bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of thin SiN film formed with electron cyclotron resonance nitrogen plasma
Authors: Machida K. , Hosoya T. , Imai K. , Arai E.
Published: July 2002

An extremely thin SiN film formed with electron cyclotron resonance (ECR) nitrogen plasma has been measured by x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), ellipsometry, and electron spin resonance (ESR). The XPS and AES results show that the SiN layer is easily formed on a silicon surface by ECR nitrogen plasma, and it has a structure with high nitrogen content similar to Si3N4 only near the surface of the film. The ellipsometry and ESR results reveal that the SiN film is very thin, 2.5–4.0 nm, and has spin density in the order of 1013 cm−2, which is reduced drastically by exposing it to hydrogen plasma. The SiN film can be applied to the inexpensive dual-polycide-gate complementary metal–oxide–semiconductor process.
Multiple-pass writing optimization for proximity x-ray mask-making using electron-beam lithography
Authors: Puisto Denise M. , Lawliss Mark S. , Rocque Janet M. , Kimmel Kurt R. , Hartley John G.
Published: July 2002

We have evaluated and implemented a multiple-pass writing scheme that significantly improves the image-placement performance of masks for proximity x-ray lithography. Masks were fabricated using a 75 kV EL-3+ electron-beam lithography system that separates the data into fields and subfields, and exposes the images by using a variable-shaped beam. Multiple-pass writing allows averaging of system noise between multiple exposure passes written at fractional doses [Jpn. J. Appl. Phys. 32, L1707 (1993)]; stitching errors can also be averaged by offsetting the locations of the tool field and subfield boundaries for each pass [Jpn. J. Appl. Phys. 32, 5933 (1993)]. Multiple-pass writing was evaluated both with and without boundary offsets. Our experiments indicated that the offset method resulted in better image placement but negatively affected image size and defect performance because of the EL-3+system limitations. The no-offset method was optimized and implemented and achieved sub-50 nm (3σ) image placement. The method was then transferred to the EL-4 electron-beam lithography system, resulting in image placement of sub-30 nm (3σ).
Approaching the liquid/air interface with scanning force microscopy
Authors: Eng L. M. , Seuret Ch. , Looser H. , Günter P.
Published: July 2002

Scanning force microscopy at both the air/solid and the liquid/solid interface is very common and understood accurately. Here we demonstrate that the scanning force microscope (SFM) is capable of investigating even at the liquid/air interface, i.e., the surface of a Langmuir film floating on the water subphase. We demonstrate the successful investigation of (a) a solid substrate surface, i.e., a polycrystalline gold sample under water, (b) a mechanically stabilized 2-docosylamino- 5-nitropyridine Langmuir–Blodgett (LB) film, and (c) a freely floating cadmium-arachidate (CdA) LB film. The SFM is constructed as a standalone, remote-controlled, and water-tight microscope that can be put upside down into the water subphase of a commercial LB trough. The SFM tip therefore approaches the air/water interface from underwater allowing the investigation of the LB chromophores. This force microscope complements our optical techniques (polarization and second-harmonic microscopy) that have already been set up on top of the LB trough and that achieve monolayer resolution on a floating Langmuir layer. Combined operation of all those techniques will provide correlated information on the optical and structural properties of the LB molecules.
Critical Review: Adhesion in surface micromechanical structures
Authors: Maboudian Roya , Howe Roger T.
Published: July 2002

We present a review on the state of knowledge of surface phenomena behind adhesion in surface micromechanical structures. After introducing the problem of release-related and in-use adhesion, a theoretical framework for understanding the various surface forces that cause strong adhesion of micromechanical structures is presented. Various approaches are described for reducing the work of adhesion. These include surface roughening and chemical modification of polycrystalline silicon surfaces. The constraints that fabrication processes such as release, drying, assembly, and packaging place on surface treatments are described in general. Finally, we briefly outline some of the important scientific and technological issues in adhesion and friction phenomena in micromechanical structures that remain to be clarified.
Field emission from gated Si emitter tips with precise gate–tip spacing, gate diameter, tip sharpness, and tip protrusion
Authors: Rakhshandehroo M. R. , Pang S. W.
Published: July 2002

A self-aligned process was developed to control the gate–tip spacing, gate diameter, tip sharpness, and tip protrusion of Si field emission devices (FEDs). Such control is needed for the fabrication of FEDs with low turn-on voltage and high emission current. Using the mask erosion technique, 2-μm-tall Si emitter tips were initially etched in a Cl2 plasma generated by an electron cyclotron resonance source. Plasma oxides with different thicknesses were grown on the Si emitters as a sacrificial layer which creates close spacing between gate and tips, as well as sharpens the tip when removed in wet etchant. Sharp emitters with 8 nm tip radius and 80 nm gate–tip spacing were formed using plasma oxidation. Polyimide was used as the insulator and Mo was sputtered to form the self-aligned gate. By changing the polyimide thickness, gate diameter ranging from 220 to 880 nm and tip apex position ranging from 320 nm below the gate (nonprotruding) to 930 nm above the gate (protruding) were demonstrated. Emission current from an array of 100 tips increased from 261 to 598 μA when the tips radii were decreased from 67 to 8 nm by sharpening. By decreasing the gate–tip spacing from 500 to 193 nm, the gate turn-on voltage was reduced from 91 to 38 V. In addition, highest emission current was found to occur when the tip apex was positioned 70 nm above the gate level.
Resonant-cavity-enhanced avalanche photodiodes grown by molecular beam epitaxy on InP for detection near 1.55 μm
Authors: Anselm K. A. , Nie H. , Lenox C. , Hansing C. , Campbell J. C. , Streetman B. G.
Published: July 2002

We report on the epitaxial growth, fabrication, and characterization of a resonant-cavity-enhanced separate-absorption and multiplication avalanche photodiode capable of detecting light at 1.55 μm. The device is grown by molecular beam epitaxy with In0.53GaxAl0.47−xAs layers lattice matched to InP. This detector has exhibited a peak external quantum efficiency greater than 70%, a gain of 8, and a dark current of only 50 nA at 90% of breakdown for a 100-μm-diam diode.
Scintillating global-fiducial grid for electron-beam lithography
Authors: Goodberlet James , Carter James , Smith Henry I.
Published: July 2002

An organic scintillator has been developed for use in electron-beam lithography. The scintillator can be deposited in a thin film (<200 nm) on the substrate, and can be patterned by an ultraviolet-interferometric exposure to produce a uniformly thick, scintillating, fiducial grid. When scanned with the electron beam, the scintillating pattern produces a high-contrast (>2) optical signal. It is expected that the signal from this type of grid will improve the pattern-placement precision to within 1 nm when used in conjunction with spatial-phase-locked electron-beam lithography.
Improving pattern placement using through-the-membrane signal monitoring
Authors: Perkins F. K. , Marrian C. R. K. , Peckerar M. C.
Published: July 2002

We describe here a means of improving pattern placement accuracy in the electron-beam lithographic manufacture of membrane masks. Our method is based on collection of the beam transmitted through the membrane with a detector fixed to the mask assembly. A fiducial grid overlaid onto the detector is used to provide a global reference for measurement of the beam position during lithographic patterning. We give results from recent experiments with components of such a system, and estimate 1σ accuracy in our method to be on the order of 1.5 nm. We discuss the effect of beam scattering on our technique, and possible improvements in our implementation.
Autoionization in Liquid Water
Authors: Geissler Phillip L. , Dellago Christoph , Chandler David , Hutter Jürg , Parrinello Michele
Published: July 2002

The dissociation of a water molecule in liquid water is the fundamental event in acid-base chemistry, determining the pH of water. Because of the short time scales and microscopic length scales involved, the dynamics of this autoionization have not been directly probed by experiment. Here, the autoionization mechanism is revealed by sampling and analyzing ab initio molecular dynamics trajectories. We identify the rare fluctuations in solvation energies that destabilize an oxygen-hydrogen bond. Through the transfer of protons along a hydrogen bond “wire,” the nascent ions separate by three or more neighbors. If the hydrogen bond wire connecting the two ions is subsequently broken, a metastable charge-separated state is visited. The ions may then diffuse to large separations. If, however, the hydrogen bond wire remains unbroken, the ions recombine rapidly. Because of their concomitant large electric fields, the transient ionic species produced in this case may provide an experimentally detectable signal of the dynamics we report.
Selective Bond Dissociation and Rearrangement with Optimally Tailored, Strong-Field Laser Pulses
Authors: Levis Robert J. , Menkir Getahun M. , Rabitz Herschel
Published: July 2002

We used strong-field laser pulses that were tailored with closed-loop optimal control to govern specified chemical dissociation and reactivity channels in a series of organic molecules. Selective cleavage and rearrangement of chemical bonds having dissociation energies up to approximately 100 kilocalories per mole (about 4 electron volts) are reported for polyatomic molecules, including (CH
3
)
2
CO (acetone), CH
3
COCF
3
(trifluoroacetone), and C
6
H
5
COCH
3
(acetophenone). Control over the formation of CH
3
CO from (CH
3
)
2
CO, CF
3
(or CH
3
) from CH
3
COCF
3
, and C
6
H
5
CH
3
(toluene) from C
6
H
5
COCH
3
was observed with high selectivity. Strong-field control appears to have generic applicability for manipulating molecular reactivity because the tailored intense laser fields (about 10
13
watts per square centimeter) can dynamically Stark shift many excited states into resonance, and consequently, the method is not confined by resonant spectral restrictions found in the perturbative (weak-field) regime.
Endothelial Apoptosis as the Primary Lesion Initiating Intestinal Radiation Damage in Mice
Authors: Paris François , Fuks Zvi , Kang Anthony , Capodieci Paola , Juan Gloria , Ehleiter Desiree , Haimovitz-Friedman Adriana , Cordon-Cardo Carlos , Kolesnick Richard
Published: July 2002

Gastrointestinal (GI) tract damage by chemotherapy or radiation limits their efficacy in cancer treatment. Radiation has been postulated to target epithelial stem cells within the crypts of Lieberkühn to initiate the lethal GI syndrome. Here, we show in mouse models that microvascular endothelial apoptosis is the primary lesion leading to stem cell dysfunction. Radiation-induced crypt damage, organ failure, and death from the GI syndrome were prevented when endothelial apoptosis was inhibited pharmacologically by intravenous basic fibroblast growth factor (bFGF) or genetically by deletion of the acid sphingomyelinase gene. Endothelial, but not crypt, cells express FGF receptor transcripts, suggesting that the endothelial lesion occurs before crypt stem cell damage in the evolution of the GI syndrome. This study provides a basis for new approaches to prevent radiation damage to the bowel.
Regional Mu Opioid Receptor Regulation of Sensory and Affective Dimensions of Pain
Authors: Zubieta Jon-Kar , Smith Yolanda R. , Bueller Joshua A. , Xu Yanjun , Kilbourn Michael R. , Jewett Douglas M. , Meyer Charles R. , Koeppe Robert A. , Stohler Christian S.
Published: July 2002

The endogenous opioid system is involved in stress responses, in the regulation of the experience of pain, and in the action of analgesic opiate drugs. We examined the function of the opioid system and μ-opioid receptors in the brains of healthy human subjects undergoing sustained pain. Sustained pain induced the regional release of endogenous opioids interacting with μ-opioid receptors in a number of cortical and subcortical brain regions. The activation of the μ-opioid receptor system was associated with reductions in the sensory and affective ratings of the pain experience, with distinct neuroanatomical involvements. These data demonstrate the central role of the μ-opioid receptors and their endogenous ligands in the regulation of sensory and affective components of the pain experience.
Activation by IKKα of a Second, Evolutionary Conserved, NF-κB Signaling Pathway
Authors: Senftleben Uwe , Cao Yixue , Xiao Gutian , Greten Florian R. , Krähn Gertraud , Bonizzi Giuseppina , Chen Yi , Hu Yinling , Fong Abraham , Sun Shao-Cong , Karin Michael
Published: July 2002

In mammals, the canonical nuclear factor κB (NF-κB) signaling pathway activated in response to infections is based on degradation of IκB inhibitors. This pathway depends on the IκB kinase (IKK), which contains two catalytic subunits, IKKα and IKKβ. IKKβ is essential for inducible IκB phosphorylation and degradation, whereas IKKα is not. Here we show that IKKα is required for B cell maturation, formation of secondary lymphoid organs, increased expression of certain NF-κB target genes, and processing of the NF-κB2 (p100) precursor. IKKα preferentially phosphorylates NF-κB2, and this activity requires its phosphorylation by upstream kinases, one of which may be NF-κB–inducing kinase (NIK). IKKα is therefore a pivotal component of a second NF-κB activation pathway based on regulated NF-κB2 processing rather than IκB degradation.
The REM Sleep-Memory Consolidation Hypothesis
Authors: Siegel Jerome M.
Published: July 2002

It has been hypothesized that REM (rapid eye movement) sleep has an important role in memory consolidation. The evidence for this hypothesis is reviewed and found to be weak and contradictory. Animal studies correlating changes in REM sleep parameters with learning have produced inconsistent results and are confounded by stress effects. Humans with pharmacological and brain lesion–induced suppression of REM sleep do not show memory deficits, and other human sleep-learning studies have not produced consistent results. The time spent in REM sleep is not correlated with learning ability across humans, nor is there a positive relation between REM sleep time or intensity and encephalization across species. Although sleep is clearly important for optimum acquisition and performance of learned tasks, a major role in memory consolidation is unproven.
Plants Compared to Animals: The Broadest Comparative Study of Development
Authors: Meyerowitz Elliot M.
Published: July 2002

If the last common ancestor of plants and animals was unicellular, comparison of the developmental mechanisms of plants and animals would show that development was independently invented in each lineage. And if this is the case, comparison of plant and animal developmental processes would give us a truly comparative study of development, which comparisons merely among animals, or merely among plants, do not—because in each of these lineages, the fundamental mechanisms are similar by descent. Evidence from studies of developmental mechanisms in both kingdoms, and data from genome-sequencing projects, indicate that development evolved independently in the lineages leading to plants and to animals.
Molecular Basis of Proton Motive Force Generation: Structure of Formate Dehydrogenase-N
Authors: Jormakka Mika , Törnroth Susanna , Byrne Bernadette , Iwata So
Published: July 2002

The structure of the membrane protein formate dehydrogenase-N (Fdn-N), a major component of
Escherichia coli
nitrate respiration, has been determined at 1.6 angstroms. The structure demonstrates 11 redox centers, including molybdopterin-guanine dinucleotides, five [4Fe-4S] clusters, two heme
b
groups, and a menaquinone analog. These redox centers are aligned in a single chain, which extends almost 90 angstroms through the enzyme. The menaquinone reduction site associated with a possible proton pathway was also characterized. This structure provides critical insights into the proton motive force generation by redox loop, a common mechanism among a wide range of respiratory enzymes.
Rapid Total Destruction of Chlorophenols by Activated Hydrogen Peroxide
Authors: Gupta Sayam Sen , Stadler Matthew , Noser Christopher A. , Ghosh Anindya , Steinhoff Bradley , Lenoir Dieter , Horwitz Colin P. , Schramm Karl-Werner , Collins Terrence J.
Published: July 2002

A practical, inexpensive, green chemical process for degrading environmental pollutants is greatly needed, especially for persistent chlorinated pollutants. Here we describe the activation of hydrogen peroxide by tetraamidomacrocylic ligand (TAML) iron catalysts, to destroy the priority pollutants pentachlorophenol (PCP) and 2,4,6-trichlorophenol (TCP). In water, in minutes, under ambient conditions of temperature and pressure, PCP and TCP are completely destroyed at catalyst:substrate ratios of 1:715 and 1:2000, respectively. The fate of about 90% of the carbon and about 99% of the chlorine has been determined in each case. Neither dioxins nor any other toxic compounds are detectable products, and the catalysts themselves show low toxicity.
Correlated Bursts of Activity in the Neonatal Hippocampus in Vivo
Authors: Leinekugel Xavier , Khazipov Rustem , Cannon Robert , Hirase Hajime , Ben-Ari Yehezkel , Buzsáki György
Published: July 2002

The behavior of immature cortical networks in vivo remains largely unknown. Using multisite extracellular and patch-clamp recordings, we observed recurrent bursts of synchronized neuronal activity lasting 0.5 to 3 seconds that occurred spontaneously in the hippocampus of freely moving and anesthetized rat pups. The influence of slow rhythms (0.33 and 0.1 hertz) and the contribution of both γ-aminobutyric acid A–mediated and glutamate receptor–mediated synaptic signals in the generation of hippocampal bursts was reminiscent of giant depolarizing potentials observed in vitro. This earliest pattern, which diversifies during the second postnatal week, could provide correlated activity for immature neurons and may underlie activity-dependent maturation of the hippocampal network.
Thermally Switchable Periodicities and Diffraction from Mesoscopically Ordered Materials
Authors: Weissman Jesse M. , Sunkara Hari B. , Tse Albert S. , Asher Sanford A.
Published: July 2002

Two switchable, mesoscopically periodic materials were created by combining crystalline colloidal array (CCA) self-assembly with the temperature-induced volume phase transition of poly(
N
-isopropylacrylamide) (PNIPAM). Body-centered-cubic CCAs of hydrated, swollen PNIPAM particles Bragg-diffract infrared, visible, and ultraviolet light weakly, whereas arrays of compact shrunken particles diffract efficiently. A tunable diffracting array was also created by embedding a CCA of polystyrene spheres within a PNIPAM hydrogel that swells and contracts with temperature; thus the array lattice constant varies with temperature, and the diffracted wavelength was thermally tunable across the entire visible spectrum. These materials may find applications in many areas of optics and materials science.
Forcing of Atlantic Equatorial and Subpolar Millennial Cycles by Precession
Authors: McIntyre Andrew , Molfino Barbara
Published: July 2002

Abundance cycles of the marine alga
Florisphaera profunda
centered on a period of 7600 carbon-14 years (8400 calendar years) are present in high-resolution records from the equatorial Atlantic spanning 0 to 45,000 years ago. These cycles correlate with Heinrich events 1 through 5, which document rapid changes in continental ice melting around the subpolar North Atlantic. These variations in
F. profunda
are a direct response to modulation in zonal wind-driven divergence produced by a precessional component of orbital variation during a time of reduced eccentricity modulation.
The Pentagon Steps Up the Battle to Save Biodiversity
Authors: Vogel Gretchen
Published: July 2002

Late last month, Secretary of the Air Force Sheila Widnall announced the completion of a new guidebook to help military base managers develop comprehensive land-management plans to protect plant and animal species on military installations. The manual is the latest signal from DOD that it wants to be viewed as a good steward of its thousands of square kilometers of real estate. But some veterans of biodiversity battles remain skeptical.
Panel Urges Cloning Ethics Boards
Authors: Marshall Eliot
Published: July 2002

A report completed last month recommends that a high-level policy board be created in the office of the Secretary of Health and Human Services to help develop policies on such sensitive issues as genetic privacy, anti-discrimination legislation, public education on genetic risks, and the regulation of genetic testing.
Drug Industry Misses Target for Funding Work on Campus
Authors: Kondro Wayne
Published: July 2002

Ottawa—Canadian drug companies won over academic researchers in their successful campaign 3 years ago to extend patent protection for brand-name drugs by promising to spend $200 million on university research. The industry hasn't kept its promise, however, and there's plenty of finger-pointing as the government prepares to look at what has happened.
A Possible Intracluster Origin for the Excess Soft X-ray Component in Some Clusters
Authors: Fabian A. C.
Published: July 2002

The soft x-ray spectra of the Virgo and Coma clusters cannot be modeled by emission from the well-known hot intracluster medium attenuated by photoelectric absorption along the line of sight in our galaxy. If the excess soft emission is due to thermal emission in the clusters from gas at about 1 million kelvin, then the gas should be rapidly cooling. The high rate of cooling poses problems for the origin of the gas and its sink. A model in which the component is due to turbulent mixing layers around clouds scattered throughout the intracluster medium may explain the excess emission. The gas in the mixing layer is reheated after cooling, so that the total mass remains relatively small.
Recognition of Unique Carboxyl-Terminal Motifs by Distinct PDZ Domains
Authors: Songyang Z. , Fanning A. S. , Fu C. , Xu J. , Marfatia S. M. , Chishti A. H. , Crompton A. , Chan A. C. , Anderson J. M. , Cantley L. C.
Published: July 2002

The oriented peptide library technique was used to investigate the peptide-binding specificities of nine PDZ domains. Each PDZ domain selected peptides with hydrophobic residues at the carboxyl terminus. Individual PDZ domains selected unique optimal motifs defined primarily by the carboxyl terminal three to seven residues of the peptides. One family of PDZ domains, including those of the Discs Large protein, selected peptides with the consensus motif Glu-(Ser/Thr)-Xxx-(Val/Ile) (where Xxx represents any amino acid) at the carboxyl terminus. In contrast, another family of PDZ domains, including those of LIN-2, p55, and Tiam-1, selected peptides with hydrophobic or aromatic side chains at the carboxyl terminal three residues. On the basis of crystal structures of the PSD-95-3 PDZ domain, the specificities observed with the peptide library can be rationalized.
The Perils of Partnership
Authors: Stone Richard
Published: July 2002

KIEV, UKRAINE
—There is a new positive outlook among the top echelon of researchers in the former Soviet Union. Gone are the days when Western agencies simply threw a lifeline to colleagues in the East—in the form of one-off grants—to stop them from going under. Now, the name of the game is collaborative research. But these new joint ventures risk having the carpet pulled out from under them as the region's research infrastructure crumbles.
Embryologists Dismayed by Sanctions Against Geneticist
Authors: Marshall Eliot
Published: July 2002

News that the National Institutes of Health (NIH) has cut off funding for Mark Hughes, a geneticist who pioneered a technique for screening for mutations in the DNA of a single cell, has dismayed Hughes's colleagues. NIH says Hughes used federal funds to conduct tests on eight-cell human embryos, in contravention of a
congressional ban on such activities. Hughes's colleagues say the incident will drive more embryology research into private clinics, where it is unregulated.
NRC Panel Enters the Fight Over Tagging Explosives
Authors: Service Robert F.
Published: July 2002

In the wake of the Oklahoma City and Atlanta bombings, Congress asked the National Research Council to study whether to implement a nationwide plan for adding chemical “tags” to explosives. But a recent workshop in Washington, D.C., showed just how difficult it will be to settle on a workable plan.
Magnetic Collapse in Transition Metal Oxides at High Pressure: Implications for the Earth
Authors: Cohen Ronald E. , Mazin I. I. , Isaak Donald G.
Published: July 2002

Magnetic collapse in transition metal ions is predicted from first-principles computations at pressures reached in the Earth's lower mantle and core. Magnetic collapse would lead to marked changes in geophysically important properties, such as elasticity and conductivity, and also to different geochemical behavior, such as element partitioning, than estimated by extrapolating low-pressure data, and thus change the understanding of Earth's structure and evolution. Magnetic collapse results from band widening rather than from changes in crystal field splitting under pressure. Seismic anomalies in the outer core and the lowermost mantle may be due to magnetic collapse of ferrous iron, dissolved in iron liquid in the outer core, and in solution in magnesiowüstite in the lowermost mantle.
Monkey Virus DNA Found in Rare Human Cancers
Authors: Pennisi Elizabeth
Published: July 2002

In the early 1960s, the discovery that some batches of polio vaccine administered in the 1950s were contaminated with a virus that causes tumors in experimental animals stirred worries that it might do so in humans. That concern was laid to rest by studies showing no increased cancer incidence in people likely to have received the vaccine. Now, several groups have discovered DNA from the virus, known as simian virus 40 (SV40), in certain relatively rare tumors. New epidemiological studies again show no elevated risk of cancer in people who may have received contaminated vaccine, but questions remain because evidence suggests that SV40 does infect humans and may have existed in the human population even before the polio vaccine.
Should Governments Support Science?
Authors: Lawler Andrew
Published: July 2002

The case for increased federal spending on research is making headway in Congress and was the focus of a new package of reports issued last week by the presidents of the National Academies of Sciences and Engineering, and the Institute of Medicine.* But it's hogwash to British biochemist Terence Kealey, whose new book argues that “governments should not fund science.”

* For more information, see the academy's
Web site.
Leptin's Other Hormonal Links
Authors: Gura Trisha
Published: July 2002

During the 2 years since its discovery, the protein hormone leptin has paraded through headlines because of its possible role in keeping fat levels in check. But that may not be its main function. New works suggests that leptin, working through glands around the body, including the adrenals, the thyroid, and even the ovaries and testes, may have more to do with helping the body deal with the stresses of starvation.
DNA Ordering on a Lipid Membrane
Authors: Spector Mark S. , Schnur Joel M.
Published: July 2002

Certain kinds of gene therapy may require targeted delivery of genetic material into cells. As Spector and Schnur discuss in their Perspective, new results reported in the same issue by Rädler
et al
. (
p. 810
) may shed light on ways to incorporate DNA into membranes.
Selective Use of TBP and TFIIB Revealed by a TATA-TBP-TFIIB Array with Altered Specificity
Authors: Tansey William P. , Herr Winship
Published: July 2002

Interaction between the TATA box-binding protein TBP and TFIIB is critical for transcription in vitro. An altered-specificity TBP-TFIIB interaction was rationally designed and linked in sequence to an altered-specificity TATA box-TBP interaction to study how TBP and TFIIB function together to support transcription in human cells. The activity of this altered-specificity TATA-TBP-TFIIB array demonstrated that many activators use the known TBP-TFIIB interaction to stimulate transcription. One activator, however, derived from a glutamine-rich activation domain of Sp1, activated transcription independently of this interaction. These results reveal that selectivity in activator function in vivo can be achieved through differential use of TBP and TFIIB.
Smoother Road for R&D Spending?
Authors: Lawler Andrew
Published: July 2002

After 2 years of uncertainty, the White House and Congress seem to be moving toward stable funding for science and technology. While researchers are pleased that R&D is getting more attention, they are delaying any celebration until Congress shows them the money.
NIF Ignites Changes at Livermore
Authors: Lawler Andrew
Published: July 2002

LIVERMORE, CALIFORNIA
—Managers at the Lawrence Livermore National Laboratory hope that a $1.1 billion laser-fusion facility will change the culture of the nuclear weapons lab, strengthen collaborations with civilian scientists, and cement its future as an important national resource.
Laser Fusion With a Fast Twist
Authors: Normile Dennis
Published: July 2002

TOKYO
—A new technique to ensure a rapid thermonuclear “burn” in a fuel pellet—which has important implications for the U.S. National Ignition Facility—will get a thorough test this year at new facilities in Osaka, Japan, and Livermore, California.
Monte Verde: Blessed But Not Confirmed
Authors: Gibbons Ann
Published: July 2002

When a team of archaeologists publicly accepted a disputed Chilean site as being 12,500 years old—and therefore proof of an early human presence in the Americas—the press compared it to the breaking of the sound barrier. But researchers say that the news on the site of Monte Verde amounted to the conversion of just two archaeologists—and that the debate isn't over yet.
Is First Extrasolar Planet a Lost World?
Authors: Glanz James
Published: July 2002

In a paper in yesterday's issue of
Nature,
a respected Canadian astronomer labels the first apparent discovery of a planet orbiting a sunlike star outside our solar system a case of mistaken identity. He argues that a subtle, periodic signal in the spectrum of the star 51 Pegasi, originally attributed to the gravitational tug of a roughly Jupiter-sized planet, was actually generated by a complex sloshing on the star's surface. The researchers who made the original claim are not conceding, however.
New Studies Explore Public Attitudes About Science
Authors: Olson Steve
Published: July 2002

SEATTLE
—Where do people get their attitudes about science? The question has bedeviled any number of scientists, who have encountered incomprehension—even hostility—in their conversations with nonscientists. But new research presented at the annual meeting of the American Association for the Advancement of Science here is uncovering some answers—and some surprising differences among people from different nations.

See last week's issue (
Science
, 21 February, p.1060) for coverage of early sessions on
global R&D funding
and
submarine vents
.
Deep Within the Proton, a Flicker of New Physics?
Authors: Glanz James
Published: July 2002

Physicists at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg announced last week that 3 years of smashing positrons and protons together at high energy have produced a handful of collisions too violent to be easily explained in the current picture of particles and forces. The most dramatic explanation for the excess is the brief appearance in each collision of a long-sought particle called a leptoquark, which would bridge the two known families of particles. But the researchers caution that the excess could still be a statistical fluke.
Did a Blast of Sea-Floor Gas Usher in a New Age?
Authors: Kerr Richard A.
Published: July 2002

The end of the Paleocene epoch 55 million years ago was a puzzling time, in which tiny marine animals died, modern mammals suddenly appeared in North America, and isotopic signals indicate a shift in the global carbon cycle. Now a new mathematical model shows that a release of methane gas from the ocean floor could be at the heart of all these changes.
Framework: ‘Unfocused, Underachieving’
Authors: Williams Nigel
Published: July 2002

BRUSSELS
—An independent review panel charged last week that the European Union's (EU's) flagship research program “lacks focus and is underachieving.” The broadside came just as EU officials are preparing to seek approval for the next 4-year block of funds for the program, known as Framework 5.
Farsighted Gravity Lens Sees Stars
Authors: Glanz James
Published: July 2002

Most stars are so distant that, even through the largest telescopes, they look like simple points of light. Now, by using the gravity of one star as a magnifying glass, a multinational team of astronomers has been able to pick out features on the face of a second star 30,000 light-years from Earth.
How Reptiles Took Wing
Authors: Wuethrich Bernice
Published: July 2002

On
page 1450
of this issue, a German-Canadian team of scientists reports on the unusual wings of the oldest flying vertebrate, the 250-million-year-old Coelurosauravus jaekeli. All other known flying animals have wings adapted from ribs or forelimbs, but this reptile's wings are supported by new bones that formed directly in the skin.
Panel Approves Gene Trial for ‘Normals’
Authors: Marshall Eliot
Published: July 2002

The panel that for more than a decade has vetted safety and ethical issues in U.S. human gene-therapy research—the Recombinant DNA Advisory Committee (RAC) of the National Institutes of Health (NIH)—ended its role as gatekeeper with a bang last week, grilling a researcher who had proposed a clinical trial that would inject engineered genes for the first time into normal, healthy volunteers. RAC's final act as enforcer also gave a preview of how it might handle the new role that NIH director Harold Varmus has envisioned for the committee—as a forum for debates on ethical issues.
Domain Names Windfall Causes Flap
Authors: Mervis Jeffrey
Published: July 2002

A $50-a-year fee to register Internet domain names has netted a pot of money that could grow to $60 million a year—and has triggered a free-for-all over who should manage the Internet. It has also sparked an internal debate within NSF over whether the agency should continue to oversee a medium that it helped create.
Quantum Squeeze Wrings Uncertainty From Atom Waves
Authors: Clery Daniel
Published: July 2002

Quantum “noise” gets in the way of ultraprecise measurements of any physical quantity, such as a particle's location or a wave's frequency. In this issue, however, a team of physicists reports finding a way around this quantum limit for the wavelike vibrations of atoms in solids called phonons. By delivering ultrafast pulses of light to a sample of potassium tantalate, they squeezed quantum noise out of the phonons at certain times while making them noisier at others.
Paths to Activation of Transcription
Authors: Geiduschek E. Peter
Published: July 2002

In bacteria, transcription—the synthesis of RNA from DNA—is carried out by the enzyme RNA polymerase, which binds to the start site of a gene, the promoter. Now two reports in this week's issue, Wyman (p.
1658
) and Miller (p.
1655
), show two ways that this complex can be triggered to start transcription, both by proteins that act to change the configuration of the RNA polymerase enzyme itself. In his Perspective, Geiduschek discusses these and other examples of transcriptional regulation, suggesting that each may act on the step in the transcription process in which the RNA polymerase-promoter complex is reconfigured in preparation for RNA synthesis.
A Member of the Frizzled Protein Family Mediating Axis Induction by Wnt-5A
Authors: He Xi , Saint-Jeannet Jean-Pierre , Wang Yanshu , Nathans Jeremy , Dawid Igor , Varmus Harold
Published: July 2002

In
Xenopus laevis
embryos, the Wingless/Wnt-1 subclass of Wnt molecules induces axis duplication, whereas the Wnt-5A subclass does not. This difference could be explained by distinct signal transduction pathways or by a lack of one or more Wnt-5A receptors during axis formation. Wnt-5A induced axis duplication and an ectopic Spemann organizer in the presence of hFz5, a member of the Frizzled family of seven-transmembrane receptors. Wnt-5A/hFz5 signaling was antagonized by glycogen synthase kinase-3 and by the amino-terminal ectodomain of hFz5. These results identify hFz5 as a receptor for Wnt-5A.
Microbiologists Explore Life's Rich, Hidden Kingdoms
Authors: Service Robert F.
Published: July 2002

For most people, biodiversity brings to mind plants, animals, or maybe insects. But a new breed of scientist, using gene-typing tools borrowed from biology's molecular revolution, is finding evidence of untold millions of new species hidden in the microbial world. Researchers are turning up dozens of groups of bacteria, archaea, and single-celled eukarya in soil, sediments, and water that are at least as genetically distinct from each other as azaleas are from aardvarks. With the new molecular techniques, scientists also are getting glimpses of how human impacts, ranging from oil spills to the buildup of greenhouse gases, are perturbing these busy microscopic communities which provide the nutrients that sustain all other forms of life.
Medical School Funding
Authors: Korn David , Shine Kenneth I.
Published: July 2002

Letters from:

Although medical schools might appear to be robust enterprises, with aggregate annual expenditures in 1995 of more than $30 billion, the fact is that on average only about 10 to 20% of their annual revenues comes from such secure sources as tuition and fees, endowment earnings and gifts, or (mainly for the public schools) state support. About 20% of their annual revenues comes from the NIH (National Institutes of Health), nearly 35% from fees generated by the faculty physicians' practice of medicine, and another roughly 15% in direct payments from teaching hospital partners. In other words, about 50% of the schools' aggregate revenues is derived from the provision of medical care; these revenues have provided surpluses that have been used by the medical schools as flexible funds for academic investments. In fiscal year 1994, the Association of American Medical Colleges survey indicated that revenues from the faculty physicians' practice alone contributed $2.4 billion to medical schools for support of education and research. Although the majority of the funds were expended for clinical education and research, not all of them were, and the fact that the funds were discretionary is their critically important feature. It is these clinical surpluses that are being wrung out of the health care system by a managed care enterprise that has demonstrated little willingness to contribute to the costs of education and research. And just as the teaching hospitals are threatened by this new environment and require additional stabilization funds, so, too, are the medical schools.

The purpose of a new Medical School Fund (K. I. Shine, Editorial,
3 Jan., p. 9
) is to replace these clinical revenues and provide the schools with flexible funds for the support of their academic objectives. Some of the new funds would go toward the support of curricular innovation, others to the support of the research infrastructure (or capacity) that enables the medical schools to partner with NIH in sharing the costs of sustaining the world's leading biomedical research enterprise. A good fraction of the funds would undoubtedly go to the support of clinical research, but that should be by choice and not by mandate. The schools must certainly be held accountable for the expenditure of any monies that might be received from a new public fund, but the overriding need of the medical schools at this time of convulsive change is for new monies that are flexible, not earmarked by prescription to overly specific applications.

There is an old adage in medical school lore which says that any policy that would gratuitously restrict a previously unrestricted source of funds is bad policy. From this perspective, and with deeper understanding of the schools' historic dependence on flexible clinical revenues to support a broad array of educational and research objectives, one should oppose the suggestion by Shine that funds to be raised from a new all-payer assessment be restricted by policy to support clinical investigation.
The Receptor for the Cytotoxic Ligand TRAIL
Authors: Pan Guohua , O'Rourke Karen , Chinnaiyan Arul M. , Gentz Reiner , Ebner Reinhard , Ni Jian , Dixit Vishva M.
Published: July 2002

TRAIL (also known as Apo-2L) is a member of the tumor necrosis factor (TNF) ligand family that rapidly induces apoptosis in a variety of transformed cell lines. The human receptor for TRAIL was found to be an undescribed member of the TNF-receptor family (designated death receptor-4, DR4) that contains a cytoplasmic “death domain” capable of engaging the cell suicide apparatus but not the nuclear factor kappa B pathway in the system studied. Unlike Fas, TNFR-1, and DR3, DR4 could not use FADD to transmit the death signal, suggesting the use of distinct proximal signaling machinery. Thus, the DR4-TRAIL axis defines another receptor-ligand pair involved in regulating cell suicide and tissue homeostasis.
Evergreen Adopts Tenurelike System
Authors: Holden Constance
Published: July 2002

To hear some critics tell it, tenure has gone the way of the one-room schoolhouse. But a closer look at Evergreen State College in Olympia, Washington, which often is cited as having spurned tenure, suggests that reports of the system's demise are premature.
Mars Images: One Fine Day on Mars
Authors: Kerr Richard A.
Published: July 2002

The Hubble Space Telescope took its sharpest image ever of the planet Mars last month, in part to scout out what the Pathfinder spacecraft will find when it lands on Mars on 4 July. A martian dust storm could play havoc with the Pathfinder lander and the small rover it will place on the surface, both of which depend on full sunlight falling on their solar power panels. The image, however, shows nary a dust storm in sight.
Astronomy: Ancient Galaxy Walls Go Up; Will Theories Tumble Down?
Authors: Appenzeller Tim
Published: July 2002

IRVINE, CALIFORNIA
--New observations described at a National Academy of Sciences colloquium here suggest that giant walls of galaxies, hundreds of millions of light-years long, may have crisscrossed the universe when it was just 15% of its present age. Such structures are similar to what we see today, which raises a problem for theorists: If gravity hasn't radically resculpted the universe over time, that implies that it may have far less mass than theorists prefer. That is in line with evidence of a scarcity of mass in the nearby universe but at odds with one measurement of how fast the cosmic expansion rate is changing, which hints at a much higher density of matter (
see p. 37
).
Seeing a Mountain in a Grain of Garnet
Authors: Liou J. G. , Maruyama S. , Ernst W. G.
Published: July 2002

The collision of continents, which results in mountain formation, takes place through subduction, in which one slab of crust is pushed below another. The rock that is subducted is put under high pressure and new mineral phases can form. As discussed in the Perspective by Liou
et al.
, a report by Darling
et al.
in the same issue (
p. 91
) describes a low-pressure mineral--cristobalite--that was found in high-pressure rocks. Understanding how this low-pressure form of silicate was created and preserved may lead to better understanding of the process of subduction and how deep material is brought to the surface.
Rescue of a
Drosophila NF1
Mutant Phenotype by Protein Kinase A
Authors: The Inge , Hannigan Gregory E. , Cowley Glenn S. , Reginald Shoba , Zhong Yi , Gusella James F. , Hariharan Iswar K. , Bernards André
Published: July 2002

The neurofibromatosis type 1 (NF1) tumor suppressor protein is thought to restrict cell proliferation by functioning as a Ras-specific guanosine triphosphatase–activating protein. However,
Drosophila
homozygous for null mutations of an
NF1
homolog showed no obvious signs of perturbed Ras1-mediated signaling. Loss of
NF1
resulted in a reduction in size of larvae, pupae, and adults. This size defect was not modified by manipulating Ras1 signaling but was restored by expression of activated adenosine 3′,5′-monophosphate–dependent protein kinase (PKA). Thus, NF1 and PKA appear to interact in a pathway that controls the overall growth of
Drosophila.
Ichthyology Transformed
Authors: Rosenblatt Richard H.
Published: July 2002

Interrelationships of Fishes.
MELANIE L. J. STIASSNY, LYNNE R. PARENTI, and G. DAVID JOHNSON, Eds. Academic Press, San Diego, 1996. xiv, 496 pp., illus. $84.95 or £65. ISBN 0-12-670950-5.
Differential Effects of Cytolytic T Cell Subsets on Intracellular Infection
Authors: Stenger Steffen , Mazzaccaro Richard J. , Uyemura Koichi , Cho Sungae , Barnes Peter F. , Rosat Jean-Pierre , Sette Alessandro , Brenner Michael B. , Porcelli Steven A. , Bloom Barry R. , Modlin Robert L.
Published: July 2002

In analyzing mechanisms of protection against intracellular infections, a series of human CD1-restricted T cell lines of two distinct phenotypes were derived. Both CD4
−
CD8
−
(double-negative) T cells and CD8
+
T cells efficiently lysed macrophages infected with
Mycobacterium tuberculosis
. The cytotoxicity of CD4
−
CD8
−
T cells was mediated by Fas-FasL interaction and had no effect on the viability of the mycobacteria. The CD8
+
T cells lysed infected macrophages by a Fas-independent, granule-dependent mechanism that resulted in killing of bacteria. These data indicate that two phenotypically distinct subsets of human cytolytic T lymphocytes use different mechanisms to kill infected cells and contribute in different ways to host defense against intracellular infection.
Engines of Biodiversity
Authors: Field Christopher
Published: July 2002

Plants in Changing Environments.
Linking Physiological, Population, and Community Ecology. F. A. BAZZAZ. Cambridge University Press, New York, 1996. x, 320 pp., illus. $75 or £55, ISBN 0-521-39190-3; paper, $29.95 or £19.95, ISBN 0-521-39843-6.
An Animal Model for Acute and Persistent Epstein-Barr Virus Infection
Authors: Moghaddam Amir , Rosenzweig Michael , Lee-Parritz David , Annis Bethany , Johnson R. Paul , Wang Fred
Published: July 2002

Epstein-Barr virus (EBV) is a human lymphocryptovirus that causes infectious mononucleosis, persists asymptomatically for life in nearly all adults, and is associated with the development of B cell lymphomas and nasopharyngeal carcinomas. A highly similar rhesus lymphocryptovirus naturally endemic in rhesus monkeys was used to orally infect naı̈ve animals from a pathogen-free colony. This animal model reproduced key aspects of human EBV infection, including oral transmission, atypical lymphocytosis, lymphadenopathy, activation of CD23
+
peripheral blood B cells, sustained serologic responses to lytic and latent EBV antigens, latent infection in the peripheral blood, and virus persistence in oropharyngeal secretions. This system may be useful for studying the pathogenesis, prevention, and treatment of EBV infection and associated oncogenesis.
Avenues for Plants
Authors: Soltis Douglas E.
Published: July 2002

The Evolutionary Biology of Plants.
KARL J. NIKLAS. University of Chicago Press, Chicago, 1997. xx, 449 pp., illus. $65 or £51.95, ISBN 0-226-58082-2; paper, $19.95 or £15.95, ISBN 0-226-58083-0.