bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma etching process development using in situ optical emission and ellipsometry
Authors: Lee J. T. C. , Blayo N. , Tepermeister I. , Klemens F. P. , Mansfield W. M. , Ibbotson D. E.
Published: July 2002

In situ optical emission and ellipsometry are used to control the etching of titanium nitride/polysilicon gate stacks deposited on 70 Å gate oxide patterned with 0.25–0.35 μm design rules. Multistep recipes using various chemistries are developed and optimized with a low pressure, high plasma density helicon source in which the goal is to obtain stringent profile control, and high selectivity to the gate oxide. The characteristic real-time optical emission and ellipsometry traces are used as a reference to evaluate reproducibility and to compare the etching rates as a function of the different processing conditions. Optical emission and ellipsometry appear crucial for the rapid development of a multistep etching sequence using various chemistries. Complementary post-process diagnostics using a spectral reflectometer for film thickness measurements and scanning electron microscopy for quantification of profile control are also presented.
Blind restoration method of scanning tunneling and atomic force microscopy images
Authors: Dongmo Samuel , Troyon Michel , Vautrot Philippe , Delain Etienne , Bonnet Noél
Published: July 2002

In the nanometer resolution range, image formation in scanning tunneling microscopy and atomic force microscopy is essentially governed by the geometrical interaction between the specimen surface and the tip surface. This nonlinear process can be described by using the tools of mathematical morphology. In principle, if the tip shape is precisely known, an image restoration can be performed. In this article, the capabilities of a blind restoration procedure which needs neither a precise knowledge of the tip shape nor the use of a known test object are presented. The efficiency of the blind restoration is demonstrated on an experimental atomic force microscopy image of a DNA molecule obtained in the ‘‘tapping mode’’.
Semiconducting, gas-sensing properties of Europium bisphthalocyanine Langmuir–Blodgett thin films
Authors: Liang Bingjie , Yuan Chunwei , Wei Yu
Published: July 2002

In this article, Europium bisphthalocyanine ( EuPc2′) ten-layer Langmuir–Blodgett films transferred to an interdigital electrode has been prepared. The LB films are fabricated microsensors for halogen gases. The sensor incorporates a microheater and a diode to control the temperature of the film. The gas concentration is measured by the conductance change. The film temperature effects on sensitivity, response and recovery time. When the sensor was operated at above 120 °C, the response had a slow downward drift, indicating the bond formation between the Cl2 and the Pc rings which caused the ring to become chlorinated and lose its conductivity. The interaction between EuPc2′ and Cl2 in the LB films was monitored by UV-vis spectroscopy. LB films exposed to Cl2 gave a red-shifted Q band which is similar to the electrochemical oxidation of the macrocycle. The response time of ten-layer LB films is 45 s and the recovery time is 1 min in the vapor of 50 ppm Cl2 in room temperature.
Low energy electron beam decomposition of metalorganic precursors with a scanning tunneling microscope at ambient atmosphere
Authors: Brückl H. , Kretz J. , Koops H. W. , Reiss G.
Published: July 2002

Electron beam induced decomposition of metalorganic precursor substances with a scanning tunneling microscope is a convenient way to create nanometer-sized structures. Up to now, the application was limited due to the necessity of vacuum conditions. In this contribution, we report experiments to form metallic nanostructures by the decomposition of dimethylgold(III)-trifluoro-acetylacetonate and cyclopentadienylplatin(IV)-trimethyl on graphite and indium–tin–oxide coated glass substrates at ambient atmosphere. Small hillocks with diameters down to 30 nm and heights of 10 nm and wire-shaped structures were produced. The amount of the deposited material depends on the energy and the dose of the electrons. A threshold voltage was found for both materials.
Patterning of self-assembled monolayers with lateral dimensions of 0.15 μm using advanced lithography
Authors: Yang Xiao M. , Peters Richard D. , Kim Tae K. , Nealey Paul F.
Published: July 2002

The use of advanced lithography to pattern self-assembled monolayers (SAMs) was investigated as a means to create surfaces with regions of different chemical functionality with dimensions of order 0.10 μm. SAMs were prepared by the chemisorption of octadecyltrichlorosilane on silicon wafers, and exposed to synchrotron x-ray (0.814 nm) radiation or extreme ultraviolet (EUV, 13.4 nm) radiation. Exposure to x rays in the presence of oxygen resulted in the incorporation of hydroxy (C–OH) and aldehyde (CH=O) functional groups on the SAM surfaces. The extent of chemical modification was a function of exposure dose and air pressure. Patterned SAMs with various shapes at scales from 50 μm to 0.15 μm were obtained by exposing SAMs to x rays through a mask, or with interferometric EUV lithography. The SAM patterns were imaged directly by condensation figures and lateral force microscopy, and were imaged indirectly using atomic force microscopy and the topography of thin films of diblock copolymers. The contrast in the indirect method resulted from a difference in film thickness due to different wetting behavior of thin films of diblock copolymers on the patterned surfaces.
Study of Pb diffusion on Si(111)−(7×7) with scanning tunneling microscopy: Low coverage
Authors: Slezak J. , Chab V. , Chvoj Z. , Mutombo P.
Published: July 2002

The diffusion of single Pb atoms and the formation of stable clusters containing two and three Pb atoms on a Si(111)−(7×7) reconstructed surface was studied with variable temperature scanning tunneling microscopy (STM). The numbers of single Pb atoms and Pb atoms in clusters were monitored as a function of time. A new and simple statistical model describing diffusion was developed. This model enables us to estimate the diffusion coefficient and the activation energy of diffusion. The main advantage is the avoidance of questionable counting of jump events in successive STM images. For substrate temperatures of 308, 311, and 313 K we obtained diffusion coefficients of 8.1×10−18, 1.2×10−17, and 1.9×10−17 cm2 s−1, respectively, and the activation energy of diffusion equaled E=0.56±0.07 eV. The energy difference ΔE between the binding energies of single Pb atoms at faulted and unfaulted halves of the Si(111)−(7×7) unit cells was estimated to be 27±9 meV.
Automated Solid-Phase Synthesis of Oligosaccharides
Authors: Plante Obadiah J. , Palmacci Emma R. , Seeberger Peter H.
Published: July 2002

Traditionally, access to structurally defined complex carbohydrates has been very laborious. Although recent advancements in solid-phase synthesis have made the construction of complex oligosaccharides less tedious, a high level of technical expertise is still necessary to obtain the desired structures. We describe the automated chemical synthesis of several oligosaccharides on a solid-phase synthesizer. A branched dodecasaccharide was synthesized through the use of glycosyl phosphate building blocks and an octenediol functionalized resin. The target oligosaccharide was readily obtained after cleavage from the solid support. Access to certain complex oligosaccharides now has become feasible in a fashion much like the construction of oligopeptides and oligonucleotides.
Josephson Junctions with Tunable Weak Links
Authors: Schön Jan Hendrik , Kloc Christian , Hwang Harold Y. , Batlogg Bertram
Published: July 2002

The electrical properties of organic molecular crystals, such as polyacenes or C
60
, can be tuned from insulating to superconducting by application of an electric field. By structuring the gate electrode of such a field-effect switch, the charge carrier density, and therefore also the superfluid density, can be modulated. Hence, weak links that behave like Josephson junctions can be fabricated between two superconducting regions. The coupling between the superconducting regions can be tuned and controlled over a wide range by the applied gate bias. Such devices might be used in superconducting circuits, and they are a useful scientific tool to study superconducting material parameters, such as the superconducting gap, as a function of carrier concentration or transition temperature.
RETRACTED: Binding of DCC by Netrin-1 to Mediate Axon Guidance Independent of Adenosine A2B Receptor Activation
Authors: Stein Elke , Zou Yimin , Poo Mu-ming , Tessier-Lavigne Marc
Published: July 2002

Netrins stimulate and orient axon growth through a mechanism requiring receptors of the DCC family. It has been unclear, however, whether DCC proteins are involved directly in signaling or are mere accessory proteins in a receptor complex. Further, although netrins bind cells expressing DCC, direct binding to DCC has not been demonstrated. Here we show that netrin-1 binds DCC and that the DCC cytoplasmic domain fused to a heterologous receptor ectodomain can mediate guidance through a mechanism involving derepression of cytoplasmic domain multimerization. Activation of the adenosine A2B receptor, proposed to contribute to netrin effects on axons, is not required for rat commissural axon outgrowth or
Xenopus
spinal axon attraction to netrin-1. Thus, DCC plays a central role in netrin signaling of axon growth and guidance independent of A2B receptor activation.
Resolving the
Hox
Paradox
Authors: Wray Gregory A.
Published: July 2002

From DNA to Diversity
Molecular Genetics and the Evolution of Animal Design. Sean B. Carroll, Jennifer K. Grenier, and Scott D. Weatherbee. Blackwell Science, Malden, MA, 2001. 230 pp. Paper, $44.95, £33.95. ISBN 0-632-04511-6.

Genomic Regulatory Systems
Development and Evolution. Eric H. Davidson. Academic Press, San Diego, 2001. 273 pp. $49.95. ISBN 0-12-205351-6.

The evolution of developmental gene networks is the focus of both of these books. Carroll
et al
. provide an easy-access introduction to the topic that relies on lessons drawn from a handful of model organisms. Davidson stresses general principles in his less accessible but deeper account, which is aimed at his colleagues in the "evo-devo" field.
Nuclear Cloning and Epigenetic Reprogramming of the Genome
Authors: Rideout William M. , Eggan Kevin , Jaenisch Rudolf
Published: July 2002

Cloning of mammals by nuclear transfer (NT) results in gestational or neonatal failure with at most a few percent of manipulated embryos resulting in live births. Many of those that survive to term succumb to a variety of abnormalities that are likely due to inappropriate epigenetic reprogramming. Cloned embryos derived from donors, such as embryonic stem cells, that may require little or no reprogramming of early developmental genes develop substantially better beyond implantation than NT clones derived from somatic cells. Although recent experiments have demonstrated normal reprogramming of telomere length and X chromosome inactivation, epigenetic information established during gametogenesis, such as gametic imprints, cannot be restored after nuclear transfer. Survival of cloned animals to birth and beyond, despite substantial transcriptional dysregulation, is consistent with mammalian development being rather tolerant to epigenetic abnormalities, with lethality resulting only beyond a threshold of faulty gene reprogramming encompassing multiple loci.
Lobster Sniffing: Antennule Design and Hydrodynamic Filtering of Information in an Odor Plume
Authors: Koehl M. A. R. , Koseff Jeffrey R. , Crimaldi John P. , McCay Michael G. , Cooper Tim , Wiley Megan B. , Moore Paul A.
Published: July 2002

The first step in processing olfactory information, before neural filtering, is the physical capture of odor molecules from the surrounding fluid. Many animals capture odors from turbulent water currents or wind using antennae that bear chemosensory hairs. We used planar laser–induced fluorescence to reveal how lobster olfactory antennules hydrodynamically alter the spatiotemporal patterns of concentration in turbulent odor plumes. As antennules flick, water penetrates their chemosensory hair array during the fast downstroke, carrying fine-scale patterns of concentration into the receptor area. This spatial pattern, blurred by flow along the antennule during the downstroke, is retained during the slower return stroke and is not shed until the next flick.
Recruitment of Mec1 and Ddc1 Checkpoint Proteins to Double-Strand Breaks Through Distinct Mechanisms
Authors: Kondo Tae , Wakayama Tatsushi , Naiki Takahiro , Matsumoto Kunihiro , Sugimoto Katsunori
Published: July 2002

In response to DNA damage, eukaryotic cells activate checkpoint pathways that arrest cell cycle progression and induce the expression of genes required for DNA repair. In budding yeast, the homothallic switching (HO) endonuclease creates a site-specific double-strand break at the mating type (
MAT
) locus. Continuous
HO
expression results in the phosphorylation of Rad53, which is dependent on products of the ataxia telangiectasia mutated–related
MEC1
gene and other checkpoint genes, including
DDC1
,
RAD9
, and
RAD24
. Chromatin immunoprecipitation experiments revealed that the Ddc1 protein associates with a region near the
MAT
locus after
HO
expression. Ddc1 association required Rad24 but not Mec1 or Rad9. Mec1 also associated with a region near the cleavage site after
HO
expression, but this association is independent of Ddc1, Rad9, and Rad24. Thus, Mec1 and Ddc1 are recruited independently to sites of DNA damage, suggesting the existence of two separate mechanisms involved in recognition of DNA damage.
Field-Effect Modulation of the Conductance of Single Molecules
Authors: Schön Jan Hendrik , Meng Hong , Bao Zhenan
Published: July 2002

Field-effect transistors based on two-component self-assembled monolayers of conjugated and insulating molecules were prepared; the conductance through them can be varied by more than three orders of magnitude by changing the applied gate bias. With very small ratios of conjugated to insulating molecules in the two-component monolayer, devices with only a few “electrically active” molecules can be achieved. At low temperatures, the peak channel conductance is quantized in units of 2
e
2
/
h
(where
e
is the electron charge and
h
is Planck's constant). This behavior is indicative of transistor action in single molecules. On the basis of such single-molecule transistors, inverter circuits with gain are demonstrated.
A Paradigm Shift in Brain Research
Authors: Carlsson Arvid
Published: July 2002

As late as the 1950s, it was assumed that communication between nerve cells in the brain occurred predominantly, if not entirely, by electrical impulses. A decade later, the theory of chemical transmission, which until then had been thought to occur only in the peripheral nervous system, had gained strong entrance for the central nervous system. This paradigm shift opened up an enormous new perspective in brain research, not least by facilitating the study of brain function by means of chemical tools, which in different ways could modify the chemical signaling between nerve cells. Moreover, such tools sometimes turned out to be useful as therapeutic agents. Thus for the first time, a variety of disorders in the central nervous system could be treated effectively.
Congress: Biomedical Research Wins Big
Authors: Marshall Eliot , Lawler Andrew
Published: July 2002

Biomedical research scored a “100% win” on Capitol Hill, as one lobbyist says, in the massive 1997 appropriation bill that Congress passed last week. The new law gives the National Institutes of Health an increase of 6.9% and launches a new prostate cancer research effort in the Department of Defense. It also provides a surprise $4 million increase for the Advanced Technology Program, an industrial partnership program that Republican lawmakers once vowed to eliminate.
Tobacco Funding Debate Smolders
Authors: Williams Nigel
Published: July 2002

Britain's medical research establishment has been embroiled in a row that has been smoldering since early summer over tobacco-industry funding for academic research. The row was sparked when Cambridge University decided to accept $2.5 million from British American Tobacco (BAT) Industries to support a new professorship in international relations. The Medical Research Council (MRC) was drawn into the fray when it was reported that it had accepted $220,000 from BAT for a study of the potential benefits of nicotine in people at risk of Alzheimer's disease. The MRC and the Cancer Research Campaign promised to announce new policies on tobacco funding last week, but instead they issued separate statements saying that they need more time to study the issues.
First Global Sequencing Effort Begins
Authors: Kaiser Jocelyn
Published: July 2002

Last week the U.S. government put up $12.7 million to begin large-scale sequencing of Arabidopsis thaliana, a small, flowering member of the mustard family. The awards will fund the U.S. portion of an international collaboration that will attempt to decipher the plant's entire genome by 2004. Arabidopsis has several features that make sequencing its genome a worthwhile challenge. Sequencing Arabidopsis should also have a significant impact on plant science, because all 250,000 species of flowering plants, from corn to tulips to cherry trees, are genetically very similar.
Year of Strange Events Leaves Standard Theory Unscathed
Authors: Glanz James
Published: July 2002

As 1996 began, particle physics had been energized by a handful of results that standard theories of particles and forces couldn't readily explain, including a bizarre blip in a detector at the Fermi National Accelerator Laboratory in Illinois and inexplicable decay rates for the fundamental particles called Z bosons at CERN, the European laboratory for particle physics in Geneva. But with new data and analysis, both anomalies have faded. That comes as a disappointment to theorists who had hoped that the mysterious events were the first glimpse of a more encompassing theory of particles and forces known as supersymmetry.
A ‘Reforestation Plan’ for Biomedical Research
Authors: Kondro Wayne
Published: July 2002

Ottawa, Canada—An idea, floated by Canadian physician and entrepreneur Calvin Stiller, became the hottest topic at a conference of health leaders from 14 countries, who met here to discuss innovative ways to fund biomedical research. Stiller outlined a breathtaking plan that would turn Canadian universities into venture capitalists: Armed with a pot of government funds and assisted by a slew of tax shelters, they would invest in companies that would commercialize their researchers' findings. Revenues would later be plowed back into medical research.
Agencies Protest Funding Reforms
Authors: Hellemans Alexander
Published: July 2002

The Dutch research community is reacting angrily to a plan to overhaul the way basic research is funded in the Netherlands. The proposal would strip the Dutch Research Council, or NWO, of its responsibility for running labs and turn it into a granting agency, much like the U.S. National Science Foundation.
Flotilla Is Heading to Mars Seeking End to Data Drought
Authors: Lawler Andrew
Published: July 2002

Next summer, if all goes well, the first Mars data in 15 years will begin streaming back to Earth thanks to three missions launched within a 4-week period this month and next: NASA's Global Surveyor, launched last week; Russia's Mars '96, scheduled for 16 November; and NASA's Mars Pathfinder, planned for 2 December.
Activists Vote $14 Million for Research
Authors: Marshall Eliot
Published: July 2002

During a tense meeting on 7 November, breast cancer activists took an extraordinary step: They rejected an attempt to spend $14.75 million to build a small fiefdom on their behalf in the Department of Health and Human Services, arguing that the money should be spent instead on peer-reviewed research.
Tiny Abacus Points to New Devices
Authors: Service Robert F.
Published: July 2002

IBM researchers have crafted a nanoscale abacus out of spherical buckyballs lined up along a steplike edge on a copper surface. The device represents the first time scientists have succeeded in using individual molecules to store numerical information at room temperatures, and it points the way to a new generation of computer chips and disc drives.
Human Influence on the Atmospheric Vertical Temperature Structure: Detection and Observations
Authors: Tett Simon F. B. , Mitchell John F. B. , Parker David E. , Allen Myles R.
Published: July 2002

Recent work suggests a discernible human influence on climate. This finding is supported, with less restrictive assumptions than those used in earlier studies, by a 1961 through 1995 data set of radiosonde observations and by ensembles of coupled atmosphere-ocean simulations forced with changes in greenhouse gases, tropospheric sulfate aerosols, and stratospheric ozone. On balance, agreement between the simulations and observations is best for a combination of greenhouse gas, aerosol, and ozone forcing. The uncertainties remaining are due to imperfect knowledge of radiative forcing, natural climate variability, and errors in observations and model response.
Generous Funding Wins a Seat at the Genome Top Table
Authors: Balter Michael
Published: July 2002

Hinxton, U.K.—The Wellcome Trust's biggest single project is its Genome Campus near Cambridge, which has become the heart of Britain's genome research effort. This major investment is giving the trust considerable influence over the coordination of international genome research.
NIH, Hopkins Team Up on Genotyping
Authors: Stone Richard
Published: July 2002

Scientists hoping to pinpoint genes involved in complex diseases have a new facility to turn to for high-powered help. Earlier this week, the National Institutes of Health (NIH) announced that it will fund a center at Johns Hopkins University in Baltimore devoted to genotyping, the painstaking process of searching for culprit genes in families afflicted with inherited diseases.
NSF Prepares to Dish Up Millimeter Array Project
Authors: Mervis Jeffrey
Published: July 2002

The world's most powerful telescope for investigating emissions in the millimeter-wavelength range—a rich source of information about early galaxies, star formation, the history of stellar evolution, and much more—will move from the drawing board to early development if Congress grants an upcoming budgetary wish from the National Science Foundation. And the proposed site for the Millimeter Array will take your breath away.
Depletion of the Outer Asteroid Belt
Authors: Liou Jer-Chyi , Malhotra Renu
Published: July 2002

During the early history of the solar system, it is likely that the outer planets changed their distance from the sun, and hence, their influence on the asteroid belt evolved with time. The gravitational influence of Jupiter and Saturn on the orbital evolution of asteroids in the outer asteroid belt was calculated. The results show that the sweeping of mean motion resonances associated with planetary migration efficiently destabilizes orbits in the outer asteroid belt on a time scale of 10 million years. This mechanism provides an explanation for the observed depletion of asteroids in that region.
ITER Review Team Takes Bullish Stance
Authors: Lawler Andrew
Published: July 2002

SAN DIEGO
—A large team of U.S. fusion researchers last week began poring over the latest blueprints for the $10 billion International Thermonuclear Experimental Reactor (ITER). The review, prompted by controversy over the reactor's design and the best way to spend the shrinking U.S. fusion budget, is likely to give ITER a green light despite concerns that the design may not be adequate to reach the ultimate goal of a self-sustaining fusion burn.
20,000 Leagues Under the Earth
Authors: Kerr Richard A.
Published: July 2002

At the bottom of Earth's mantle lies a strange realm, where “continents” may fall from above, fiery bogs stew above the molten core, and whole chunks of landscape can loft upward like so many hot-air balloons.
Advances Painted in Shades of Gray at a D.C. Conference
Authors: Cohen Jon
Published: July 2002

At the influential 4th Conference on Retroviruses and Opportunistic Infections last week, researchers praised the potent new drugs that can pound the AIDS virus so hard that even the most sensitive tests cannot detect it in the blood of HIV-infected people. But studies reported at the meeting also highlighted an important caveat about the new drugs: They have yet to cure anyone of HIV infection—and it's not yet clear whether they ever will.
NSF Revamps Graduate Training Grants
Authors: Mervis Jeffrey
Published: July 2002

A new National Science Foundation program is intended to encourage universities to broaden the training of graduate students and improve their job prospects by putting a premium on interdisciplinary traineeships and industrial partnerships. Full details of NSF's budget request are available on the
Web.
Europe Starts Search for Lone Electron
Authors: Hellemans Alexander
Published: July 2002

PARIS
—Fabrication methods for computer memory chips are reaching the physical limit of how small they can create circuits, and energy consumption of chips is becoming excessive. Designers are now looking around for new ways to store information on a chip, and this challenge is the focus of a new $3.7 million research program announced last week by the European Union. Its aim: to build a chip capable of storing a terabit of information with each bit recorded by a single electron.
A Zebrafish Genome Project?
Authors: Roush Wade
Published: July 2002

BOSTON
—The Human Genome Project already studies such organisms as yeast, roundworms, and mice; if an intrepid band of biologists has their way, the zebrafish—which is very useful for developmental biology but has an almost unknown genome—will be the next species to hitch a ride on the mammoth project.
Superconductivity and Antiferromagnetism in High-
T
c
Cuprates
Authors: Nagaosa Naoto
Published: July 2002

High-transition temperature copper oxide superconductors have puzzled physicists since these materials were discovered 10 years ago. Nagaosa's Perspective discusses a new theory described by Zhang (
1089
) in the same issue in which superconductivity is related to another important property, antiferromagnetism, by an elegant symmetry principle.
Structural Convergence in the Active Sites of a Family of Catalytic Antibodies
Authors: Charbonnier Jean-Baptiste , Golinelli-Pimpaneau Béatrice , Gigant Benoît , Tawfik Dan S. , Chap Rachel , Schindler Daniel G. , Kim Se-Ho , Green Bernard S. , Eshhar Zelig , Knossow Marcel
Published: July 2002

The x-ray structures of three esterase-like catalytic antibodies identified by screening for catalytic activity the entire hybridoma repertoire, elicited in response to a phosphonate transition state analog (TSA) hapten, were analyzed. The high resolution structures account for catalysis by transition state stabilization, and in all three antibodies a tyrosine residue participates in the oxyanion hole. Despite significant conformational differences in their combining sites, the three antibodies, which are the most efficient among those elicited, achieve catalysis in essentially the same mode, suggesting that evolution for binding to a single TSA followed by screening for catalysis lead to antibodies with structural convergence.
Activation of Auditory Cortex During Silent Lipreading
Authors: Calvert Gemma A. , Bullmore Edward T. , Brammer Michael J. , Campbell Ruth , Williams Steven C. R. , McGuire Philip K. , Woodruff Peter W. R. , Iversen Susan D. , David Anthony S.
Published: July 2002

Watching a speaker’s lips during face-to-face conversation (lipreading) markedly improves speech perception, particularly in noisy conditions. With functional magnetic resonance imaging it was found that these linguistic visual cues are sufficient to activate auditory cortex in normal hearing individuals in the absence of auditory speech sounds. Two further experiments suggest that these auditory cortical areas are not engaged when an individual is viewing nonlinguistic facial movements but appear to be activated by silent meaningless speechlike movements (pseudospeech). This supports psycholinguistic evidence that seen speech influences the perception of heard speech at a prelexical stage.
Brain Regions Responsive to Novelty in the Absence of Awareness
Authors: Berns Gregory S. , Cohen Jonathan D. , Mintun Mark A.
Published: July 2002

Brain regions responsive to novelty, without awareness, were mapped in humans by positron emission tomography. Participants performed a simple reaction-time task in which all stimuli were equally likely but, unknown to them, followed a complex sequence. Measures of behavioral performance indicated that participants learned the sequences even though they were unaware of the existence of any order. Once the participants were trained, a subtle and unperceived change in the nature of the sequence resulted in increased blood flow in a network comprising the left premotor area, left anterior cingulate, and right ventral striatum. Blood flow decreases were observed in the right dorsolateral prefrontal and parietal areas. The time course of these changes suggests that the ventral striatum is responsive to novel information, and the right prefrontal area is associated with the maintenance of contextual information, and both processes can occur without awareness.
Using Neutron Stars and Black Holes in X-ray Binaries to Probe Strong Gravitational Fields
Authors: Kaaret Philip , Ford Eric C.
Published: July 2002

Neutron stars and black holes can be studied by observation of the radiation produced as matter falls into their gravitational fields. X-ray binaries, which are systems consisting of a neutron star or black hole and a companion gaseous star, produce radiation in this manner. Recently, oscillations at frequencies near 1000 cycles per second have been detected from x-ray binaries. These oscillations are likely produced in regions of very strong gravitational fields within a few tens of kilometers of the compact star. The oscillations have been interpreted as evidence for the existence of an innermost stable orbit near a compact star, a key prediction of general relativity theory. The study of x-ray binaries has also advanced the search for definitive evidence of black holes. Recent developments in our understanding of accretion flows in x-ray binaries have provided evidence for the existence of event horizons in x-ray binaries thought to contain black holes.
X-Rays and Beyond
Authors: Boyer Paul
Published: July 2002

Naked to the Bone.
Medical Imaging in the Twentieth Century. BETTYANN HOLTZMANN KEVLES. Rutgers University Press, New Brunswick, NJ, 1997. xvi, 379 pp., illus. $35.95. ISBN 0-8135-2358-3. Sloan Technology Series.
Failure of Parturition in Mice Lacking the Prostaglandin F Receptor
Authors: Sugimoto Yukihiko , Yamasaki Atsushi , Segi Eri , Tsuboi Kazuhito , Aze Yoshiya , Nishimura Tatsuya , Oida Hiroji , Yoshida Nobuaki , Tanaka Takashi , Katsuyama Masato , Hasumoto Ken-yuh , Murata Takahiko , Hirata Masakazu , Ushikubi Fumitaka , Negishi Manabu , Ichikawa Atsushi , Narumiya Shuh
Published: July 2002

Mice lacking the gene encoding the receptor for prostaglandin F
2α
(FP) developed normally but were unable to deliver normal fetuses at term. Although these FP-deficient mice showed no abnormality in the estrous cycle, ovulation, fertilization, or implantation, they did not respond to exogenous oxytocin because of the lack of induction of oxytocin receptor (a proposed triggering event in parturition), and they did not show the normal decline of serum progesterone concentrations that precedes parturition. Ovariectomy at day 19 of pregnancy restored induction of the oxytocin receptor and permitted successful delivery in the FP-deficient mice. These results indicate that parturition is initiated when prostaglandin F
2α
interacts with FP in ovarian luteal cells of the pregnant mice to induce luteolysis.
NF-AT Activation Induced by a CAML-Interacting Member of the Tumor Necrosis Factor Receptor Superfamily
Authors: von Bülow Götz-Ulrich , Bram Richard J.
Published: July 2002

Activation of the nuclear factor of activated T cells transcription factor (NF-AT) is a key event underlying lymphocyte action. The CAML (calcium-modulator and cyclophilin ligand) protein is a coinducer of NF-AT activation when overexpressed in Jurkat T cells. A member of the tumor necrosis factor receptor superfamily was isolated by virtue of its affinity for CAML. Cross-linking of this lymphocyte-specific protein, designated TACI (transmembrane activator and CAML-interactor), on the surface of transfected Jurkat cells with TACI-specific antibodies led to activation of the transcription factors NF-AT, AP-1, and NFκB. TACI-induced activation of NF-AT was specifically blocked by a dominant-negative CAML mutant, thus implicating CAML as a signaling intermediate.
A TEL-JAK2 Fusion Protein with Constitutive Kinase Activity in Human Leukemia
Authors: Lacronique Virginie , Boureux Anthony , Della Valle Véronique , Poirel Hélène , Quang Christine Tran , Mauchauffé Martine , Berthou Christian , Lessard Michel , Berger Roland , Ghysdael Jacques , Bernard Olivier A.
Published: July 2002

The Janus family of tyrosine kinases (JAK) plays an essential role in development and in coupling cytokine receptors to downstream intracellular signaling events. A t(9;12)(p24;p13) chromosomal translocation in a T cell childhood acute lymphoblastic leukemia patient was characterized and shown to fuse the 3′ portion of
JAK2
to the 5′ region of
TEL
, a gene encoding a member of the ETS transcription factor family. The TEL-JAK2 fusion protein includes the catalytic domain of JAK2 and the TEL-specific oligomerization domain. TEL-induced oligomerization of TEL-JAK2 resulted in the constitutive activation of its tyrosine kinase activity and conferred cytokine-independent proliferation to the interleukin-3–dependent Ba/F3 hematopoietic cell line.
Taxonomy Recapitulates Society
Authors: Lyons Sherrie
Published: July 2002

The Platypus and the Mermaid and Other Figments of the Classifying Imagination.
HARRIET RITVO. Harvard University Press, Cambridge, MA, 1997. xvi, 288 pp., illus. $29.95. ISBN 0-674-67357-3.
Where Sea Meets Sky
Authors: Wanninkhof Rik
Published: July 2002

The Sea Surface and Global Change.
PETER S. LISS and ROBERT A. DUCE, Eds. Cambridge University Press, Cambridge, 1997. 519 pp. $95. ISBN 0-521-56273-2.
A Search for Endogenous Amino Acids in Martian Meteorite ALH84001
Authors: Bada Jeffrey L. , Glavin Daniel P. , McDonald Gene D. , Becker Luann
Published: July 2002

Trace amounts of glycine, serine, and alanine were detected in the carbonate component of the martian meteorite ALH84001 by high-performance liquid chromatography. The detected amino acids were not uniformly distributed in the carbonate component and ranged in concentration from 0.1 to 7 parts per million. Although the detected alanine consists primarily of the
l
enantiomer, low concentrations (<0.1 parts per million) of endogenous
d
-alanine may be present in the ALH84001 carbonates. The amino acids present in this sample of ALH84001 appear to be terrestrial in origin and similar to those in Allan Hills ice, although the possibility cannot be ruled out that minute amounts of some amino acids such as
d
-alanine are preserved in the meteorite.
Extraterrestrial Tales
Authors: Bainbridge William Sims
Published: July 2002

UFO Crash at Roswell.
The Genesis of a Modern Myth. BENSON SALER, CHARLES A. ZIEGLER, and CHARLES B. MOORE. Smithsonian Institution Press, Washington, DC, 1997. xii, 198 pp., illus. $24.95. ISBN 1-56098-751-0.
The Minor Histocompatibility Antigen HA-1: A Diallelic Gene with a Single Amino Acid Polymorphism
Authors: den Haan Joke M. M. , Meadows Leslie M. , Wang Wei , Pool Jos , Blokland Els , Bishop Tracie L. , Reinhardus Carla , Shabanowitz Jeffrey , Offringa Rienk , Hunt Donald F. , Engelhard Victor H. , Goulmy Els
Published: July 2002

The minor histocompatibility antigen (mHag) HA-1 is the only known mHag for which mismatching is correlated with the development of severe graft versus host disease (GvHD) after human leukocyte antigen–identical bone marrow transplantation. HA-1 was found to be a nonapeptide derived from an allele of the
KIAA0223
gene. The HA-1–negative allelic counterpart encoded by
KIAA0223
had one amino acid difference from HA-1. Family analysis with HA-1 allele-specific polymerase chain reaction showed an exact correlation between this allelic polymorphism and the HA-1 phenotype. HA-1 allele typing of donor and recipient should improve donor selection and allow the determination of bone marrow transplantation recipients with high risk for HA-1–induced GvHD development.
Unraveling Complex Events
Authors: Brush Stephen G.
Published: July 2002

Physics in the Nineteenth Century.
ROBERT D. PURRINGTON. Rutgers University Press, New Brunswick, NJ, 1997. xx, 251 pp. $55, ISBN 0-8135-2441-5; paper, $25, ISBN 0-8135- 2442-3.
Kinetic Intermediates Trapped by Native Interactions in RNA Folding
Authors: Treiber Daniel K. , Rook Martha S. , Zarrinkar Patrick P. , Williamson James R.
Published: July 2002

In the magnesium ion–dependent folding of the
Tetrahymena
ribozyme, a kinetic intermediate accumulates in which the P4-P6 domain is formed, but the P3-P7 domain is not. The kinetic barriers to P3-P7 formation were investigated with the use of in vitro selection to identify mutant RNA molecules in which the folding rate of the P3-P7 domain was increased. The critical mutations disrupt native tertiary interactions within the P4-P6 domain and increase the rate of P3-P7 formation by destabilizing a kinetically trapped intermediate. Hence, kinetic traps stabilized by native interactions, and not simply by mispaired nonnative structures, can present a substantial barrier to RNA folding.
Structuring Nurture
Authors: Gupta Sunetra
Published: July 2002

Life's Other Secret.
The New Mathematics of the Living World. IAN STEWART. Wiley, New York, 1998. xiv, 285 pp., illus, + plates. $24.95 or C$34.95. ISBN 0-471-15845-3.
Almost All Things Dinosaurian
Authors: Ruben John
Published: July 2002

Encyclopedia of Dinosaurs.
PHILIP J. CURRIE and KEVIN PADIAN, Eds. Academic Press, San Diego, 1997. xxx, 869 pp., illus., + plates. $99.95. ISBN 0-12-226810-5.
Power and the People
Authors: Morgan M. Granger
Published: July 2002

Consuming Power.
A Social History of American Energies. DAVID E. NYE. MIT Press, Cambridge, MA, 1997. xiv, 331 pp., illus. $25. ISBN 0-262-14063-2.
Palaeobiography
Authors: Copper Paul
Published: July 2002

Life.
A Natural History of the First Four Billion Years of Life on Earth. RICHARD FORTEY. Knopf, New York, 1998. xiv, 347 pp., + plates. $30 or C$42. ISBN 0-375-40119-9.
Developmental Diversity
Authors: Emlet Richard
Published: July 2002

Embryology
. Constructing the Organism. SCOTT F. GILBERT and ANNE M. RAUNIO, Eds. Sinauer, Sunderland, MA, 1997. xii, 537 pp., illus. $69.95. ISBN 0-87893-237-2.
A Reduction-Pyrolysis-Catalysis Synthesis of Diamond
Authors: Li Yadong , Qian Yitai , Liao Hongwei , Ding Yi , Yang Li , Xu Cunyi , Li Fangqing , Zhou Guien
Published: July 2002

Diamond powder was synthesized through a metallic reduction-pyrolysis-catalysis route with the reaction of carbon tetrachloride and sodium at 700°C, in which the sodium was used as reductant and flux. This temperature is much lower than that of traditional methods. The x-ray powder diffraction patterns showed three strong peaks of diamond. The Raman spectrum showed a sharp peak at 1332 inverse centimeters, which is characteristic of diamond. Although the yield was only 2 percent, this method is a simple means of forming diamond.
Regulation of a Transcription Factor Network Required for Differentiation and Metabolism
Authors: Duncan Stephen A. , Navas M. Angeles , Dufort Daniel , Rossant Janet , Stoffel Markus
Published: July 2002

Hepatocyte nuclear factors (HNFs) are a heterogeneous class of evolutionarily conserved transcription factors that are required for cellular differentiation and metabolism. Mutations in
HNF-1α
and
HNF-4α
genes impair insulin secretion and cause type 2 diabetes. Regulation of HNF-4/HNF-1 expression by
HNF-3α
and
HNF-3β
was studied in embryoid bodies in which one or both
HNF-3α
or
HNF-3β
alleles were inactivated.
HNF-3β
positively regulated the expression of
HNF-4α/HNF-1α
and their downstream targets, implicating a role in diabetes.
HNF-3β
was also necessary for expression of
HNF-3α
. In contrast,
HNF-3α
acts as a negative regulator of
HNF-4α/HNF-1α
demonstrating that
HNF-3α
and
HNF-3β
have antagonistic transcriptional regulatory functions in vivo.
HNF-3α
does not appear to act as a classic biochemical repressor but rather exerts its negative effect by competing for HNF-3 binding sites with the more efficient activator
HNF-3β
. In addition, the
HNF-3α/HNF-3β
ratio is modulated by the presence of insulin, providing evidence that the HNF network may have important roles in mediating the action of insulin.
Induced Massive Star Formation in the Trifid Nebula?
Authors: Cernicharo J. , Lefloch B. , Cox P. , Cesarsky D. , Esteban C. , Yusef-Zadeh F. , Méndez D. I. , Acosta-Pulido J. , Garcı́a López R. J. , Heras A.
Published: July 2002

The Trifid nebula is a young (10
5
years) galactic HII region where several protostellar sources have been detected with the infrared space observatory. The sources are massive (17 to 60 solar masses) and are associated with molecular gas condensations at the edges or inside the nebula. They appear to be in an early evolutionary stage and may represent the most recent generation of stars in the Trifid. These sources range from dense, apparently still inactive cores to more evolved sources, undergoing violent mass ejection episodes, including a source that powers an optical jet. These observations suggest that the protostellar sources may have evolved by induced star formation in the Trifid nebula.
A Handler for Big Data
Authors: Cass Tony
Published: July 2002

HiQ
. National Instruments Corporation. $495 (students, $45). Phone: 512-794-0100.
www.natinst.com

Cass reviews the program HiQ, a data analysis program especially suited for large data sets.
Pieces of the Geologic Frame, Assembled
Authors: Eaton Gordon P.
Published: July 2002

Annals of the Former World
. John McPhee. Farrar, Straus, and Giroux, New York, 1998. 704 pp. $35, C$51. ISBN 0-374-10520-0.

McPhee assembles a geologic cross section of North America at about the 40th parallel by combining slightly revised and edited versions of four earlier books with a thematic overview and a new section that explores the midcontinent's buried Precambrian basement. Through a melange of journeys, set pieces, biographical sketches, and histories of humans and rocks, the resulting many-layered tale provides a primer on geology, plate tectonics, and geologic time.
Spinodal Dewetting in Liquid Crystal and Liquid Metal Films
Authors: Herminghaus Stephan , Jacobs Karin , Mecke Klaus , Bischof Jörg , Fery Andreas , Ibn-Elhaj Mohammed , Schlagowski Stefan
Published: July 2002

Theory predicts that dewetting of a homogeneous liquid film from a solid surface may proceed via unstable surface waves on the liquid. This phenomenon, usually termed spinodal dewetting, has been sought after in many systems. Observations in liquid crystal and liquid metal films showed that, as expected, the emerging structures were similar to those found for spinodal decomposition in mixtures. Certain differences, however, could be attributed to peculiarities of the wetting forces in these two dissimilar systems, thereby demonstrating the role of nonlinearities inherent in the wetting forces.
Large-Scale Nitrogen Oxide Plumes in the Tropopause Region and Implications for Ozone
Authors: Brunner Dominik , Staehelin Johannes , Jeker Dominique
Published: July 2002

Continuous measurements of nitrogen oxide and ozone were performed from a commercial airliner during 1 year at cruising altitudes below and above the tropopause. The upper tropospheric nitrogen oxides distribution was found to be strongly influenced by large-scale plumes extending about 100 to 1300 kilometers along the flight track. The plumes were frequently observed downwind of thunderstorms and frontal systems, which most probably caused upward transport of polluted air from the continental boundary layer or nitrogen oxide production in lightning strokes, or both. Particularly in summer, average ozone concentrations in the plumes were enhanced compared to the tropospheric background levels.
Eight Calves Cloned from Somatic Cells of a Single Adult
Authors: Kato Yoko , Tani Tetsuya , Sotomaru Yusuke , Kurokawa Kazuo , Kato Jun-ya , Doguchi Hiroshi , Yasue Hiroshi , Tsunoda Yukio
Published: July 2002

Eight calves were derived from differentiated cells of a single adult cow, five from cumulus cells and three from oviductal cells out of 10 embryos transferred to surrogate cows (80 percent success). All calves were visibly normal, but four died at or soon after birth from environmental causes, and postmortem analysis revealed no abnormality. These results show that bovine cumulus and oviductal epithelial cells of the adult have the genetic content to direct the development of newborn calves.
Low-Voltage Organic Transistors on Plastic Comprising High-Dielectric Constant Gate Insulators
Authors: Dimitrakopoulos C. D. , Purushothaman S. , Kymissis J. , Callegari A. , Shaw J. M.
Published: July 2002

The gate bias dependence of the field-effect mobility in pentacene-based insulated gate field-effect transistors (IGFETs) was interpreted on the basis of the interaction of charge carriers with localized trap levels in the band gap. This understanding was used to design and fabricate IGFETs with mobility of more than 0.3 square centimeter per volt per second and current modulation of 10
5
, with the use of amorphous metal oxide gate insulators. These values were obtained at operating voltage ranges as low as 5 volts, which are much smaller than previously reported results. An all-room-temperature fabrication process sequence was used, which enabled the demonstration of high-performance organic IGFETs on transparent plastic substrates, at low operating voltages for organic devices.
Seeing Is Believing, But What Do We See?
Authors: Laubichler Manfred D.
Published: July 2002

The Birth of the Cell
. Henry Harris. Yale University Press, New Haven, 1999. 224 pp. $30. ISBN 0-300-07384-4.

Paying particular attention to the original literature, Harris provides a history of the cell doctrine that illuminates the contributions of those who actually made the discoveries, not merely the better-known researchers who elaborated the theory.
Held in Place By Practice
Authors: Oldroyd David
Published: July 2002

The Rejection of Continental Drift
Theory and Method in American Earth Science. Naomi Oreskes. Oxford University Press, New York, 1999. 432 pp. $55, £49.50. ISBN 0-19-511732-8. Paper, $29.95, £21.50. ISBN 0-19-511733-6.

Oreskes examines the history of geological theory and method in the United States to explain why American geologists were so slow to accept the idea of mobile continents. She concludes that drift was rejected not for want of a causal mechanism, but because it seemed to conflict with the accepted standards of practice.
Spatial in Formation
Authors: Stone Jon R.
Published: July 2002

Theoretical Morphology
The Concept and Its Applications. George R. McGhee Jr. Columbia University Press, New York, 1999. 328 pp. $60, £48. ISBN 0-231-10666-1. Paper, $26.50, £13.95. ISBN 0-231-10667-X.

Paleobiologist McGhee reviews approaches to examining the range of possible biological forms through considerations of geometric parameters and simulations of morphogenetic processes.