bluuebunny/crossref_metadata_2025 huggingface dataset:
Probing Interfaces Involving Liquids
Authors: Robinson Arthur L.
Published: October 2006

Last month in Washington, D.C., the National Academy of Sciences held the first of what it hopes will be a series of seminars in forefront fields of science, technology, and medicine. The idea is to bring the academy closer to the frontlines of research and to help spread the word to federal science policy-makers. The subject of the 23 and 24 March seminar was interfaces and thin films, and the talks, though tutorial in nature, contained a pleasantly large number of still unpublished results. Interfaces, such as the surface of a solid exposed to a liquid or gas, and thin films, whose properties are heavily influenced by interfaces, have long been of considerable technological importance and have always been so in biological processes, but researchers are now getting access to the experimental and theoretical tools needed to explore these complex physical systems that are neither ideally two-dimensional nor fully three-dimensional. The briefings that follow give a peek at three ways to probe interfaces involving liquids.
Limits on Sensitivity of Large Silicon Bolometers for Solar Neutrino Detection
Authors: Martoff C. J.
Published: October 2006

Estimates are given for ultimate limits on background in proposed direct-counting measurements of neutrino scattering from large silicon crystals. Methods of background reduction are discussed. In the best case, the limiting backgrounds due to activities from cosmic-ray spallation of silicon would be less than the expected true event rate for reactor neutrino measurements of coherent neutral-current scattering from silicon nuclei. Considerable reduction of the estimated high-energy backgrounds would be required for a good signal-to-noise ratio in solar neutrino detection.
The Surface Composition of Charon: Tentative Identification of Water Ice
Authors: Marcialis Robert L. , Rieke George H. , Lebofsky Larry A.
Published: October 2006

The 3 March 1987 Charon occultation by Pluto was observed in the infrared at 1.5, 1.7, 2.0, and 2.35 micrometers. Subtraction of fluxes measured between second and third contacts from measurements made before and after the event has yielded individual spectral signatures for each body at these wavelengths. Charon's surface appears depleted in methane relative to Pluto. Constancy of flux at 2.0 micrometers throughout the event shows that Charon is effectively black at this wavelength, which is centered on a very strong water absorption band. Thus, the measurements suggest the existence of water ice on Pluto's moon.
Diel Periodicity of Photosynthesis in Polar Phytoplankton: Influence on Primary Production
Authors: Rivkin R. B. , Putt M.
Published: October 2006

In the Southern Ocean, primary production estimated from seasonal chemical and geochemical changes is two to four times greater than the value calculated from carbon-14 uptake. Since carbon uptake had typically been measured only during midday incubations, the influence of diel periodicity of photosynthesis on daily productions was not considered. Phytoplankton from McMurdo Sound, Antarctica, exhibited distinct, but seasonally variable diel patterns of light-saturated and light-limited photosynthesis. Maximum photosynthetic capacity occurred about noon in early September, and its occurrence progressively shifted to about midnight by late October. This shift was accompanied by a concomitant phase shift in the occurrence of minimum photosynthetic capacity from midnight to midday. Daily production estimated from time-of-day corrected photosynthetic characteristics and from 24-hour incubations was 2.5 to 4 times greater than that predicted from 6-hour midday incubations. If similar diel periodicity in photosynthesis occurs in other polar oceans, primary production would be significantly higher than previously estimated from carbon-14 uptake measurements.
Science and Product
Authors: Gomory Ralph E. , Schmitt Roland W.
Published: October 2006

Much of what needs to be changed in U.S. industry involves close ties to manufacturing, design for manufacturability, a rapid design cycle, and up-to-date technical knowledge on the part of the engineers themselves. Being up-to-date requires conscious company effort. Traveling to meetings, reading the technical literature, and being a part of the engineering community are necessities if we are to compete with others who make these efforts and are thus better able to incorporate technical change rapidly into their own products.

Outsidethe product improvement cycle, a research (as opposed to development) organization in industry must have close ties to development and manufacturing in order to succeed. With these close ties, researchers can understand the progress of the cycle and can introduce new steps at the appropriate time and in an acceptable form. A research organization that surmounts the internal barriers and becomes an accepted contributor to the development and manufacturing process can, because of its greater technical depth, its scientific knowledge, and its close ties with the university world, become a forceful initiator of progress. It is more difficult, in our opinion, to make these contributions from a university base and from government laboratories as they are now constituted.

Much has been said by industry and government leaders about reforming the educational system and strengthening the national science base—things that help build a strong foundation. A strong science base supplies a vast storehouse of new ideas, and a good educational system provides engineers and manufacturing workers with knowledge; but strength here cannot make up for inadequacies in the functioning of the development and manufacturing cycle. The United States must learn to succeed, not only in the ladder type of innovation in which a wholly new idea from science creates a wholly new product (the science-dominated process at which we have succeeded in the past), but also in the rapid, cyclical, engineer-dominated process of incremental product improvement. Neither process is a substitute for the other; we need both.
Topological Solutions in Gauge Theory and Their Computer Graphic Representation
Authors: Hey Anthony J. G. , Merlin John H. , Ricketts Martin William , Vaughn Michael T. , Williams David C.
Published: October 2006

A diverse range of physical phenomena, both observed and hypothetical, are described by topological solutions to nonlinear gauge field theories. Computer-generated color graphic displays can provide a clear and detailed representation of some of these solutions, which might otherwise be physically unintelligible because of their mathematical complexity. Graphical representations are presented here for two topological solutions: (i) the solutions of a model that represents the filaments of quantized magnetic flux in a superconductor, and (ii) the solutions of an SO(3) gauge theory corresponding to a pair of separated magnetic monopoles. An introduction is provided to the gauge field theories giving rise to these solutions.
The Deficit Is Not a Well-Defined Measure of Fiscal Policy
Authors: Kotlikoff Laurence J.
Published: October 2006

Notwithstanding its widespread use, the government's deficit is not a well-defined measure of fiscal policy from the perspective of neoclassical economics; the equations of neoclassical models do not define the deficit. Rather than being a fundamental economic concept, the deficit is an arbitrary cash flow accounting construct with no necessary relation to the true stance of fiscal policy. Although the deficit is supposed to indicate how the burden of paying for the government's consumption is spread across different generations, actual changes in the measured deficit in the United States have had little if any relation to changes in the burden imposed by the government on different generations. The deficit's lack of definition is illustrated with a simple model, and the potential for misreading fiscal policy is discussed with U.S. fiscal policy in the 1980s as an example. In this article, creation of present value generational accounts are called for that would properly measure the intergenerational stance of fiscal policy.
Detection of DNA Sequences in Nuclei in Suspension by in Situ Hybridization and Dual Beam Flow Cytometry
Authors: Trask Barbara , van den Engh Ger , Landegent Jim , in de Wal Nico Jansen , van der Ploeg Mels
Published: October 2006

This report describes the fluorescence hybridization of DNA sequence probes to interphase nuclei in suspension and the quantification of bound probe by dual beam flow cytometry. Nuclear proteins were first cross-linked with dimethylsuberimidate to prevent disintegration of the nuclei during denaturation and hybridization. To demonstrate that in situ hybridization can be performed in suspension, stabilized mouse thymocyte nuclei were hybridized with a probe for mouse satellite DNA sequences. The DNA probes were labeled with 2-acetylaminofluorene. After hybridization, an indirect immunofluorescent labeling procedure was used to visualize the target sequences. With dual beam flow cytometry, both the amount of hybridized probe and the DNA content of individual nuclei were determined. Thus, the specificity of DNA hybridization can be combined with the speed and quantitative analysis provided by flow cytometry.
The Paleomagnetic Field from Equatorial Deep-Sea Sediments: Axial Symmetry and Polarity Asymmetry
Authors: Schneider David A. , Kent Dennis V.
Published: October 2006

Paleomagnetic data from 89 equatorial deep-sea sediment cores indicate that the configuration of the time-averaged geomagnetic field depends strongly on polarity state but that it remains within 1 degree of axial symmetry throughout the Pliocene and Pleistocene (last 5 million years). The relative magnitude of the nondipole field was greater by almost a factor of 2 during reverse than during normal polarity intervals. These results thus support earlier suggestions that there may be a standing (nonreversing) component of the geomagnetic dynamo.
Pancreatic Zymogen Granules Differ Markedly in Protein Composition
Authors: Mroz E. A. , Lechene C.
Published: October 2006

The activities of both chymotrypsin and amylase in individual zymogen granules of rat pancreas were measured by means of micromanipulation and microfluorometric methods. The enzyme content and the ratio of amylase to chymotrypsin varied widely among granules taken from the same animal. These results are compatible with short-term nonparallel bulk secretion of the two enzymes through exocytosis. The distribution of each enzyme activity in a population of granules suggests quantal packaging of amylase and chymotrypsinogen into the granules.
Radar Detection of Phobos
Authors: Ostro S. J. , Jurgens R. F. , Yeomans D. K. , Standish E. M. , Greiner W.
Published: October 2006

Radar echoes from the martian satellite Phobos provide information about that object's surface properties at scales near the 3.5-cm observing wavelength. Phobos appears less rough than the moon at centimeter-to-decimeter scales. The uppermost few decimeters of the satellite's regolith have a mean bulk density within 20% of 2.0 g cm
-3
. The radar signature of Phobos (albedo, polarization ratio, and echo spectral shape) differs from signatures measured for small, Earth-approaching objects, but resembles those of large (≥100-km), C-class, mainbelt asteroids.
Increased Numbers of Ion Channels Promoted by an Intracellular Second Messenger
Authors: Gunning Richard
Published: October 2006

The anomalous rectifier potassium current in
Aplysia
neurons was examined to determine the immediate cause of an increase in conductance induced by serotonin and mediated by adenosine 3′,5′-monophosphate. Voltage-dependent cesium ion block and steady-state current power spectral density were measured under voltage clamp before and after application of serotonin. The amplitude of the anomalous rectifier conductance was increased by adding serotonin, but the shapes of the conductance-voltage curve and the power spectrum were not altered. Calculation of the number of functional channels and of the single-channel conductance from the power spectra indicates that the serotonin-induced increase in conductance resulted from an increase in the number of functional channels, while the single-channel conductance and the open-channel probability were unchanged.
Diffusible Factors Essential for Epidermal Cell Redifferentiation in
Catharanthus roseus
Authors: Siegel Bruce A. , Verbeke Judith A.
Published: October 2006

During postgenital tissue fusions, some plant epidermal cells redifferentiate into parenchyma, a different cell type. Diffusible factors cause this response in the fusing gynoecium of the Madagascar periwinkle (
Catharanthus roseus
). Surgical manipulations of the gynoecium showed that epidermal cells from normally nonfusing surfaces could transmit and respond to the diffusible factors. Furthermore, the diffusible factors could be trapped in agar-impregnated barriers, as shown by the redifferentiation of carpel epidermal cells from nonfusing regions when the factor-loaded barriers were appressed to them.
Observations in Particle Physics from Two Neutrinos to the Standard Model
Authors: Lederman Leon M.
Published: October 2006

The two-neutrino experiment established a relationship between particles, muon and muon neutrino, electron and electron neutrino, which evolved into the standard model of particle physics. The theme of this article is a personal one, which reviews a series of experiments at the Columbia Synchrocyclotron, the Brookhaven Cosmotron, the Alternating Gradient Synchrotron, the CERN intersecting storage rings, the Fermilab 400-gigavolt proton synchrotron, and the Cornell electron storage rings, all of which were important in the evolution of the standard model. In some cases the fermion particles were discovered (the second neutrino ν
μ
, b quark); in other cases fields of research were opened (muon spin resonance, neutral kaons and charge-parity violation, dimuons and the Drell-Yan process), which led to further development of the standard model. Finally, the current ignorance about the properties of now three neutrinos is reviewed.
The Heliosphere as an Astrophysical Laboratory for Particle Acceleration
Authors: Terasawa T. , Scholer M.
Published: October 2006

Particle acceleration is one of the most important topics in plasma astrophysics as well as in cosmic-ray astrophysics. The heliosphere is an ideal astrophysical laboratory, wherein one can observe in situ the elementary mechanisms involved in the particle acceleration processes. Two phenomena of special interest are stochastic acceleration in the magnetohydrodynamic turbulence around comets and stochastic shock acceleration at interplanetary shock waves.
Experiments with High-Energy Neutrino Beams
Authors: Steinberger J.
Published: October 2006

Experiments in which high-energy neutrinos were used as projectiles have made substantial contributions to our understanding of both weak and strong interactions, as well as the structure of hadrons. This article offers some illustrations. It recalls the discovery of the neutral weak current and some experiments on its nature. The sections on charged-current inclusive scattering recall the important role of these experiments in the understanding of the quark structure of the nucleon and the validity of quantum chromodynamics. The section on dimuon production illustrates the role of neutrino experiments in establishing the Glashow-Iliopoulos-Maiani current as well as the measurement of the structure function of the strange quark in the nucleon.
High-Resolution Microwave Images of Saturn
Authors: Grossman A. W. , Muhleman D. O. , Berge G. L.
Published: October 2006

An analysis of high-resolution microwave images of Saturn and Saturn's individual rings is presented. Radio interferometric observations of Saturn taken at the Very Large Array in New Mexico at wavelengths of 2 and 6 centimeters reveal interesting new features in both the atmosphere and rings. The resulting maps show an increase in brightness temperature of about 3 K from equator to pole at both wavelengths, while the 6-centimeter map shows a bright band at northern mid-latitudes. The data are consistent with a radiative transfer model of the atmosphere that constrains the well-mixed, fully saturated, NH
3
mixing ratio to be 1.2 × 10
-4
in a region just below the NH
3
clouds, while the observed bright band indicates a 25 percent relative decrease of NH
3
in northern mid-latitudes. Brightness temperatures for the classical rings are presented. Ring brightness shows a variation with azimuth and is linearly polarized at an average value of about 5 percent. The variations in ring polarization suggest that at least 20 percent of the ring brightness is the result of a single scattering process.
Epitopes Recognized by Human T Cells Map Within the Conserved Part of the GP190 of
P. Falciparum
Authors: Crisanti Andrea , Müller Hans-Michael , Hilbich Caroline , Sinigaglia Francesco , Matile Hugues , McKay Martin , Scaife John , Beyreuther Konrad , Bujard Hermann
Published: October 2006

In a study aimed at developing a vaccine against the asexual blood stages of
Plasmodium falciparum
, two T cell epitopes were identified within a nonpolymorphic region of gp190 of
Plasmodium falciparum
merozoites. The two epitopes, which were revealed by deletion analysis, stimulated human T cell clones. Peptides containing sequences of the epitopes stimulated the cloned T cells and peripheral blood mononuclear cells (PBMC) from malaria-infected individuals. Moreover, the T cell clones responded to 11 different
Plasmodium falciparum
isolates in culture, showing that the epitopes are recognized in native parasites.
Alpha-2-Antiplasmin: a Serpin with Two Separate But Overlapping Reactive Sites
Authors: Potempa J. , Shieh B.-H. , Travis J.
Published: October 2006

Although the proteinase inhibitor alpha-2-antiplasmin (α
2
AP) is known to control the activity of plasmin through rapid formation of stable complexes, it also efficiently inactivates chymotrypsin. These interactions are shown to occur at adjacent, overlapping sites so that plasmin attacks the inhibitor at an Arg
364
-Met
365
peptide bond, while chymotrypsin interacts at a Met
365
-Ser
366
sequence one residue downstream. Thus, a naturally occurring plasma serine proteinase inhibitor can have multiple specificities through interactions at adjacent sites. It also illustrates the potential flexibility of the reactive site loop in this class of inhibitors.
A
Mycobacterium leprae
-Specific Human T Cell Epitope Cross-Reactive with an HLA-DR2 Peptide
Authors: Anderson D. C. , van Schooten Wim C. , Barry Michael E. , Janson Anneke A. M. , Buchanan Tom M. , de Vries René R. P.
Published: October 2006

Mycobacterium leprae
induces T cell reactivity and protective immunity in the majority of exposed individuals, but the minority that develop leprosy exhibit various types of immunopathology. Thus, the definition of epitopes on
M. leprae
antigens that are recognized by T cells from different individuals might result in the development of an effective vaccine against leprosy. A sequence from the 65-kD protein of this organism was recognized by two HLA-DR2-restricted,
M. leprae
-specific helper T cell clones that were derived from a tuberculoid leprosy patient. Synthetic peptides were used to define this epitope as Leu-Gln-Ala-Ala-Pro-Ala-Leu-Asp-Lys-Leu. A similar peptide that was derived from the third hypervariable region of the HLA-DR2 chain, Glu-Gln-Ala-Arg-Ala-Ala-Val-Asp-Thr-Tyr, also activated the same clones. The unexpected cross-reactivity of this
M. leprae
-specific DR2-restricted T cell epitope with a DR2 peptide may have to be considered in the design of subunit vaccines against leprosy.
A Passion for the Little Things Among the Planets
Authors: Kerr Richard A.
Published: October 2006

If mass were the only criterion, asteroids, satellites, and the smallest planet, Pluto, would not rate much attention. But they often held center stage early this month when planetary scientists gathered in Providence, Rhode Island, for the annual meeting of the Division of Planetary Science of the American Astronomical Society. Here is a selection of the news about the lesser bodies that so many researchers hold dear.
U.S. Trade Policy at a Crossroad
Authors: Litan Robert E. , Suchman Peter O.
Published: October 2006

U.S. trade policy since the end of World War II has rested on two pillars: a multilateral approach to trade agreements and a commitment to rules rather than results. Support for each principle is rapidly eroding because of, among other things, record trade deficits and pessimism about the effects of exchange rate movements on trade flows. In fact, however, U.S. trade deficits are largely "homemade," and trade flows are responsive to changes in exchange rates. The U.S. has played a leadership role in promoting freer trade on a multilateral basis. Adoption of any one of a number of recently proposed alternative trade policy frameworks would be counter to that role.
Paleomagnetism and the Nature of the Geodynamo
Authors: Merrill R. T. , McFadden P. L.
Published: October 2006

Records of direct observations of the earth's magnetic field cover less than a ten-millionth of the known lifetime of the field. Thus our knowledge of several geomagnetic phenomena, critical to our understanding of the geodynamo, must come from the paleomagnetic record. A combination of substantial advances during the past decade or so both in dynamo theory (previously the domain of the mathematician) and in paleomagnetism (previously the domain of the geologist) has led to provocative models of the earth's magnetic field and a better understanding of the geodynamo.
Shedding Light on Baryonic Dark Matter
Authors: Silk Joseph
Published: October 2006

Halo dark matter, if it is baryonic, may plausibly consist of compact stellar remnants. Jeans mass clouds containing 10
6
to 10
8
solar masses could have efficiently formed stars in the early universe and could plausibly have generated, for a suitably top-heavy stellar initial mass function, a high abundance of neutron stars as well as a small admixture of long-lived low mass stars. Within the resulting clusters of dark remnants, which eventually are tidally disrupted when halos eventually form, captures of neutron stars by non-degenerate stars resulted in formation of close binaries. These evolve to produce, by the present epoch, an observable x-ray signal associated with dark matter aggregations in galaxy halos and galaxy cluster cores.
Structure and Specificity of a Class II MHC Alloreactive γδ T Cell Receptor Heterodimer
Authors: Matis Louis A. , Fry Alicia M.. , Cron Randy Q. , Cotterman Melissa M. , Dick Robert F. , Bluestone Jeffrey A.
Published: October 2006

Two distinct CD3-associated T cell receptors (TCRαβ and TCRγδ) are expressed in a mutually exclusive fashion on separate subsets of T lymphocytes. While the specificity of the TCRαβ repertoire for major histocompatibility complex (MHC) antigens is well established, the diversity of expressed γδ receptors and the ligands they recognize are less well understood. An alloreactive CD3
+
CD4
-
CD8
-
T cell line specific for murine class II MHC (Ia) antigens encoded in the I-E subregion of the H-2 gene complex was identified, and the primary structure of its γδ receptor heterodimer was characterized. In contrast to a TCRαβ-expressing alloreactive T cell line selected for similar specificity, the TCRγδ line displayed broad cross-reactivity for multiple distinct I-E-encoded allogeneic Ia molecules.
(Rb

x

K
1
–
x
)
3
C
60
Superconductors: Formation of a Continuous Series of Solid Solutions
Authors: Chen Chia-Chun , Kelty Stephen P. , Lieber Charles M.
Published: October 2006

By means of an approach that employs alkali-metal alloys, bulk single-phase (Rb

x

K

1–
x

)
3
C
60
superconductors have been prepared for all
x
between 0 and 1. For
x
= 1 it is shown that the maximum superconducting fraction, which approaches 100% in sintered pellets, occurs at a Rb to C
60
ratio of 3:1. More importantly, single-phase superconductors are formed at all intermediate values of
x
, and it is shown that the transition temperature (
T
c
) increases linearly with
x
in this series of materials. The formation of a continuous range of solid solutions demonstrates that the rubidium- and potassium-doped C
60
superconducting phases must be isostructural, and furthermore, suggests that the linear increase in
T
c
with
x
results from a chemical pressure effect.
Myths and Realities of U.S. Competitiveness
Authors: Krugman Paul A.
Published: October 2006

Most discussion of U.S. competitiveness misstates the problem, focusing on the trade deficit and on fears that an economy whose productivity lags that of its rivals will face economic disaster. In fact, strong automatic forces ensure that the U.S. economy will remain in business and indeed roughly balance its trade even if its productivity performance is dismal. The real issue is the effect of international competition on the mix of goods that the U.S. economy produces. In some industries high productivity is an effect as well as a cause of international competitiveness. There is an intellectually respectable but politically problematic case for government action to create or preserve advantage in such industries.
Magnetic Flux-Line Lattices and Vortices in the Copper Oxide Superconductors
Authors: Bishop D. J. , Gammel P. L. , Huse D. A. , Murray C. A.
Published: October 2006

A variety of recent experiments on both the static and the dynamic properties of vortices and flux-line lattices in the mixed state of the copper oxide superconductors are discussed. The experiments are of two basic types: (i) experiments that image the magnetic flux patterns either with magnetic decoration or neutrons and give information about static structures, and (ii) experiments that explore the dynamics of vortices either through the resistivity or other electrodynamic responses of the material. Results of these experiments argue in favor of the existence of a true phase transition in the high-field vortex state from a low-temperature superconducting vortex glass phase into a disordered high-temperature vortex fluid phase. The vortex glass phase transition model does a good job of explaining high-precision measurements of the dynamics at the transition. At low fields and temperatures, very long range hexatic order in the flux-line lattice is observed.
Toward the Realization of a Josephson Computer
Authors: Hasuo S.
Published: October 2006

High-quality Josephson junctions, with both electrodes made from niobium and with an aluminum-oxide insulating barrier, were introduced in 1983. This niobium junction is very stable, reliable, controllable, and reproducible. Because of these excellent characteristics, these junctions can be applied to large-scale integrated (LSI) circuits, such as microprocessors having a few thousand gates and a few kilobits of memory. These circuits operate much faster and consume less power than any semiconductor circuit now available. Integrated Josephson circuits are now being tested in a closed-cycle refrigerator. The next step is to design a special-purpose, small-scale Josephson computer and to demonstrate its high performance.
Anthropologists Bet on Their Latest Data in Las Vegas
Authors: Gibbons Ann
Published: October 2006

Anthropologists need luck on their side when they search for key fossils or study monkeys in the wild, but their work can still hit the jackpot. That was clear at the 61st annual meeting of the American Association of Physical Anthropology, which brought more than 800 anthropologists to Las Vegas in early April. Among the reports was one on new fossils of early hominids in Ethiopia and another on extinct giant sloth lemurs in Madagascar.
Stress Diffusion Along the San Andreas Fault at Parkfield, California
Authors: Malin P. E. , Alvarez M. G.
Published: October 2006

Beginning in January 1990, the epicenters of microearthquakes associated with a 12-month increase in seismicity near Parkfield, California, moved northwest to southeast along the San Andreas fault. During this sequence of events, the locally variable rate of cumulative seismic moment increased. This increase implies a local increase in fault slip. These data suggest that a southeastwardly diffusing stress front propagated along the San Andreas fault at a speed of 30 to 50 kilometers per year. Evidently, this front did not load the Parkfield asperities fast enough to produce a moderate earthquake; however, a future front might do so.
Shock Waves in Stellar Atmospheres and Breaking Waves on an Ocean Beach
Authors: Wallerstein George , Elgar Steve
Published: October 2006

The phenomenon of ocean waves breaking on a beach is analogous to shock waves in the atmosphere of a pulsating star. In both cases a velocity discontinuity is clearly present. In stars the upper, expanding layer halts and falls back so as to interact with the rising gas at a shock. Similarly, a bore on a beach reaches its maximum extension before sliding back onto the next incoming wave. Analogous quantities such as the surface gravity of the star and the beach gradient in the ocean have similar effects on the flows and the nature of the discontinuity between them. Phenomena that are not analogous include the thermodynamic properties of the two media. Ocean observations may help solve some problems in shock phenomena associated with stellar pulsation.
Spin Susceptibility Scaling in High-Temperature Superconductors
Authors: Ruvalds J. , Rieck C. T. , Zhang J. , Virosztek A.
Published: October 2006

The spin response of a nested Fermi surface represented by a tight binding energy band is found to exhibit scaling in frequency divided by temperature within a restricted regime close to half-filling of the band. Computations of the spin susceptibility reveal a surprising momentum variation at various temperatures and frequencies. Neutron scattering data on the high-temperature superconductor YBa
2
Cu
3
O

6+
x

are analyzed for scaling near a momentum vector that spans nested regions of the orbit. Changes in the Fermi energy remove the scaling properties and reduce the susceptibility to the conventional Fermi liquid behavior of ordinary metals. These results imply that pairing mechanisms of superconductivity need to cope with competing spin density wave and charge density wave instabilities.
A Lunar Occultation of the Dust-Scattering Halo Around GX 5-1 Observed with ROSAT
Authors: Predehl Peter , Schmitt Jürgen H. M. M. , Snowden Steven L. , Trümper Joachim
Published: October 2006

The x-ray source GX 5-1 in the galactic bulge has been observed with the position-sensitive proportional counter onboard the Röntgen satellite (ROSAT) during and after a lunar occultation. Extended emission around the source was unambiguously discovered while the central source was behind the lunar rim. This emission is interpreted as a dust-scattering halo around GX 5-1 that has a fractional intensity of 28 percent, implying a grain column density between GX 5-1 and Earth of ∼3 × 10
10
per square centimeter. The halo derived from imaging during the ROSAT all-sky survey is identical to that obtained from the lunar occultation, thus demonstrating that the ROSAT x-ray mirror scattering has not changed as compared with the mirror properties as measured in preflight calibrations.
High-Velocity Pulsars in the Galactic Halo
Authors: Eichler David , Silk Joseph
Published: October 2006

It is proposed that high-velocity pulsars are produced in extended galactic halos, and possibly in extragalactic space, from primordial (population III) stars. Such a population of neutron stars could provide an explanation for the gamma-ray bursters and would then accommodate the possibility that most bursters are not in the visible parts of galaxies.
Crop Scientists Break Down Barriers at Ames Meeting
Authors: Moffat Anne Simon
Published: October 2006

For years, crop science has been balkanized, with specialists in rice, corn, and soybeans, for example, working on their own commodities and attending their own meetings. But at the First International Crop Science Congress, held in July in Ames, Iowa—an 8-day event 3 years in the making—the discipline displayed a newfound hybrid vigor. More than 1000 researchers of various persuasions, including plant molecular biology, classical plant breeding, agronomy, and soil science, representing 85 countries, shared their expertise in basic and applied studies. Here are a couple of proposals for expanding world food production and another that shows the diverse roles crops can play.
Volcanic Activity on Io at the Time of the Ulysses Encounter
Authors: Spencer John R. , Howell Robert R. , Clark Beth E. , Klassen David R. , O'Connor Daniel
Published: October 2006

The population of heavy ions in Io's torus is ultimately derived from Io volcanism. Ground-based infrared observations of Io between October 1991 and March 1992, contemporaneous with the 8 February 1992 Ulysses observations of the Io torus, show that volcanic thermal emission was at the low end of the normal range at all Io longitudes during this period. In particular, the dominant hot spot Loki was quiescent. Resolved images show that there were at least four hot spots on Io's Jupiter-facing hemisphere, including Loki and a long-lived spot on the leading hemisphere (Kanehekili), of comparable 3.5-micrometer brightness but higher temperature.
Contribution of Oceanic Gabbros to Sea-Floor Spreading Magnetic Anomalies
Authors: Kikawa Efichi , Ozawa Kazuhito
Published: October 2006

The contribution of oceanic gabbros, representative rocks for layer 3 of the oceanic crust, to sea-floor spreading magnetic anomalies has been controversial because of the large variation in magnetic properties. Ocean Drilling Program (ODP) Leg 118 contains a continuous 500.7-meter section of oceanic gabbro that allows the relations between magnetization and petrologic characteristics, such as the degree of metamorphism and the magmatic evolution, to be clarified. The data suggest that oceanic gabbros, together with the effects of metamorphism and of magmatic evolution, account for a significant part of the marine magnetic anomalies.
Reversibility of Progression of the Transformed Phenotype in Ad5-Transformed Rat Embryo Cells
Authors: Babiss Lee E. , Zimmer Stephen G. , Fisher Paul B.
Published: October 2006

The carcinogenic process is extremely complex and is affected by diverse environmental and host factors. The mechanism for the gradual development of the transformed phenotype (a process termed "progression") was studied in type 5 adenovirus (Ad5)-transformed rat embryo cells. Progression was not correlated with major changes in the pattern of integration of viral DNA sequences. Instead, it was associated with an increased methylation of integrated viral sequences other than those corresponding to the E1 transforming genes of Ad5. A single exposure of progressed cells to the demethylating agent 5-azacytidine (Aza) resulted in a stable reversion to the unprogressed state of the original parental clone. A further selection of cells after growth in agar allowed the isolation of Aza-treated clones that had regained the progressed phenotype. These observations indicate that progression is a reversible process and suggest that progression may be associated with changes in the state of methylation of one or more specific genes.
Correction: Recombinant 47-Kilodalton Cytosol Factor Restores NADPH Oxidase in Chronic Granulomatous Disease
Authors: Lomax Karen J. , Leto Thomas L. , Nunoi Hiroyuki , Gallin John I. , Malech Harry L.
Published: October 2006

After our characterization of cDNA encoding a 47-kD neutrophil cytosol oxidase factor was published, a second group published characterizations of similar cDNA clones. On the basis of an exchange of primary sequence data and resequencing, we have identified minor errors in both published sequences and have agreed on a corrected sequence. In the original numbering of our published sequence, an extra "C" should be added after base pair 900, a "GCC" should be inserted after base pair 1008, and base pairs 1013 and 1014 should be "GC." These changes alter the carboxyl terminus of the predicted protein beginning at amino acid 301 and ending at 390: RRSSIRNAHS IHQRSRKRLS QDAYRRNSVR FLQQRRRQAR PGPQSPGSPL EEERQTQRSK PQPAVPPRPS ADLILNRCSE STKRKLASAV. The new predicted protein sequence is 17 amino acids longer. The region of similarity to p21-ras- GAP is unaffected, and the carboxyl terminus remains very arginine- and serine-rich with several potential sites of phosphorylation by protein kinase C. Thus, all of the general statements made about the protein in our original paper still apply.

In addition to the three polymorphic base pair variants we reported in our original paper, four additional base pair polymorphisms have been identified, none of which affects encoded amino acids. In the original numbering, these are base pair 387 "G" or "A," base pair 825 "C" or "T," base pair 849 "A" or "G," and base pair 935 "C" or "T." These changes have been sent to Gen- Bank and entered under accession number M25665. Readers may also request from us the complete corrected sequence.
Gravity Field over Northern Eurasia and Variations in the Strength of the Upper Mantle
Authors: Kogan Mikhail G. , McNutt Marcia K.
Published: October 2006

The correlation of long-wavelength gravity anomalies in northern Eurasia with seismic velocity anomalies in the upper mantle reverses in sign between western and eastern Eurasia. The difference between western and eastern Eurasia can be explained by the presence of a low-viscosity zone in the uppermost mantle beneath eastern Eurasia that is absent to the west. The location of the lateral change in viscosity corresponds with the geologic boundary between the older shields and platforms of the Baltics, Russia, and Siberia and the younger, geologically active mountain belts of eastern Asia. This relation provides evidence that differences in the strength of the upper mantle control the locus of intracontinental deformation.
Mediation of Sulfur Speciation by a Black Sea Facultative Anaerobe
Authors: Perry K. A. , Kostka J. E. , Luther G. W. , Nealson K. H.
Published: October 2006

Shewanella putrefaciens
, a respiratory facultative anaerobe isolated from the Black Sea, can reduce thiosulfate, sulfite, and elemental sulfur to sulfide readily and quantitatively. This widespread and anaerobically versatile microorganism, which is incapable of reducing sulfate, uses oxidized sulfur intermediates as electron acceptors during the respiratory oxidation of organic matter. Because of its widespread distribution and abundance, it may play a significant role in sulfur and trace metal cycling in the Black Sea and in other marine and freshwater anaerobic environments.
What Do We Learn from Neutrinos?
Authors: Steinberger J.
Published: October 2006

Each type of particle, by definition, is special. The special property of neutrinos is that they are penetrating. This has made their discovery and the understanding of their properties elusive, but it has also made them a useful tool in the study of particles and their interactions. In astrophysics, on account of this property, neutrinos provide an important means for energy transfer and permit insight into the interior of stars hidden to other radiation. The special conditions in space permit, in turn, the study of neutrino properties not possible in the laboratory.
Light Emission from Silicon
Authors: Iyer S. S. , Xie Y. -H.
Published: October 2006

The possibility induction of light emission from silicon, an indirect bandgap material in which radiative transitions are unlikely, raises several interesting and technologically important possibilities, especially the fabrication of a truly integrated optoelectronic microchip. In this article, the natural considerations that constrain silicon from emitting light efficiently are examined, as are several engineered solutions to this limitation. These include intrinsic and alloy-induced luminescence; radiatively active impurities; quantum-confined structures, including zone folding and the recent developments in porous silicon; and a hybrid approach, the integration of direct bandgap materials onto silicon.
A Photoinduced Persistent Structural Transformation of the Special Pair of a Bacterial Reaction Center
Authors: Reddy N. Raja S. , Kolaczkowski Stephen V. , Small Gerald J.
Published: October 2006

Structural modification of photosynthetic reaction centers is an important approach for understanding their charge-separation processes. An unprecedented persistent structural transformation of the special pair (dimer) of bacteriochlorophyll molecules can be produced by light absorption alone. The nonphotochemical hole-burned spectra for the reaction center of
Rhodopseudomonas viridis
show that the phototransformation leads to a red shift of 150 wave numbers for the special pair's lowest energy absorption band, P960, and a comparable blue shift for a state at 850 nanometers, which can now be definitively assigned as being most closely associated with the upper dimer component. Additional insights on excited-state electronic structure include the identification of a new state.
Condensed-Matter Energetics from Diatomic Molecular Spectra
Authors: Kim In Ho , Jeanloz Raymond , Jhung Kyu Soo
Published: October 2006

Analyses of molecular spectra and compression data from crystals show that a single function successfully describes the dependence on interatomic separation of both the potential energy of diatomic molecules and the cohesive binding energy of condensed matter. The empirical finding that one function describes interatomic energies for such diverse forms of matter and over a wide range of conditions can be used to extend condensed-matter equations of state but warrants further theoretical study.
Directionally Aligned Helical Peptides on Surfaces
Authors: Whitesell James K. , Chang Hye Kyung
Published: October 2006

Directionally oriented peptide layers 1000 angstroms thick were constructed by polymerization on gold and indium-tin-oxide glass. A key feature is the use of an appropriately functionalized surface on which the initiation sites for polymerization are spaced at distances consistent with the helical diameter of the peptide. Completely helical polyalanine and polyphenylalanine layers have been constructed. The helicity of the polyalanine layer was completely retained after heating at 180°C for 7 days.
Formation of Magnetic Single-Domain Magnetite in Ocean Ridge Basalts with Implications for Sea-Floor Magnetism
Authors: Shau Yen-Hong , Peacor Donald R. , Essene Eric J.
Published: October 2006

Although magnetic data are the primary evidence for ocean floor spreading, the processes by which magnetic phases in ocean floor basalts are formed remain poorly constrained. Scanning transmission electron microscopic observations show that magnetic single-domain magnetite in sheeted dike basalts of Deep Sea Drilling Project hole 504B formed through oxidation-exsolution of ilmenite, exsolution of ulvöspinel lamellae, and recrystallization of end-member magnetite by interaction with convecting fluids. The data suggest that the sheeted dike basalts, with single-domain magnetite as an efficient and stable magnetic carrier, contribute significantly to sea-floor magnetism.
Microcolumn Separations and the Analysis of Single Cells
Authors: Kennedy Robert T. , Oates Mary D. , Cooper Bruce R. , Nickerson Beverly , Jorgenson James W.
Published: October 2006

Capillary zone electrophoresis and open tubular liquid chromatography are two examples of an emerging area of analytical instrumentation known as microcolumn separations. The high resolution and small sample requirements of these methods make them suitable for the quantitative, multicomponent chemical analysis of single cells. Appropriate instrumentation for the analysis of nanoliter and subnanoliter samples is discussed. Data from the analysis of individual neurons are presented, including amino acid and neurotransmitter content.
Activators of Protein Kinase C Induce Dissociation of CD4, But Not CD8, from p56

lck
Authors: Hurley Tamara R. , Luo Kunxin , Sefton Bartholomew M
Published: October 2006

The CD4 and CD8 T cell receptor accessory molecules can both be isolated from T lymphocytes in association with p56
lck
, a membrane-associated, cytoplasmic tyrosine protein kinase that is expressed exclusively in lymphoid cells. The enzymatic activity of p56
lck
may therefore be regulated by CD4 and CD8 and be important in antigen-induced T cell activation. Exposure of human T cells and some mouse T cells to the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), an activator of protein kinase C, caused the dissociation of p56
lck
and CD4. Activation of protein kinase C may therefore interrupt regulation of p56
lck
by CD4 and alter the ability of p56
lck
to interact with polypeptide substrates. In contrast, exposure of cells to TPA did not cause dissociation of p56
lck
and CD8. Regulation of p56
lck
by CD4 may therefore differ from regulation by CD8.
Induction of Differentiation in Human Promyelocytic Leukemia Cells by Tumor Promoters
Authors: Rovera Giovanni , O'Brien Thomas G. , Diamond Leila
Published: October 2006

Phorbol diester tumor promoters and the promoter mezerein convert human promyelocytic leukemia cells in culture into adherent, nonproliferating cells with many of the characteristics of macrophages. Other types of promoters such as anthralin, phenobarbital, and saccharin do not have this effect. Various compounds that can inhibit some of the biological and biochemical effects of tumor promoters do not interfere with the induction of cell adherence and differentiation by the effective promoters.
Pheromone-Mediation of Host-Selection in Bont Ticks (
Amblyomma hebraeum
Koch)
Authors: Norval R. A. I. , Andrew Howard R. , Yunker C. E.
Published: October 2006

The bont tick,
Amblyomma hebraeum
, is the principal vector to southern African ruminants of heartwater (
Cowdria ruminantium
infection). The role of feeding male ticks, which emit an aggregation-attachment pheromone, in attracting unfed ticks to cattle was investigated. Calves infested with feeding male ticks were more attractive to unfed adult ticks than were uninfested calves. The presence of the pheromone on previously infested cattle apparently allows unfed ticks to discriminate between hosts on which these parasites have fed successfully (suitable hosts) and those on which they have not (potentially unsuitable hosts). The use of acaricides is thus unlikely to reduce bont tick populations in areas where adequate numbers of alternate (wild) hosts are present. Also, cattle so treated may lose their resistance to heartwater through lessened exposure to infected ticks.
Structure of the Lambda Complex at 2.5 Å Resolution: Details of the Repressor-Operator Interactions
Authors: Jordan Steven R. , Pabo Carl O.
Published: October 2006

The crystal structure of a complex containing the DNA-binding domain of lambda repressor and a lambda operator site was determined at 2.5 Å resolution and refined to a crystallographic R factor of 24.2 percent. The complex is stabilized by an extensive network of hydrogen bonds between the protein and the sugar-phosphate backbone. Several side chains form hydrogen bonds with sites in the major groove, and hydrophobic contacts also contribute to the specificity of binding. The overall arrangement of the complex is quite similar to that predicted from earlier modeling studies, which fit the protein dimer against linear B-form DNA. However, the cocrystal structure reveals important side chain-side chain interactions that were not predicted from the modeling or from previous genetic and biochemical studies.