bluuebunny/crossref_metadata_2025 huggingface dataset:
Sea Anemone with Zooxanthellae: Simultaneous Contraction and Expansion in Response to Changing Light Intensity
Authors: Gladfelter William B.
Published: October 2006

Under increasing intensity of light, the normal tentacles of
Lebrunea
contract whereas the pseudotentacles expand; in decreasing light the reverse is true. This behavior may be correlated with greater numbers of zooxanthellae in the pseudotentacles. Simultaneous but opposite response of parts suggests adaptations toward photosynthesis by day and predation by night.
Signal Transduction by Interferon-α Through Arachidonic Acid Metabolism
Authors: Hannigan Gregory E. , Williams Bryan R. G.
Published: October 2006

Molecular mechanisms that mediate signal transduction by growth inhibitory cytokines are poorly understood. Type I (α and β) interferons (IFNs) are potent growth inhibitory cytokines whose biological activities depend on induced changes in gene expression. IFN-α induced the transient activation of phospholipase A
2
in 3T3 fibroblasts and rapid hydrolysis of [
3
H]arachidonic acid (AA) from prelabeled phospholipid pools. The phospholipase inhibitor, bromophenacyl bromide (BPB), specifically blocked IFN-induced binding of nuclear factors to a conserved, IFN-regulated enhancer element, the interferon-stimulated response element (ISRE). BPB also caused a dose-dependent inhibition of IFN-α-induced ISRE-dependent transcription in transient transfection assays. Specific inhibition of AA oxygenation by eicosatetraynoic acid prevented IFN-α induction of factor binding to the ISRE. Treatment of intact cells with inhibitors of fatty acid cyclooxygenase or lipoxygenase enzymes resulted in amplification of IFN-α-induced ISRE binding and gene expression. Thus, IFN-α receptor-coupled AA hydrolysis may function in activation of latent transcription factors by IFN-α and provides a system for studying the role of AA metabolism in transduction of growth inhibitory signals.
Regeneration of Oligodendroglia During Recovery from Demyelinating Disease
Authors: Herndon Robert M. , Price Donald L. , Weiner Leslie P.
Published: October 2006

Infection of mice with the JHM strain of mouse hepatitis virus causes demyelination as a result of a cytolytic infection of oligodendroglia. In recovery, animals show remyelination, which could result either from surviving oligodendrocytes extending their territory or by generation of new oligodendroglia. Electron microscopic autoradiographic studies with
3
H-labeled thymidine demonstrate that the cells associated with remyelination are newly generated oligodendroglia.
Paleogene Terrestrial Vertebrates: Northernmost Occurrence, Ellesmere Island, Canada
Authors: Dawson Mary R. , West Robert M. , Langston Wann , Hutchison J. Howard
Published: October 2006

Recently discovered Paleogene land vertebrates from the Eureka Sound Formation at about latitude 78° north in Arctic Canada include fish, turtles, an alligatorid, and several taxa of mammals. The assemblage, which is probably early or middle Eocene in age, adds to previously known paleobotanical evidence in suggesting temperate to warm-temperate climatic conditions.
Dinoflagellates: Fossil Motile-Stage Tests from the Upper Cretaceous of the Northern New Jersey Coastal Plain
Authors: May Fred E.
Published: October 2006

Fossil dinoflagellate tests have been considered to represent encysted, nonmotile stages. The discovery of flagellar porelike structures and probable trichocyst pores in the Upper Cretaceous genus
Dinogymnium
suggests that motile stage tests are also preserved as acid-resistant, organic-walled microfossils.
Search for the Viking 2 Landing Site
Authors: Masursky H. , Crabill N. L.
Published: October 2006

The search for the landing site of Viking 2 was more extensive than the search for the Viking 1 site. Seven times as much area (4.5 million square kilometers) was examined as for Viking 1. Cydonia (B1) and Capri (C1) sites were examined with the Viking 1 orbiter. The B latitude band (40° to 50°N) was selected before the final midcourse maneuver of Viking 2 because of its high scientific interest (that is, high atmospheric water content, surface temperature, possible near-surface permafrost, and a different geological domain). The Viking 1 orbiter continued photographing the Cydonia (B1) site to search for an area large and smooth enough on which to land (three-sigma ellipse; 100 by 260 kilometers); such an area was not found. The second spacecraft photographed and made infrared measurements in large areas in Arcadia (B2) and Utopia Planitia (B3). Both areas are highly textured, mottled cratered plains with abundant impact craters like Cydonia (B1), but smaller sectors in each area are partially mantled by wind-formed deposits. The thermal inertia, from which the grain size of surface material can be computed, and atmospheric water content were determined from the infrared observations. A region in Utopia Planitia, west of the crater Mie, was selected: the landing took place successfully on 3 September 1976 at 3:58:20 p.m. Pacific Daylight Time, earth received time.
Rare-Earth Manganites: Surface-Segregated Platinum Increases Catalytic Activity
Authors: Croat John J. , Tibbetts Gary G. , Katz Seymour
Published: October 2006

Crushed and etched lanthanum lead manganite (La
0.7
Pb
0.3
MnO
3
) crystals containing as little as 0.005 atomic percent platinum have significantly higher catalytic activity than free platinum crystals. This higher activity is due to an almost 100-fold segregation of platinum on the surface. The surface platinum concentration found, 0.5 atomic percent, is sufficient to account for the enhanced activity provided that the platinum has the same activity as platinum supported on alumina.
Bioenergetic Considerations in Cereal Breeding for Protein Improvement
Authors: Bhatia C. R. , Rabson R.
Published: October 2006

The bioenergetic implications of changing cereal grain protein concentrations and amino acid compositions by plant breeding are examined. It is shown that increased inputs of carbon assimilates and nitrogen are necessary when increasing protein concentration in cereal grains while maintaining high yields. Also, energetic requirements for obtaining endosperm proteins with a high lysine content in genotypes of maize and barley are slightly higher than in normal lysine stocks. The implications for plant breeding are discussed.
Cloning and Expression of a Cocaine-Sensitive Dopamine Transporter Complementary DNA
Authors: Shimada Shoichi , Kitayama Shigeo , Lin Chien-Liang , Patel Amrat , Nanthakumar Elizabeth , Gregor Paul , Kuhar Michael , Uhl George
Published: October 2006

A rat dopamine (DA) transporter complementary DNA has been isolated with combined complementary DNA homology and expression approaches. The DA transporter is a 619-amino acid protein with 12 hydrophobic putative membrane-spanning domains and homology to the norepinephrine and γ-aminobutyric acid transporters. The expressed complementary DNA confers transport of [
3
H]DA in
Xenopus
oocytes and in COS cells. Binding of the cocaine analog [
3
H]CFT {[
3
H]2β-carbomethoxy-3β-(4-fluorophenyl)tropane} to transfected COS cell membranes yields a pharmacological profile similar to that in striatal membranes.
Region-Specific Neural Induction of an
engrailed
Protein by Anterior Notochord in
Xenopus
Authors: Hemmati-Brivanlou Ali , Stewart Ronald M. , Harland Richard M.
Published: October 2006

Anterior-specific neural induction can be assayed by means of an antibody that recognizes the
Xenopus
homeobox-containing protein En-2. The En-2 antigen is an excellent early marker, since it is present as a discrete band in the anterior neural plate of neurula embryos. Regional induction was assayed by combining dorsal mesoderm with competent ectoderm. Anterior notochord from the early neurula induced En-2 frequently, while posterior notochord induced En-2 less frequently. Presumptive somitic mesoderm and presumptive head mesoderm, though they induced neural tissue, were not strong inducers of En-2. Thus, anterior notochord may be the primary mesodermal tissue responsible for the patterning of the anterior neural plate.
Gravitational Compression of Crystallized Suspensions of Polystyrene Spheres
Authors: Crandall Richard S. , Williams Richard
Published: October 2006

In a crystallized suspension of polystyrene spheres, the earth's gravitational field, acting on a vertical column of material several centimeters high, produces an elastic deformation that can be readily observed through its effect on the crystal lattice constant. This effect has been used to determine that Young's modulus for the crystalline material ranges from 1 to 3 dynes per square centimeter, depending on the concentration of spheres.
Implications of Solar Evolution for the Earth's Early Atmosphere
Authors: Newman Michael J. , Rood Robert T.
Published: October 2006

The roughly 25 percent increase in luminosity over the life of the sun shared by many different solar models is shown to be a very general result, independent of the uncertainties suggested by the solar neutrino experiment. Superficially, this leads to a conflict with the climatic history of the earth, and if basic concepts of stellar evolution are not fundamentally in error, compensating effects must have occurred, as first pointed out by Sagan and Mullen. One possible interpretation supported by recent detailed models of the earth's atmosphere is that the greenhouse effect was substantially more important than at present even as recently as 1 billion to 2 billion years ago.
The Berger Inquiry: An Impact Assessment Process
Authors: Gamble D. J.
Published: October 2006

The Mackenzie Valley Pipeline Inquiry, conducted by the Honorable Mr. Justice T. R. Berger, undertook to explore thoroughly the issues surrounding the building of a northern pipeline. In doing so, the Inquiry provided a forum for the interplay of the technical and environmental issues with very personalized social and cultural concerns. As a process, it reached out beyond the direct participants: it became one in which all Canadians, north and south, participated. It touched some of Canada's deepest concerns—concerns about energy policy, resource allocation, the price and priority of industrial development, cultural sovereignty, and self-definition. These have become national concerns, not just regional. And so, no matter what the final decision is about the pipeline, the Inquiry will have a profound and lasting national influence.
Mount Agung Eruption Provides Test of a Global Climatic Perturbation
Authors: Hansen James E. , Wang Wei-Chyung , Lacis Andrew A.
Published: October 2006

The Mount Agung volcanic eruption in 1963 provides the best-documented global radiative perturbation to the earth's atmosphere currently available. Data on stratospheric aerosols produced by this eruption have been used as input to a model for the atmospheric thermal structure. The computed magnitude, sign, and phase lag of the temperature changes in both the stratosphere and the troposphere are in good agreement with observations, providing evidence that the climatic response to a global radiative perturbation is significant, as well as support for the use of theoretical models to predict climatic effects.
Ultraviolet-Photoproduced Organic Solids Synthesized Under Simulated Jovian Conditions: Molecular Analysis
Authors: Khare B. N. , Sagan Carl , Bandurski Eric L. , Nagy Bartholomew
Published: October 2006

In an earlier paper, Khare and Sagan reported the production of a brownish polymeric material from the near-ultraviolet irradiation of simulated jovian atmospheres with a low hydrogen abundance. Examination of this product indicates that hydrogen sulfide is the initial photon acceptor; the powder resulting after extraction with benzene is 84 percent sulfur, largely S
8
. In results reported here, the remaining 16 percent was pyrolyzed and then examined by gas chromatography-mass spectrometry. Pyrolysis at 450°C yielded a series of alkanes, alkenes, C
3
-alkylbenzenes, aromatics, thiophenes, alkylthiophenes, alkylmercaptans, alkyldisulfides, together with the nitrogenous compounds hydrogen cyanide, methyl cyanide, alkylisothiocyanates, acrylonitrile, and allylisothiocyanates. Some of these compounds might be sought on Jupiter and Saturn and their satellites by remote infrared and ultraviolet spectroscopy and directly by entry probes.
Amorphous Ice on Saturnian Rings and on Icy Satellites: Its Formation, Stability, and Observability
Authors: Smoluchowski R.
Published: October 2006

Saturnian rings and icy satellites may be covered with amorphous rather than crystalline ice. Its likely source is water molecules sputtered by particles in the radiation belts, it may be stable, and its presence could be deduced from the rate of temperature drop in a shadow. Observation of this effect is, however, difficult, especially for the rings. A possible relation to the brightness anisotropy of ring A is pointed out.
Red - Green Opponent Spectral Sensitivity: Disparity Between Cancellation and Direct Matching Methods
Authors: Ingling Carl R. , Russell Phillip W. , Rea Mark S. , Tsou Brian H.-P.
Published: October 2006

The spectral sensitivity at the opponent stage of the visual system is traditionally measured by a hue-cancellation procedure. Comparison with a direct hue-matching method shows that cancellation overestimates short-wavelength sensitivity by as much as a factor of 30. The observation implies that different mechanisms control the perception of short-wavelength and long-wavelength redness.
Stabilized Lasers and Precision Measurements
Authors: Hall J. L.
Published: October 2006

This article traces the development of stabilized lasers from the Massachusetts Institute of Technology passive-stabilization experiments of the early 1960's up through the current epoch of highly stabilized helium-neon and carbon dioxide and continuous wave dye lasers. The utility, present performance, and limitations of stabilized lasers as standards of length or frequency for precision measurements are discussed. Examples considered of laser applications to physical measurements of outstanding scientific interest include determination of the speed of light, redefinition of the meter, resolution of the photon recoil-induced spectral doubling, use of optical "Ramsey" interference fringes from ultrahigh-resolution spectroscopy, and two improved tests of special relativity.
Ozone Formation Related to Power Plant Emissions
Authors: Miller David F. , Alkezweeny Abdul J. , Hales Jeremy M. , Lee Richard N.
Published: October 2006

A curious and unambiguous event of excess ozone formation downwind of a power plant has been analyzed. A kinetic model used to simulate the event indicates that the excess ozone can be reconciled entirely on the basis of excess nitrogen oxides in the polluted air.
Pentobarbital: Differential Postsynaptic Actions on Sympathetic Ganglion Cells
Authors: Nicoll R. A.
Published: October 2006

The frog sympathetic ganglion has been used as a model to elucidate the cellular mechanism of barbiturate anesthesia. Anesthetic concentrations of pentobarbital markedly reduced the fast nicotinic excitatory postsynaptic potential while having no effect on the slow excitatory postsynaptic potential or slow inhibitory postsynaptic potential, even though all three synaptic potentials depend on the presynaptic release of acetylcholine. A similar differential effect was seen for nicotinic and muscarinic responses to exogenously applied agonists, while the depolarizing action of γ-aminobutyric acid (GABA) was enhanced. These results indicate that pentobarbital has remarkably selective actions on the sympathetic ganglion and further indicate that blockade of ganglionic transmission by anesthetic concentrations of pentobarbital can be entirely explained by a postsynaptic action. The present results strengthen the concept that pentobarbital anesthesia results from a postsynaptic blockade of central excitatory synapses which increase sodium conductance coupled with a postsynaptic enhancement of GABA-mediated synaptic inhibition.
Millikan "Oil Drop" Stabilized by Growth
Authors: Sun Light K. , Gertler Alan W. , Reiss Howard
Published: October 2006

A diffusion cloud chamber has been used to qualitatively study some dynamic properties of liquid drops by suspending them in an electric field at the plane of saturation (
p
/
p
s
= 1, where p is the actual partial pressure of the vapor at a given elevation and
p
s
is the equilibrium pressure at that temperature characteristic of that elevation). By varying the strength of the electric field, it is possible to change the size of the suspended droplets and even, if desired, to isolate a single drop.
The Ross Ice Shelf Project
Authors: Clough John W. , Hansen B. Lyle
Published: October 2006

A hole was drilled through the Ross Ice Shelf 450 kilometers from the barrier. Scientific sampling through this hole revealed a sparse population of crustaceans, fish, and microbial biomass. The seabed consists of mid-Miocene glaciomarine mud. Geothermal heat flow is average. Oceanographic data indicate an active circulation and melting at the base of the ice.
Tritium and Carbon-14 Distributions in Seawater from Under the Ross Ice Shelf Project Ice Hole
Authors: Michel R. L. , Linick T. W. , Williams P. M.
Published: October 2006

The tritium and carbon-14 activities of seawater samples collected from 22 to 200 meters below the ice at the Ross Ice Shelf Project ice hole are reported. The tritium results show that the waters below the ice have exchanged with Ross Sea water since the advent of nuclear testing. The carbon-14 results indicate that waters in the upper layer exchange in time periods of less than 6 years. Measurements of these isotopes in seawater under the Ross Ice Shelf in McMurdo Sound show that this water has a different history.
Occurrence and Metabolic Activity of Organisms Under the Ross Ice Shelf, Antarctica, at Station J9
Authors: Azam F. , Beers J. R. , Campbell L. , Carlucci A. F. , Holm-Hansen O. , Reid F. M. H. , Karl D. M.
Published: October 2006

Seawater samples below the Ross Ice Shelf were collected through an access hole at J9, approximately 400 kilometers from the Ross Sea, Antarctica. The 237-meter water column had sparse populations of bacteria (8.7 × 10
6
to 1.2 × 10
7
per liter), microplankters (10
2
to 10
3
per cubic meter), and zooplankters (10 to 20 per cubic meter) at the depths studied. Microbial biomass estimates from cellular adenosine 5′-triphosphate measurements were very low (10 to 150 nanograms of carbon per liter), comparable with values for the abyssal ocean. Microbial populations assimilated tritiated D-glucose, thymidine, uridine, and adenosine triphosphate at extremely low rates, comparable with deep-sea heterotrophic populations. Sediment samples had 10
7
to 10
8
bacteria per gram (dry weight), which were metabolically active as shown by respiration of uniformly labeled D-[
14
C]glucose. From this study it cannot be determined whether these organisms in the water column and sediments constitute a functioning food web.
Thermal Structure and Major Ion Composition of the Venus Ionosphere: First RPA Results from Venus Orbiter
Authors: Knudsen W. C. , Spenner K. , Whitten R. C. , Spreiter J. R. , v K. L. , Novak V.
Published: October 2006

Thermal plasma quantities measured by the retarding potential analyzer (RPA) are, together with companion Pioneer Venus measurements, the first in situ measurements of the Venus ionosphere. High ionospheric ion and electron temperatures imply significant solar wind heating of the ionosphere. Comparison of the measured altitude profiles of the dominant ions with an initial model indicates that the ionosphere is close to diffusive equilibrium. The ionopause height was observed to vary from 400 to 1000 kilometers in early orbits. The ionospheric particle pressure at the ionopause is apparently balanced at a solar zenith angle of about 70° by the magnetic field pressure with little contribution from energetic solar wind particles. The measured ratio of ionospheric scale height to ionopause radius is consistent with that inferred from previously measured bow shock positions.
Preferential Utilization of Free Cholesterol From High-Density Lipoproteins for Biliary Cholesterol Secretion in Man
Authors: Schwartz Charles C. , Halloran L. Gregg , Vlahcevic Z. Reno , Gregory Daniel H. , Swell Leon
Published: October 2006

High- and low-density lipoproteins carrying free cholesterol labeled with
3
H or
14
C were administered to a patient with a bile fistula. The free cholesterol from high-density lipoproteins was more rapidly incorporated into biliary cholesterol than the free cholesterol from low-density lipoproteins. These findings show that the liver in man selectively utilizes and secretes the free cholesterol from a particular lipoprotein.
Mating Preference and the Direction of Evolution in
Drosophila
Authors: Watanabe Takao K. , Kawanishi Masaoki
Published: October 2006

Differences in the degree of successful matings between pairs of reciprocal hybrid matings indicate the direction of evolution among related species of
Drosophila
. Females of a derived species do not mate with males of the ancestral species, whereas females of the ancestral species readily mate with males of the derived species.
Atmospheric Carbon Tetrafluoride: A Nearly Inert Gas
Authors: Cicerone Ralph J.
Published: October 2006

An analysis of existing thermodynamic, photochemical, and kinetic data indicates that the dominant sinks for atmospheric carbon tetrafluoride (CF
4
) are in and above the mesosphere. Theoretical calculations predict an atmospheric residence time for CF
4
of over 10,000 years, about 100 times that for dichlorodifluoromethane (CF
2
Cl
2
) and monofluorotrichloromethane (CFCl
3
). It is predicted that CF
4
will be well mixed through the stratosphere and mesosphere; only one or two parts of hydrogen fluoride in 10
12
are predicted in the high stratosphere as a result of the decomposition of CF
4
. Although natural sources of CF
4
cannot be ruled out, there are several likely industrial sources that may account for its present concentration. The principal environmental effect of CF
4
could be the trapping of outgoing planetary infrared energy in its intense bands near 8 micrometers.
Voyager 2 Encounter with the Jovian System
Authors: Stone E. C. , Lane A. L.
Published: October 2006

An overview of the Voyager 2 encounter with Jupiter is presented, including a brief discussion of the trajectory, the major sequence modifications performed because of the Jupiter measurements obtained with Voyager 1, and highlights of the results that are described in the subsequent reports.
The Helium Question
Authors: Cook Earl
Published: October 2006

Helium appears indispensable for certain energy-related uses that may be important 50 years from now, when helium-bearing natural gas, a much cheaper source than air, may be exhausted. Present demand, however, is lower than productive capacity, and much helium is being dissipated into the atmosphere as natural gas is burned for fuel. Controversy over the need for a government-directed helium-conservation program reflects fundamental differences in viewpoints on the economic future of industrial society, on the limits of substitution of labor and capital for a depleting resource, and on intergenerational equity and risk-bearing.
Ocean Energy: Forms and Prospects
Authors: Isaacs John D. , Schmitt Walter R.
Published: October 2006

The nature and distribution of power sources of the sea other than petroleum are discussed, along with possible entrées for their use. Waves, tides, currents, and salinity and temperature gradients all have the potential to contribute useful power. Submarine geothermal sources, salt domes, ice, and other marine-associated concentrations may be more important. There are opportunities to employ these marine power resources directly rather than for contributions to power grids or power-intensive products. Ancillary employment of the seawater as a coolant and of the sediments below the seabed for the disposal of nuclear wastes may be even more important uses than employment of the power that the sea contains.
Phosphorus Sources for Aquatic Weeds: Water or Sediments?
Authors: Carignan R. , Kalff J.
Published: October 2006

Nine common species of aquatic macrophytes took all their phosphorus from the sediments when grown in situ in both a mesotrophic and a mildly eutrophic bay. Even under hypertrophic conditions, the sediments contributed an average of 72 percent of all the phosphorus taken up during growth. These experiments unambiguously demonstrate for the first time that submergent macrophytes in nature overwhelmingly depend on the sediments for their phosphorus supply and characterize them as potential nutrient pumps to the open water.
Electron—Atom (Molecule) Collision Processes
Authors: Trajmar Sandor
Published: October 2006

Electron-atom (molecule) collision processes at low and intermediate energies are discussed. Measurements of collision cross sections are described briefly. The experimental techniques and the interpretation of observations are illustrated by specific examples.
Radiant Heat for Energy Conservation
Authors: Pound R. V.
Published: October 2006

It is proposed that human comfort could be provided in otherwise chilly surroundings by filling the occupied space with electromagnetic energy of centimeter wavelength. Very considerable reductions in the consumption of energy required for the heating of buildings should result from the lowering of interior temperatures thereby permitted.
Detecting Climate Change due to Increasing Carbon Dioxide
Authors: Madden Roland A. , Ramanathan V.
Published: October 2006

The observed interannual variability of temperature at 60°N has been investigated. The results indicate that the surface warming due to increased carbon dioxide which is predicted by three-dimensional climate models should be detectable now. It is not, possibly because the predicted warming is being delayed more than a decade by ocean thermal inertia, or because there is a compensating cooling due to other factors. Further consideration of the uncertainties in model predictions and of the likely delays introduced by ocean thermal inertia extends the range of time for the detection of warming, if it occurs, to the year 2000. The effects of increasing carbon dioxide should be looked for in several variables simultaneously in order to minimize the ambiguities that could result from unrecognized compensating cooling.
Geomorphic Reconstructions in the Environs of Ancient Troy
Authors: Kraft John C. , Kayan Ilhan , Erol Oğuz
Published: October 2006

Sea level rise, deltaic progradation, and floodplain aggradation have changed the landscape in the vicinity of ancient Troy during the past 10,000 years. With the waning of the last major world glaciation and resultant sea level rise and fluctuation, a marine embayment protruded nearly 10 kilometers south of the site of Troy at Hisarlik in the Troad of northwest Turkey. As the sea approached its present level approximately 6000 years ago, fluvial and marine deposition caused a northerly migration of the delta and floodplain of the Scamander and Simois Rivers past the site of Troy toward the present-day coast about 6 kilometers north of the site. In view of these major changes in morphology, interpretations of ancient geographies related to historical or historical-mythological settings must be changed. A number of paleogeographic maps have been reconstructed with the use of subsurface data that records the continuing landscape change since the first occupancy of the site at Troy 5000 years ago. These show that ancient Troy was located on an embayment of the sea. If the Trojan War occurred, then the axis of the battlefield and associated events must be relocated to the south and west of Troy.
Aztec Arithmetic: Positional Notation and Area Calculation
Authors: Harvey H. R. , Williams B. J.
Published: October 2006

Texcocan-Aztec peoples in the Valley of Mexico used both picture symbols and lines and dots for numerical notation. Decipherment and analysis of mid-16th-century native pictorial land documents from the Texcocan region indicate that the line-and-dot system incorporated a symbol for zero and used position to ascribe values. Positional line-and-dot notation was used to record areas of agricultural fields, and analysis of the documentary data suggests that areas were calculated arithmetically. These findings demonstrate that neither positional notation nor the zero were unique to the Maya area, and they imply an equally sophisticated mathematical development among the Aztecs.
Mitochondrial Thyroid Hormone Receptor: Localization and Physiological Significance
Authors: Sterling Kenneth , Lazarus John H. , Milch Peter O. , Sakurada Toshiro , Brenner Milton A.
Published: October 2006

Binding studies of thyroid hormone to submitochondrial fractions from rat liver suggest that the component responsible for high-affinity, low-capacity (saturable) binding of hormones arises from the inner mitochondrial membrane. The partially purified component, approximately 150,000 daltons, appears to be half protein and half lipid, largely phospholipids, tentatively identified as lecithin, phosphatidyl ethanolamine, and cardiolipin. A similar hormone-binding macromolecule was found in mitochondria from rabbit kidney, from human liver and kidney, and from rat kidney, myocardium, skeletal muscle, intestinal mucosa, whole small intestine, adipose tissue, and lung. It was absent from mitochondria of adult rat brain, spleen, and testis, organs calorigenically unresponsive to thyroid hormones injected in vivo, but was present in mitochondria from brains of rats 12 days old and younger. The organ distribution of the hormone-binding protein and its presence in neonatal brain mitochondria supports the biological relevance of the mitochondrial component as a thyroid hormone receptor.
Rod-Cone Dysplasia in Irish Setters: A Defect in Cyclic GMP Metabolism in Visual Cells
Authors: Aquirre G. , Farber D. , Lolley R. , Fletcher R. T. , Chader G. J.
Published: October 2006

An abnormality in retinal guanosine 3′,5′-monophosphate (cyclic GMP) metabolism is demonstrated in the inherited rod-cone dysplasia of Irish Setter dogs. Affected visual cells are deficient in cyclic GMP phosphodiesterase activity and have elevated levels of cyclic GMP. The biochemical abnormalities observed in affected retinas of Irish Setters are similar to those in the retinas of mice with inherited retinal degeneration before visual cell degeneration begins. A defect in cyclic GMP metabolism may be characteristic of early-onset degenerative diseases of the retina, possibly including those that affect humans.
Observations of Solar Irradiance Variability
Authors: Willson R. C. , Gulkis S. , Janssen M. , Hudson H. S. , Chapman G. A.
Published: October 2006

High-precision measurements of total solar irradiance, made by the active cavity radiometer irradiance monitor on the Solar Maximum Mission satellite, show the irradiance to have been variable throughout the first 153 days of observations. The corrected data resolve orbit-to-orbit variations with uncertainties as small as 0.001 percent. Irradiance fluctuations are typical of a band-limited noise spectrum with high-frequency cutoff near 0.15 day
–1
; their amplitudes about the mean value of 1368.31 watts per square meter approach ± 0.05 percent. Two large decreases in irradiance of up to 0.2 percent lasting about 1 week are highly correlated with the development of sunspot groups. The magnitude and time scale of the irradiance variability suggest that considerable energy storage occurs within the convection zone in solar active regions.
Chlorine Oxide in the Stratospheric Ozone Layer: Ground-Based Detection and Measurement
Authors: Parrish A. , de Zafra R. L. , Solomon P. M. , Barrett J. W. , Carlson E. R.
Published: October 2006

Stratospheric chlorine oxide, a significant intermediate product in the catalytic destruction of ozone by atomic chlorine, has been detected and measured by a ground-based 204-gigahertz, millimeter-wave receiver. Data taken at latitude 42°N on 17 days between 10 January and 18 February 1980 yield an average chlorine oxide column density of ∼1.05 × 10
14
per square centimeter or ∼2/3 that of the average of eight in situ balloon flight measurements (excluding the anomalously high data of 14 July 1977) made over the past 4 years at 32°N. We find less chlorine oxide below 35 kilometers and a larger vertical gradient than predicted by theoretical models of the stratospheric ozone layer.
Prevention of HIV-1 Infection and Preservation of CD4 Function by the Binding of CPFs to gp120
Authors: Finberg Robert W. , Diamond David C. , Mitchell Darren B. , Rosenstein Yvonne , Soman Gopalan , Norman Thea C. , Schreiber Stuart L. , Burakoff Steven J.
Published: October 2006

Infection by human immunodeficiency virus type-1 (HIV-1) is initiated when its envelope protein, gp120, binds to its receptor, the cell surface glycoprotein CD4. Small molecules, termed
N
-carbomethoxycarbonyl-prolyl-phenylalanyl benzyl esters (CPFs), blocked this binding. CPFs interacted with gp120 and did not interfere with the binding of CD4 to class II major histocompatibility complex molecules. One CPF isomer, CPF(DD), preserved CD4-dependent T cell function while inhibiting HIV-1 infection of H9 tumor cells and human T cells. Although the production of viral proteins in infected T cells is unaltered by CPF(DD), this compound prevents the spread of infection in an in vitro model system.
Transcription Factor Interactions: Selectors of Positive or Negative Regulation from a Single DNA Element
Authors: Diamond Marc I. , Miner Jeffrey N. , Yoshinaga Steven K. , Yamamoto Keith R.
Published: October 2006

The mechanism by which a single factor evokes opposite regulatory effects from a specific DNA sequence is not well understood. In this study, a 25-base pair element that resides upstream of the mouse proliferin gene was examined; it conferred on linked promoters either positive or negative glucocorticoid regulation, depending upon physiological context. This sequence, denoted a "composite" glucocorticoid response element (GRE), was bound selectively in vitro both by the glucocorticoid receptor and by c-Jun and c-Fos, components of the phorbol ester-activated AP-1 transcription factor. Indeed, c-Jun and c-Fos served as selectors of hormone responsiveness: the composite GRE was inactive in the absence of c-Jun, whereas it conferred a positive glucocorticoid effect in the presence of c-Jun, and a negative glucocorticoid effect in the presence of c-Jun and relatively high levels of c-Fos. The receptor also interacted selectively with c-Jun in vitro. A general model for composite GRE action is proposed that invokes both DNA binding and protein-protein interactions by receptor and nonreceptor factors.
A Novel Illusion of Bars Made from Triangles
Authors: Leguire L. E. , Blake R. , Sloane M. E.
Published: October 2006

A repetitive pattern of a triangular luminance profile may be perceived as a triangular-wave grating or as a square-wave grating. This illusion may reflect the operation of cortical phase-selective mechanisms that are biased toward particular phase relations and favor abrupt luminance gradients.
The Mount St. Helens Volcanic Eruption of 18 May 1980: Minimal Climatic Effect
Authors: Robock Alan
Published: October 2006

An energy-balance numerical climate model was used to simulate the effects of the Mount St. Helens volcanic eruption of 18 May 1980. The resulting surface temperature depression is a maximum of 0.1°C in the winter in the polar region, but is an order of magnitude smaller than the observed natural variability from other effects and will therefore be undetectable.
A Test for Responsiveness to Song Structure and Programming in Female Sparrows
Authors: Searcy William A. , Marler Peter
Published: October 2006

Female song sparrows, primed with implants of estradiol, gave the solicitation display for copulation in response to acoustic stimulation with song. This technique demonstrated that female song sparrows respond more strongly to conspecific song than to alien songs, that they discriminate on the basis of both overall temporal pattern and syllabic structure, that they respond more to several song types than to repetitions of one song, and that they are most responsive to several song types if the songs are organized in bouts of a single type, as they are normally delivered by a male song sparrow. These results demonstrate a substantial correspondence between the structure and programming of the singing behavior of male birds and female responsiveness to song.
Presence of a Potent Transcription Activating Sequence in the p53 Protein
Authors: Fields Stanley , Jang Sung Key
Published: October 2006

The p53 gene is frequently mutated in a wide variety of human cancers. However, the role of the wild-type p53 gene in growth control is not known. Hybrid proteins that contain the DNA binding domain of yeast GAL4 and portions of p53 have been used to show that the p53 protein contains a transcription-activating sequence that functions in both yeast and mammalian cells. The NH
2
-terminal 73 residues of p53 activated transcription in mammalian cells as efficiently as the herpes virus protein VP16, which contains one of the strongest known activation domains. Combined with previous data that showed p53 is localized to the nucleus and can bind to DNA, these results support the idea that one function of p53 is to activate the transcription of genes that suppress cell proliferation.
Transcriptional Activation by Wild-Type but Not Transforming Mutants of the p53 Anti-Oncogene
Authors: Raycroft Loretta , Wu Hongyun , Lozano Guillermina
Published: October 2006

The protein encoded by the wild-type p53 proto-oncogene has been shown to suppress transformation, whereas certain mutations that alter p53 become transformation competent. Fusion proteins between p53 and the GAL4 DNA binding domain were made to anchor p53 to a DNA target sequence and to allow measurement of transcriptional activation of a reporter plasmid. The wild-type p53 stimulated transcription in this assay, but two transforming mutations in p53 were unable to act as transcriptional activators. Therefore, p53 can activate transcription, and transformation-activating mutations result in a loss of function of the p53 protein. The inability of the p53 mutant proteins to activate transcription may enable them to be transformation competent.
Cellular Analysis of Long-Term Habituation of the Gill-Withdrawal Reflex of
Aplysia californica
Authors: Castellucci V. F. , Carew T. J. , Kandel E.R.
Published: October 2006

Long-term habituation training in
Aplysia californica
produces a profound depression in the efficacy of synaptic transmission between mechanoreceptor neurons and gill motor neurons. This depression persists for more than 3 weeks. Thus a critical synaptic site for plasticity underlying long-term habituation is the same as that for short-term habituation. For this simple form of learning, short- and long-term memory share a common locus and aspects of a common mechanism: synaptic depression.
Thermal Insulating Capabilities of Outdoor Clothing Materials
Authors: Kaufman W. C. , Bothe D. , Meyer S. D.
Published: October 2006

A single heat transfer measurement technique was used to determine the thermal insulating capabilities of four materials used in outdoor clothing—goose down, wool, polyester, and polyolefin. It was found that all provide very similar degrees of insulation.
Nuclear Magnetic Resonance at High Pressure
Authors: Jonas Jiri
Published: October 2006

Nuclear magnetic resonance relaxation measurements at high pressure provide unique information about the microscopic behavior of liquids. This article presents the principles of this technique; illustrates its usefulness by several specific examples of studies of molecular liquids, water, and supercritical dense fluids; and indicates the promising future of high-resolution nuclear magnetic resonance spectroscopy at high pressure with examples of studies of chemical exchange and homogeneous catalytic processes.
Functional Organization of Primate Visual Cortex Revealed by High Resolution Optical Imaging
Authors: Ts'o Daniel Y. , Frostig Ron D. , Lieke Edmund E. , Grinvald Amiram
Published: October 2006

A high spatial resolution optical imaging system was developed to visualize cerebral cortical activity in vivo. This method is based on activity-dependent intrinsic signals and does not use voltage-sensitive dyes. Images of the living monkey striate (VI) and extrastriate (V2) visual cortex, taken during visual stimulation, were analyzed to yield maps of the distribution of cells with various functional properties. The cytochrome oxidase-rich blobs of V1 and the stripes of V2 were imaged in the living brain. In V2, no ocular dominance organization was seen, while regions of poor orientation tuning colocalized to every other cytochrome oxidase stripe. The orientation tuning of other regions of V2 appeared organized as modules that are larger and more uniform than those in V1.
Fast Ion Bombardment of Ices and Its Astrophysical Implications
Authors: Brown W. L. , Lanzerotti L. J. , Johnson R. E.
Published: October 2006

Ices such as water, carbon dioxide, and methane are now known to be pervasive constituents of the solar system and probably of the interstellar medium as well. Many of these ices and ice-covered surfaces are exposed to bombardment by the energetic ions of space. Laboratory experiments have been carried out to study the effects of such bombardment. Surprisingly efficient erosion of ice layers is associated with electronic excitation of the ices by the ions. These results are a challenge to an understanding of the physical processes involved and have implications for a number of astrophysical problems of current interest.
New Sources for Fuel and Materials
Authors: Calvin Melvin
Published: October 2006

A selection of new plant sources with high potential for production of chemicals and liquid fuels is reviewed. Some productivity data are given, and suggestions are made for modification of both the product character and the productivity of the plants.
Cosmic-Ray Record in Solar System Matter
Authors: Reedy Robert C. , Arnold James R. , Lal Devendra
Published: October 2006

The energetic nuclei in cosmic rays interact with meteoroids, the moon, planets, and other solar system matter. The nuclides and heavy nuclei tracks produced by the cosmic-ray particles in these targets contain a wealth of information about the history of the objects and temporal and spatial variations in the particle fluxes. Most lunar samples and many meteorites have complex histories of cosmic-ray exposure from erosion, gardening, fragmentation, orbital changes, and other processes. There appear to be variations in the past fluxes of solar particles, and possibly also galactic cosmic rays, on time scales of 104to 107years.
Metabolic Detoxification: Mechanism of Insect Resistance to Plant Psoralens
Authors: Ivie G. Wayne , Bull Don L. , Beier Ross C. , Pryor Nan W. , Oertli Ernest H.
Published: October 2006

Larvae of the black swallowtail butterfly,
Papilio polyxenes
Stoll, forage successfully on plants that contain high levels of photosensitizing psoralens. These insects rapidly detoxify psoralens, particularly in the midgut tissue prior to absorption, with the result that appreciable levels of unmetabolized phototoxin do not enter the body circulation where deleterious light-induced interactions with dermal or subdermal tissues would occur.
In Search of Methuselah: Estimating the Upper Limits to Human Longevity
Authors: Olshansky S. Jay , Carnes Bruce A. , Cassel Christine
Published: October 2006

Estimates of the upper limits to human longevity have important policy implications that directly affect forecasts of life expectancy, active life expectancy, population aging, and social and medical programs tied to the size and health status of the elderly population. In the past, investigators have based speculations about the upper limits of human longevity on observations of past trends in mortality. Here the estimate of the upper bound is based on hypothesized reductions in current mortality rates necessary to achieve a life expectancy at birth from 80 to 120 years and an expectation of life at age 50 from 30 to 70 years. With the use of conditional probabilities of death from complete life tables for the United States, reductions in mortality required to achieve extreme longevity (that is, 80 to 120 years) were compared with those resulting from hypothetical cures for all cardiovascular diseases, ischemic heart disease, diabetes, and cancer. Results indicate that in order for life expectancy at birth to increase from present levels to what has been referred to as the average biological limit to life (age 85), mortality rates from all causes of death would need to decline at all ages by 55%, and at ages 50 and over by 60%. Given that hypothetical cures for major degenerative diseases would reduce overall mortality by 75%, it seems highly unlikely that life expectancy at birth will exceed the age of 85.
Xochicalco: Urban Growth and State Formation in Central Mexico
Authors: Hirth Kenneth
Published: October 2006

The appearance of regional city-states in pre-Hispanic Central Mexico corresponds with the disruption of socioeconomic relationships throughout Teotihuacán's political domain after 650 A.D. Surface reconnaissance and mapping at Xochicalco provided information on the growth and organization of one of these urban centers. The data indicate that Xochicalco was a well-planned urban center and capital of a regional city-state that extended its domain throughout western Morelos by military conquest.
Identification of a Specialized Adenylyl Cyclase That May Mediate Odorant Detection
Authors: Bakalyar Heather A. , Reed Randall R.
Published: October 2006

The mammalian olfactory system may transduce odorant information via a G protein-mediated adenosine 3′,5′-monophosphate (cAMP) cascade. A newly discovered adenylyl cyclase, termed type III, has been cloned, and its expression was localized to olfactory neurons. The type III protein resides in the sensory neuronal cilia, which project into the nasal lumen and are accessible to airborne odorants. The enzymatic activity of the type III adenylyl cyclase appears to differ from nonsensory cyclases. The large difference seen between basal and stimulated activity for the type III enzyme could allow considerable modulation of the intracellular cAMP concentration. This property may represent one mechanism of achieving sensitivity in odorant perception.
Laser-Induced Chemistry for Microelectronics
Authors: Osgood R. M. , Deutsch T. F.
Published: October 2006

Laser-controlled chemical reactions are being explored for use in all phases of the processing of semiconductor devices. Laser-induced chemical processing can produce submicrometer features without the aid of photolithography. Research is also providing new information on light-excited and light-enhanced interface reactions.
Hemolin: an Insect-Immune Protein Belonging to the Immunoglobulin Superfamily
Authors: Sun Shao-Cong , Lindström Ingrid , Boman Hans G. , Faye Ingrid , Schmidt Otto
Published: October 2006

Insects have an efficient defense system against infections. Their antibacterial immune proteins have been well characterized. However, the molecular mechanisms by which insects recognize foreignness are not yet known. Data are presented showing that hemolin (previously named P4), a bacteria-inducible hemolymph protein of the giant silk moth
Hyalophora cecropia
, belongs to the immunoglobulin superfamily. Functional analyses indicate that hemolin is one of the first hemolymph components to bind to the bacterial surface, taking part in a protein complex formation that is likely to initiate the immune response.