bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Atmospheric Circulation over North America During the Early Holocene: Evidence from Lake Superior
Authors: Halfman John D. , Johnson Thomas C.
Published: October 2006

Profiles of grain sizes in five cores recovered from Lake Superior show that grain size increased with burial depth to the postglacial-glacial contact. The results reflect a substantial reduction in bottom-current velocity and the corresponding wind velocity from 9500 to 6500 years ago.
Topography from Single Radar Images
Authors: Wildey Robert L.
Published: October 2006

A mathematical theory and a corresponding numerical procedure have been developed to produce digital topography from radar images as digital photometric arrays. Thus, as radargrammetry is to photogrammetry, so radarclinometry is to photoclinometry. Photoclinometry encompasses a fundamental indeterminacy principle even for terrain that is homogeneous in normal albedo, because the surface normal consistent with a given reflected specific intensity is not unique. A geometric locus of such normal directions is implied, which generates a surface. For microwave backscatter, in specific application to radarclinometry, this surface is a cone whose half-angle is the incidence angle, whose axis contains the radar, and whose apex coincides with the terrain point. Although the indeterminacy can be removed if a properly directed profile of ground truth is available as a constraint, such is seldom the case. In its absence, an auxiliary assumption, such as that the strike line runs perpendicular to the illumination line, is needed. If metric integrity is a goal, then this is an absurd assumption. Herein, "the hypothesis of local cylindricity" has been assumed, a premise regarding the nature of topographic curvature that seems more realistic and that makes possible the production of topography as a set of parallel line integrals.
Ocean Circulation: Its Effects on Seasonal Sea-Ice Simulations
Authors: Hibler W. D. , Bryan Kirk
Published: October 2006

A diagnostic ice-ocean model of the Arctic, Greenland, and Norwegian seas is constructed and used to examine the role of ocean circulation in seasonal sea-ice simulations. The model includes lateral ice motion and three-dimensional ocean circulation. The ocean portion of the model is weakly forced by observed temperature and salinity data. Simulation results show that including modeled ocean circulation in seasonal sea-ice simulations substantially improves the predicted ice drift and ice margin location. Simulations that do not include lateral ocean movement predict a much less realistic ice edge.
Use of Carbon Dioxide in Enhanced Oil Recovery
Authors: Orr F. M. , Taber J. J.
Published: October 2006

Large volumes of oil will remain in U.S. oil reservoirs when standard recovery methods have been completed. Supercritical carbon dioxide can be used to recover part of that remaining oil. If carbon dioxide is dense enough, it extracts hydrocarbons from the oil to make a mixture miscible with crude oil. Such a mixture can recover 95 percent of the oil in controlled laboratory flow settings. Heterogeneity of reservoir rocks and the low viscosity of carbon dioxide reduce the fraction of oil recovered in projects to lower but still significant levels. With the construction of three pipelines to carry naturally occurring carbon dioxide from Colorado and New Mexico to Permian basin oil fields, large-scale implementation of enhanced oil recovery by carbon dioxide flooding is now beginning.
The Origin of Galaxies and Clusters of Galaxies
Authors: Peebles P. J. E.
Published: October 2006

Debate on how galaxies and clusters of galaxies formed has reached an interesting stage at which one can find arguments for quite different scenarios. The galaxy distribution has a complex "frothy" character that could be the fossil of a network of protoclusters or pancakes that produced galaxies. However, there are galaxies like our own that seem never to have been in a protocluster but are physically similar to the galaxies in dense clusters. Some clues to be assessed in resolving this dilemma are the possible existence of galaxy filaments, the relative ages of galaxies and clusters of galaxies, and the continuity between cluster and field galaxies and between galaxies and clusters of galaxies.
Inherently Safe Reactors and a Second Nuclear Era
Authors: Weinberg Alvin M. , Spiewak Irving
Published: October 2006

The Swedish PIUS reactor and the German-American small modular high-temperature gas-cooled reactor are inherently safe—that is, their safety relies not upon intervention of humans or of electromechanical devices but on immutable principles of physics and chemistry. A second nuclear era may require commercialization and deployment of such inherently safe reactors, even though existing light-water reactors appear to be as safe as other well-accepted sources of central electricity, particularly hydroelectric dams.
Specific Nonopiate Receptors for β-Endorphin
Authors: Hazum Eli , Chang Kwen-Jen , Cuatrecasas Pedro
Published: October 2006

Iodinated β
H
-[2-D-alanine]endorphin exhibits specific binding to cultured human lymphocytes. The binding is inhibited by low concentrations of β-endorphin and its D-alanine
2
derivative, but is not affected by opiate agonists and antagonists, or by enkephalin analogs, β-lipotropin, adrenocorticotrophic hormone, or α-melanocyte-stimulating hormone; this suggests the existence of a specific, nonopiate binding site (receptor) for β-endorphin. The carboxy-terminal region of β-endorphin is essential for this binding activity, since α-endorphin is not active. β-Endorphin may be a circulating hormone with peripheral physiological effects that are not primarily mediated through interactions with opiate or enkephalin receptors.
Molecular Cloning of Polyoma Virus DNA in
Escherichia coli
: Oncogenicity Testing in Hamsters
Authors: Israel Mark A. , Chan Hardy W. , Martin Malcolm A. , Rowe Wallace P.
Published: October 2006

Inoculation of suckling hamsters with 2 × 10
8
live cells of
Escherichia coli
K12 strain χ1776, carrying the complete genome of polyoma virus in a recombinant plasmid, failed to induce tumors in any of 32 recipients. Also, lambda phage DNA and particles with a monomeric insert of polyoma DNA did not induce tumors. Purified recombinant plasmid DNA, as well as phage particles and DNA containing a head-to-tail dimer of polyoma DNA, showed a low degree of oncogenicity, comparable to that of polyoma DNA prepared from mouse cells. These findings support the previous conclusions, based on infectivity assays in mice, that propagation of polyoma virus DNA as a component of recombinant DNA molecules in
E. coli
K12 reduces its biologic activity many orders of magnitude relative to the virus itself.
Unidirectional Solidification of Cast Iron
Authors: Luyendijk T. , Nieswaag H. , Alsem W. H. M.
Published: October 2006

The segregation of sulfur in liquid cast iron was studied under conditions of microgravity on Spacelab 1. A rod of cast iron containing carbon, silicon, sulfur, and phosphorus was unidirectionally solidified at four different rates. The influence of sulfur on the graphite structure and the stability of an aluminum oxide skin deposited on the surface of the specimen were investigated.
Tribology Experiment in Zero Gravity
Authors: Pan C. H. T. , Gause Raymond L. , Whitaker Ann F.
Published: October 2006

A tribology experiment in zero gravity was performed during the orbital flight of Spacelab 1 to study the motion of liquid lubricants over solid surfaces. The absence of a significant gravitational force facilitates studies of the motion of liquid lubricants over solid surfaces as controlled by interfacial and capillary forces. Observations were made of phenomena associated with the liquid on one solid surface and also with the liquid between a pair of closely spaced surfaces. Typical photographic records obtained on Spacelab 1 are described.
The Fine Structure of Fossil Plant Cell Walls
Authors: Smoot Edith L. , Taylor Thomas N.
Published: October 2006

The cell walls of sieve elements in the primary phloem of the Carboniferous fern
Tubicaulis
contain structural features that morphologically resemble cellulose microfibrils in extant plants. This may be the oldest example of distinct fibrillar structures in the fossil record. The possible identity and significance of these features are discussed and their structure is compared with that of cell walls in other fossil and extant plants.
The Magnetic Activity Sunlike Stars
Authors: Vaughan Arthur H.
Published: October 2006

Sunspots, flares, and the myriad time-varying "events" observable in the Sun—the only star whose surface we can examine in detail—are testimony that the Sun is a magnetically variable or active star. Its magnetic field, carried into interplanetary space by the solar wind, produces observable changes in Earth's magnetosphere and variations in the flux of galactic cosmic-ray particles incident upon Earth's upper atmosphere. Centuries of observation have enabled solar scientists to recognize that the Sun's magnetism exists and varies in a globally organized pattern that is somehow coupled to the Sun's rotation. Within the past decade O. C. Wilson demonstrated that analogs of solar activity exist and can be studied in many other dwarf stars. From the continuing study, knowledge of the precise rates of rotation of the stars under investigation is being gained for the first time. The results are expected to increase our understanding of the origin of solar activity and stellar activity in general.
Spread of
Diadema
Mass Mortality Through the Caribbean
Authors: Lessios H. A. , Robertson D. R. , Cubit J. D.
Published: October 2006

Populations of the ecologically important sea urchin
Diadema antillarum
suffered severe mass mortalities throughout the Caribbean. This mortality was first observed at Panama in January 1983; by January 1984 it had spread to the rest of the Caribbean and to Bermuda. The sequence of mortality events in most areas is consistent with the hypothesis that the causative agent was dispersed by major surface currents over large distances. However, some of the late die-offs in the southeastern Caribbean do not fit this pattern. Several lines of indirect evidence suggest that the phenomenon is due to a water-borne pathogen. If so, this is the most extensive epidemic documented for a marine invertebrate.
Photocontraction of Liquid Spiropyran-Merocyanine Films
Authors: Cabrera Ivan , Shvartsman Felix , Veinberg Olga , Krongauz Valeri
Published: October 2006

Amorphous films of a photochromic spiropyran containing a mesogenic group melt, when exposed to heat together with irradiation, to yield a red fluid. This fluid contains aggregates of merocyanine molecules and exhibits marked contraction under light illumination. The mechanism of the photocontraction is dependent upon a specialized microstructure, which may be termed a "quasi-liquid."
Noninvasive Three-Dimensional Computer Imaging of Matrix-Filled Fossil Skulls by High-Resolution Computed Tomography
Authors: Conroy Glenn C. , Vannier Michael W.
Published: October 2006

A noninvasive computer imaging technique allows three-dimensional images of fossil skulls to be generated from two-dimensional serial computerized tomographic scan data. The computer programs can "dissect" the skull in different planes by making portions of it and any obstructing matrix transparent in order to reveal intracranial morphology. The computer image is geometrically precise so that linear distances, angles, areas, volumes, and evaluations of symmetry can be determined.
Aldehyde Pheromones in Lepidoptera: Evidence for an Acetate Ester Precursor in
Choristoneura fumiferana
Authors: Morse David , Meighen Edward
Published: October 2006

Labeling studies of the eastern spruce budworm in vivo indicate that
trans
-11-tetradecenyl acetate is synthesized specifically in the pheromone-producing gland and is degraded in concert with pheromone release; hence it may be a precursor to the
trans
-11-tetradecenal pheromone. Radioactivity from exogenously added labeled fatty acids did not appear to be directly incorporated into the ester, suggesting that de novo biosynthesis from acetate is the major route of ester biosynthesis. Conversion of the acetate ester to alcohol and aldehyde functional groups may be the principal method of regulating pheromone specificity between species of
Choristoneura
.
Subtropical Atlantic Climate Studies: Introduction
Authors: Molinari Robert L. , Maul George A. , Chew Frank , Wilson William D. , Bushell Mark , Mayer Dennis , Leaman Kevin , Schott Friedrich , Lee Tom , Zantopp Rainer , Larsen Jimmy C. , Sanford Thomas B.
Published: October 2006

This report is an introduction to the accompanying collection of reports that present the results of a 2-year period of intensive monitoring of the Florida Current. Both direct observing systems (ship-deployed current profilers and moored current meters) and indirect observing systems (coastal tide gauge stations, bottom pressure gauge arrays, a submarine cable, acoustic arrays, and radar installations) were used to measure temperature and volume transport.
Laser Probing of Chemical Reaction Dynamics
Authors: Leone Stephen R.
Published: October 2006

Lasers are used in increasingly sophisticated ways to carry out reactions between molecules in selected vibrational, rotational, and electronic states and to probe the product states of chemical reactions. Such investigations are providing unprecedented insights into chemical reaction dynamics, the study of the detailed motions that molecules undergo in simple chemical reactions. In many cases it is possible to describe the influence that specific types of molecular excitation have on reactive events. Experiments are also being carried out to learn about chemical reactivity as a function of the alignment of reagents. There is increasing excitement concerning the potential of laser methods to interrogate the transition states of molecular reactions.
Exotic Nuclei and Their Decay
Authors: Hardy J. C.
Published: October 2006

Recent advances in nuclear accelerators and experimental techniques have led to an increased ability to synthesize new isotopes. As isotopes are produced with more and more extreme combinations of neutrons and protons in their nuclei, new phenomena are observed, and the versatility of the nucleus is increased as a laboratory for studying fundamental forces. Among the newly discovered decay modes are (i) proton radioactivity, (ii) triton, two-proton, two-neutron, and three-neutron decays that are β-delayed, as well as (iii)
14
C emission in radioactive decay. Precise tests of the properties of the weak force have also been achieved.
Ground Water as a Silica Source for Diatom Production in a Precipitation-Dominated Lake
Authors: Hurley James P. , Armstrong David E. , Kenoyer Galen J. , Bowser Carl J.
Published: October 2006

The short-term, seasonal input of ground water to a small, precipitation-dominated oligotrophic lake in northern Wisconsin amounts to less than 10 percent of the annual water budget of the lake but accounts for nearly all the external silica loading. Silica is a necessary nutrient for diatoms. A large spring diatom bloom occurs coincident with high silica inputs from ground water when other possible silica sources are low. The mass budgets of ground water and silica in the lake system demonstrate the importance of ground-water solute inputs to the lake.
Zinc Mediation of the Binding of Human Growth Hormone to the Human Prolactin Receptor
Authors: Cunningham Brian C. , Bass Steven , Fuh Germaine , Wells James A.
Published: October 2006

Human growth hormone (hGH) elicits a diverse set of biological activities including lactation that derives from binding to the prolactin (PRL) receptor. The binding affinity of hGH for the extracellular binding domain of the hPRL receptor (hPRLbp) was increased about 8000-fold by addition of 50 micromolar ZnCl
2
. Zinc was not required for binding of hGH to the hGH binding protein (hGHbp) or for binding of hPRL to the hPRLbp. Other divalent metal ions (Ca
2+
, Mg
2+
, Cu
2+
, Mn
2+
, and Co
2+
) at physiological concentrations did not support such strong binding. Scatchard analysis indicated a stoichiometry of one Zn
2+
per hGH⋅hPRLbp complex. Mutational analysis showed that a cluster of three residues (His
18
, His
21
, and Glu
174
) in hGH and His
188
from the hPRLbp (conserved in all PRL receptors but not GH receptors) are probable Zn
2+
ligands. This polypeptide hormone-receptor "zinc sandwich" provides a molecular mechanism to explain why nonprimate GHs are not lactogenic and offers a molecular link between zinc deficiency and its association with altered functions of hGH.
Avian and Mammalian Mitochondrial Ammonia-Detoxifying Systems in Tortoise Liver
Authors: Campbell James W. , Smith Darwin D. , Vorhaben Jean E.
Published: October 2006

Liver mitochondria from the desert tortoise
Gopherus agassizii
and the Texas tortoise
G. berlandieri
contain glutamine synthetase, the enzyme used by birds and higher reptiles to detoxify ammonia generated intramitochondrially during amino acid catabolism. Tortoise mitochondria also contain carbamyl phosphate synthetase-I and ornithine transcarbamylase, the enzymes used by mammals for this purpose. Since chelonid reptiles have changed little since their divergence from the stem reptiles, this finding suggests that both systems were present in the latter before the emergence of the ruling reptile, avian, and mammalian lines of descent.
Personal Computers on Campus
Authors: Waldrop M. Mitchell
Published: October 2006

Colleges and universities are becoming test beds for the much-heralded "information society" as they incorporate a new series of information technologies. These include on-line databases, magnetic and optical data storage, digital telecommunications, computer networks, and, most visibly and dramatically, personal computers. The transition is presenting administrators and faculty with major challenges, however. This article discusses some of the issues involved, including access to computers and to computer networking, managing the transition, and the educational uses of personal computers. A final section discusses efforts at Massachusetts Institute of Technology, Brown University, and Carnegie-Mellon University to shape a new-generation personal computer, the so-called "scholar's workstation."
A Theory for El Niño and the Southern Oscillation
Authors: Cane Mark A. , Zebiak Stephen E.
Published: October 2006

A coupled atmosphere-ocean model is presented for El Niño and the Southern Oscillation that reproduces its major features, including its recurrence at irregular intervals. The interannual El Niño-Southern Oscillation cycle is maintained by deterministic interactions in the tropical Pacific region. Ocean dynamics alter sea-surface temperature, changing the atmospheric heating; the resulting changes in surface wind alter the ocean dynamics. Annually varying mean conditions largely determine the spatial pattern and temporal evolution of El Niño events.
The Very Long Baseline Array
Authors: Kellermann K. I. , Thompson A. R.
Published: October 2006

The Very Long Baseline Array is a high-resolution synthesis radio telescope consisting of ten antennas, each 25 meters in diameter, located throughout the United States from Puerto Rico to Hawaii. Each antenna will be equipped with low-noise receivers spaced throughout the frequency range from 330 megahertz to 43 gigahertz, a hydrogen-maser frequency standard for time and frequency reference, and broadband digital tape recorders. Tapes recorded at each antenna will be simultaneously replayed and correlated in a specially built digital correlator, and the correlator output will, by Fourier transformation, be used to construct images of celestial radio sources with an angular resolution better than one thousandth of an arc second.
Conservation Genetics of Endangered Fish Populations in Arizona
Authors: Vrijenhoek Robert C. , Douglas Michael E. , Meffe Gary K.
Published: October 2006

Genetic diversity in remnant populations of the Sonoran topminnow
Poeciliopsis occidentalis
(Pisces: Poeciliidae) from Arizona, where the species is endangered, is compared with that in populations from Sonora, Mexico, where the fish is widespread and abundant. Geographically peripheral Arizona populations contain substantially lower levels of genetic variation than do Mexican populations near the center of the species' range. Allelic differences among three genetically and geographically distinct groups are responsible for 53 percent of the total genetic diversity in this species, 26 percent is due to differences among local populations within the groups, and 21 percent is due to heterozygosity within local populations. Recommendations for conservation and restocking efforts in Arizona are based on these genetic findings.
Reforms and Open Policy in China
Authors: Jian Song
Published: October 2006

Reforms of the economic and research and development management systems are spreading far and wide in China in a planned manner. The creative and pragmatic spirit demonstrated by the Chinese government in these reforms has won enthusiastic support of the Chinese people and aroused keen interest of statesmen, economists, and scientists the world over. The four previously established special economic zones, the opening up of 14 coastal cities and Hainan Island to foreign investment, and the smooth settlement of the Hong Kong issue by means of "one country, two systems" have brought new splendor to China's reforms. Many people in the press regard the decision of "one country, two systems" as the most courageous and fascinating creation of the 20th century.
Mid-Oligocene Extinction Event in North American Land Mammals
Authors: Prothero Donald R.
Published: October 2006

Interest in extraterrestrial causes for the apparent 26- to 32-million-year periodicity of mass extinctions has focused on the terminal Eocene event and older events, although there is now evidence of a mid-Oligocene event near the early/late Oligocene boundary, or about 32.4 million years ago. An abrupt (200,000 years or less) mid-Oligocene extinction event appears in the record of North American land mammals, which results in the selective disappearance of archaic members of the fauna and later diversification of other taxa. The selective nature of the extinctions suggests climatic and ecological causes rather than an extraterrestrial catastrophe. Increased mid-Oligocene glaciation, worldwide cooling, a major regression event, and abrupt changes in the flora are probably the immediate causes, and these may have resulted from changes in global oceanic circulation.
A Local Time-Dependent Sverdrup Balance in the Eastern North Pacific Ocean
Authors: Niiler Pearn P. , Koblinsky Chester J.
Published: October 2006

Direct observations of the dynamic balance between time-dependent winds and deep ocean currents are described for the eastern North Pacific Ocean at 42°N, 152°W. Currents from 150 to 4000 meters below the surface at frequencies from 0.01 to 0.1 cycle per day are significantly correlated with the wind stress curl derived from U.S. Navy operational wind fields. The horizontal currents are depth-independent below 300 meters, and they flow parallel to the potential vorticity gradient derived from the earth's rotation and the large-scale bottom topography. These characteristics are expected for such periodic motions with horizontal scales larger than 500 kilometers and represent a generalized Sverdrup balance between the atmospheric forcing and the oceanic response.
Derepression of Ferritin Mmessenger RNA Translation by Hemin in Vitro
Authors: Lin Jih-Jing , Daniels-McQueen Susan , Patino Maria M. , Gaffield Livia , Walden William E. , Thach Robert E.
Published: October 2006

Incubation of a 90-kilodalton ferritin repressor protein (FRP), either free or complexed with an L-ferritin transcript, with hemin or Co
3+
-protoporphyrin IX prevented subsequent repression of ferritin synthesis in a wheat germ extract. Neither FeCl
3
in combinations with H
2
O
2
, nor Fe
3+
or Fe
2+
chelated with EDTA, nor Zn
2+
-protoporphyrin IX, nor protoporphyrin IX caused significant inactivation of FRP. FRP that had been inactivated by hemin remained chemically intact, as revealed by SDS-polyacrylamide gel electrophoresis. Inclusion of chelators of iron or free radical scavengers did not alter the inactivation produced by hemin. These and other results indicate that hemin derepresses ferritin synthesis in vitro.
Halite Particles Injected into the Stratosphere by the 1982 El Chichón Eruption
Authors: Woods David C. , Chuan Raymond L. , Rose William I.
Published: October 2006

Halite particles about 2 micrometers in size were collected by a quartz crystal microbalance cascade impactor from the El Chichón eruption cloud in the lower stratosphere during April and May 1982. These particles are probably derived from the erupted chloride-rich, alkalic magma. Enrichments of hydrogen chloride and increases in optical depolarization in the eruption cloud observed by lidar measurements may reflect the influence of the halite particles. There is evidence that the halite particles reacted with sulfuric acid after about 1 month, releasing gaseous hydrogen chloride, which can influence the catalytic destruction of ozone in the stratosphere.
Slow Neutron Scattering Experiments
Authors: Moon Ralph M.
Published: October 2006

Neutron scattering is a versatile technique that has been successfully applied to condensed-matter physics, biology, polymer science, chemistry, and materials science. The United States lost its leadership role in this field to Western Europe about 10 years ago. Recently, a modest investment in the United States in new facilities and a positive attitude on the part of the national laboratories toward outside users have resulted in a dramatic increase in the number of U.S. scientists involved in neutron scattering research. Plans are being made for investments in new and improved facilities that could return the leadership role to the United States.
Predation in the Paleozoic: Gastropod-Like Drillholes in Devonian Brachiopods
Authors: Smith Stephanie A. , Thayer Charles W. , Brett Carlton E.
Published: October 2006

Middle Devonian articulate brachiopods (Ludlowville and Moscow Formations, Hamilton Group, New York) have external tapered holes with a central boss that are indistinguishable from drillholes of naticid gastropods that are known from the Triassic and later. Drillholes are specific to prey (ribbed shells were avoided) and specific to sites on prey. Healed drillholes suggest penetration of live prey. As many as 44 percent of the preferred prey are drilled, indicating a level of predation that has been reported only from post-Paleozoic strata.
Calcium-Sensitive Cross-Bridge Transitions in Mammalian Fast and Slow Skeletal Muscle Fibers
Authors: Metzger Joseph M. , Moss Richard L.
Published: October 2006

The fundamental mechanism underlying the differing rates of tension development in fast and slow mammalian skeletal muscle is still unknown. Now, in skinned (membrane-permeabilized) single fibers it has been shown that the rate of formation of the strongly bound, force-producing cross-bridge between actin and myosin is calcium-sensitive in both fast and slow fibers and that the rate is markedly greater in fast fibers. The transition rates obtained at high calcium concentrations correlated with myosin isoform content, whereas at low calcium concentrations the thin filament regulatory proteins appeared to modulate the rate of tension development, especially in fast fibers. Fiber type-dependent differences in rates of cross-bridge transitions may account for the characteristic rates of tension development in mammalian fast and slow skeletal muscles.
Selenium in Organic Synthesis
Authors: Liotta Dennis , Monahan Robert
Published: October 2006

The introduction, manipulation, and ultimate removal of selenium-containing functional groups allow a variety of synthetically useful processes to be accomplished in high overall yields under mild conditions. In particular, transformations such as allylic oxidations, nucleophile-induced cleavage reactions, regiospecific alkylations, and olefin cofunctionalizations can be readily achieved by taking advantage of selenium's unique properties.
Ingestion of Petroleum by Seabirds Can Serve as a Monitor of Water Quality
Authors: Boersma P. D.
Published: October 2006

The ingestion by seabirds of fossil fuel hydrocarbons and other pollutants has been of great interest. This paper reports that storm-petrels ingest petroleum at sea and that residues can be detected in their stomach oil. The incidence of gut samples containing fossil fuel hydrocarbons (dirty samples) increased significantly after oil spills, and significantly more birds regurgitated dirty samples after large nearby spills than small distant ones. This appears to be one of the first reported instances where individuals of a natural population of marine birds have been shown to ingest sublethal doses of oil from sources of low-level, long-term pollution or from oil spills. Because of certain natural traits, Procellariiformes could serve as monitors of pollutants in the marine environment.
Massively Parallel Computers: The Connection Machine and NON-VON
Authors: Gabriel Richard P.
Published: October 2006

The demand for high-speed computers is increasing, and as the limits on single-processor computers are approached, researchers are turning their attention to parallel computers. Parallel computers have more than one processing element; massively parallel computers contain many processing elements. Constructing computers on this scale and learning how to program them effectively will be major challenges in the next decade. Several such computers, for example the Connection Machine and the NON-VON, are under development.
The Direction of Membrane Lipid Flow in Locomoting Polymorphonuclear Leukocytes
Authors: Lee Juliet , Gustafsson Mikael , Magnusson Karl-Eric , Jacobson Ken
Published: October 2006

The objective of this study was to determine the direction of membrane lipid flow in locomoting cells. The plasma membrane of human polymorphonuclear leukocytes was stained with a fluorescent lipid analog dihexadecanoyl indocarbocyanine. A line was photobleached on the cell surface perpendicular to the direction of cell motion. Low-light-level fluorescence microscopy and digital image-processing techniques were used to analyze a series of images taken at short intervals after photobleaching. The bleached line remained visible for about 5 seconds before being erased by diffusional recovery. Examination of fluorescence intensity profiles allowed a comparison to be made between the velocities of line and cell movement. Results indicate that the bleached line moves forward with the same velocity as the cell during locomotion, refuting the retrograde lipid flow model of locomotion. Instead, the plasma membrane lipid appears to move forward according to either the unit movement of membrane or the tank track model of locomotion.
The Geochemical Behavior of Aluminum in Acidified Surface Waters
Authors: Nordstrom Darrell Kirk , Ball James W.
Published: October 2006

Speciation calculations for aluminum, in water samples taken from a drainage basin containing acid mine waters, demonstrate a distinct transition from conservative behavior for
p
H below 4.6 to nonconservative behavior for
p
H above 4.9. This transition corresponds to the
pK
for the first hydrolysis constant of the aqueous aluminum ion and appears to be a consistent phenomenon independent of field location, ionic strength, and sulfate concentration. Nonconservative behavior is closely correlated with the equilibrium solubility of a microcrystalline gibbsite or amorphous aluminum hydroxide.
Interannual Variability of Atmospheric Methane: Possible Effects of the El Niño—Southern Oscillation
Authors: Khalil M. A. K. , Rasmussen R. A.
Published: October 2006

Nearly continuous measurements at Cape Meares, Oregon, revealed that methane was increasing in the earth's atmosphere and that its concentration varied cyclically with the seasons. After 6 years of measurements, results show that the rate of increase in methane undergoes interannual variations; the most prominent of these coincided with the last major El Niño—Southern Oscillation, when methane concentrations fell far below expected levels. One of the consequences of the interannual variability is that the long-term rate of increase at Cape Meares is now about 16 parts per billion by volume per year, or about 1 percent annually, which is significantly less than that indicated by the earliest calculations.
Interstellar Molecular Clouds
Authors: Bally John
Published: October 2006

The interstellar medium in our galaxy contains matter in a variety of states ranging from hot plasma to cold and dusty molecular gas. The molecular phase consists of giant clouds, which are the largest gravitationally bound objects in the galaxy, the primary reservoir of material for the ongoing birth of new stars, and the medium regulating the evolution of galactic disks.
Ontogeny in Animal Colonies: A Persistent Trend in the Bryozoan Fossil Record
Authors: Lidgard Scott
Published: October 2006

The principal modes of zooid and colony growth in encrusting cheilostome bryozoans have undergone a major evolutionary transition during the last 100 million years. Comparisons of species within successive North American fossil faunas reveal a persistent trend in which one mode of growth is gradually supplanted by another. Ecological evidence from living faunas and the polyphyletic nature of this trend suggest that the transition has adaptive significance.
El Niño: A Chaotic Dynamical System?
Authors: Vallis Geoffrey K.
Published: October 2006

Most of the principal qualitative features of the El Niño—Southern Oscillation phenomenon can be explained by a simple but physically motivated theory. These features are the occurrence of sea-surface warmings in the eastern equatorial Pacific and the associated trade wind reversal; the aperiodicity of these events; the preferred onset time with respect to the seasonal cycle; and the much weaker events in the Atlantic and Indian oceans. The theory, in its simplest form, is a conceptual model for the interaction of just three variables, namely near-surface temperatures in the east and west equatorial ocean and a wind-driven current advecting the temperature field. For a large range of parameters, the model is naturally chaotic and aperiodically produces El Niño—like events. For a smaller basin, representing a smaller ocean, the events are proportionally less intense.
Plasma Diagnosis from Thermal Noise and Limits on Dust Flux or Mass in Comet Giacobini-Zinner
Authors: Meyer-Vernet N. , Couturier P. , Hoang S. , Perche C. , Steinberg J. L. , Fainberg J. , Meetre C.
Published: October 2006

Thermal noise spectroscopy was used to measure the density and temperature of the main (cold) electron plasma population during 2 hours (1.5 × 10
5
kilometers perpendicular to the tail axis) around the point of closest approach of the International Cometary Explorer (ICE) to comet Giacobini-Zinner. The time resolution was 18 seconds (370 kilometers) in the plasma tail and 54 seconds (1100 kilometers) elsewhere. Near the tail axis, the maximum plasma density was 670 per cubic centimeter and the temperature slightly above 1 electron volt. Away from the axis, the plasma density dropped to 100 per cubic centimeter (temperature, 2 × 10
4
K) over 2000 kilometers, then decreased to 10 (1.5 × 10
5
K) over 15,000 kilometers; outside that region (plasma tail), the density fluctuated between 10 and 30 per cubic centimeter and the temperature between 1 × 10
5
and 4 × 10
5
K. The relative density of the hot population rarely exceeded a few percent. The tail was highly asymmetrical and showed much structure. On the other antenna, shot noise was recorded from the plasma particle impacts on the spacecraft body. No evidence was found of grain impacts on the antennas or spacecraft in the plasma tail. This yields an upper limit for the dust flux or particle mass, indicating either fluxes or masses in the tail smaller than implied by the models or an anomalous grain structure. This seems to support earlier suggestions that these grains are featherlike. Outside the tail, and particularly near 10
5
kilometers from its axis, impulsive noises indicating plasma turbulence were observed.
Ion Composition Results During the International Cometary Explorer Encounter with Giacobini-Zinner
Authors: Ogilvie Keith W. , Coplan M. A. , Bochsler P. , Geiss J.
Published: October 2006

The International Cometary Explorer spacecraft passed through the coma of comet Giacobini-Zinner about 7800 kilometers antisunward of the nucleus on 11 September 1985. The ion composition instrument was sensitive to ambient ions with mass-to-charge ratios in the ranges 1.4 to 3 atomic mass units per electron charge (amu e
-1
) and 14 to 33 amu e
-1
. Initial interpretation of the measurements indicates the presence of H
2
O
+
, H
3
O
+
, probably CO
+
and HCO
+
, and ions in the mass range 23 to 24; possible candidates are Na
+
and Mg
+
. In addition to these heavy ions, measured over the velocity range 80 to 223 kilometers per second, the instrument measured He
2+
of solar wind origin over the range 237 to 463 kilometers per second. The heavy ions have a velocity distribution which indicates that they have been picked up by the motional electric field, whereas the light ions are steadily decelerated as the comet tail axis is approached. These results are in agreement with the picture of a comet primarily consisting of water ice, together with other material, that sublimes, streams away from the nucleus, becomes ionized, and interacts with the solar wind.
Natural Sources of Acid Neutralizing Capacity in Low Alkalinity Lakes of the Precambrian Shield
Authors: Schindler D. W. , Turner M. A. , Stainton M. P. , Linsey G. A.
Published: October 2006

A detailed alkalinity budget was constructed for Lake 239 in the Experimental Lakes Area of northwestern Ontario and for three small watersheds in its terrestrial basin. Alkalinity generation in the lake averaged 118 milliequivalents per square meter per year, 4.5 times as high as the areal rate in the terrestrial basin. Although acid deposition in the area is low, only one of the three terrestrial watersheds was a significant source of alkalinity. A second terrestrial watershed yielded very little alkalinity. The third watershed, which contains a wetland, was a sink for, rather than a source of, alkalinity. An analysis of ion budgets for the lake revealed that more than half of the in situ alkalinity production was by biological rather than geochemical processes. The major processes that generated alkalinity were: biological reduction of SO
4
2-
(53%), exchange of H
+
for Ca
2+
in sediments (39%), and biological reduction of NO
3
-
(26%). Comparison with experimentally acidified Lake 223 revealed that alkalinity production by sulfate reduction increased in response to increased inputs of sulfuric acid.
Engineering Human Prolactin to Bind to the Human Growth Hormone Receptor
Authors: Cunningham Brian C. , Henner Dennis J. , Wells James A.
Published: October 2006

A strategy of iterative site-directed mutagenesis and binding analysis was used to incorporate the receptor-binding determinants from human growth hormone (hGH) into the nonbinding homolog, human prolactin (hPRL). The complementary DNA for hPRL was cloned, expressed in
Escherichia coli
, and mutated to introduce sequentially those substitutions from hGH that were predicted by alanine-scanning mutagenesis and other studies to be most critical for binding to the hGH receptor from human liver. After seven rounds of site-specific mutagenesis, a variant of hPRL was obtained containing eight mutations with an association constant for the hGH receptor that was increased more than 10,000-fold. This hPRL variant binds one-sixth as strongly as wild-type hGH, but shares only 26 percent overall sequence identity with hGH. These studies show the feasibility of recruiting receptor-binding properties from distantly related and functionally divergent hormones and show that a detailed functional database can be used to guide the design of a protein-protein interface in the absence of direct structural information.
Voyager 2 Radio Observations of Uranus
Authors: Warwick James W. , Evans David R. , Romig Joseph H. , Sawyer Constance B. , Desch Michael D. , Kaiser Michael L. , Alexander Joseph K. , Carr Thomas D. , Staelin David H. , Gulkis Samuel , Poynter Robert L. , Aubier Monique , Boischot Andre , Leblanc Yolande , Lecacheux Alain , Pedersen Bent M. , Zarka Philippe
Published: October 2006

Within distances to Uranus of about 6 × 10
6
kilometers (inbound) and 35 × 10
6
kilometers (outbound), the planetary radio astronomy experiment aboard Voyager 2 detected a wide variety of radio emissions. The emission was modulated in a period of 17.24 ± 0.01 hours, which is identified as the rotation period of Uranus' magnetic field. Of the two poles where the axis of the off-center magnetic dipole (measured by the magnetometer experiment aboard Voyager 2) meets the planetary surface, the one closer to dipole center is now located on the nightside of the planet. The radio emission generally had maximum power and bandwidth when this pole was tipped toward the spacecraft. When the spacecraft entered the nightside hemisphere, which contains the stronger surface magnetic pole, the bandwidth increased dramatically and thereafter remained large. Dynamically evolving radio events of various kinds embedded in these emissions suggest a Uranian magnetosphere rich in magnetohydrodynamic phenomena.
Organic Synthesis in Japan: From Natural Products to Synthetic Control
Authors: Mukaiyama Teruaki
Published: October 2006

Organic chemistry in present day Japan, which has developed from early interest in natural products chemistry, now includes total synthesis, physical organic chemistry, synthetic methods, and organometallic chemistry. In this article, the current state of Japanese organic chemistry is briefly reviewed and a representative aspect of today's organic chemistry—exploration of new synthetic methodology—is discussed.
Eruption of the Nevado del Ruiz Volcano, Colombia, On 13 November 1985: Tephra Fall and Lahars
Authors: Naranjo J. L. , Sigurdsson H. , Carey S. N. , Fritz W.
Published: October 2006

A small Plinian eruption of the Nevado del Ruiz volcano in Colombia ejected 3.5 × 10
10
kilograms of mixed dacite and andesite tephra on 13 November 1985, with a maximum column height of 31 kilometers above sea level. Small pyroclastic flows and surges, generated during the initial stage of the eruption, caused surface melting of approximately 10% of the volcano's ice cap, leading to meltwater floods. The erosive floods incorporated soils and loose sediments from the volcano's flanks and developed into lahars, which claimed at least 25,000 lives.
Natural Philosophy in the Constitution
Authors: Piel Gerard
Published: October 2006

The natural philosophers who wrote the U.S. social contract held the advancement of science to be the supreme exercise of citizen sovereignty. The rising nation, in the late 19th century, established the seat of that sovereignty in its universities. Today those institutions have come to be regarded as contract research centers at the service of the federal government. Research contracts in support of the proposed Strategic Defense Initiative are pressed on them against the consensus of the scientific community that holds this "Star Wars" enterprise to be technically infeasible. The time has come to reconstruct the relation between the federal government and university science in the spirit of our social contract.
Abnormal Polarity of Thunderclouds Grown from Negatively Charged Air
Authors: Moore C. B. , Vonnegut B. , Rolan T. D. , Cobb J. W. , Holden D. N. , Hignight R. T. , McWilliams S. M. , Cadwell G. W.
Published: October 2006

Experiments were carried out in New Mexico to determine whether the electrification processes that lead to the formation of lightning in clouds are influenced by the polarity of the charges in the air from which the clouds grow. The normal, positive space charge in the sub-cloud air was reversed by negative charge released from an electrified wire, suspended across a 2-kilometer-wide canyon. On more than four occasions when the clouds over the wire grew and became electrified, they were of abnormal polarity with dominant positive charges instead of the usual negative charges in the lower part of the cloud. The formation of these abnormally electrified clouds suggests both that the electrification process in thunderclouds can be initiated and that its polarity may be determined by the small charges that are present in the atmosphere.
Third World Debt
Authors: Dornbusch Rudiger , Fischer Stanley
Published: October 2006

The international debt crisis arose from imprudent borrowing, imprudent lending, and major shocks to the world economy from 1980 to 1982. The initial impulse in 1982 was to treat the debt problem as one of illiquidity and thus provide further lending while the debtor countries tried to adjust to the shock. This strategy produced massive recessions in the major debtors (mostly in Latin America) and led in 1985 to the Baker plan, the aim of which is to find ways to permit the debtor countries to resume growth while not defaulting on the debt. The Mexican case is highlighted.
Diadema antillarum
Was Not a Keystone Predator in Cryptic Reef Environments
Authors: Jackson Jeremy B. C. , Kaufmann Karl W.
Published: October 2006

The ecological impact of the disappearance of a major predator depends on the responsiveness of the prey. Mass mortality of the most abundant grazer in Caribbean cryptic reef environments, the sea urchin
Diadema antillarum
, selectively decreased rates of mortality of encrusting organisms by half, yet community composition hardly changed because alternative species failed to become established.
Space Research: At a Crossroads
Authors: McDonald Frank B.
Published: October 2006

The current state and future directions of the U.S. space-science program are assessed in the wake of the Challenger accident, the Gramm-Rudman-Hollings budget reduction act, and the report of the National Commission on Space. A renewed emphasis on moderate-scale, quick-response missions will be of special importance for scientific progress and will compensate in part for the postponement of most major space missions. Satellites and manned space stations in Earth orbit, along with unmanned planetary missions, will continue to be the dominant elements in the space program. Future progress and the continuation of U.S. leadership depend on the vitality of U.S. space research.
Uncertainties in Building a Strategic Defense
Authors: Zraket C. A.
Published: October 2006

Building a strategic defense against nuclear ballistic missiles involves complex and uncertain functional, spatial, and temporal relations. Such a defensive system would evolve and grow over decades. It is too complex, dynamic, and interactive to be fully understood initially by design, analysis, and experiments. Uncertainties exist in the formulation of requirements and in the research and design of a defense architecture that can be implemented incrementally and be fully tested to operate reliably. The analysis and measurement of system survivability, performance, and cost-effectiveness are critical to this process. Similar complexities exist for an adversary's system that would suppress or use countermeasures against a missile defense. Problems and opportunities posed by these relations are described, with emphasis on the unique characteristics and vulnerabilities of space-based systems.