversing a historic pattern. The new data reveal that the dispersion of population growth beyond metropolitan areas was not so much a movement to small towns as a movement to the open countryside. The trends appear strong enough to suggest a new shift toward rural life-styles.
Termites: A Potentially Large Source of Atmospheric Methane, Carbon Dioxide, and Molecular Hydrogen
Authors: Zimmerman P. R. , Greenberg J. P. , Wandiga S. O. , Crutzen P. J.
Published: October 2006

Termites may emit large quantities of methane, carbon dioxide, and molecular hydrogen into the atmosphere. Global annual emissions calculated from laboratory measurements could reach 1.5 × 10
14
grams of methane and 5 × 10
16
grams of carbon dioxide. As much as 2 × 10
14
grams of molecular hydrogen may also be produced. Field measurements of methane emissions from two termite nests in Guatemala corroborated the laboratory results. The largest emissions should occur in tropical areas disturbed by human activities.
The Staphylococcal Enterotoxins and Their Relatives
Authors: Marrack P , Kappler J
Published: October 2006

Staphylococcal enterotoxins and a group of related proteins made by
Streptococci
cause food poisoning and shock in man and animals. These proteins share an ability to bind to human and mouse major histocompatibility complex proteins. The complex ligand so formed has specificity for a particular part of T cell receptors, V
β
, and by engaging V
β
can stimulate many T cells. It is likely that some or all of the pathological effects of these toxins are caused by their ability to activate quickly so many T cells. It is also possible that encounters with such toxins have caused mice, at least, to evolve mechanisms for varying their T cell V
β
repertoires, such that they are less susceptible to attack by the toxins.
Hardened Subtidal Stromatolites, Bahamas
Authors: Dravis Jeffrey J.
Published: October 2006

Hardened, high-relief stromatolites have been discovered along the margins of some Bahamian platforms. They occur in high-energy (tidal) oolitic sand environments in waters ranging in depth from about 1 to 5 meters. Physical stress produced by actively migrating bed forms of oolitic sand appears to exclude grazing gastropods and subsequent community successions, permitting stromatolite growth.
The Cretaceous-Tertiary Transition
Authors: Officer Charles B. , Drake Charles L.
Published: October 2006

The fossil sequences from cores across the Cretaceous-Tertiary boundary show a range of transition times and transition time intervals depending on the fossil indicators and the location of the site. These variations, together with the pattern of iridium distribution with depth at some sites, differences in total amounts of iridium, variations in noble metal abundances normalized to extraterrestrial concentrations, the depositional effects that might be expected in a reducing environment, and the clay mineralogy of the boundary layer clays, put into question the interpretation that an extraterrestrial event was the cause of the faunal changes and the iridium anomaly in the vicinity of the Cretaceous-Tertiary transition. It seems more likely that an explanation for the changes during the transition will come from continued examination of the great variety of terrestrial events that took place at that time, including extensive volcanism, major regression of the sea from the land, geochemical changes, and paleoclimatic and paleoceanographic changes.
The Separation of Madagascar and Africa
Authors: Rabinowitz Philip D. , Coffin Millard F. , Falvey David
Published: October 2006

Identification of a sequence of east-west trending magnetic anomalies of Mesozoic age in the western Somali Basin helps define the position of Madagascar in the Gondwana reconstruction. The anomalies are symmetric about ancient ridge segments and are flanked to the north and south by the Jurassic magnetic quiet zone. The motion of Madagascar relative to Africa was from the north and began in the middle Jurassic, about the same time as the initial breakup of Gondwanaland. Sea-floor spreading ceased when Madagascar assumed its present position in the Early Cretaceous.
Photochemical Formation of Hydrogen Peroxide in Surface and Ground Waters Exposed to Sunlight
Authors: Cooper William J. , Zika Rod G.
Published: October 2006

A rapid increase in the concentration of hydrogen peroxide was observed when samples of natural surface and ground water from various locations in the United States were exposed to sunlight. The hydrogen peroxide is photochemically generated from organic constituents present in the water; humic materials are believed to be the primary agent producing the peroxide. Studies with superoxide dismutase suggest that the superoxide anion is the precursor of the peroxide.
Multiple Microtektite Horizons in Upper Eocene Marine Sediments: No Evidence for Mass Extinctions
Authors: Keller Gerta , D'Hondt Steven , Vallier Tracy L.
Published: October 2006

Microtektites have been recovered from three horizons in eight middle Eocene to middle Oligocene marine sediment sequences. Five of these occurrences are coeval and of latest Eocene age (37.5 to 38.0 million years ago); three are coeval and of early late Eocene age (38.5 to 39.5 million years ago); and three are of middle Oligocene age (31 to 32 million years ago). In addition, rare probable microtektites have been found in sediments with ages of about 36.0 to 36.5 million years. The microtektite horizon at 37.5 to 38.0 million years can be correlated with the North American tektite-strewn field, which has a fission track age (minimum) of 34 to 35 million years and a paleomagnetic age of 37.5 to 38.0 million years. There is no evidence for mass faunal extinctions at any of the microtektite horizons. Many of the distinct faunal changes that occurred in the middle Eocene to middle Oligocene can be related to the formation of the Antarctic ice sheet and the associated cooling phenomena and intensification of bottom currents that led to large-scale dissolution of calcium carbonate and erosion, which created areally extensive hiatuses in the deep-sea sediment records. The occurrence of microtektite horizons of several ages and the lack of evidence for faunal extinctions suggest that the effects of extraterrestrial bolide impacts may be unimportant in the biologic realm during middle Eocene to middle Oligocene time.