bluuebunny/crossref_metadata_2025 huggingface dataset:
Acid Precipitation in the Northeastern United States:
p
H and Acidity
Authors: Galloway James N. , Likens Gene E. , Edgerton Eric S.
Published: October 2006

Detailed chemical analyses reveal that acid precipitation (
p
H < 5.6) in the northeastern United States is caused by the strong mineral acids sulfuric and nitric. There is a large array of other proton sources in precipitation, weak acids and Brønsted acids; however, although these other acids contribute to the total acidity of precipitation, they have a minimal influence on the free acidity (ambient
p
H) of acid precipitation.
Quantitation of Hepatic Glycogenolysis And Gluconeogenesis in Fasting Humans With
13
C NMR
Authors: Rothman Douglas L. , Magnusson Inger , Katz Lee D. , Shulman Robert G. , Shulman Gerald I.
Published: October 2006

The rate of net hepatic glycogenolysis was assessed in humans by serially measuring hepatic glycogen concentration at 3- to 12-hour intervals during a 68-hour fast with
13
C nuclear magnetic resonance spectroscopy. The net rate of gluconeogenesis was calculated by subtracting the rate of net hepatic glycogenolysis from the rate of glucose production in the whole body measured with tritiated glucose. Gluconeogenesis accounted for 64 ± 5% (mean ± standard error of the mean) of total glucose production during the first 22 hours of fasting. In the subsequent 14-hour and 18-hour periods of the fast, gluconeogenesis accounted for 82 ± 5% and 96 ± 1% of total glucose production, respectively. These data show that gluconeogenesis accounts for a substantial fraction of total glucose production even during the first 22 hours of a fast in humans.
Generation and Analysis of Interleukin-4 Deficient Mice
Authors: Kühn R. , Rajewsky K. , Müller W.
Published: October 2006

Interleukin-4 (IL-4) promotes the growth and differentiation of many hematopoietic cells in vitro; in particular, it directs the immunoglobulin (Ig) class switch to IgG1 and IgE. Mice homozygous for a mutation that inactivates the IL-4 gene were generated to test the requirement for IL-4 in vivo. In the mutant mice T and B cell development was normal, but the serum levels of IgG1 and IgE were strongly reduced. The IgG1 dominance in a T cell-dependent immune response was lost, and IgE was not detectable upon nematode infection. Thus, some but not all of the in vitro properties of IL-4 are critical for the physiology of the immune system in vivo.
Central Crime Computer Project Draws Mixed Reviews
Authors: Shapley Deborah
Published: October 2006

After committing a crime in Ohio, an offender from California, for example, may flee to Florida, having profitably disposed of his stolen goods in still another State. With all the marvels of modern transportation, all this can and does occur while the police pore over the fresh traces at the crime scene.

To solve crime in the space-age tempo of today's society demands that law enforcement officers have available immediately the facts of crime whenever or wherever they are likely to confront suspected elements of it.
Asteroid Families: Observational Evidence for Common Origins
Authors: Gradie J. , Zellner B.
Published: October 2006

Colors of minor planets in the
UBV
system indicate compositions quite distinct from those of the field population in each of three Hirayama families. The Eos and Koronis families apparently originated from the collisional fragmentation of undifferentiated silicate bodies, and the Nysa group from a geochemically differentiated parent body.
High-Frequency
P
n
Phases Observed in the Pacific at Great Distances
Authors: Walker Daniel A.
Published: October 2006

Earlier observations of a seismic waveguide in the northwestern Pacific with a velocity of 8.3 kilometers per second to distances of approximately 30° are complemented by suggestions of a possible waveguide with a velocity of 7.8 kilometers per second to distances well in excess of 30°.
A New Satellite of Saturn?
Authors: Fountain John W. , Larson Stephen M.
Published: October 2006

Analysis of all available observations of faint objects near Saturn during the 1966 passage of the earth through the plane of Saturn's rings suggests the existence of at least one previously undiscovered satellite of Saturn. The data support the previously published orbit for Janus. These satellites may be major members of an extended ring.
Nucleon Stability: A Geochemical Test Independent of Decay Mode
Authors: Evans John C. , Steinberg Richard I.
Published: October 2006

By analyzing published geochemical data on xenon isotopes measured in a 2.46 × 10
9
-year-old telluride ore, a lower limit of 1.6 × 10
25
years has been obtained for the mean lifetime of the nucleons in the tellurium-130 nucleus. This result is insensitive to the particular mode by which the nucleons decay and therefore provides a rigorous limit on possible baryon number nonconservation. The new limit is about two orders of magnitude better than the previous rigorous limit on nucleon stability.
Plant Genetics: Increasing Crop Yield
Authors: Day P. R.
Published: October 2006

Cell cultures of crop plants provide new opportunities to recover induced mutations likely to increase crop yield. Approaches include regulating respiration to conserve carbon fixed by photosynthesis, and increasing the nutritive value of seed protein. They depend on devising selecting conditions which only desired mutant cells can survive. Protoplast fusion offers some promise of tapping sources of genetic variation now unavailable because of sterility barriers between species and genera. Difficulties in regenerating cell lines from protoplasts, and plants from cells, still hamper progress but are becoming less severe. Recombinant DNA techniques may allow detection and selection of bacterial cell lines carrying specific DNA sequences. Isolation and amplification of crop plant genes could then lead to ways of transforming plants that will be useful to breeders.
Murine Developmental Control Genes
Authors: Kessel Michael , Gruss Peter
Published: October 2006

Various strategies have been used to isolate genes that participate in the regulation of mouse development. Gene families that have been identified on the basis of their homology to motifs within
Drosophila
control genes or human transcription factor genes, namely homeobox (Hox), paired-box (Pax), and POU genes, can be compared with respect to gene organization, structure, and expression patterns. The functions of these genes can be analyzed molecularly in vitro and in vivo with the use of available mouse mutants or transgenic mice. In addition, it has been possible to generate gain- or loss-of-function mutations by random or targeted introduction of transgenes. Models derived from these studies can reveal the successive steps of developmental control on a genetic level.
Conservation of Potassium in the
Pinus resinosa
Ecosystem
Authors: Stone Earl L. , Kszystyniak Richard
Published: October 2006

Rubidium-potassium ratios were determined on foliage, litter, and surface soils of plots in two plantations of
Pinus resinosa
41 to 46 years old previously fertilized once with potassium. Calculations based on indigenous soil rubidium as the "tagging" ion demonstrate that after 9 years some 60 percent of the foliage potassium is still derived from the fertilizer, and after 23 years about 40 percent of the foliage potassium is derived from the fertilizer. Additional fertilizer potassium is present in soil and litter, indicating the high retention of this mobile element in the pine ecosystem.
Slope Profiles of Cycloidal Form
Authors: Bridge B. J. , Beckman G. G.
Published: October 2006

Concave profiles of basalt hills in the Darling Downs area of southeastern Queensland can be cycloidal or exponential in form. Where the complete hillslope consists of shallow soils the form is cycloidal. Where colluvial lower slopes are present the overall slope is exponential but the upper, dominantly sedentary portion is cycloidal. The cycloidal form, which corresponds to the curve of least time, appears to be associated with erosional processes and the exponential form with depositional processes.
Antarctica: A Deep-Freeze Storehouse for Meteorites
Authors: Cassidy W. A. , Olsen E. , Yanai K.
Published: October 2006

Meteorites that fall on the Antarctic ice cap are preserved for long periods of time under very clean conditions as they are carried toward the continental margin. If the host ice encounters a barrier it cannot flow over or around, it tends to dissipate by ablation, leaving an accumulation of meteorites on the surface.
Planetary Radiation Balance as a Function of Atmospheric Dust: Climatological Consequences
Authors: Idso Sherwood B. , Brazel Anthony J.
Published: October 2006

An analysis of several atmospheric dust-loading events at Phoenix, Arizona, under background cloudless sky conditions, allowed determination of dust-induced changes in both the net solar and net thermal radiation received at the earth's surface. The resultant climatological forcing function for surface temperature change was plotted against the ratio of diffuse to normal-incidence solar radiation. It was found that initial increases in atmospheric dust concentration tend to warm the planet's surface. After a certain critical concentration has been reached, continued dust buildup reduces this warming effect until at a second critical dust concentration a cooling trend begins. This second critical dust concentration is so great, however, that any particulate pollution of the lower atmosphere by man will have a tendency to increase surface temperatures. Thus, anthropogenically produced tropospheric aerosols cannot be looked on as offsetting the warming tendency of increased carbon dioxide: their concurrent buildups must inexorably tend to warm the planet's surface.
The Oceanic Microcosm of Particles
Authors: Lal D.
Published: October 2006

Analyses of suspended particulate matter larger than 1 micrometer, filtered from thousands of liters of surface and deep waters during GEOSECS expeditions to the Atlantic and Pacific oceans, have provided new information on the nature and time scales of chemical processes associated with the particles. Trace element and radionuclide data show that particles scavenge trace elements such as Th, Pu, Fe, Pb, and Cu from the ocean column, thereby controlling their concentrations. For other elements, however, particles are a source: carbon and silicon, for example, are introduced at depths as sinking particles dissolve. Studies of both particulate concentrations by filtration of seawater and particulate fluxes by using sediment traps seem necessary to delineate the intricate nature of chemical processes in the oceans.
Water Vapor Maser "Turn-On" in the HII Region W3 (OH)
Authors: Haschick A. D. , Burke B. F. , Spencer J. H.
Published: October 2006

A line in the water vapor maser spectrum of the HII region W3 (OH) was observed to increase in brightness over an 8-day period and then decline to its original intensity over the following 4 weeks. The intensity variation can be explained by a simple maser model, with an impulse of energy suddenly applied. The observed time scale and energy output are consistent with a maser on the outskirts of a dust cocoon surrounding an O5 star, with a momentary "leak," lasting a day or. two, supplying the necessary energy.
Superstition: A Matter of Bias, Not Detectability
Authors: Killeen Peter R.
Published: October 2006

Pigeons discriminated between stimulus changes dependent on their pecking and stimulus changes occurring independently of their behavior. Their performance was accurate, and when the payoffs for "hits" and "correct rejections" were varied, their response bias varied in a fashion similar to that of human observers detecting signals in a background of noise.
Images of Io's Sodium Cloud
Authors: Matson Dennis L. , Goldberg Bruce A. , Johnson Torrence V. , Carlson Robert W.
Published: October 2006

The first direct images of Io's sodium cloud are reported and analyzed. The observed cloud extends for more than 10
5
kilometers along Io's orbit and is a somewhat "banana-shaped" partial toroid. More sodium atoms precede Io than follow it. A model based on the escape of sodium from a specific localized area on Io provides a reasonable fit to the observed intensity distribution whereas isotropic escape does not.
Process Innovation and Changes in Industrial Energy Use
Authors: Berg Charles A.
Published: October 2006

American industry in the 19th century switched from wood to coal as its primary energy resource. The history of this switch is reviewed, along with the history of preceding similar trends in Europe and later trends in the switch from coal to oil and gas. Important conceptual advances in the technology of such basic processes as glassmaking, cementmaking, and steelmaking emerged as the switch from wood to coal proceeded in the United States. These advances may have been more important than the relative prices of wood and coal in motivating the conversion of American industry to the use of coal. The historical role of process advances in determining the choice of energy resources suggests that the physics and chemistry of industrial processes may be as important an area of energy research as the various technologies of energy conversion.
Phobos Transit of Mars as Viewed by the Viking Cameras
Authors: Duxbury T. C.
Published: October 2006

A Viking orbiting spacecraft successfully obtained pictures of the martian satellite Phobos with Mars in the background. This is the first time that a single picture was obtained from a spacecraft which contained both a planet and a moon and had significant surface detail visible on both. The region of Mars below Phobos included volcanoes in the Tharsis Montes region. These pictures showed Phobos to be smaller than previously thought. The image of Phobos can be used as a control point to determine the map coordinates of surface features on Mars.
Peyote Alkaloids: Identification in a Prehistoric Specimen of
Lophophora
from Coahuila, Mexico
Authors: Bruhn J. G. , Lindgren J.-E. , Holmstedt B. , Adovasio J. M.
Published: October 2006

Mescaline, anhalonine, lophophorine, pellotine, and anhalonidine have been identified in alkaloid extracts of a prehistoric specimen of
Lophophora
from a burial cave in west central Coahuila, Mexico. The specimen is associated with radiocarbon dates of A.D. 810 to 1070 and is one of the oldest materials ever submitted to alkaloid analysis.
The Evolution of Sex Chromosomes
Authors: Charlesworth Brian
Published: October 2006

Structurally distinct sex chromosomes (X and Y) are the most familiar mode of genetic sex determination and have evolved independently in many different taxa. The evolutionary paths by which their characteristic properties may have evolved are reviewed. These properties include the failure of X and Y to recombine through much or all of their length, the genetic inertness of much of the Y chromosome, dosage compensation of the activity of X chromosomal loci, and the accumulation of repeated DNA sequences on the Y chromosome.
Orangutan Death and Scavenging by Pigs
Authors: Galdikas Biruté M. F.
Published: October 2006

Pongid remains are rarely recovered from tropical rain forests. Observations of a Bornean bearded pig (
Sus barbatus
) scavenging an orangutan (
Pongo pygmaeus
) carcass and the recovery of an orangutan skull fragment corroborates evidence from Africa and suggests that the scavenging of wild pigs may play an important role in the destruction of pongid remains.
Brazil: Energy Options and Current Outlook
Authors: Goldemberg J.
Published: October 2006

Brazil's energy options and current outlook are examined, and a summary of known reserves of fossil and renewable energy resources is given. Brazil has abundant renewable energy resources but very modest reserves of fossil fuels. Consequently, the emphasis in the future will have to be on the utilization of solar energy, hydroelectric power, and biomass in a program designed to preserve local traditions and culture.
Energy Options and Strategies for Western Europe
Authors: Häfele Wolf , Sassin Wolfgang
Published: October 2006

Western Europe, now largely dependent on oil imports, has to prepare for strong competition for oil and energy imports in general before the year 2000. The more unlikely it is for Western Europe to secure from outside rich supplies of coal or uranium at readily acceptable economic and political conditions, the more serious this competition becomes. Even exceptionally low projections of economic growth and optimistic assumptions about energy conservation urgently call for vigorous and simultaneous development of indigenous coal and nuclear sources, including the breeder. Long-term contracts for the possession and deployment of foreign oil, gas, and coal deposits are mandatory and should be negotiated in view of the possible aggravation of north-south confrontation.
Synthesis of Ammonium Cyanate and Urea by Reduction of Nitric Oxide on Platinum, Rhodium, and Ruthenium Catalysts
Authors: Voorhoeve R. J. H. , Trimble L. E. , Freed D. J.
Published: October 2006

Nearly quantitative conversion of nitric oxide (NO) into N
2
H
4
CO has been obtained in the reduction of NO with carbon monoxide and hydrogen over platinum and rhodium catalysts. Depending on the temperature of collection, N
2
H
4
CO is isolated as ammonium cyanate or its isomer, urea. The process is an effective way of recovering fixed nitrogen from dilute industrial streams containing NO. Ammonium cyanate may play a role in the reduction of NO in automotive exhaust control.
Teotihuacán, Tepeapulco, and Obsidian Exploitation
Authors: Charlton Thomas H.
Published: October 2006

Current cultural ecological models of the development of civilization in central Mexico emphasize the role of subsistence production techniques and organization. The recent use of established and productive archeological surface survey techniques along natural corridors of communication between favorable niches for cultural development within the Central Mexican symbiotic region resulted in the location of sites that indicate an early development of a decentralized resource exploitation, manufacturing, and exchange network. The association of the development of this system with Teotihuacán indicates the importance such nonsubsistence production and exchange had in the evolution of this first central Mexican civilization. The later expansion of Teotihuacán into more distant areas of Mesoamerica was based on this resource exploitation model. Later civilizations centered at Tula and Tenochtitlán also used such a model in their expansion.
Sex Ratio and Local Resource Competition in a Prosimian Primate
Authors: Clark Anne Barrett
Published: October 2006

Competition between female kin for local limiting resources may explain a male-biased secondary sex ratio in the prosimian
Galago crassicaudatus.
Data demonstrating the skewed sex ratio, a brief summary of field observations on the species, and a simple mathematical statement of the hypothesis are presented. Local resource competition may influence sex ratio in other mammals.
Volatile Metal Complexes
Authors: Sievers Robert E. , Sadlowski Jean E.
Published: October 2006

Fundamental investigations of the chemical and physical properties of metal β-diketonate complexes have revealed unusual volatility, as well as solvolytic and thermal stability and solubility in organic solvents. Certain general rules describing the volatility of metal β-diketonates on the basis of ligand shell character and metal ion size have arisen from extensive gas chromatographic and vapor pressure studies. Several practical applications of volatile β-diketonates teke advantage of their special properties. In ultratrace metal analysis by gas chromatography, use of these chelates has allowed the detection of smaller amounts of certain metals than can be detected by any other analytic method. Certain rare earth β-diketonates have been found useful as antiknock additives in gasoline and as catalysts for the removal of carbonaceous deposits from the combustion chambers of internal combustion engines.
Human Issues in Human Rights
Authors: Kates Robert W.
Published: October 2006

The National Academy of Sciences' Committee on Human Rights and its 350 correspondent academy members seeks to ease the plight of individual scientists, engineers, and medical personnel suffering severe repression. It has engaged in a program of private inquiry, public remonstrance, and moral support in behalf of individuals from 11 countries. In developing this activity, members of the committee had to engage in a series of troubling issues related to the nature of human rights, the choice of cases, and the format of protest. But most troubling of all are the issues raised by the profound distortions of humanness, nationhood, and science that follow in the wake of repression.
Evolution of a Nitrogen Atmosphere on Titan
Authors: Atreya Sushil K. , Donahue Thomas M. , Kuhn William R.
Published: October 2006

Photochemical calculations indicate that if NH
3
outgassed from Titan it should have been converted to a dense N
2
atmosphere during the lifetime of the satellite. A crucial step in the process involves a gas phase reaction of N
2
H
4
with H. The most favorable conditions for this step would be the intermediate production of a CH
4
-H
2
greenhouse capable of raising the gas temperature to 150°K. Subsequently about 20 bars of N
2
could have evolved. The pressure-induced opacity of 20 bars of N
2
should suffice to explain the recently measured 200°K surface temperature. Unlike the situation on Jupiter, NH
3
is not recycled on Titan by reactions involving N
2
or N
2
H
4
. This may explain the failure of recent attempts to detect NH
3
in the upper atmosphere of Titan.
Early Archeological Evidence for Shellfish Collecting
Authors: Volman Thomas P.
Published: October 2006

Geologic evidence, supported by infinite carbon-14 dates and Middle Stone Age cultural associations, indicates that two open-air shell middens recently found at Sea Harvest and Hoedjies Punt, Saldanha Bay, South Africa, date from the terminal part of the Last Interglacial, about 70,000 to 60,000 years ago. These middens are among the oldest known records for systematic human exploitation of marine resources anywhere in the world. The faunal contents of the middens suggest that the Middle Stone Age people who accumulated them utilized marine resources less intensively than their Later Stone Age successors in similar coastal settings.
Social Inhibition of Maturation in Natural Populations of
Xiphophorus variatus
(Pisces: Poeciliidae)
Authors: Borowsky Richard
Published: October 2006

According to analyses of field samples, social inhibition of maturation is at work in natural populations of the variable platyfish,
Xiphophorus variatus
. In the laboratory, adult males inhibit the maturation of juveniles; the inhibition is overcome as the juveniles increase in size. The proportion of maturing males in any field collection is related to the number of adult males present and the size of the juveniles. The more adults, the fewer maturing males are present; the larger the average juvenile, the greater the number of males maturing. The evolution of this system is best understood in terms of individual selection, but consequences of the system buffer the population against the effects of predation.
Genetic Improvement of Wild Fish Populations
Authors: Moav Rom , Brody Thomas , Hulata Gideon
Published: October 2006

A plan for the genetic improvement of commercially exploited wild animals is presented. It consists of crossing wild with domesticated breeds to produce heterotic hybrids and to upgrade the wild stocks. Empirical evidence is presented from experiments with the carp. Procedures for monitoring the manipulated populations are outlined. The suggested plan is ecologically reasonable and would counteract the negative genetic changes caused by excessive commercial exploitation of many species.
Chemical and Biological Microstructures as Probed by Dynamic Processes
Authors: Drake J. M. , Klafter J. , Levitz P.
Published: October 2006

The dynamic process of electronic energy transfer is shown to be an important tool for probing the microstructure of molecular systems, particularly those in which donors and acceptors occupy specifically labeled sites of spatially confining host matrices. Special attention is given to analyzing the temporal behavior of the direct energy transfer reaction for systems in which the dipolar coupling is between a donor and randomly distributed acceptors. This dynamic process is dependent on two competing lengths when the donor and acceptor distribution is determined by the microstructure of the confining system:
R
p
, the dominant length characterizing the size of the confinement, and
R
0
, which scales the strength of the dipolar coupling. When energy transfer processes are viewed in the context of these two competing lengths, a picture emerges of the microstructure of the confinement that is consistent with and corroborated by other structural probes.
Spiral Calcium Wave Propagation and Annihilation in
Xenopus laevis
Oocytes
Authors: Lechleiter James , Girard Steven , Peralta Ernest , Clapham David
Published: October 2006

Intracellular calcium (Ca
2+
) is a ubiquitous second messenger. Information is encoded in the magnitude, frequency, and spatial organization of changes in the concentration of cytosolic free Ca
2+
. Regenerative spiral waves of release of free Ca
2+
were observed by confocal microscopy in
Xenopus laevis
oocytes expressing muscarinic acetylcholine receptor subtypes. This pattern of Ca
2+
activity is characteristic of an intracellular milieu that behaves as a regenerative excitable medium. The minimal critical radius for propagation of focal Ca
2+
waves (10.4 micrometers) and the effective diffusion constant for the excitation signal (2.3 × 10
-6
square centimeters per second) were estimated from measurements of velocity and curvature of circular wavefronts expanding from foci. By modeling Ca
2+
release with cellular automata, the absolute refractory period for Ca
2+
stores (4.7 seconds) was determined. Other phenomena expected of an excitable medium, such as wave propagation of undiminished amplitude and annihilation of colliding wavefronts, were observed.
Carbon-13/Carbon-12 Isotope Fractionation of Organic Matter Associated with Uranium Ores Induced by Alpha Irradiation
Authors: Leventhal Joel S. , Threlkeld Charles N.
Published: October 2006

Analyses of stable carbon isotopes from two sample suites from sandstone uranium (tabular) ores show interesting variations. Organic carbon associated with high-grade uranium ore is heavy (δ
13
C = –16.9 to –19.6 per mil, where δ
13
C =
13
C/
12
C relative to the Pee Dee belemnite standard) relative to the adjacent lower-grade samples (–22.7 to –26.4 per mil). It is suggested that the heavy isotopic values for the are samples are related to a radiation and chemical isotope effect that has occurred mainly because of an alpha-radiation dose of 10
11
rads.
Stone Tools from Mid-Pleistocene Sediments in Java
Authors: Jacob T. , Soejono R. P. , Freeman L. G. , Brown F. H.
Published: October 2006

Two stone tools (a chopper and a retouched flake) were found in mid-Pleistocene channel fills at Sambungmachan (Java), which earlier yielded a hominid skull cap with characteristics of Solo man and a Trinil-like fauna. The artifacts are the first discovered in place in deposits on Java that are assigned to the mid-Pleistocene on faunal grounds.
Gamma-Ray Astrophysics: A New Look at the Universe
Authors: Trombka Jacob , Fichtel Carl , Grindlay Jonathan , Hofstadter Robert
Published: October 2006

Progress in γ-ray astronomy has been very encouraging in recent years. These observations provide the most direct means of studying the largest transfer of energy occurring in astrophysical processes: the dynamic effects of the energetic charged cosmic-ray particles, element synthesis, and particle acceleration. Gamma-ray astronomical observations also find important application in studies of the development of the planets from the primitive solar nebula and of the nature of high-energy processes in the sun's atmosphere and their relation to the basic problems of solar activity.
A Proposal to Modernize the American Antiquities Act
Authors: Collins Robert Bruce , Green Dee F.
Published: October 2006

The Antiquities Act of 1906, which has provided the legal basis for protecting the U.S.'s prehistoric and historic heritage, is no longer adequate. Artifact hunters and collectors have descended on national forests and U.S. parks in ever-increasing numbers. The drafters of the 1906 act could not have anticipated the lucrative market in prehistoric artifacts in the 1970's. The act has come under attack in the courts as being unconstitutionally vague. In light of the recent criminal prosecutions under the Antiquities Act and the constitutional challenges, reviewed in this article, the authors propose a new Antiquities Act which expands the scope of the act to include those who would deal in artifacts taken unlawfully from federal lands and increases the criminal penalties for a violation of the act.
Crystal Structure of Bee-Venom Phospholipase A
2
: Correction
Authors: Scott David L. , Otwinowski Zbyszek , Gelb Michael H. , Sigler Paul B.
Published: October 2006

We would like to call attention to some errors in our report "Crystal structure of bee-venom phospholipase A
2
in a complex with a transition-state analogue" (14 Dec., p. 1563).

1) The legend to figure 2B should have read '. . . bee-venom PLA
2
(blue) superimposed upon that of the uninhibited form of the bovine pancreative PL
2
(red)."

2) The sequence used to interpret the structure of the bee-venom phospholipase
2
and cited in figure 2A is in error and differs from that inferred from the published cDNA sequence as follows. Leu should have been Glu at position 20, Arg should have been Lys at positions 47 and 72, Thr should have been His at position 56, Ala should have been Asp at position 92, and Arg should have been Thr at position 57. Lys was typographically omitted at position 124. Re-refinement of the structure with the corrected sequence neither alters the backbone conformation nor affects the disposition of surface residues 20, 47, 72, and 92. Thr57 replaces Arg57 in forming the hydrogen bond with the nonbridged oxygen of the inhibitor's
sn
-3 phosphate, and His56 replaces Thr56 at the opening of the hydrophobic channel. These changes do not alter our conclusions or those of its companion papers on phospholipase
2
. Corrected stereopairs (figures 3 and 4) are available from the authors on request, and the revised coordinates have been deposited in the Brookhaven Protein Data Bank.
Australian Prehistory: New Aspects of Antiquity
Authors: White J. Peter , O'Connell James F.
Published: October 2006

Human occupation of greater Australia occurred by 50,000 years ago, probably through deliberate voyaging by a small group of people. Later migrations, if any, are unlikely to have significantly changed the original genetic and cultural make-up. While early Aborigines may have hunted extinct megafauna, the data do not support a rapid "Pleistocene overkill" hypothesis. Finally, aspects of Australian Aboriginal economy, especially plant utilization, and technology—the small tool tradition, ground stone hatchets and boomerangs—are of considerable antiquity and probably originated locally.
Thermoclines: A Solar Thermal Energy Resource for Enhanced Hydroelectric Power Production
Authors: McNichols J. L , Ginell W. S , Cory J. S.
Published: October 2006

The solar thermal energy stored in hydroelectric reservoir thermoclines is very large and greatly exceeds the gravitational hydroenergy of the surface water, even after limitations arising from the second law of thermodynamics have been taken into account. Greatly enhanced power production can be obtained at present hydroelectric facilities if heat engines are adapted to exploit this large thermal energy resource.
Ultraviolet Spectroscopy of Venus: Initial Results from the Pioneer Venus Orbiter
Authors: Stewart A. I. , Anderson D. E. , Esposito L. W. , Barth C. A.
Published: October 2006

Ultraviolet spectroscopy of the Venus cloud tops reveals absorption features attributed to sulfur dioxide in the atmosphere above the cloud tops. Measurements of scattered sunlight at 2663 angstroms show evidence for horizontal and vertical inhomogeneities in cloud structure. Images of the planet at SO
2
absorption wavelengths show albedo features similar to those seen at 3650 angstroms from Mariner 10. Airglow emissions are consistent with an exospheric temperature of ∼275 K, and a night airglow emission has been detected, indicating the precipitation of energy into the dark thermosphere.
Venus Lower Atmospheric Composition: Preliminary Results from Pioneer Venus
Authors: Hoffman J. H. , Hodges R. R. , McElroy M. B. , Donahue T. M. , Kolpin M.
Published: October 2006

Initial examination of data from the neutral mass spectrometer on the Pioneer Venus sounder probe indicates that the abundances of argon-36, argon-38, and neon-20 in the Venus atmosphere are much higher than those of the corresponding gases in Earth's atmosphere, although the abundance of radiogenic argon-40 is apparently similar for both planets. The lower atmosphere of Venus includes significant concentrations of various gaseous sulfur compounds. The inlet leak to the mass spectrometer was temporarily blocked by an apparently liquid component of the Venus clouds during passage through the dense cloud layer. Analysis of gases released during the evaporation of the droplets shows the presence of water vapor to some compound or compounds of sulfur.
Wind Velocities on Venus: Vector Determination by Radio Interferometry
Authors: Counselman C. C. , Gourevitch S. A. , King R. W. , Pettengill G. H. , Prinn R. G. , Shapiro I. I. , Miller R. B. , Smith J. R. , Ramos R. , Liebrecht P.
Published: October 2006

To determine the wind directions and speeds on Venus, as each Pioneer probe fell to the surface we tracked its motion in three dimensions using a combination of Doppler and long-baseline radio interferometric methods. Preliminary results from this tracking, coupled with results from test observations of other spacecraft, enable us to estimate the uncertainties of our eventual determinations of the velocity vectors of the probes with respect to Venus. For altitudes below about 65 kilometers and with time-averaging over 100-second intervals, all three components of the velocity should have errors of the order of 0.3 meter per second or less.
Capture Enhancement in a Carnivorous Aquatic Plant: Function of Antennae and Bristles in
Utricularia vulgaris
Authors: Meyers Dewey G. , Strickler J. Rudi
Published: October 2006

Traps of the carnivorous hydrophyte
Utricularia vulgaris
Linnaeus (Lentibulariaceae) have structures termed antennae and bristles around their trapdoors that increase their rate of entrapment of the substrate-dwelling prey
Chydorus sphaericus
(Chydoridae, Crustacea). The kind and number of these structures are important in determining capture rate. Experimental data and corresponding behavioral observations support Darwin's hypothesis that antennae and bristles function as a "funnel" leading potential prey toward the trapdoor and their capture by offering the prey a favorable substrate that exploits their natural locomotor and feeding behavior.
Efficiency of Convection in Variable Stars and the Sun
Authors: Cogan Bruce C.
Published: October 2006

Observed changes in the pulsation periods of Cepheid variables can be used to place an upper limit on changes in convective efficiency in their outer layers. This limit implies changes no larger than those recently suggested as occurring in the sun.
Surface Observations for the Evaluation of Geophysical Measurements from Seasat
Authors: Wilkerson J. C. , Brown R. A. , Cardone V. J. , Coons R. E. , Loomis A. A. , Overland J. E. , Peteherych S. , Pierson W. J. , Woiceshyn P. M. , Wurtele M. G.
Published: October 2006

The surface observations used in the initial assessment of Seasat are discussed with emphasis on their ability to describe the synoptic-scale winds over the ocean.
Seasat Scanning Multichannel Microwave Radiometer: Results of the Gulf of Alaska Workshop
Authors: Lipes R. G. , Bernstein R. L. , Cardone V. J. , Katsaros K. B. , Njoku E. G. , Riley A. L. , Ross D. B. , Swift C. T. , Wentz F. J.
Published: October 2006

The scanning multichannel microwave radiometer results for the Gulf of Alaska Seasat Experiment Workshop are quite encouraging, especially in view of the immaturity of the data-processing algorithms. For open ocean, rain-free cells of highest-quality surface truth wind determinations exhibit standard deviations of 3 meters per second about a bias of 1.5 meters per second. The sea-surface temperature shows a standard deviation of approximately 1.5°C about a bias of 3° to 5°C under a variety of changing meteorological conditions.
Empirical Models of the Electron Temperature and Density in the Nightside Venus Ionosphere
Authors: Brace L. H. , Theis R. F. , Niemann H. B. , Mayr H. G. , Hoegy W. R. , Nagy A. F.
Published: October 2006

Empirical models of the electron temperature and electron density of the late afternoon and nightside Venus ionosphere have been derived from Pioneer Venus measurements acquired between 10 December 1978 and 23 March 1979. The models describe the average ionosphere conditions near 18° N latitude between 150 and 700 kilometers altitude for solar zenith angles of 80° to 180° . The average index of solar flux was 200. A major feature of the density model is the factor of 10 decrease beyond 90° followed by a very gradual decrease between 120° and 180° . The density at 150° is about five times greater than observed by Venera 9 and 10 at solar minimum (solar flux ≈80), a difference that is probably related to the effects of increased solar activity on the processes that maintain the nightside ionosphere. The nightside electron density profile from the model (above 150 kilometers) can be reproduced theoretically either by transport of O
+
ions from the dayside or by precipitation of low-energy electrons. The ion transport process would require a horizontal flow velocity of about 300 meters per second, a value that is consistent with other Pioneer Venus observations. Although currently available energetic electron data do not yet permit the role of precipitation to be evaluated quantitatively, this process is clearly involved to some extent in the formation of the nightside ionosphere. Perhaps the most surprising feature of the temperature model is that the electron temperature remains high throughout the nightside ionosphere. These high nocturnal temperatures and the existence of a well-defined nightside ionopause suggest that energetic processes occur across the top of the entire nightside ionosphere, maintaining elevated temperatures. A heat flux of 2 × 10
10
electron volts per square centimeter per second, introduced at the ionopause, is consistent with the average electron temperature profile on the nightside at a solar zenith angle of 140° .
Venus Ionosphere: Photochemical and Thermal Diffusion Control of Ion Composition
Authors: Bauer Siegfried J. , Donahue Thomas M. , Hartle Richard E. , Taylor Harry A.
Published: October 2006

The major photochemical sources and sinks for ten of the ions measured by the ion mass spectrometer on the Pioneer Venus bus and orbiter spacecraft that are consistent with the neutral gas composition measured on the same spacecraft have been identified. The neutral gas temperature (
T
n
) as a function of solar zenith angle (χ) derived from measured ion distributions in photochemical equilibrium is given by
T
n
(
K
) = 323 cos
1/5
χ. Above 200 kilometers, the altitude behavior of ions is generally controlled by plasma diffusion, with important modifications for minor ions due to thermal diffusion resulting from the observed gradients of plasma temperatures. The dayside equilibrium distributions of ions are sometimes perturbed by plasma convection, while lateral transport of ions from the dayside seems to be a major source of the nightside ionosphere.
Electron Observations and Ion Flows from the Pioneer Venus Orbiter Plasma Analyzer Experiment
Authors: Intriligator D. S. , Collard H. R. , Mihalov J. D. , Whitten R. C. , Wolfe J. H.
Published: October 2006

Additional plasma measurements in the vicinity of Venus are presented which show that (i) there are three distinct plasma electron populations—solar wind electrons, ionosheath electrons, and nightside ionosphere electrons; (ii) the plasma ion flow pattern in the ionosheath is consistent with deflected flow around a blunt obstacle; (iii) the plasma ion flow velocities near the downstream wake may, at times, be consistent with the deflection of plasma into the tail, closing the solar wind cavity downstream from Venus at a relatively close distance (within 5 Venus radii) to the planet; (iv) there is a separation between the inner boundary of the downstream ionosheath and the upper boundary of the nightside ionosphere; and (v) during the first 4.5 months in orbit the measured solar wind plasma speed continued to vary, showing a number of high-speed, but generally nonrecurrent, streams.
Thermal Contrast in the Atmosphere of Venus: Initial Appraisal from Pioneer Venus Probe Data
Authors: Seiff Alvin , Kirk Donn B. , Young Richard E. , Sommer Simon C. , Blanchard Robert C. , Findlay John T. , Kelly G. M.
Published: October 2006

The altitude profiles of temperature and pressure measured during the descent of the four Pioneer Venus probes show small contrast below the clouds but significant differences within the clouds at altitudes from 45 to 61 kilometers. At 60 kilometers, the probe which entered at 59.3° north latitude sensed temperatures 25 K below those of the lower latitude probes, and a sizable difference persisted down to and slightly below the cloud base. It also sensed pressure below those of the other probes by as much as 49 millibars at a mean pressure of 200 millibars. The measured pressure differences are consistent with cyclostrophic balance of zonal winds ranging from 130 ° 20 meters per second at 60 kilometers to 60 ° 17 meters per second at 40 kilometers, with evidence in addition of a nonaxisymmetric component of the winds. The clouds were found to be 10 to 20 K warmer than the extended profiles of the lower atmosphere, and the middle cloud is convectively unstable. Both phenomena are attributed to the absorption of thermal radiation from below. Above the clouds, in the lower stratosphere, the lapse rate decreases abruptly to 3.5 K per kilometer, and a superimposed wave is evident. At 100 kilometers, the temperature is minimum, with a mean value of about 170 K.
A Nodule-Specific Plant Protein (Nodulin-35) from Soybean
Authors: Legocki Roman P. , Verma Desh Pal S.
Published: October 2006

Nodulin-35, a 35,000-molecular-weight protein, is present in soybean root nodules developed by different strains of
Rhizobium japonicum
, irrespective of their effectiveness in fixing atmospheric nitrogen. This protein is not detected in uninfected plants and bacteroids or in free-living
Rhizobium
and appears to be synthesized by the plant during the formation of root nodules.
Photosynthetic Pathway and Biomass Energy Production
Authors: Marzola D. L. , Bartholomew D. P.
Published: October 2006

The current interest in locating new or alternative sources of energy has focused attention on solar energy capture by crops that can be subsequently utilized as a substitute for fossil fuels. The very high productivity of sugarcane and the fact that it accumulates sugars that are directly fermentable to alcohol may have caused seemingly less productive crops to be overlooked. We show here that recoverable alcohol from achievable commercial yields of pineapple can actually equal that of sugarcane, with the pineapple crop requiring only a fraction of the water used by sugarcane. Pineapple is well adapted to the subhumid or semiarid tropics and thus is particularly well suited for exploiting large areas not now under cultivation with any crop of commercial value.
Carbon-13 in Tree Rings Indicates No Record of Sea-Surface Temperature
Authors: MacIntyre Ferren
Published: October 2006

When the correct values for the temperature coefficient of carbon dioxide solubility in seawater are used, theoretical calculations show that no measurable carbon-isotope redistribution occurs between sea and air for any plausible change in the sea-surface temperature. Although this fact invalidates one possible paleothermometer, it somewhat simplifies the interpretation of carbon-13 data in terrestrial biological samples.
Determination of the Pore Size of Cell Walls of Living Plant Cells
Authors: Carpita Nicholas , Sabularse Dario , Montezinos David , Delmer Deborah P.
Published: October 2006

The limiting diameter of pores in the walls of living plant cells through which molecules can freely pass has been determined by a solute exclusion technique to be 35 to 38 angstroms for hair cells of
Raphanus sativus
roots and fibers of
Gossypium hirsutum
, 38 to 40 angstroms for cultured cells of
Acer pseudoplatanus
, and 45 to 52 angstroms for isolated palisade parenchyma cells of the leaves of
Xanthium strumarium
and
Commelina communis
. These results indicate that molecules with diameters larger than these pores would be restricted in their ability to penetrate such a cell wall, and that such a wall may represent a more significant barrier to cellular communication than has been previously assumed.
Use of Barley in the Egyptian Late Paleolithic
Authors: Wendorf Fred , Schild Romuald , El Hadidi Nabil , Close Angela E. , Kobusiewicz Michael , Wieckowska Hanna , Issawi Bahay , Haas Herbert
Published: October 2006

Several grains of barley have been recovered from archeological sites at Wadi Kubbaniya, near Aswan in Egypt. The sites are typical Late Paleolithic and are firmly dated between 18,300 and 17,000 years ago. They seem to represent a very early use of ground grain in the Nile Valley, and evidence is presented for its continued use over the subsequent 6000 years. The Egyptian findings possibly record an initial stage of food production, and if they indeed do, then they suggest that food production may not have been brought about by environmental stress and may not have led inevitably to radical social changes.
Single Crystals of Linear Polyethylene Crystallized from the Glass
Authors: Lam R. , Geil P. H.
Published: October 2006

Isolated single crystals of polyethylene have been crystallized from the glassy state by annealing uniformly thick films of amorphous linear polyethylene just above their glass transition temperature. In agreement with previous results for polycarbonate, substantial molecular mobility at the glass transition temperature is implied.
Sibling Matings in a Hunting Wasp: Adaptive Inbreeding?
Authors: Cowan David P.
Published: October 2006

Upon emergence as adults, brothers of
Euodynerus foraminatus
compete among themselves for the microterritory around their natal nest. The winning male inseminates his sisters as they emerge several days later. Unlike most species that inbreed in a similar fashion, both sexes of this common wasp are strong fliers. The possibility is raised that siblings may be preferred as mates even when outbreeding is possible.
Precision Optical Testing
Authors: Wyant James C.
Published: October 2006

Increased performance requirements for modern optical systems have necessitated the development of more precise optical testing techniques. The need for accurate and rapid measurements is being met by the use of laser interferometers, microprocessors to gather test data, and computers to analyze the data and remove errors in the test equipment.
Size of the Permo-Triassic Bottleneck and Its Evolutionary Implications
Authors: Raup David M.
Published: October 2006

Rarefaction analysis of extinctions in the Late Permian indicates that as many as 96 percent of all marine species may have died out, thus forcing the marine biosphere to pass through a small bottleneck. With such severity of extinction, chance elimination of certain biologic groups would have been probable. Some of the changes in biologic composition observed at the Permo-Triassic boundary may be explained as an evolutionary founder effect that followed the bottleneck.