bluuebunny/crossref_metadata_2025 huggingface dataset:
Sequence-Specific Binding of Human Ets-1 to the T Cell Receptor α Gene Enhancer
Authors: Ho I-Cheng , Bhat Narayan K. , Gottschalk Lisa R. , Lindsten Tullia , Thompson Craig B. , Papas Takis S. , Leiden Jeffrey M.
Published: October 2006

Expression of the human T cell receptor (TCR) α gene is regulated by a T cell-specific transcriptional enhancer that is located 4.5 kilobases (kb) 3′ to the Cα gene segment. The core enhancer contains two nuclear protein binding sites, Tα1 and Tα2, which are essential for full enhancer activity. Tα1 contains a consensus cyclic adenosine monophosphate (cAMP) response element (CRE) and binds a set of ubiquitously expressed CRE binding proteins. In contrast, the transcription factors that interact with the Tα2 site have not been defined. In this report, a λgt11 expression protocol was used to isolate a complementary DNA (cDNA) that programs the expression of a Tα2 binding protein. DNA sequence analysis demonstrated that this clone encodes the human
ets
-1 proto-oncogene. Lysogen extracts produced with this cDNA clone contained a β-galactosidase-Ets-1 fusion protein that bound specifically to a synthetic Tα2 oligonucleotide. The Ets-1 binding site was localized to a 17-base pair (bp) region from the 3′ end of Tα2. Mutation of five nucleotides within this sequence abolished both Ets-1 binding and the activity of the TCR α enhancer in T cells. These results demonstrate that Ets-1 binds in a sequence-specific fashion to the human TCR α enhancer and suggest that this developmentally regulated proto-oncogene functions in regulating TCR α gene expression.
A Map of Visual Space Induced in Primary Auditory Cortex
Authors: Roe Anna W. , Pallas Sarah L. , Hahm Jong-On , Sur Mriganka
Published: October 2006

Maps of sensory surfaces are a fundamental feature of sensory cortical areas of the brain. The relative roles of afferents and targets in forming neocortical maps in higher mammals can be examined in ferrets in which retinal inputs are directed into the auditory pathway. In these animals, the primary auditory cortex contains a systematic representation of the retina (and of visual space) rather than a representation of the cochlea (and of sound frequency). A representation of a two-dimensional sensory epithelium, the retina, in cortex that normally represents a one-dimensional epithelium, the cochlea, suggests that the same cortical area can support different types of maps. Topography in the visual map arises both from thalamocortical projections that are characteristic of the auditory pathway and from patterns of retinal activity that provide the input to the map.
Inhibition of the Complement Cascade by the Major Secretory Protein of Vaccinia Virus
Authors: Kotwal Girish J. , Isaacs Stuart N. , McKenzie Robin , Frank Michael M. , Moss Bernard
Published: October 2006

The complement system contributes to host defenses against invasion by infectious agents. A 35-kilodalton protein, encoded by vaccinia virus and secreted from infected cells, has sequence similarities to members of a gene family that includes complement control proteins. Biochemical and genetic studies showed that the viral protein binds to derivatives of the fourth component of complement and inhibits the classical complement cascade, suggesting that it serves as a defense molecule to help the virus evade the consequences of complement activation.
Regulation of Gene Expression with Double-Stranded Phosphorothioate Oligonucleotides
Authors: Bielinska Anna , Shivdasani Ramesh A. , Zhang Liquan , Nabel Gary J.
Published: October 2006

Alteration of gene transcription by inhibition of specific transcriptional regulatory proteins is necessary for determining how these factors participate in cellular differentiation. The functions of these proteins can be antagonized by several methods, each with specific limitations. Inhibition of sequence-specific DNA-binding proteins was achieved with double-stranded (ds) phosphorothioate oligonucleotides that contained octamer or κB consensus sequences. The phosphorothioate oligonucleotides specifically bound either octamer transcription factor or nuclear factor (NF)-κB. The modified oligonucleotides accumulated in cells more effectively than standard ds oligonucleotides and modulated gene expression in a specific manner. Octamer-dependent activation of a reporter plasmid or NF-κB-dependent activation of the human immunodeficiency virus (HIV) enhancer was inhibited when the appropriate phosphorothioate oligonucleotide was added to a transiently transfected B cell line. Addition of phosphorothioate oligonucleotides that contained the octamer consensus to Jurkat T leukemia cells inhibited interleukin-2 (IL-2) secretion to a degree similar to that observed with a mutated octamer site in the IL-2 enhancer. The ds phosphorothioate oligonucleotides probably compete for binding of specific transcription factors and may provide anti-viral, immunosuppressive, or other therapeutic effects.
The Appearance of Sustained Equatorial Surface Westerlies During the 1982 Pacific Warm Event
Authors: Harrison D. E.
Published: October 2006

In June 1982 a band of anomalous southerly surface wind, extending from the equator as far south as the Tasman Sea, formed east of Australia (150°E to 160°E). This flow crossed the equator just before the appearance of sustained westerly winds on the equator somewhat west of the date line. Because these westerly winds induced the initial strong equatorial warming of the ocean east of the date line during the 1982 El Niño-Southern Oscillation (ENSO) event, the southerly jet appears to be an important atmospheric component leading to the onset of the vigorous phase of this event. Some historical evidence suggests that anomalous southerly winds in the same region occurred prior to the appearance of sustained equatorial westerly winds in the major ENSO events of 1957, 1965, and 1972.
Community Recovery After Storm Damage: A Case of Facilitation in Primary Succession
Authors: Harris Larry G. , Ebeling Alfred W. , Laur David R. , Rowley Robert J.
Published: October 2006

Manipulations of early arriving, fast-growing algal stands, which appeared soon after a severe storm denuded a Southern California marine reef habitat, indicated that the dense cover protected newly settled kelp plants from excessive damage by grazing fishes. This is an example of refuge facilitation in primary succession after a major natural disturbance, a mechanism that may contribute substantially to the regeneration of a kelp forest.
Bishop Tuff Revisited: New Rare Earth Element Data Consistent with Crystal Fractionation
Authors: Cameron Kenneth L.
Published: October 2006

The Bishop Tuff of eastern California is the type example of a high-silica rhyolite that, according to Hildreth, supposedly evolved by liquid-state differentiation. New analyses establish that the Bishop Tuff "early/late" rare earth element trend reported by Hildreth mimics the relations between groundmass glasses and whole rocks for allanite-bearing pumice. Differences in elemental concentrations between whole rock and groundmass are the result of phenocryst precipitation; thus the data of Hildreth are precisely those expected to result from crystal fractionation.
The 1984 Morgan Hill, California, Earthquake
Authors: Bakun W. H. , Clark M. M. , Cockerham R. S. , Ellsworth W. L. , Lindh A. G. , Prescott W. H. , Shakal A. F. , Spudich P.
Published: October 2006

The Morgan Hill, California, earthquake (magnitude 6.1) of 24 April 1984 ruptured a 30-kilometer-long segment of the Calaveras fault zone to the east of San Jose. Although it was recognized in 1980 that an earthquake of magnitude 6 occurred on this segment in 1911 and that a repeat of this event might reasonably be expected, no short-term precursors were noted and so the time of the 1984 earthquake was not predicted. Unilateral rupture propagation toward the south-southeast and an energetic late source of seismic radiation located near the southeast end of the rupture zone contributed to the highly focused pattern of strong motion, including an exceptionally large horizontal acceleration of 1.29
g
at a site on a dam abutment near the southeast end of the rupture zone.
Brain Factor Control of Sex Pheromone Production in the Female Corn Earworm Moth
Authors: Raina Ashok K. , Klun Jerome A.
Published: October 2006

Sex pheromone production in the female corn earworm moth
Heliothis zea
is controlled by a hormonal substance produced in the female's brain. It is present in the brain in scotophase as well as photophase, but it is released into the hemolymph to stimulate pheromone production only in the scotophase. The stimulatory activity was also detected in the brains of male corn earworm moths and of other moths.
Holocene History of Cedar and Native Indian Cultures of the North American Pacific Coast
Authors: Hebda Richard J. , Mathewes Rolf W.
Published: October 2006

A comparison of paleobotanical records with archeological and ethnographic evidence from the Pacific Northwest shows a strong correlation between the expansion of Western red cedar (
Thuja plicata
) in coastal forests between 5000 and 2500 years ago and the evolution of a massive woodworking technology by native cultures. This suggests that an important component of cultural development was environmentally constrained until large cedar trees, the basic resource for canoe-building and plank-house construction, had become available in late Holocene time.
Crop Productivity and Photoassimilate Partitioning
Authors: Gifford Roger M. , Thorne J. H. , Hitz W. D. , Giaquinta Robert T.
Published: October 2006

The photosynthetic basis for increasing the yield of major field crops is examined in terms of improving the interception of seasonal solar radiation by crop foliage, the efficiency of conversion of intercepted light to photosynthetic assimilates, and the partitioning of photoassimilates to organs of economic interest. It is concluded that, in practice, genetic and chemical manipulation of light interception over the season and of partitioning offer the most potential for achieving further increases in yield. During the history of improvement of genetic yield potential of crops, increase in the partitioning of photoassimilates to harvested organs has been of primary importance.
Side-Scan Sonar Assessment of Gray Whale Feeding in the Bering Sea
Authors: Johnson Kirk R. , Nelson C. Hans
Published: October 2006

Side-scan sonar was used to map and measure feeding pits of the California gray whale over 22,000 square kilometers of the northeastern Bering Sea floor. The distribution of pits, feeding whales, ampeliscid amphipods (whale prey), and a fine-sand substrate bearing the amphipods were all closely correlated. The central Chirikov Basin and nearshore areas of Saint Lawrence Island supply at least 6.5 percent of the total gray whale food resource in summer. While feeding, the whales resuspend at least 1.2 × 10
8
cubic meters of sediment annually; this significantly affects the geology and biology of the region.
Detection of Radial Crossbridge Force by Lattice Spacing Changes in Intact Single Muscle Fibers
Authors: Cecchi G. , Bagni M. A. , Griffiths P. J. , Ashley C. C. , Maeda Y.
Published: October 2006

Time-resolved lattice spacing changes were measured (10-millisecond time resolution) by x-ray diffraction of synchrotron radiation in single intact muscle fibers of the frog
Rana temporaria
undergoing electrically stimulated tension development during application of stretches and releases. Ramp releases, which decreased fiber length at constant speed, caused a lattice expansion. After the ramp, increasing tension during recovery was accompanied by lattice compression. Ramp stretches caused a compression of the lattice. While the fiber was held at a constant length after the stretch, tension decreased and lattice spacing increased. These observations demonstrate the existence of a previously undetected radial component of the force generated by a cycling crossbridge. At sarcomere lengths of 2.05 to 2.2 micrometers, the radial force compresses the myofilament lattice. Hence, the myofilament lattice does not maintain a constant volume during changes in force.
The Jovian Nebula: A Post-Voyager Perspective
Authors: Trauger John T.
Published: October 2006

Voyager 1 carried a diverse collection of magnetospheric probes through the inner Jovian magnetosphere in March 1979. The ensuing data analysis and theoretical investigation provided a comprehensive description of the Jovian nebula, a luminous torus populated with newly released heavy ions drawn from Io's surface. Recent refinements in Earth-based imaging instrumentation are used to extend the Voyager in situ picture in temporal and spatial coverage. An analysis of [SIII] and [SII] optical emissions observed during the Jovian apparitions of 1981 through 1983 reveals three distinct torus components. Regularities have been identified in the ion partitioning and ion densities in the hot outer and inner tori, sharply defined radial structure is found in the plasma near Io, and the relative permanence of the cool inner torus is inferred. An extended cloud of neutral material is required as a source of fresh ions in the nebula.
The Dark Night-Sky Riddle: A "Paradox" That Resisted Solution
Authors: Harrison E. R.
Published: October 2006

The riddle of a dark night sky, now known as "Olbers's paradox," can be traced back to Thomas Digges in 1576. Since the time of Edmund Halley (1721) the riddle of a dark night sky in an infinite universe uniformly populated with stars has been regarded as a paradox. Constant emphasis on the paradoxical aspect of the problem of darkness at night, however, leads to a one-sided interpretation of the riddle. Calling the phenomenon a "paradox" distorts the historical perspective, and consequently we incorrectly attribute the origin of the riddle to Edmund Halley. Also it distorts the cosmological perspective and quite probably has greatly delayed the solution of the riddle.
Speciation and Stasis in Marine Ostracoda: Climatic Modulation of Evolution
Authors: Cronin Thomas M.
Published: October 2006

Morphologic and paleozoogeographic analysis of Cenozoic marine Ostracoda from the Atlantic, Caribbean, and Pacific indicates that climatic change modulates evolution by disrupting long-term stasis and catalyzing speciation during sustained, unidirectional climatic transitions and, conversely, by maintaining morphologic stasis during rapid, high-frequency climatic oscillations. In the middle Pliocene, 4 to 3 million years ago, at least six new species of
Puriana
suddenly appeared as the Isthmus of Panama closed, changing oceanographic circulation and global climate. Since then morphologic stasis has characterized ancestral and descendant species during many glacial-interglacial cycles. The frequency and duration of climatic events have more impact on ostracode evolution than the magnitude of climatic changes.
The Agricultural Mechanization Controversy
Authors: Martin Philip L. , Olmstead Alan L.
Published: October 2006

Attorneys of California Rural Legal Assistance are suing the University of California on behalf of 19 farm workers, alleging that publicly funded mechanization research displaces farm workers, eliminates small farmers, hurts consumers, impairs the quality of rural life, and impedes collective bargaining. This article reviews the evidence and finds that it does not support the charges. The mechanization lawsuit is important because applied research by universities is often authorized by legislation stipulating multiple goals, leaving researchers and universities vulnerable to lawsuits alleging that only some of the legislative goals are being pursued.
Electrically Conductive Metallomacrocyclic Assemblies
Authors: Marks Tobin J.
Published: October 2006

The design, synthesis, and study of electrically conductive molecular and polymeric substances constitute a new scientific endeavor involving the interaction of chemists, physicists, and materials scientists. The strategies, developments, and challenges in these two closely related fields are analyzed via a class of materials that bridges both: assemblies of electrically conductive metallomacrocycles. It is seen that efforts to rationally synthesize tailored, "metal-like" molecular arrays lead logically to structure-enforced polymeric assemblies of linked molecular subunits such as metallophthalocyanines. The properties of these assemblies and fragments thereof provide information on the relationship between atomic-level local architecture, electronic structure, and macroscopic transport properties. Electrically conductive, processable polymeric materials also follow from these results.
High-Resolution Nuclear Magnetic Resonance of Inorganic Solids
Authors: Oldfield Eric , Kirkpatrick R. James
Published: October 2006

Recent improvements in instrumentation and technique now permit the observation of high-resolution nuclear magnetic resonance spectra of many nuclei in inorganic solids. The application of nuclear magnetic resonance to the study of the structures of materials of interest in chemistry, earth science, and materials science are discussed together with a prognosis for future work.
Around-the-World Relativistic Sagnac Experiment
Authors: Allan D. W. , Weiss M. A. , Ashby N.
Published: October 2006

In 1971 Hafele and Keating carried portable atomic clocks east and then west around the world and verified the Sagnac effect, a special relativity effect attributable to the earth's rotation. In the study reported here observations of the effect were made by using electromagnetic signals instead of portable clocks to make clock comparisons. Global Positioning System satellites transmit signals that can be viewed simultaneously from remote stations on the earth; thus an around-the-world Sagnac experiment can be performed with electromagnetic signals. The effect is larger than that occurring when portable clocks are used. The average error over a 3-month experiment was only 5 nanoseconds.
Selection for Increased Safety Factors of Biological Structures as Environmental Unpredictability Increases
Authors: Lowell Richard B.
Published: October 2006

Theory predicts that selection should increase the ratio of the performance of a biological structure or system to the requirements placed upon it (that is, its safety factor) as conditions become increasingly unpredictable. Although conventional safety factors are rarely measurable, an alternative, truncation safety factor (the ratio of mean strength to maximum possible load), can be measured quantitatively for certain load-bearing structures. For intertidal limpet shells subject to prying forces, truncation safety factor was found to increase with increased variability in shell strength, thus providing direct support for the theory.
Dragonfly Flight: Novel Uses of Unsteady Separated Flows
Authors: Somps Chris , Luttges Marvin
Published: October 2006

Studies of insect flight have revealed novel mechanisms of production of aerodynamic lift. In the present study, large lift forces were measured during flight episodes elicited from dragonflies tethered to a force balance. Simultaneously, stroboscopic photographs provided stop-action views of wing motion and the flow-field structure surrounding the insect. Wing kinematics were correlated with both instantaneous lift generation and vortex-dominated flow fields. The large lift forces appear to be produced by unsteady flow-wing interactions. This successful utilization of unsteady separated flows by insects may signal the existence of a whole new class of fluid dynamic uses that remain to be explored.
The Dielectric Constant of Phospholipid Bilayers and the Permeability of Membranes to Ions
Authors: Dilger James P. , McLaughlin Stuart G. A. , McIntosh Thomas J. , Simon Sidney A.
Published: October 2006

The Born charging equation predicts that the permeability of a phospholipid bilayer membrane to ions should depend markedly on the dielectric constant of the membrane. Increasing the dielectric constant of an artificial bilayer increases its permeability to perchlorate or thiocyanate by a factor of 1000, to a value comparable to that of mitochondrial membranes.
A Unique Symbiosis in the Gut of Tropical Herbivorous Surgeonfish (Acanthuridae: Teleostei) from the Red Sea
Authors: Fishelson Lev , Montgomery W. Linn , Myrberg Arthur A.
Published: October 2006

Herbivorous surgeonfish (
Acanthurus
species) in the Red Sea harbor gut symbionts that include bacteria, trichomonadid flagellates, and a peculiar putative protist that attains densities of 20,000 to 100,000 cells per milliliter of gut contents. The structure, mode of reproduction, and within-gut distribution of the latter are described. This may be the first report of an organism of this type and the first evidence of a consistent endosymbiosis in the gut of a herbivorous marine fish.
A Pea Mutant for the Study of Hydrotropism in Roots
Authors: Jaffe M. J. , Takahashi H. , Biro R. L.
Published: October 2006

Plant roots grow in the direction of increasing soil moisture, but studies of hydrotropism have always been difficult to interpret because of the effect of gravity. In this study it was found that roots of the mutant pea 'Ageotropum' are neither gravitropic nor phototropic, but do respond tropically to a moisture gradient, making them an ideal subject for the study of hydrotropism. When the root caps were removed, elongation was not affected but hydrotropism was blocked, suggesting that the site of sensory perception resides in the root cap.
Novel Role for Phycoerythrin in a Marine Cyanobacterium,
Synechococcus
Strain DC2
Authors: Wyman M. , Gregory R. P. F. , Carr N. G.
Published: October 2006

Cyanobacterial picoplankton contribute substantially to oceanic primary productivity. The colored protein phycoerythrin is the major component of their light-harvesting apparatus. It was found that in
Synechococcus
strain DC2 a variable proportion of the light energy absorbed by phycoerythrin is lost as autofluorescence and therefore is not passed to a photoreaction center. Phycoerythrin may serve two functionally distinct roles in this organism: as a nitrogen reserve and as a collector of quanta for photosynthesis.
Fluid Beds: At Last, Challenging Two Entrenched Practices
Authors: Squires Arthur M. , Kwauk Mooson , Avidan Amos A.
Published: October 2006

Originating in the 1920's and 1930's, two distinct fluidization arts have emerged, one for treating coarse solids and the other for fine powders. Fluidization research has tended to focus on bubbling beds of coarse solids, but designers of such beds for burning coal have learned to appreciate the importance of combustion of fine char particles in the freeboard. Designers of successful processes for powders have focused on bubble suppression. Since about 1980, combustion fluid beds of both types are challenging the conventional pulverized-coal boiler; they provide better means for controlling emissions from the combustion of high-sulfur fuels. Progress in the "bubbleless" fluidization of fine powders is increasing the fluid bed's competitiveness with the fixed-bed catalytic reactor. Efforts to advance the fluid bed for catalysis, besides increasing gas velocities beyond levels that most researchers have used in the past, must include systematic study of the level of fine particles smaller than 40 micrometers.
Identification of Fructose 3-Phosphate in the Lens of Diabetic Rats
Authors: Szwergold Benjamin S. , Kappler Francis , Brown Truman R.
Published: October 2006

Fructose 3-phosphate, a novel monosaccharide phosphate, has been identified in the lens of diabetic rats. This compound, which is not present in normal lenses, is a protein glycosylating agent and enzyme inactivator. In addition, because of its structural features, this metabolite is relatively labile and undergoes hydrolysis to yield inorganic phosphate and the potent glycosylating agent, 3-deoxyglucosone. The increase in the concentration of fructose 3-phosphate in the lens of diabetic rats suggests that it and its hydrolysis product, 3-deoxyglucosone, may be responsible in part for the development of some diabetic complications in the lens.
Race and Imprisonment Decisions in California
Authors: Klein Stephen , Petersilia Joan , Turner Susan
Published: October 2006

Data were analyzed for 11,553 California offenders who in 1980 were convicted of assault, robbery, burglary, theft, forgery, or drug crimes. Whether an offender was given probation or sentenced to prison for such crimes could be predicted with about 80 percent accuracy from a combination of variables that described defendant and crime characteristics and criminal justice processing. The addition of race to the prediction equation for a given crime type did not improve the accuracy of the prediction. In addition, there was no evidence that other factors related to imprisonment (for example, number of conviction counts, going to trial) masked a relation between race and imprisonment. Race also was not related to the length of prison term imposed.
HTLV-I Trans-Activator Protein, Tax, is a Trans-Repressor of the Human β-Polymerase Ggene
Authors: Jeang Kuan-Teh , Widen Stevev G. , Semmes Oliver J. , Wilson Samuel H.
Published: October 2006

Human T cell leukemia virus type I (HTLV-I) is the etiological agent for adult T cell leukemia (ATL). The HTLV-I trans-activator protein Tax can activate the expression of its own long terminal repeat (LTR) and many cellular and viral genes. Tax down-regulated the expression of human β-polymerase (huβ-pol), a cellular enzyme involved in host cell DNA repair. This finding suggests a possible correlation between HTLV-I infection and host chromosomal damage, which is often seen in ATL cells.
Sevenless
: A Cell-Specific Homeotic Mutation of the
Drosophila
Eye
Authors: Tomlinson Andrew , Ready Donald F.
Published: October 2006

Each ommatidium in the compound eye of the
Drosophila
mutant
sevenless
lacks photoreceptor number seven (R7) from the normal ommatidial complement of eight photoreceptors. A comparison of mutant and normal development reveals that this deficit is caused by the cell-specific transformation of the cell normally fated to produce R7 into a lens-secreting accessory cell, a cone cell.
Bacterial Grazing by Planktonic Lake Algae
Authors: Bird David F. , Kalff Jacob
Published: October 2006

Six common species of lake algae were found to ingest bacteria. The ingestion rates measured were of the same magnitude as those recorded for marine microflagellates totally dependent on external sources of carbon. A large biomass of
Dinobryon
species removed more bacteria from the water column of a lake than crustaceans, rotifers, and ciliates combined.
Evolution of the Ratio of Strontium-87 to Strontium-86 in Seawater from Cretaceous to Present
Authors: Hess Jennifer , Bender Michael L. , Schilling Jean-Guy
Published: October 2006

A detailed record of the strontium-87 to strontium-86 ratio in seawater during the last 100 million years was determined by measuring this ratio in 137 well-preserved and well-dated fossil foraminifera samples. Sample preservation was evaluated from scanning electron microscopy studies, measured strontium-calcium ratios, and pore water strontium isotope ratios. The evolution of the strontium isotopic ratio in seawater offers a means to evaluate long-term changes in the global strontium isotope mass balance. Results show that the marine strontium isotope composition can be used for correlating and dating well-preserved authigenic marine sediments throughout much of the Cenozoic to a precision of ±1 million years. The strontium-87 to strontium-86 ratio in seawater increased sharply across the Cretaceous/Tertiary boundary, but this feature is not readily explained as strontium input from a bolide impact on land.
Long-Chain Diols: A New Class of Membrane Lipids from a Thermophilic Bacterium
Authors: Pond Jean L. , Langworthy Thomas A. , Holzer Gunther
Published: October 2006

Glycerol-derived membrane lipids are essentially absent in the thermophilic bacterium
Thermomicrobium roseum
. A series of straight chain and internally methyl-branched 1,2-diols of carbon numbers C
18
to C
23
were found to replace glycerolipids in this bacterium. Fatty acids were present but were ester-linked to the diols or amide-linked to polar heads groups and not to glycerol. This thermophile has evolved the integration of diols as a novel approach for the construction of its cytoplasmic membrane.
The VEGA Venus Balloon Experiment
Authors: Sagdeev R. Z. , Linkin V. M. , Blamont J. E. , Preston R. A.
Published: October 2006

In June 1985, two instrumented balloons were placed in the atmosphere of Venus as part of the VEGA mission. Each balloon traveled about 30 percent of the way around the planet at a float altitude near 54 kilometers. In situ sensors measured pressure, temperature, vertical wind velocity, cloud particle backscatter, ambient light level, and frequency of lightning. A ground-based network of 20 radio antennas tracked the balloons by very long baseline interferometry (VLBI) techniques to monitor the Venus winds. The history, organization, and principal characteristics of this international balloon experiment are described.
Implications of the VEGA Balloon Results for Venus Atmospheric Dynamics
Authors: Blamont J. E. , Young R. E. , Seiff A. , Ragent B. , Sagdeev R. , Linkin V. M. , Kerzhanovich V. V. , Ingersoll A. P. , Crisp D. , Elson L. S. , Preston R. A. , Golitsyn G. S. , Ivanov V. N.
Published: October 2006

Both VEGA balloons encountered vertical winds with typical velocities of 1 to 2 meters per second. These values are consistent with those estimated from mixing length theory of thermal convection. However, small-scale temperature fluctuations for each balloon were sometimes larger than predicted. The approximate 6.5-kelvin difference in temperature consistently seen between VEGA-1 and VEGA-2 is probably due to synoptic or planetary-scale nonaxisymmetric disturbances that propagate westward with respect to the planet. There is also evidence from Doppler data for the existence of solar-fixed nonaxisymmetric motions that may be thermal tides. Surface topography may influence atmospheric motions experienced by the VEGA-2 balloon.
Simulation of Paleocortex Performs Hierarchical Clustering
Authors: Ambros-Ingerson José , Granger Richard , Lynch Gary
Published: October 2006

Simulations were performed of layers I and II of olfactory paleocortex, as connected to its primary input structure, olfactory bulb. Induction of synaptic long-term potentiation by means of repetitive sampling of inputs caused the simulation to organize encodings of learned cues into a hierarchical memory that uncovered statistical relationships in the cue environment, corresponding to the performance of hierarchical clustering by the biological network. Simplification led to characterization of those parts of the network responsible for the mechanism, resulting in a novel, efficient algorithm for hierarchical clustering. The hypothesis is put forward that these corticobulbar networks and circuitry of similar design in other brain regions contain computational elements sufficient to construct perceptual hierarchies for use in recognizing environmental cues.
Lesser-Known Plants of Potential Use in Agriculture and Forestry
Authors: Vietmeyer Noel D.
Published: October 2006

To help feed, clothe, and house an increasing population, to make marginal lands more productive, to meet challenging resource needs, and to reforest the devastated tropics, we need a revitalized worldwide investigation of little-known plant species. Such an effort would expand our agricultural resource base and ease our dangerous dependence on a relative handful of crops. It would build a more stable food supply for drought-stricken Africa and other parts of the Third World, and it would reclothe many of the barren lands where erosion now threatens disaster. Some plants that are now virtually unknown are likely to become mainstays of international agriculture and industry.
Atmospheric Trace Gases: Trends and Distributions Over the Last Decade
Authors: Rasmussen R. A. , Khalil M. A. K.
Published: October 2006

Concentrations of the halocarbons CCl
3
F (F-11), CCl
2
F
2
(F-12), CCl
4
, and CH
3
CCl
3
, methane (CH
4
), and nitrous oxide (N
2
O) over the decade between 1975 and 1985 are reported, based on measurements taken every January at the South Pole and in the Pacific Northwest. The concentrations of F-11, F-12, and CH
3
CCl
3
in both hemispheres are now more than twice their concentrations 10 years ago. However, the annual rates of increase of F-11, F-12, and CH
3
CCl
3
are now considerably slower than earlier in the decade, reflecting in part the effects of a ban on their nonessential uses. Continued increases in these trace gas concentrations may warm the earth and deplete the stratospheric ozone layer, which may cause widespread climatic changes and affect global habitability.
Voyager 2 Radio Science Observations of the Uranian System: Atmosphere, Rings, and Satellites
Authors: Tyler G. L. , Sweetnam D. N. , Anderson J. D. , Campbell J. K. , Eshleman V. R. , Hinson D. P. , Levy G. S. , Lindal G. F. , Marouf E. A. , Simpson R. A.
Published: October 2006

Voyager 2 radio occultation measurements of the Uranian atmosphere were obtained between 2 and 7 degrees south latitude. Initial atmospheric temperature profiles extend from pressures of 10 to 900 millibars over a height range of about 100 kilometers. Comparison of radio and infrared results yields mole fractions near the tropopause of 0.85 and 0.15 ± 0.05 for molecular hydrogen and helium, respectively, if no other components are present; for this composition the tropopause is at about 52 kelvins and 110 millibars. Distinctive features in the signal intensity measurements for pressures above 900 millibars strongly favor model atmospheres that include a cloud deck of methane ice. Modeling of the intensity measurements for the cloud region and below indicates that the cloud base is near 1,300 millibars and 81 kelvins and yields an initial methane mole fraction of about 0.02 for the deep atmosphere. Scintillations in signal intensity indicate small-scale structure throughout the stratosphere and upper troposphere. As judged from data obtained during occultation ingress, the ionosphere consists of a multilayer structure that includes two distinct layers at 2,000 and 3,500 kilometers above the 100-millibar level and an extended topside that may reach altitudes of 10,000 kilometers or more. Occultation measurements of the nine previously known rings at wavelengths of 3.6 and 13 centimeters show characteristic values of optical depth between about 0.8 and 8; the maximum value occurs in the outer region of the ε ring, near its periapsis. Forward-scattered signals from this ring have properties that differ from those of any of Saturn's rings, and they are inconsistent with a discrete scattering object or local (three-dimensional) assemblies of orbiting objects. These signals suggest a new kind of planetary ring feature characterized by highly ordered cylindrical substructures of radial scale on the order of meters and azimuthal scale of kilometers or more. From radio data alone the mass of the Uranian system is GM
sys
= 5,794,547 ± 60 cubic kilometers per square second; from a combination of radio and optical navigation data the mass of Uranus alone is GM
u
= 5,793,939 ± 60 cubic kilometers per square second. From all available Voyager data, including imaging radii, the mean uncompressed density of the five major satellites is 1.40 ± 0.07 grams per cubic centimeter; this value is consistent with a solar mix of material and apparently rules out a cometary origin of the satellites.
Semiclassical Methods in Chemical Physics
Authors: Miller William H.
Published: October 2006

Semiclassical theory finds use in chemical physics both as a computational method and as a conceptual framework for interpreting quantum features in experiments and in numerical quantum calculations. The semiclassical description of one-dimensional dynamical systems is essentially a solved problem for eigenvalue and scattering situations and for general topologies of potential functions (simple potential wells, multiple wells, multiple barriers, and so forth). Considerable progress has also been made in generalizing semiclassical theory to multidimensional dynamical systems (such as inelastic and reactive scattering of atoms and molecules and vibrational energy levels of polyatomic molecules), and here, too, it provides a useful picture of quantum features (interference in product state distribution, generalized tunneling phenomena, and others) in these more complex systems.
Engineering Herbicide Tolerance in Transgenic Plants
Authors: Shah Dilip M. , Horsch Robert B. , Klee Harry J. , Kishore Ganesh M. , Winter Jill A. , Tumer Nilgun E. , Hironaka Cathy M. , Sanders Patricia R. , Gasser Charles S. , Aykent Serdar , Siegel Ned R. , Rogers Stephen G. , Fraley Robert T.
Published: October 2006

The herbicide glyphosate is a potent inhibitor of the enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase in higher plants. A complementary DNA (cDNA) clone encoding EPSP synthase was isolated from a complementary DNA library of a glyphosate-tolerant
Petunia hybrida
cell line (MP4-G) that overproduces the enzyme. This cell line was shown to overproduce EPSP synthase messenger RNA as a result of a 20-fold amplification of the gene. A chimeric EPSP synthase gene was constructed with the use of the cauliflower mosaic virus 35
S
promoter to attain high level expression of EPSP synthase and introduced into petunia cells. Transformed petunia cells as well as regenerated transgenic plants were tolerant to glyphosate.
High Nitrite Levels off Northern Peru: A Signal of Instability in the Marine Denitrification Rate
Authors: Codispoti L. A. , Friederich G. E. , Packard T. T. , Glover H. E. , Kelly P. J. , Spinrad R. W. , Barber R. T. , Elkins J. W. , Ward B. B. , Lipschultz F. , Lostaunau N.
Published: October 2006

During February and March 1985, nitrite levels along the northern (approximately 7° to 10°S) Peruvian coast were unusually high. These accumulations occurred in oxygen-deficient waters, suggesting intensified denitrification. In a shallow offshore nitrite maximum, concentrations were as high as 23 micromoles per liter (a record high). Causes for the unusual conditions may include a cold anomaly that followed the 1982-83 El Niño. The removal of combined nitrogen (approximately 3 to 10 trillion grams of nitrogen per year) within zones of new or enhanced denitrification observed between 7° to 16°S suggests a significant increase in oceanic denitrification.
A Genetic Test of the Natal Homing Versus Social Facilitation Models for Green Turtle Migration
Authors: Meylan Anne B. , Bowen Brian W. , Avise John C.
Published: October 2006

Female green turtles exhibit strong nest-site fidelity as adults, but whether the nesting beach is the natal site is not known. Under the natal homing hypothesis, females return to their natal beach to nest, whereas under the social facilitation model, virgin females follow experienced breeders to nesting beaches and after a "favorable" nesting experience, fix on that site for future nestings. Differences shown in mitochondrial DNA genotype frequency among green turtle colonies in the Caribbean Sea and Atlantic Ocean are consistent with natal homing expectations and indicate that social facilitation to nonnatal sites is rare.
Transformation of
Arabidopsis thaliana
with
Agrobacterium tumefaciens
Authors: Lloyd Alan M. , Barnason Arlene R. , Rogers Stephen G. , Byrne Michael C. , Fraley Robert T. , Horsch Robert B.
Published: October 2006

Transformed
Arabidopsis thaliana
plants have been produced by a modified leaf disk transformation-regeneration method. Leaf pieces from sterilely grown plants were precultured for 2 days and inoculated with an
Agrobacterium tumefaciens
strain containing an avirulent Ti (tumor-inducing) plasmid with a chimeric gene encoding hygromycin resistance. After cocultivation for 2 days, the leaf pieces were placed on a medium that selects for hygromycin resistance. Shoots regenerated within 3 months and were excised, rooted, and transferred to soil. Transformation was confirmed by opine production, hygromycin resistance, and DNA blot hybridization of both primary transformants and progeny. This process for producing transgenic
Arabidopsis
plants should enhance the usefulness of the species for experimental biology.
A Two-Dimensional Analog VLSI Circuit for Detecting Discontinuities in Early Vision
Authors: Harris John G. , Koch Christof , Luo Jin
Published: October 2006

A large number of computer vision algorithms for finding intensity edges, computing motion, depth, and color, and recovering the three-dimensional shape of objects have been developed within the framework of minimizing an associated "energy" or "cost" functional. Particularly successful has been the introduction of binary variables coding for discontinuities in intensity, optical flow field, depth, and other variables, allowing image segmentation to occur in these modalities. The associated nonconvex variational functionals can be mapped onto analog, resistive networks, such that the stationary voltage distribution in the network corresponds to a minimum of the functional. The performance of an experimental analog very-large-scale integration (VLSI) circuit implementing the nonlinear resistive network for the problem of two-dimensional surface interpolation in the presence of discontinuities is demonstrated; this circuit is implemented in complementary metal oxide semiconductor technology.
Identification of Mutations in the COL4A5 Collagen Gene in Alport Syndrome
Authors: Barker David F. , Hostikka Sirkka Liisa , Zhou Jing , Chow Louise T. , Oliphant Arnold R. , Gerken Steven C. , Gregory Martin C. , Skolnick Mark H. , Atkin Curtis L. , Tryggvason Karl
Published: October 2006

X-linked Alport syndrome is a hereditary glomerulonephritis in which progressive loss of kidney function is often accompanied by progressive loss of hearing. Ultrastructural defects in glomerular basement membranes (GBM) of Alport syndrome patients implicate an altered structural protein as the cause of nephritis. The product of COL4A5, the α5(IV) collagen chain, is a specific component of GBM within the kidney, and the gene maps to the same X chromosomal region as does Alport syndrome. Three structural aberrations were found in COL4A5, an intragenic deletion, a Pst I site variant, and an uncharacterized abnormality, which appear to cause nephritis and deafness, with allele-specific severity, in three Alport syndrome kindreds in Utah.
Fish in Offshore Kelp Forests Affect Recruitment to Intertidal Barnacle Populations
Authors: Gaines Steven D. , Roughgarden Jonathan
Published: October 2006

Kelp forests along the coast of central California harbor juvenile rockfish that prey on the larvae of invertebrates from the rocky intertidal zone. This predation reduces recruitment to barnacle populations to 1/50 of the level in the absence of fish. The dynamics of the intertidal community are thus strongly coupled to the dynamics of the offshore kelp community.
Disordered Materials: A Survey of Amorphous Solids
Authors: Cheng Yang-Tse , Johnson William L.
Published: October 2006

A brief historical perspective and a review of the current research on amorphous or glassy materials are presented. Glass formation by natural processes and by laboratory synthesis techniques is described. Recent efforts to characterize and model the atomic scale structure of amorphous phases are surveyed. The relation between amorphous and liquid states is emphasized in a discussion of thermodynamics and kinetics. The topic of crystal-to-glass transformation in the solid state and the related issue of crystal stability and melting are discussed.
Chromatography with Supercritical Fluids
Authors: Lee Milton L. , Markides Karin E.
Published: October 2006

In supercritical fluid chromatography (SFC) the mobile phase is neither a gas nor a liquid, but is a supercritical fluid. As a result of the unique properties of supercritical fluids, SFC is rapidly becoming a prominent separation technique for the analysis of reactive, thermally labile, and nonvolatile compounds. This article reviews the history, instrumentation, and practice of the technique. Particular emphasis is placed on the different programming methods that allow elution to be selectively controlled in ways that are unique to SFC.
Signaling for Growth Orientation and Cell Differentiation by Surface Topography in
Uromyces
Authors: Hoch Harvey C. , Staples Richard C. , Whitehead Brian , Comeau Jerry , Wolf Edward D.
Published: October 2006

The dimensions of the topographical signals for growth orientation and infection structure formation, a cell differentiation event that includes nuclear division, were determined for the stomatal penetrating rust fungus
Uromyces appendiculatus.
The differentiation signal was found to be a simple ridge on the substrate surface that had a markedly optimum height of 0.5 micrometer. Such ridges were microfabricated on silicon wafers by using electron-beam lithography. A similar ridge, in the form of a stomatal lip, was found associated with the stomatal guard cells of the bean
(Phaseolus vulgaris)
leaf. Ridge elevations greater than 1.0 micrometer or less than 0.25 micrometer did not serve as effective signals. Germ tubes of the fungus were highly oriented by ridge spacings of 0.5 to 6.7 micrometers. The data indicate that the fungus is able to distinguish uniquely minute differences in leaf surface topography in order to infect the host plant.
Herbivory in Rocks and the Weathering of a Desert
Authors: Shachak Moshe , Jones Clive G. , Granota Yigal
Published: October 2006

Two species of snail,
Euchondrus albulus
and
Euchondrus desertorum
, eat endolithic lichens growing under the surface of limestone rocks in the Negev Desert, Israel. This unusual type of herbivory has the unexpected and major impact of weathering this rocky desert at a rate of 0.7 to 1.1 metric tons per hectare per year. The biotic weathering contributes to the process of soil formation at a rate that is similar to windborne dust deposition. These findings demonstrate that herbivores can have a significant regulatory impact on ecosystem processes, even in cases where the total amount of primary production consumed is small.
Attentional Modulation of Neural Processing of Shape, Color, and Velocity in Humans
Authors: Corbetta Maurizio , Miezin Francis M. , Dobmeyer Susan , Shulman Gordon L. , Petersen Steven E.
Published: October 2006

Positron emission tomography (PET) was used to measure changes in regional cerebral blood flow of normal subjects, while they were discriminating different attributes (shape, color, and velocity) of the same set of visual stimuli. Psychophysical evidence indicated that the sensitivity for discriminating subtle stimulus changes was higher when subjects focused attention on one attribute than when they divided attention among several attributes. Correspondingly, attention enhanced the activity of different regions of extrastriate visual cortex that appear to be specialized for processing information related to the selected attribute.
R&D and Productivity: Measurement Issues and Econometric Results
Authors: Griliches Zvi
Published: October 2006

The direct successes of space, defense, and health research are not reflected in the national productivity accounts. Nor are many of the improvements in technologically complex new products. Econometric studies underestimate, therefore, the full contribution of R&D, especially since it is difficult to trace its spillover effects. Nevertheless, a recent study finds a significant contribution of R&D to productivity growth in the largest U.S. manufacturing corporations, with no evidence of a major decline in it, and a larger role for basic research and a smaller one for federally financed R&D expenditures than is implied by their relative importance in total R&D expenditures.