bluuebunny/crossref_metadata_2025 huggingface dataset:
Energetics of Running Cockroaches
Authors: Herreid Clyde F. , Prawel David A. , Full Robert J.
Published: October 2006

Male cockroaches
Gromphadorhina portentosa
were made to run at 0.03, 0.07, and 0.12 kilometer per hour on a miniature treadmill within a small respirometer. Oxygen consumption was directly related to running velocity. The half-time necessary for oxygen consumption to reach a steady state during exercise was about 1 minute and the half-time for recovery was 4 to 6 minutes. The energetic cost of transport was comparable to that for bipedal and quadrupedal vertebrates.
Biophysical and Molecular Mechanisms of
Shaker
Potassium Channel Inactivation
Authors: Hoshi Toshinori , Zagotta William N. , Aldrich Richard W.
Published: October 2006

The potassium channels encoded by the
Drosophila
Shaker
gene activate and inactivate rapidly when the membrane potential becomes more positive. Site-directed mutagenesis and single-channel patch-clamp recording were used to explore the molecular transitions that underlie inactivation in
Shaker
potassium channels expressed in
Xenopus
oocytes. A region near the amino terminus with an important role in inactivation has now been identified. The results suggest a model where this region forms a cytoplasmic domain that interacts with the open channel to cause inactivation.
Sensitive and Rapid Diagnosis of Potato Spindle Tuber Viroid Disease by Nucleic Acid Hybridization
Authors: Owens Robert A. , Diener T. O.
Published: October 2006

A sensitive and reliable new method for the detection of potato spindle tuber viroid in potato tubers has been developed. The method is based on hybridization of highly radioactive recombinant DNA to viroid RNA that has been attached to a solid support. The method can be automated and permits the rapid testing of large numbers of tubers.
Tetramesityldisilene, a Stable Compound Containing a Silicon-Silicon Double Bond
Authors: West Robert , Fink Mark J. , Michl Josef
Published: October 2006

Irradiation of 2,2-bis(2,4,6-trimethylphenyl)hexamethyltrisilane in hydrocarbon solution produces tetramesityldisilene, which can be isolated as a yellow-orange solid stable to room temperature and above in the absence of air. Like the olefins of carbon chemistry, tetramesityldisilene undergoes addition reactions across the silicon-silicon double bond.
Neotropical Anachronisms: The Fruits the Gomphotheres Ate
Authors: Janzen Daniel H. , Martin Paul S.
Published: October 2006

Frugivory by extinct horses, gomphotheres, ground sloths, and other Pleistocene megafauna offers a key to understanding certain plant reproductive traits in Central American lowland forests. When over 15 genera of Central American large herbivores became extinct roughly 10,000 years ago, seed dispersal and subsequent distributions of many plant species were altered. Introduction of horses and cattle may have in part restored the local ranges of such trees as jicaro (
Crescentia alata
) and guanacaste (
Enterolobium cyclocarpum
) that had large mammals as dispersal agents. Plant distributions in neotropical forest and grassland mixes that are moderately and patchily browsed by free-ranging livestock may be more like those before megafaunal extinction than were those present at the time of Spanish conquest.
Catalytic Coal Gasification: An Emerging Technology
Authors: Hirsch Robert L. , Gallagher John E. , Lessard Richard R. , Wesslhoft Robert D.
Published: October 2006

Catalytic coal gasification is being developed as a more efficient and less costly approach to producing methane from coal. With a potassium catalyst all the reactions can take place at one temperature, so that endothermic and exothermic reactions can be integrated in a single reactor. A key aspect of the concept involves continuous recycling of product carbon monoxide and hydrogen to the gasifier following separation of methane. Development of the process has advanced steadily since the basic concept was proposed in 1971. A 23-day demonstration run was recently completed in a process development unit with a coal feed rate of 1 ton per day. The next major step in the program will be to design and construct a large pilot plant to bring the technology to commercial readiness in the late 1980's.
The Rise of Global Mean Sea Level as an Indication of Climate Change
Authors: Etkins Robert , Epstein Edward S.
Published: October 2006

Rising mean sea level, it is proposed, is a significant indicator of global climate change. The principal factors that can have contributed to the observed increases of global mean sea level in recent decades are thermal expansion of the oceans and the discharge of polar ice sheets. Calculations indicate that thermal expansion cannot be the sole factor responsible for the observed rise in sea level over the last 40 years; significant discharges of polar ice must also be occurring. Global warming, due in some degree presumably to increasing atmospheric carbon dioxide, has been opposed by the extraction of heat necessary to melt the discharged ice. During the past 40 years more than 50,000 cubic kilometers of ice has been discharged and has melted, reducing the surface warming that might otherwise have occurred by as much as a factor of 2. The transfer of mass from the polar regions to a thin spherical shell covering all the oceans should have increased the earth's moment of inertia and correspondingly reduced the speed of rotation by about 1.5 parts in 10
8
. This accounts for about three quarters of the observed fractional reduction in the earth's angular velocity since 1940. Monitoring of global mean sea level, ocean surface temperatures, and the earth's speed of rotation should be complemented by monitoring of the polar ice sheets, as is now possible by satellite altimetry. All parts of the puzzle need to be examined in order that a consistent picture emerge.
Photosynthetic Hydrogen and Oxygen Production: Kinetic Studies
Authors: Greenbaum Elias
Published: October 2006

Steady-state turnover times for simultaneous photosynthetic production of hydrogen and oxygen have been measured for two systems: the in vitro system comprised of isolated chloroplasts, ferredoxin, and hydrogenase, and the anaerobically adapted green alga
Chlamydomonas reinhardtii
[137c(+) mating type]. In both systems, the simultaneous photoproduction of hydrogen and oxygen was measured by driving the systems into the steady state with repetitive, single-turnover, flash illumination. The turnover times for production of both oxygen and hydrogen in photosynthetic water splitting are in milliseconds and are equal to or less than the turnover time for carbon dioxide reduction in intact algal cells. The oxygen and hydrogen turnover times are therefore compatible with each other and partially compatible with the excitation rate of the photosynthetic reaction centers under conditions of solar irradiation.
A New Look at the Saturn System: The Voyager 2 Images
Authors: Smith Bradford A. , Soderblom Laurence , Batson Raymond , Bridges Patricia , Inge Jay , Masursky Harold , Shoemaker Eugene , Beebe Reta , Boyce Joseph , Briggs Geoffrey , Bunker Anne , Collins Stewart A. , Hansen Candice J. , Johnson Torrence V. , Mitchell Jim L. , Terrile Richard J. , Cook Allan F. , Cuzzi Jeffrey , Pollack James B. , Danielson G. Edward , Ingersoll Andrew P. , Davies Merton E. , Hunt Garry E. , Morrison David , Owen Tobias , Sagan Carl , Veverka Joseph , Strom Robert , Suomi Verner E.
Published: October 2006

Voyager 2 photography has complemented that of Voyager I in revealing many additional characteristics of Saturn and its satellites and rings. Saturn's atmosphere contains persistent oval cloud features reminiscent of features on Jupiter. Smaller irregular features track out a pattern of zonal winds that is symmetric about Saturn's equator and appears to extend to great depth. Winds are predominantly eastward and reach 500 meters per second at the equator. Titan has several haze layers with significantly varying optical properties and a northern polar "collar" that is dark at short wavelengths. Several satellites have been photographed at substantially improved resolution. Enceladus' surface ranges from old, densely cratered terrain to relatively young, uncratered plains crossed by grooves and faults. Tethys has a crater 400 kilometers in diameter whose floor has domed to match Tethys' surface curvature and a deep trench that extends at least 270° around Tethys' circumference. Hyperion is cratered and irregular in shape. Iapetus' bright, trailing hemisphere includes several dark-floored craters, and Phoebe has a very low albedo and rotates in the direction opposite to that of its orbital revolution with a period of 9 hours. Within Saturn's rings, the "birth" of a spoke has been observed, and surprising azimuthal and time variability is found in the ringlet structure of the outer B ring. These observations lead to speculations about Saturn's internal structure and about the collisional and thermal history of the rings and satellites.
Atlantic Herring: Stock Discreteness and Abundance
Authors: Iles T. D. , Sinclair M.
Published: October 2006

The number of genetically distinct herring stocks is determined by the number of distinct, geographically stable larval retention areas. Spawning sites in these areas may be highly localized or dispersed. Absolute population size mostly depends on the retention area available to the density-dependent larval-postlarval stage. Although the extreme seasonal range of spawning time shown by Atlantic herring is not fully accounted for by a new hypothesis, current theory is not supported by the hypothesis or by empirical data. The management implications are discussed.
Electronics and Computers: An Overview
Authors: Branscomb Lewis M.
Published: October 2006

Microelectronics has been the key to the computer's improved performance and decreased costs. In electronics and computers, "small is beautiful" because small is cheaper, faster, and more reliable. As computers become a daily part of more and more people's lives, emphasis is shifting to programming, ease of use, and applications. Responsiveness to human needs has become the primary challenge facing system designers. How well the industry fulfills this goal will determine whether the emerging information services of the 1980's realize their potential both for improving the quality of life and achieving much-needed productivity gains.
Escape of Hydrogen from Venus
Authors: McElroy Michael B. , Prather Michael J. , Rodriguez Jose M.
Published: October 2006

Recombination of O
2
+
represents a source of fast oxygen atoms in Venus' exosphere, and subsequent collisions of oxygen atoms with hydrogen atoms lead to escape of about 10
7
hydrogen atoms per square centimeter per second. Escape of deuterium atoms is negligible, and the ratio of deuterium to hydrogen should increase with time. It is suggested that the mass-2 ion observed by Pioneer Venus is D
+
, which implies a ratio of deuterium to hydrogen in the contemporary atmosphere of about 10
–2
, an initial ratio of 5 × 10
–5
, and an original H
2
O abundance not less than 800 grams per square centimeter.
Deformation Studies on Soufriere, St. Vincent, Between 1977 and 1981
Authors: Fiske Richard S. , Shepherd John B.
Published: October 2006

Dry-tilt measurements at two stations indicate that Soufriere Volcano gradually inflated at least 10 microradians prior to the initial explosions of April 1979 and then rapidly deflated more than 20 microradians after the activity got under way. The tilt measured at the station 6.5 kilometers from the summit was about twice that measured at a distance of 2.5 kilometers. This finding suggests the existence of a magma chamber at a depth of more than 10 kilometers.
Calmodulin Activation of Calcium-Dependent Sodium Channels in Excised Membrane Patches of
Paramecium
Authors: Saimi Y. , Ling K.-Y.
Published: October 2006

Calmodulin is a calcium-binding protein that participates in the transduction of calcium signals. The electric phenotypes of calmodulin mutants of
Paramecium
have suggested that the protein may regulate some calcium-dependent ion channels. Calcium-dependent sodium single channels in excised patches of the plasma membrane from
Paramecium
were identified, and their activity was shown to decrease after brief exposure to submicromolar concentrations of calcium. Channel activity was restored to these inactivated patches by adding calmodulin that was isolated from
Paramecium
to the cytoplasmic surface. This restoration of channel activity did not require adenosine triphosphate and therefore, probably resulted from direct binding of calmodulin, either to the sodium channel itself or to a channel regulator that was associated with the patch membrane.
Ancient Maya Mercury
Authors: Pendergast David M.
Published: October 2006

Discovery of mercury in an ancient Maya offering at Lamanai, Belize, has stimulated examination of possible sources of the material in the Maya area. Two zones of cinnabar and native mercury deposits can be defined in the Maya highlands, and the presence of the native metal suggests that the ancient Maya collected rather than extracted the mercury from ore.
Obligate Necrophagy in a Social Bee
Authors: Roubik David W.
Published: October 2006

The social beeTrigona hypogeauses carrion instead of pollen as a protein source. Nests lack stored pollen, pollen is absent in larval provisions, and corbiculae for pollen transport on worker hind legs are reduced. Glandular secretions of 20 percent protein content appear to replace stored pollen. Toothed mandibles, pheromonal recruitment to resources, and aggressive foraging behavior facilitated evolution of necrophagy in this tropical forest bee lineage.
Control of Yeast Mating Signal Transduction by a Mammalian β
2
-adrenergic Receptor and G
s
α Subunit
Authors: King Klim , Dohlman Henrik G. , Thorner Jeremy , Caron Marc G. , Lefkowitz Robert J.
Published: October 2006

To facilitate functional and mechanistic studies of receptor—G protein interactions, the human β
2
-adrenergic receptor (hβ-AR) has been expressed in
Saccharomyces cerevisiae
. This was achieved by placing a modified hβ-AR gene under control of the galactose-inducible
GAL1
promoter. After induction by galactose, functional hβ-AR was expressed at a concentration several hundred times as great as that found in any human tissue. As determined from competitive ligand binding experiments, hβ-AR expressed in yeast displayed characteristic affinities, specificity, and stereoselectivity. Partial activation of the yeast pheromone response pathway by β-adrenergic receptor agonists was achieved in cells coexpressing hβ-AR and a mammalian G protein (G
s
) α subunit-demonstrating that these components can couple to each other and to downstream effectors when expressed in yeast. This in vivo reconstitution system provides a new approach for examining ligand binding and G protein coupling to cell surface receptors.
Complex Venation Patterns in the Leaves of
Selaginella
: Megaphyll-Like Leaves in Lycophytes
Authors: Wagner Warren H. , Beitel Joseph M. , Wagner Florence S.
Published: October 2006

Venation patterns of the leaves of two lycophytes,
Selaginella adunca
and
Selaginella schaffneri
, do not fit the definition of microphylls as having a single, unbranched vein. Although
S. adunca
has a simple pattern,
S. schaffneri
has a complexity matching that of many megaphylls, with numerous branching veins. The veins of
S. schaffneri
undergo an average of 13 branchings (range, 8 to 21), and reticulation between veins is frequent. The discovery of this radical departure from the familiar microphylls of lycophytes indicates that complex venation patterns in leaves do not necessarily arise from fusion of whole branches. The microphyll may not be as structurally stable as formerly believed.
The Giles County, Virginia, Seismic Zone
Authors: Bollinger G. A. , Wheeler Russell L.
Published: October 2006

A well-defined seismic zone recently detected in Virginia has an orientation that is not related to the surrounding geologic structures. The orientation of the zone appears to be related to features below the Appalachian overthrust belt. A damaging earthquake that is important in evaluating seismic hazard in the southeastern United States may have occurred in the zone in 1897.
Response of Agronomic and Forest Species to Elevated Atmospheric Carbon Dioxide
Authors: Rogers Hugo H. , Thomas Judith F. , Bingham Gail E.
Published: October 2006

The effects of atmospheric carbon dioxide on corn, soybeans, loblolly pine, and sweetgum were studied in the field during a growing season. The plants were exposed to a range of concentrations of carbon dioxide day and night in open-topped, flow-through chambers. At a mean daytime carbon dioxide concentration of 910 parts per million, increases in total biomass ranged from 157 to 186 percent of the control values. Seed yield and wood volume increased and there were changes in plant anatomy and form. Net photosynthesis increased with increasing carbon dioxide concentration in soybeans and sweetgum, but was unaffected in corn. Water use efficiency also increased in corn, soybeans, and sweetgum.
Prehistoric Blood Residues: Detection on Tool Surfaces and Identification of Species of Origin
Authors: Loy Thomas H.
Published: October 2006

Blood residues from several animal species have been discovered on the surfaces of chert, basalt, and obsidian prehistoric tools (1000 to 6000 years old) from open-air sites along the western coast and in the northern boreal forest of Canada. A screening test has been developed to detect residual blood. Hemoglobin has been crystallized from the residues, and the species of origin determined.
Specific Tropism of HIV-1 for Microglial Cells in Primary Human Brain Cultures
Authors: Watkins Brynmor A. , Dorn Henry H. , Kelly Walter B. , Armstrong Regina C. , Potts arbara J. , Michaels Frank , Kufta Conrad V. , Dubois-Dalcq Monique
Published: October 2006

Human immunodeficiency virus (HIV) frequently causes neurological dysfunction and is abundantly expressed in the central nervous system (CNS) of acquired immunodeficiency syndrome (AIDS) patients with HIV encephalitis or myelopathy. The virus is found mostly in cells of the monocyte-macrophage lineage within the CNS, but the possibility of infection of other glial cells has been raised. Therefore, the effects of different HIV-1 and HIV-2 strains were studied in primary cultures of adult human brain containing microglial cells, the resident CNS macrophages, and astrocytes. These cultures could be productively infected with macrophage-adapted HIV-1 isolates but not with T lymphocyte-adapted HIV-1 isolates or two HIV-2 isolates. As determined with a triple-label procedure, primary astrocytes did not express HIV
gag
antigens and remained normal throughout the 3-week course of infection. In contrast, virus replicated in neighboring microglial cells, often leading to their cell fusion and death. The death of microglial cells, which normally serve immune functions in the CNS, may be a key factor in the pathogenesis of AIDS encephalitis or myelopathy.
Boron in Sillimanite
Authors: Grew Edward S. , Hinthorne James R.
Published: October 2006

Sillimanite in six granulite-facies, kornerupine-bearing rocks contains 0.035 to 0.43 percent B2O3and 0.02 to 0.23 percent MgO (by weight). Substitution of boron for silicon and magnesium for aluminum is coupled such that the ratio of magnesium to boron is about 0.5. Sillimanite incorporates more than 0.1 percent B2O3only at high temperatures in a boron-rich environment at very low partial pressures of water. In the amphibolite facies, the sillimanite boron contents are too low to appreciably affect the stability relations of sillimanite with kyanite and andalusite.
Protection from Chemotherapy-Induced Alopecia in a Rat Model
Authors: Hussein Atif M. , Jimenez Joaquin J. , McCall Catherine A. , Yunis Adel A.
Published: October 2006

Alopecia (hair loss) is among the most distressing side effects of cancer chemotherapy. Little progress has been made, however, in its prevention or treatment, partly because of the lack of suitable experimental model. In recent work on the treatment of myelogenous leukemia in the rat, the following observations were made: (i) treatment of 8-day-old rats with cytosine arabinoside consistently produced alopecia, and (ii) ImuVert, a biologic response modifier derived from the bacterium
Serratia marcescens
, uniformly produced complete protection against the alopecia. In subsequent experiments, both cyclophosphamide and doxorubicin also produced alopecia in this model, and the doxorubicin-induced alopecia was prevented by treatment with ImuVert. The potential relevance of these observations to chemotherapy-induced alopecia in the clinical setting should be examined.
Transport and Storage of Vitamin A
Authors: Blomhoff Rune , Green Michael H. , Berg Trond , Norum Kaare R.
Published: October 2006

The requirement of vitamin A (retinoids) for vision has been recognized for decades. In addition, vitamin A is involved in fetal development and in the regulation of proliferation and differentiation of cells throughout life. This fat-soluble organic compound cannot be synthesized endogenously by humans and thus is an essential nutrient; a well-regulated transport and storage system provides tissues with the correct amounts of retinoids in spite of normal fluctuations in daily vitamin A intake. An overview is presented here of current knowledge and hypotheses about the absorption, transport, storage, and metabolism of vitamin A. Some information is also presented about a group of ligand-dependent transcription factors, the retinoic acid receptors, that apparently mediate many of the extravisual effects of retinoids.
Tilt and Seismicity Changes in the Shumagin Seismic Gap
Authors: Beavan J. , Hauksson E. , McNutt S. R. , Bilham R. , Jacob K. H.
Published: October 2006

Changes in the ground surface tilt and in the rate of seismicity indicate that an aseismic deformation event may have occurred between 1978 and 1980 along the plate boundary in the eastern Aleutians, Alaska, within the Shumagin seismic gap. Pavlof Volcano was unusually quiescent during this period. The proposed event would cause an increase of stress on the shallow locked portion of the plate boundary, bringing it closer to rupture in a great earthquake.
Onshore-Offshore Patterns in the Evolution of Phanerozoic Shelf Communities
Authors: Jablonski David , Sepkoski J. John , Bottjer David J. , Sheehan Peter M.
Published: October 2006

Cluster analysis of Cambrian-Ordovician marine benthic communities and community-trophic analysis of Late Cretaceous shelf faunas indicate that major ecological innovations appeared in nearshore environments and then expanded outward across the shelf at the expense of older community types. This onshore-innovation, offshore-archaic evolutionary pattern is surprising in light of the generally higher species turnover rates of offshore clades. This pattern probably results from differential extinction rates of onshore as compared to offshore clades, or from differential origination rates of new ecological associations or evolutionary novelties in nearshore environments.
Carbon Compounds in Interplanetary Dust: Evidence for Formation by Heterogeneous Catalysis
Authors: Bradley J. P. , Brownlee D. E. , Fraundorf P.
Published: October 2006

Associations of carbonaceous material with iron-nickel alloy, carbides, and oxides were identified by analytical electron microscopy in ten unmelted chondritic porous micrometeorites from the earth's stratosphere. These associations, which may be interpreted in terms of reactions between a carbon-containing gas and catalytically active dust grains, suggest that some of the carbon in the chondritic porous subset of interplanetary dust was emplaced through heterogeneous catalysis.
Early Results from the Infrared Astronomical Satellite
Authors: Neugebauer G. , Beichman C. A. , Soifer B. T. , Aumann H. H. , Chester T. J. , Gautier T. N. , Gillett F. C. , Hauser M. G. , Houck J. R. , Lonsdale C. J. , Low F. J. , Young E. T.
Published: October 2006

For 10 months the Infrared Astronomical Satellite (IRAS) provided astronomers with what might be termed their first view of the infrared sky on a clear, dark night. Without IRAS, atmospheric absorption and the thermal emission from both the atmosphere and Earthbound telescopes make the task of the infrared astronomer comparable to what an optical astronomer would face if required to work only on cloudy afternoons. IRAS observations are serving astronomers in the same manner as the photographic plates of the Palomar Observatory Sky Survey; just as the optical survey has been used by all astronomers for over three decades, as a source of quantitative information about the sky and as a "roadmap" for future observations, the results of IRAS will be studied for years to come. IRAS has demonstrated the power of infrared astronomy from space. Already, from a brief look at a miniscule fraction of the data available, we have learned much about the solar system, about nearby stars, about the Galaxy as a whole and about distant extragalactic systems. Comets are much dustier than previously thought. Solid particles, presumably the remnants of the star-formation process, orbit around Vega and other stars and may provide the raw material for planetary systems. Emission from cool interstellar material has been traced throughout the Galaxy all the way to the galactic poles. Both the clumpiness and breadth of the distribution of this material were previously unsuspected. The far-infrared sky away from the galactic plane has been found to be dominated by spiral galaxies, some of which emit more than 50 percent and as much as 98 percent of their energy in the infrared—an exciting and surprising revelation. The IRAS mission is clearly the pathfinder for future missions that, to a large extent, will be devoted to the discoveries revealed by IRAS.
Major Carbon-14 Deficiency in Modern Snail Shells from Southern Nevada Springs
Authors: Riggs Alan C.
Published: October 2006

Carbon-14 contents as low as 3.3 ± 0.2 percent modern (apparent age, 27,000 years) measured from the shells of snails
Melanoides tuberculatus
living in artesian springs in southern Nevada are attributed to fixation of dissolved HCO
3
-
with which the shells are in carbon isotope equilibrium. Recognition of the existence of such extreme deficiencies is necessary so that erroneous ages are not attributed to freshwater biogenic carbonates.
A New Charge-Mosaic Membrane from a Multiblock Copolymer
Authors: Fujimoto Teruo , Ohkoshi Koji , Miyaki Yoshiyuki , Nagasawa Mitsuru
Published: October 2006

A charge-mosaic membrane was prepared from a pentablock copolymer of the BABCB type by selectively introducing anion and cation exchange groups into the microseparated phases. The three-layer lamellar structure of the starting pentablock copolymer film was not disturbed by the modifications. The membrane obtained was highly permeable only to sodium chloride in mixed aqueous solutions of sodium chloride and organic species of low molecular weight, such as sucrose. Marked
p
H-dependent permeabilities were also observed for amino acids.
Prudent Practices for Disposal of Chemicals from Laboratories
Authors: Joyce Robert M.
Published: October 2006

A recent report of the National Research Council contains guidelines and recommendations for handling and disposing of unneeded chemicals from laboratories. Suggestions are also made for simplifying various procedures imposed by the regulatory agencies with authority over the disposal of laboratory chemicals.
Computer Vision and Natural Constraints
Authors: Brown C. M.
Published: October 2006

Computer vision, the automatic construction of scene descriptions from image input data, has just entered its second decade. Approaches have varied widely, especially in the amounts of symbolic, domain-dependent knowledge and inference that are incorporated into the vision process. Much current research addresses the extraction of physical properties of the scene (depth, surface orientation, reflectance) from images by using only a few general assumptions about the scene domain. Extraction of physical parameters is part of a hierarchy of operations needed to transform image input data to symbolic descriptions. Two other processes that serve as examples are stereo fusion and the partitioning of image phenomena into related groups. Computer vision research is influencing theories of animal perception as well as the design of computing architectures for artificial intelligence.
Protein Single Crystal Growth Under Microgravity
Authors: Littke Walter , John Christina
Published: October 2006

The preparation of suitably large protein single crystals is essentially the rate-determining step of protein x-ray structure determinations. Attempts to produce single crystals with two model compounds—β-galactosidase and lysozyme—under conditions of microgravity were successful. Crystals formed by salting out from solutions kept free of convection were 27 and 1000 times larger in volume, respectively, than those produced in the same apparatus but exposed to terrestrial gravitation.
El Niño-Southern Oscillation Events Recorded in the Stratigraphy of the Tropical Quelccaya Ice Cap, Peru
Authors: Thompson Lonnie G. , Mosley-Thompson Ellen , Arnao Benjamín Morales
Published: October 2006

Snow accumulation measured during 1982-1983 on the Quelccaya ice cap, Peru, was 70 percent of the average from 1975 through 1983. Inspection of 19 years (1964 through 1983) of accumulation measured near the summit of Quelccaya reveals a substantial decrease (∼30 percent) in association with the last five El Niño-Southern Oscillation (ENSO) occurrences in the equatorial Pacific. The ENSO phenomenon is now recognized as a global event arising from large-scale interactions between the ocean and the atmosphere. Understanding this extreme event, with the goal of prediction, requires a record of past occurrences. The Quelccaya ice cap, which contains 1500 years of annually accumulated ice layers, may provide a long and detailed record of the most extreme ENSO events.
Deepest Known Plant Life Discovered on an Uncharted Seamount
Authors: Littler Mark M. , Littler Diane S. , Blair Stephen M. , NORRIS JAMES N.
Published: October 2006

The discovery of abundant autotrophic macrophytes living below 200 meters indicates their importance to primary productivity, food webs, sedimentary processes, and as reef builders in clear oceanic waters. Estimates concerning minimum light levels for macroalgal photosynthesis and macrophytic contributions to the biology and geology of tropical insular and continental borderlands must now be revised.
The World Bank's Support for Science and Technology
Authors: Weiss Charles
Published: October 2006

The World Bank, the largest aid-granting agency in the world, has played a substantial but largely unsung role in helping the scientific and technological development of developing countries. Its investments, totaling $15.5 billion in fiscal year 1984, involve choosing appropriate technology and financing local technological development. Since 1980, the Bank has lent $0.5 billion for agricultural research and about $1 billion for scientific and technological education. It contributes to and mobilizes finances for large international research programs in agriculture and the health sciences. It supports research on labor-based construction, low-cost sanitation, renewable energy resources, and control of traffic congestion. It provides training in the technological aspects of development policy. As funds for aid become scarce, the Bank is reexamining its approach to science and technology.
Multiple Stable Isotopes Used to Trace the Flow of Organic Matter in Estuarine Food Webs
Authors: Peterson Bruce J. , Howarth Robert W. , Garritt Robert H.
Published: October 2006

The use of a combination of the stable isotopes of sulfur, carbon, and nitrogen allows the flow of organic matter and trophic relations in salt marshes and estuaries to be traced while eliminating many ambiguities that accompany the use of a single isotopic tracer. Salt-marsh grasses take up the isotopically light sulfides formed during sulfate reduction, and the transfer of this light sulfur through the marsh food web is illustrated with data on the ribbed mussel (
Geukensia demissa
) from various locations in a New England marsh. The multiple isotope approach shows that this filter feeder consumes both marsh grass (
Spartina
) detritus and plankton, with the relative proportions of each determined by the location of the mussels in the marsh.
Catastrophic Anoxia in the Chesapeake Bay in 1984
Authors: Seliger H. H , Boggs J. A , Biggley W. H
Published: October 2006

In 1984, four climatic sequences combined to produce what may be a major anoxic catastrophe in the northern Chesapeake Bay, sufficient to severely threaten the major benthic species. These sequences are (i) the highest late-winter streamflow on record from the Susquehanna River watershed; (ii) streamflows from the Susquehanna River for the consecutive months of June, July, and August that are higher by 2 standard deviations than the respective monthly mean values measured over the last 34 years; (iii) a stationary high in August off the Atlantic Coast; and (iv) an absence of strong storm events in summer. An empirical equation is proposed for the prediction of the monthly trend of dissolved oxygen decrease in terms of a temperature-dependent subpycnoclinal respiration and a modified estuarine Richardson number. As of 23 August 1984, the summer pycnocline of the northern bay had eroded upward from its historically recorded depth below 10 meters to an abnormally shallow 5 meters, with higher stratification than in earlier years. Dissolved oxygen concentrations directly below the pycnocline decreased to zero during June, 2 months earlier than for previous wet years. At present, oxygen-deficient waters containing significant concentrations of hydrogen sulfide have penetrated into Eastern Bay and the Choptank and Potomac rivers. Because most remaining shellfish-spawning and seed-bed areas in these tributaries are located at depths between 4 and 8 meters, the continued absence of major destratifying events will prolong the present anoxic trend and may result in high benthic mortalities.
Microbial Degradation of Halogenated Compounds
Authors: Ghosal D. , You I.-S. , Chatterjee D. K. , Chakrabarty A. M.
Published: October 2006

The mode of degradation of various halogenated compounds in isolated pure cultures and the disposition of the degradative genes have been studied. In many cases the degradative genes are found to be clustered on plasmids and appear to be under positive control. Genetic selection in vivo and genetic manipulations in vitro have allowed construction of strains having wider biodegradative potentials than their natural counterparts. Molecular cloning of the degradative gene clusters for halogenated compounds in vectors with a broad host range also allows the transfer of such genes to a large number of Gram-negative bacteria. The application of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-degrading microorganisms has demonstrated the effectiveness of this strain in removing large amounts of 2,4,5-T from contaminated soil within a short period, and such soil has been shown to support the growth of plants normally sensitive to low concentrations of 2,4,5-T. The two major challenges that must be addressed in the near future are the development of appropriate microbial technology for the decontamination of soil containing hazardous halogenated compounds, and the promulgation of appropriate regulations to ensure the safety and well-being of the public during the application of genetically improved strains in an open environment.
Workstations in Science
Authors: Joy William , Gage John
Published: October 2006

Recent advances in microprocessor technology are making a new generation of personal computers feasible and affordable. These computers, called "workstations," can be connected with other workstations, with mainframe computers, with supercomputers, and with remote networks. Workstations provide the graphical interface to supercomputers and can run applications that formerly required the use of mainframe computers. Emerging standards for communications, graphics, databases, numerical algorithms, and languages allow workstations to share programs with various types of computers, including mainframe and personal computers.
Disturbance and Ecologic Succession in an Upper Ordovician Cobble-Dwelling Hardground Fauna
Authors: Wilson Mark A.
Published: October 2006

An Ordovician hardground fauna in northern Kentucky provides an example from the fossil record of the maintenance of species diversity by periodic disturbance of an autogenic ecologic succession. The marine invertebrates found encrusting limestone cobbles show an order of community development from a low-diversity pioneer assemblage through a high-diversity association to a monospecific stable fauna. All species, including the late successional dominants, were present in the early stages of colonization. Periodic overturning of the cobbles killed the encrusters and opened up new spaces on which succession was reinitiated. These disturbances maintained high diversity within the encrusting community by limiting the spatial distribution of the most efficient space competitors.
The Parkfield, California, Earthquake Prediction Experiment
Authors: Bakun W. H. , Lindh A. G.
Published: October 2006

Five moderate (magnitude 6) earthquakes with similar features have occurred on the Parkfield section of the San Andreas fault in central California since 1857. The next moderate Parkfield earthquake is expected to occur before 1993. The Parkfield prediction experiment is designed to monitor the details of the final stages of the earthquake preparation process; observations and reports of seismicity and aseismic slip associated with the last moderate Parkfield earthquake in 1966 constitute much of the basis of the design of the experiment.
Life at High Temperatures
Authors: Brock Thomas D.
Published: October 2006

Water environments with temperatures up to and above boiling are commonly found in association with geothermal activity. At temperatures above 60°C, only bacteria are found. Bacteria with temperature optima over the range 65° to 105°C have been obtained in pure culture and are the object of many research projects. The upper temperature limit for life in liquid water has not yet been defined, but is likely to be somewhere between 110° and 200°C, since amino acids and nucleotides are destroyed at temperatures over 200°C. Because bacteria capable of growth at high temperatures are found in many phylogenetic groups, it is likely that the ability to grow at high temperature had a polyphyletic origin. The macromolecules of these organisms are inherently more stable to heat than those of conventional organisms, but only small changes in sequence can lead to increases in thermostability. Because of their unique properties, thermophilic organisms and their enzymes have many potential biotechnological uses, and extensive research on industrial applications is under way.
Cell-Assisted Growth of a Fastidious Spiroplasma
Authors: Hackett Kevin J. , Lynn Dwight E.
Published: October 2006

The Colorado potato beetle spiroplasma, which is not cultivable in conventional cell-free media, grew in tissue culture media in the presence of several coleopteran and lepidopteran insect cell lines. The cultured organisms attained titers of 1.2 × 10
9
spiroplasmas per milliliter of culture at the 100th passage and retained infectivity and a high capacity for translational motility at the 15th passage. Cell culture systems may facilitate the isolation of other presently uncultivable microorganisms and may be useful in the study of the role of microbial physiology and behavior in pathogenicity.
Endocranial Features of
Australopithecus africanus
Revealed by 2- and 3-D Computed Tomography
Authors: Conroy Glenn C. , Vannier Michael W. , Tobias Phillip V.
Published: October 2006

The earliest hominid from South Africa,
Australopithecus africanus
, is known from only six specimens in which accurate assessment of endocranial capacity and cranial venous outflow pattern can be obtained. This places a severe limit on a number of hypotheses concerning early hominid evolution, particularly those involving brain-body size relationships and adaptations of the circulatory system to evolving upright posture. Advances in high-resolution two- and three-dimensional computed tomography (CT) now allow the inclusion of another important specimen to this list, MLD 37/38 from Makapansgat. A new computer imaging technique is described that "reconstructs" the missing portions of the endocranial cavity in order to determine endocranial capacity. In addition, CT evaluation allows assessment of cranial venous outflow pattern even in cases where the endocranial cavity is completely filled with stone matrix. Results show that endocranial capacity in this specimen is less than originally proposed and also support the view that gracile and robust australopithecines evolved different cranial venous outflow patterns in response to upright postures.
Surface Functionalization of Electrodes with Molecular Reagents
Authors: Wrighton Mark S.
Published: October 2006

The use of molecular reagents to manipulate the properties of electrode surfaces has broad application in areas such as electrochemical synthesis, energy conversion and storage, displays, sensors, and new kinds of microelectronic devices. Surface modification of electrodes has contributed to a revival of interest in basic and applied research in electrochemistry and electrochemical devices. This article is focused on specific examples of systems modified electrodes where basic developments provide promising opportunities for applications stemming from the properties of molecules attached to an electrode surface.
Atmospheric Deposition and Canopy Interactions of Major Ions in a Forest
Authors: Lindberg S. E. , Lovett G. M. , Richter D. D. , Johnson D. W.
Published: October 2006

Airborne particles and vapors contributed significantly to the nutrient requirements and the pollutant load of a mixed hardwood forest in the eastern United States. Dry deposition was an important mechanism of atmospheric input to the foliar canopy, occurring primarily by vapor uptake for sulfur, nitrogen, and free acidity and by particle deposition for calcium and potassium. The canopy retained 50 to 70 percent of the deposited free acidity and nitrogen, but released calcium and potassium. Atmospheric deposition supplied 40 and 100 percent of the nitrogen and sulfur requirements, respectively, for the annual woody increment. This contribution was underestimated significantly by standard bulk deposition collectors.
Molecular Cloning of the
Bombyx mori
Prothoracicotropic Hormone
Authors: Kawakami Atsushi , Kataoka Hiroshi , Oka Tadanori , Mizoguchi Akira , Kimura-Kawakami Mina , Adachi Takashi , Iwami Masafumi , Nagasawa Hiromichi , Suzuki Akinori , Ishizaki Hironori
Published: October 2006

Prothoracicotropic hormone (PTTH), a brain secretory polypeptide of insects, stimulates the prothoracic glands to produce and release ecdysone, the steroid essential to insect development. The complementary DNAs encoding PTTH of the silkmoth
Bombyx mori
were cloned and characterized, and the complete amino acid sequence was deduced. The data indicated that PTTH is first synthesized as a 224-amino acid polypeptide precursor containing three proteolytic cleavage signals. The carboxyl-terminal component (109 amino acids) that follows the last cleavage signal represents one PTTH subunit. Two PTTH subunits are linked together by disulfide bonds, before or after cleavage from prepro-PTTH, to form a homodimeric PTTH. When introduced into
Escherichia coli
cells, the complementary DNA directed the expression of an active substance that was functionally indistinguishable from natural PTTH. In situ hybridization showed the localization of the prepro-PTTH mRNA to two dorsolateral neurosecretory cells of the
Bombyx
brain.
The Locale Map of Honey Bees: Do Insects Have Cognitive Maps?
Authors: Gould James L.
Published: October 2006

Whereas higher vertebrates are able to construct a mental "map" of their home area and so use their knowledge of the spatial relations between landmarks to navigate along novel routes, invertebrates have been thought able to use landmarks in their navigation only as a familiar, route-specific series. Experiments with honey bees show that these insects have and use landmark maps thus invalidating this presumed invertebrate-vertebrate dichotomy.
Sulfate and Nitrate Concentrations from a South Greenland Ice Core
Authors: Mayewski P. A. , Lyons W. B. , Spencer M. J. , Twickler M. , Dansgaard W. , Koci B. , Davidson C. I. , Honrath R. E.
Published: October 2006

An ice core in south Greenland covering the period 1869 to 1984 was analyzed for oxygen isotopes and chloride, nitrate, and sulfate concentrations. The data show that the "excess" (nonsea-salt) sulfate concentration has tripled since approximately 1900 to 1910 and the nitrate concentration has doubled since approximately 1955. The increases may be attributable to the deposition of these chemical species from air masses carrying North American and Eurasian anthropogenic emissions.
Tumor Cells Exhibit Deregulation of the Cell Cycle Histone Gene Promoter Factor HiNF-D
Authors: Holthuis Joost , Owen Thomas A. , van Wijnen Andre J. , Wright Kenneth L. , Ramsey-Ewing Anna , Kennedy Mary Beth , Carter Ruth , Cosenza Stephen C. , Soprano Kenneth J. , Lian Jane B. , Stein Janet L. , Stein Gary S.
Published: October 2006

Cell cycle-regulated gene expression is essential for normal cell growth and development and loss of stringent growth control is associated with the acquisition of the transformed phenotype. The selective synthesis of histone proteins during the S phase of the cell cycle is required to render cells competent for the ordered packaging of replicating DNA into chromatin. Regulation of H4 histone gene transcription requires the proliferation-specific promoter binding factor HiNF-D. In normal diploid cells, HiNF-D binding activity is regulated during the cell cycle; nuclear protein extracts prepared from normal cells in S phase contain distinct and measurable HiNF-D binding activity, while this activity is barely detectable in G1 phase cells. In contrast, in tumor-derived or transformed cell lines, HiNF-D binding activity is constitutively elevated throughout the cell cycle and declines only with the onset of differentiation. The change from cell cycle-mediated to constitutive interaction of HiNF-D with the promoter of a cell growth-controlled gene is consistent with, and may be functionally related to, the loss of stringent cell growth regulation associated with neoplastic transformation.
A Wind-Forced Ekman Spiral as a Good Statistical Fit to Low-Frequency Currents in a Coastal Strait
Authors: Stacey Michael W. , Pond Stephen , LeBlond Paul H.
Published: October 2006

Ekman's classical analysis of wind-driven currents is a fundamental component of the modern circulation theory of the oceans, but there have been few good observations of the predicted Ekman spiral, where the velocity vector rotates clockwise in direction (in the Northern Hemisphere) and decays exponentially in magnitude with increasing depth. An analysis of recent cyclesonde velocity measurements based on the use of empirical orthogonal functions, however, suggests that a classical Ekman spiral was a good statistical fit to a significant portion of the low-frequency current fluctuations in the Strait of Georgia, British Columbia, for fluctuation periods of about 5 to 10 days.