bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of CoSi2 formation by x-ray photoelectron spectroscopy
Authors: Zhao Jin , Jones Clive M. , Poirier Derrick M.
Published: July 2002

Formation of CoSi2 in the conversion sequence of pure Co, CoSi, and CoSi2 was characterized using x-ray photoelectron spectroscopy (XPS). With pure Co deposited on single crystalline Si wafers and capped by Ti thin film, the wafers were rapid thermal annealed (RTA) at 470 °C for 60 s so as to convert Co to CoSi. These wafers were then stripped with APM (NH4OH/H2O2/H2O) and SPM (H2SO4/H2O2), followed by RTA at 700 °C for 60 s to obtain final CoSi2. XPS was used to determine the chemical composition of these thin films and the Co Auger parameter was continuously monitored along with ion sputtering to provide chemical state depth profile. After the RTA at 470 °C, the XPS depth profile shows that a mixed Ti/Co/Si region exists between the CoSi film and Ti cap. After the strip, the Ti cap and Ti/Co/Si region were removed. The uniformed CoSi2 film was present after the RTA at 700 °C. The Co Auger parameters of pure Co, CoSi, and CoSi2 are 1552.1, 1551.6, and 1551.4 eV, respectively. Monitoring the Co Auger parameter along with the ion sputtering depth profile indicates that CoSi2 has the most stable cobalt chemical state after RTA at 700 °C. The interface region with film composition of Co/Si ratio less than 1:2 is a mixture of CoSi2 and pure Si. For the interface regions with film composition of Co/Si ratio less than 1:2 of the as-deposited Co wafer and the wafer after RTA at 470 °C, the Co Auger parameters are 1551.2 eV, which suggests that a possible distinctive cobalt chemical state exists.
Simulation based plasma reactor design for improved ion bombardment uniformity
Authors: Kim Heon Chang , Manousiouthakis Vasilios I.
Published: July 2002

The geometric effects of plasma processing tools on the ion bombardment uniformity are studied through a plasma model that employs the first two and three moments of the Boltzmann equation for ions and electrons, respectively. The reactor considered is a parallel plate rf diode enclosed with insulators. The governing equations coupled with Poisson’s equation are self-consistently solved using a simplified 4th order accurate ENO scheme which determines the choice of stencils depending only on the characteristic direction. Reactor geometries are varied so as to improve the ion bombardment uniformity on the wafer while operating conditions are fixed. Two dimensional simulation results indicate that uniformity of ion bombardment impinging on the wafer can be improved by using a thicker insulating sidewall due to its higher impedance to rf currents. A longer electrode and a larger reactor diameter also improve the uniformity because sudden changes of electrical properties at the interface between electrode and insulator or between the bulk and sheath regions, can be located away from the wafer edge. These results demonstrate that plasma reactors can be more carefully designed to obtain a better reactor performance through multidimensional simulations.
Strain compensation in In0.75Ga0.25As/InP pseudomorphic high electron mobility transistors using strained InAlAs buffers
Authors: Goorsky M. S. , Sandhu R. , Hsing R. , Naidenkova M. , Wojtowicz M. , Chin T. P. , Block T. R. , Streit D. C.
Published: July 2002

We compare the structural and electronic properties of compressively strained high In-concentration InGaAs-based pseudomorphic high electron mobility transistors (pHEMTs) grown with either lattice-matched or tensile strained InAlAs buffers on InP. We demonstrate that strain-compensating InxAl1−xAs/In0.75Ga0.25As/InP pHEMTs can eliminate the formation of misfit dislocations and improve transport properties. We compared structures with lattice-matched (XIn=0.52) and tensile strained (XIn=0.48) InxAl1−xAs buffers and barriers grown by molecular beam epitaxy. The channel thickness ranged from 15 to 40 nm. Both 60° mixed dislocations and 90° edge dislocations form at the interface between the strained In0.75Ga0.25As channel and the lattice-matched InAlAs buffer layer grown on InP by molecular beam epitaxy with higher dislocation densities for thicker channel layers. For structures with the channel layer thickness of 15–25 nm grown on a tensile strained InAlAs layer, misfit dislocations cannot be seen in atomic force microscopy or Nomarski images. Transport properties also show that the channel mobility is higher for the tensile strained structures. Excess stress in the channel layer drives relaxation, and calculations based on the excess force acting on dislocations confirm that the growth of tensile strained layers before and after the compressive strained channel reduces the driving force for misfit dislocation nucleation in the channel.
Fascinations of the Third Domain
Authors: Doolittle W. Ford
Published: July 2002

The Surprising Archaea
Discovering Another Domain of Life. John L. Howland. Oxford University Press, New York, 2000. 214 pp. $29.95, £ 19.95. ISBN 0-19-511183-4

Howland's "biography" of the Archaea, written for a general audience, discusses the discovery of the group, the ecological and evolutionary importance of the organisms, and the directions of future research in the field.
Receptor-Mediated Activation of Heterotrimeric G-Proteins in Living Cells
Authors: Janetopoulos Chris , Jin Tian , Devreotes Peter
Published: July 2002

Receptor-mediated activation of heterotrimeric GTP–binding proteins (G-proteins) was visualized in living
Dictyostelium discoideum
cells by monitoring fluorescence resonance energy transfer (FRET) between α- and β- subunits fused to cyan and yellow fluorescent proteins. The G-protein heterotrimer rapidly dissociated and reassociated upon addition and removal of chemoattractant. During continuous stimulation, G-protein activation reached a dose-dependent steady-state level. Even though physiological responses subsided, the activation did not decline. Thus, adaptation occurs at another point in the signaling pathway, and occupied receptors, whether or not they are phosphorylated, catalyze the G-protein cycle. Construction of similar energy-transfer pairs of mammalian G-proteins should enable direct in situ mechanistic studies and applications such as drug screening and identifying ligands of newly found G-protein–coupled receptors.
Recolonizing Carnivores and Naïve Prey: Conservation Lessons from Pleistocene Extinctions
Authors: Berger Joel , Swenson Jon E. , Persson Inga-Lill
Published: July 2002

The current extinction of many of Earth's large terrestrial carnivores has left some extant prey species lacking knowledge about contemporary predators, a situation roughly parallel to that 10,000 to 50,000 years ago, when naı̈ve animals first encountered colonizing human hunters. Along present-day carnivore recolonization fronts, brown (also called grizzly) bears killed predator-naı̈ve adult moose at disproportionately high rates in Scandinavia, and moose mothers who lost juveniles to recolonizing wolves in North America's Yellowstone region developed hypersensitivity to wolf howls. Although prey that had been unfamiliar with dangerous predators for as few as 50 to 130 years were highly vulnerable to initial encounters, behavioral adjustments to reduce predation transpired within a single generation. The fact that at least one prey species quickly learns to be wary of restored carnivores should negate fears about localized prey extinction.
Hydrogel Control of Xylem Hydraulic Resistance in Plants
Authors: Zwieniecki Maciej A. , Melcher Peter J. , Michele Holbrook N.
Published: July 2002

Increasing concentrations of ions flowing through the xylem of plants produce rapid, substantial, and reversible decreases in hydraulic resistance. Changes in hydraulic resistance in response to solution ion concentration, pH, and nonpolar solvents are consistent with this process being mediated by hydrogels. The effect is localized to intervessel bordered pits, suggesting that microchannels in the pit membranes are altered by the swelling and deswelling of pectins, which are known hydrogels. The existence of an ion-mediated response breaks the long-held paradigm of the xylem as a system of inert pipes and suggests a mechanism by which plants may regulate their internal flow regime.
An h
Per2
Phosphorylation Site Mutation in Familial Advanced Sleep Phase Syndrome
Authors: Toh Kong L. , Jones Christopher R. , He Yan , Eide Erik J. , Hinz William A. , Virshup David M. , Ptáček Louis J. , Fu Ying-Hui
Published: July 2002

Familial advanced sleep phase syndrome (FASPS) is an autosomal dominant circadian rhythm variant; affected individuals are “morning larks” with a 4-hour advance of the sleep, temperature, and melatonin rhythms. Here we report localization of the FASPS gene near the telomere of chromosome 2q. A strong candidate gene (h
Per2
), a human homolog of the
period
gene in
Drosophila
, maps to the same locus. Affected individuals have a serine to glycine mutation within the casein kinase I
ɛ
(CKI
ɛ
) binding region of hPER2, which causes hypophosphorylation by CKI
ɛ
in vitro. Thus, a variant in human sleep behavior can be attributed to a missense mutation in a clock component, hPER2, which alters the circadian period.
A Goddess of Earth or the Imagination of a Man?
Authors: Schneider Stephen H.
Published: July 2002

Homage to Gaia
The Life of an Independent Scientist. James Lovelock. Oxford University Press, Oxford, 2000. 416 pp. £19.99. ISBN 0-19-286213-8.

In this autobiography, Lovelock discusses his experiences as an inventor and scientist, the Gaia hypothesis, and his holistic perspective of organisms and the world they inhabit.
Westward Impulse Embodied
Authors: Pyne Stephen J.
Published: July 2002

A River Running West
The Life of John Wesley Powell. Donald Worster. Oxford University Press, New York, 2000. 687 pp. $35. ISBN 0-19-509991-5.

Worster's biography of the explorer and scientist who became a patriarch of science-based government bureaus and the conservation of the American West places Powell and his fervor for reform in the context of the United States of his times.
Painting the Skies
Authors: Trimble Virginia
Published: July 2002

Star Struck
1000 Years of the Art and Science of Astronomy. Ronald Brashear and Daniel Lewis, Curators. Huntington Library, San Marino, CA. To 13 May 2001.

Star Struck
One Thousand Years of the Art and Science of Astronomy. Ronald Brashear and Daniel Lewis. Huntington Library, San Marino, CA, and the University of Washington Press, Seattle, 2001. 167 pp. $39.95. ISBN 0-295-98096-6. Paper, $24.95, ISBN 0-295-98097-4.

The Huntington Library's current exhibit of rare books, images, and instruments is part of a collaboration among eight Pasadena institutions that explores artistic and scientific responses to the cosmos.
Controlled Rotation of Optically Trapped Microscopic Particles
Authors: Paterson L. , MacDonald M. P. , Arlt J. , Sibbett W. , Bryant P. E. , Dholakia K.
Published: July 2002

We demonstrate controlled rotation of optically trapped objects in a spiral interference pattern. This pattern is generated by interfering an annular shaped laser beam with a reference beam. Objects are trapped in the spiral arms of the pattern. Changing the optical path length causes this pattern, and thus the trapped objects, to rotate. Structures of silica microspheres, microscopic glass rods, and chromosomes are set into rotation at rates in excess of 5 hertz. This technique does not depend on intrinsic properties of the trapped particle and thus offers important applications in optical and biological micromachines.
Killing Other Peoples
Authors: Kakar Sudhir
Published: July 2002

The Deadly Ethnic Riot
. Donald L. Horowitz. University of California Press, Berkeley, 2001. 606 pp. $35, £22. ISBN 0-520-22447-7.

On the basis of a broad sample of ethnic rioting, Horowitz offers both insightful theoretical analysis and practical suggestions for reducing the occurrence of such deadly violence.
Requirement of
CHROMOMETHYLASE3
for Maintenance of CpXpG Methylation
Authors: Lindroth Anders M. , Cao Xiaofeng , Jackson James P. , Zilberman Daniel , McCallum Claire M. , Henikoff Steven , Jacobsen Steven E.
Published: July 2002

Epigenetic silenced alleles of the
Arabidopsis SUPERMAN
locus (the
clark kent
alleles) are associated with dense hypermethylation at noncanonical cytosines (CpXpG and asymmetric sites, where X = A, T, C, or G). A genetic screen for suppressors of a hypermethylated
clark kent
mutant identified nine loss-of-function alleles of
CHROMOMETHYLASE3
(
CMT3
), a novel cytosine methyltransferase homolog. These
cmt3
mutants display a wild-type morphology but exhibit decreased CpXpG methylation of the
SUP
gene and of other sequences throughout the genome. They also show reactivated expression of endogenous retrotransposon sequences. These results show that a non-CpG DNA methyltransferase is responsible for maintaining epigenetic gene silencing.
Hydrated Salt Minerals on Ganymede's Surface: Evidence of an Ocean Below
Authors: McCord Thomas B. , Hansen Gary B. , Hibbitts Charles A.
Published: July 2002

Reflectance spectra from Galileo's near-infrared mapping spectrometer (NIMS) suggests that the surface of Ganymede, the largest satellite of Jupiter, contains hydrated materials. These materials are interpreted to be similar to those found on Europa, that is, mostly frozen magnesium sulfate brines that are derived from a subsurface briny layer of fluid.
Adapt or Perish? Zoos Must Choose
Authors: Robinson Michael H.
Published: July 2002

A Different Nature
The Paradoxical World of Zoos and Their Uncertain Future. David Hancocks. University of California Press, Berkeley, 2001. 302 pp. $35, £19.95. ISBN 0-520-21879-5.

Through his discussion of the origins and evolution of zoos, Hancocks considers their successes and failures at meeting diverse goals of recreation, education, research, and conservation. He calls for a reinvention of zoos to better deal with the current biodiversity crisis.
Vital Involvement of a Natural Killer Cell Activation Receptor in Resistance to Viral Infection
Authors: Brown Michael G. , Dokun Ayotunde O. , Heusel Jonathan W. , Smith Hamish R. C. , Beckman Diana L. , Blattenberger Erika A. , Dubbelde Chad E. , Stone Laurie R. , Scalzo Anthony A. , Yokoyama Wayne M.
Published: July 2002

Natural killer (NK) cells are lymphocytes that can be distinguished from T and B cells through their involvement in innate immunity and their lack of rearranged antigen receptors. Although NK cells and their receptors were initially characterized in terms of tumor killing in vitro, we have determined that the NK cell activation receptor, Ly-49H, is critically involved in resistance to murine cytomegalovirus in vivo. Ly-49H requires an immunoreceptor tyrosine-based activation motif (ITAM)–containing transmembrane molecule for expression and signal transduction. Thus, NK cells use receptors functionally resembling ITAM-coupled T and B cell antigen receptors to provide vital innate host defense.
Impulsive Choice Induced in Rats by Lesions of the Nucleus Accumbens Core
Authors: Cardinal Rudolf N. , Pennicott David R. , Lakmali C. , Sugathapala  , Robbins Trevor W. , Everitt Barry J.
Published: July 2002

Impulsive choice is exemplified by choosing a small or poor reward that is available immediately, in preference to a larger but delayed reward. Impulsive choice contributes to drug addiction, attention-deficit/hyperactivity disorder, mania, and personality disorders, but its neuroanatomical basis is unclear. Here, we show that selective lesions of the nucleus accumbens core induce persistent impulsive choice in rats. In contrast, damage to two of its afferents, the anterior cingulate cortex and medial prefrontal cortex, had no effect on this capacity. Thus, dysfunction of the nucleus accumbens core may be a key element in the neuropathology of impulsivity.
Beautiful Reef Builders
Authors: Cairns Stephen D.
Published: July 2002

Corals of the World
. J. E. N. Veron. Australian Institute of Marine Science, Townsville, Queensland. 2000. 3 vols. 1410 pp. $175, $A265. ISBN 0-642-32236-8.

This three-volume set covers all (nearly 800) extant species of reef corals. The brief descriptions and exquisite color photographs are intended to facilitate the field identification of living corals.
Piecing Together a Puzzling World
Authors: Sternberg Esther M.
Published: July 2002

Memento
. Christopher Nolan, Director. Newmarket Film Group, 2001. See:
www.otnemem.com

This film noir, with a protagonist whose injury prevents him from processing short-term memories, offers an intriguing perspective on the neurobiology of memory.
Evolution and Our Reproductive Physiology
Authors: Kaplan Hillard S.
Published: July 2002

On Fertile Ground
A Natural History of Human Reproduction. Peter Ellison. Harvard University Press, Cambridge, MA, 2001. 368 pp. $27.95. ISBN 0-674-00463-9.

Ellison explores human reproduction from the perspectives of anthropology, ecology, and evolutionary biology. His discussion ranges from the experiences of subsistence farmers in African rain forests to developments in modern fertility clinics.
Principles for Measurement of Chemical Exposure Based on Recognition-Driven Anchoring Transitions in Liquid Crystals
Authors: Shah Rahul R. , Abbott Nicholas L.
Published: July 2002

The competitive binding of a molecule forming a liquid crystal and a targeted analyte to a common molecular receptor presented at a solid surface possessing nanometer-scale topography is used to trigger an easily visualized surface-driven change in the orientation of a micrometer-thick film of liquid crystal. Diffusion of the targeted analyte from atmosphere to surface-immobilized receptor across the micrometer-thick film of liquid crystal is fast (on the order of seconds), and the competitive interaction of the targeted analyte and liquid crystal with the receptor provides a high level of tolerance to nontargeted species (water, ethanol, acetone, and hexanes). Systems that provide parts-per-billion (by volume) sensitivity to either organoamine or organophosphorus compounds are demonstrated, and their use for imaging of spatial gradients in concentration is reported. This approach does not require complex instrumentation and could provide the basis of wearable personalized sensors for measurement of real-time and cumulative exposure to environmental agents.
Design of Bioelectronic Interfaces by Exploiting Hinge-Bending Motions in Proteins
Authors: Benson David E. , Conrad David W. , de Robert M. , Lorimier  , Trammell Scott A. , Hellinga Homme W.
Published: July 2002

We report a flexible strategy for transducing ligand-binding events into electrochemical responses for a wide variety of proteins. The method exploits ligand-mediated hinge-bending motions, intrinsic to the bacterial periplasmic binding protein superfamily, to establish allosterically controlled interactions between electrode surfaces and redox-active, Ru(II)-labeled proteins. This approach allows the development of protein-based bioelectronic interfaces that respond to a diverse set of analytes. Families of these interfaces can be generated either by exploiting natural binding diversity within the superfamily or by reengineering the specificity of individual proteins. These proteins may have numerous medical, environmental, and defense applications.
Beautiful Transfer of Information
Authors: Kennedy Mary B.
Published: July 2002

Synapses
. W. Maxwell Cowan, Thomas C. Südhof, and Charles F. Stevens, Eds. Johns Hopkins University Press, Baltimore, 2000. 783 pp. $69.95, £48. ISBN 0-8018-6498-4.

This comprehensive overview of the current state of knowledge of the organization and function of synapses will interest both seasoned neurobiologists and newcomers to the field.
Nota Bene: Sounds of Silence
Authors: Uppenbrink Julia
Published: July 2002

Antarctic Symphony
. Peter Maxwell Davies. Information on performances is availabe at
www.maxopus.com

The sounds of sea ice and the silence after an avalanche are among the elements Davies has incorporated into his symphony, which was commissioned by the British Antarctic Survey.
Extraordinary Talents of Autistic Minds
Authors: Sigman Marian
Published: July 2002

Bright Splinters of the Mind
A Personal Story of Research with Autistic Savants. Beate Hermelin. Jessica Kingsley, Philadelphia, 2001. 192 pp. $49.95, £29.95. ISBN 1-85302-931-9. Paper, $19.95, £13.95. ISBN 1-85302-932-7.

Drawing on two decades of research by herself and her collaborators, Hermelin presents an informative account of artistic, musical, linguistic, and mathematical talents found is some individuals with autism.
The Influence of the Proinflammatory Cytokine, Osteopontin, on Autoimmune Demyelinating Disease
Authors: Chabas Dorothée , Baranzini Sergio E. , Mitchell Dennis , Bernard Claude C. A. , Rittling Susan R. , Denhardt David T. , Sobel Raymond A. , Lock Christopher , Karpuj Marcela , Pedotti Rosetta , Heller Renu , Oksenberg Jorge R. , Steinman Lawrence
Published: July 2002

Multiple sclerosis is a demyelinating disease, characterized by inflammation in the brain and spinal cord, possibly due to autoimmunity. Large-scale sequencing of cDNA libraries, derived from plaques dissected from brains of patients with multiple sclerosis (MS), indicated an abundance of transcripts for osteopontin (OPN). Microarray analysis of spinal cords from rats paralyzed by experimental autoimmune encephalomyelitis (EAE), a model of MS, also revealed increased OPN transcripts. Osteopontin-deficient mice were resistant to progressive EAE and had frequent remissions, and myelin-reactive T cells in OPN
–/–
mice produced more interleukin 10 and less interferon-γ than in OPN
+/+
mice. Osteopontin thus appears to regulate T helper cell–1 (T
H
1)–mediated demyelinating disease, and it may offer a potential target in blocking development of progressive MS.
Endocannabinoid Signaling in the Brain
Authors: Wilson Rachel I. , Nicoll Roger A.
Published: July 2002

The primary psychoactive ingredient in cannabis, Δ
9
-tetrahydrocannabinol (Δ
9
-THC), affects the brain mainly by activating a specific receptor (CB1). CB1 is expressed at high levels in many brain regions, and several endogenous brain lipids have been identified as CB1 ligands. In contrast to classical neurotransmitters, endogenous cannabinoids can function as retrograde synaptic messengers: They are released from postsynaptic neurons and travel backward across synapses, activating CB1 on presynaptic axons and suppressing neurotransmitter release. Cannabinoids may affect memory, cognition, and pain perception by means of this cellular mechanism.
Glacial Surface Temperatures of the Southeast Atlantic Ocean
Authors: Sachs Julian P. , Anderson Robert F. , Lehman Scott J.
Published: July 2002

A detailed record of sea surface temperature from sediments of the Cape Basin in the subtropical South Atlantic indicates a previously undocumented progression of marine climate change between 41 and 18 thousand years before the present (ky B.P.), during the last glacial period. Whereas marine records typically indicate a long-term cooling into the Last Glacial Maximum (around 21 ky B.P.) consistent with gradually increasing global ice volume, the Cape Basin record documents an interval of substantial temperate ocean warming from 41 to 25 ky B.P. The pattern is similar to that expected in response to changes in insolation owing to variations in Earth's tilt.
Direct Interaction of
Arabidopsis
Cryptochromes with COP1 in Light Control Development
Authors: Wang Haiyang , Ma Li-Geng , Li Jin-Ming , Zhao Hong-Yu , Deng Xing Wang
Published: July 2002

Arabidopsis
seedling photomorphogenesis involves two antagonistically acting components, COP1 and HY5. COP1 specifically targets HY5 for degradation via the 26
S
proteasome in the dark through their direct physical interaction. Little is known regarding how light signals perceived by photoreceptors are transduced to regulate COP1.
Arabidopsis
has two related cryptochromes (cry1 and cry2) mediating various blue/ultraviolet-A light responses. Here we show that both photoactivated cryptochromes repress COP1 activity through a direct protein-protein contact and that this direct regulation is primarily responsible for the cryptochrome-mediated blue light regulation of seedling photomorphogenic development and genome expression profile.
Liver Organogenesis Promoted by Endothelial Cells Prior to Vascular Function
Authors: Matsumoto Kunio , Yoshitomi Hideyuki , Rossant Janet , Zaret Kenneth S.
Published: July 2002

The embryonic role of endothelial cells and nascent vessels in promoting organogenesis, prior to vascular function, is unclear. We find that early endothelial cells in mouse embryos surround newly specified hepatic endoderm and delimit the mesenchymal domain into which the liver bud grows. In
flk-1
mutant embryos, which lack endothelial cells, hepatic specification occurs, but liver morphogenesis fails prior to mesenchyme invasion. We developed an embryo tissue explant system that permits liver bud vasculogenesis and show that in the absence of endothelial cells, or when the latter are inhibited, there is a selective defect in hepatic outgrowth. We conclude that vasculogenic endothelial cells and nascent vessels are critical for the earliest stages of organogenesis, prior to blood vessel function.
The Initiation of Subduction: Criticality by Addition of Water?
Authors: Regenauer-Lieb Klaus , Yuen Dave A. , Branlund Joy
Published: July 2002

Subduction is a major process of plate tectonics; however, its initiation is not understood. We used high-resolution (less than 1 kilometer) finite-element models based on rheological data of the lithosphere to investigate the role played by water on initiating subduction. A solid-fluid thermomechanical instability is needed to drive a cold, stiff, and negatively buoyant lithosphere into the mantle. This instability can be triggered slowly by sedimentary loading over a time span of 100 million years. Our results indicate that subduction can proceed by a double feedback mechanism (thermoelastic and thermal-rheological) promoted by lubrication due to water.
Identification of Novel Genes Coding for Small Expressed RNAs
Authors: Lagos-Quintana Mariana , Rauhut Reinhard , Lendeckel Winfried , Tuschl Thomas
Published: July 2002

In
Caenorhabditis elegans
,
lin-4
and
let-7
encode 22- and 21-nucleotide (nt) RNAs, respectively, which function as key regulators of developmental timing. Because the appearance of these short RNAs is regulated during development, they are also referred to as small temporal RNAs (stRNAs). We show that many 21- and 22-nt expressed RNAs, termed microRNAs, exist in invertebrates and vertebrates and that some of these novel RNAs, similar to
let-7
stRNA, are highly conserved. This suggests that sequence-specific, posttranscriptional regulatory mechanisms mediated by small RNAs are more general than previously appreciated.
Fermi Surface Sheet-Dependent Superconductivity in 2
H
-NbSe
2
Authors: Yokoya T. , Kiss T. , Chainani A. , Shin S. , Nohara M. , Takagi H.
Published: July 2002

High-resolution angle-resolved photoemission spectroscopy was used to study the superconducting energy gap and changes in the spectral function across the superconducting transition in the quasi–two-dimensional superconductor 2
H
-NbSe
2
. The momentum dependence of the superconducting gap was determined on different Fermi surface sheets. The results indicate Fermi surface sheet–dependent superconductivity in this low–transition temperature multiband system and provide a description consistent with thermodynamic measurements and the anomalous de Haas–van Alphen oscillations observed in the superconducting phase. The present data suggest the importance of Fermi surface sheet–dependent superconductivity in explaining exotic superconductivity in other multiband systems with complex Fermi surface topology, such as the borides and f-electron superconductors.
Visionary Architect of the Net
Authors: Naughton John
Published: July 2002

The Dream Machine
J.C.R. Licklider and the Revolution That Made Computing Personal. M. Mitchell Waldrop. Viking, New York, 2001. $29.95, C$43.99. 512 pp. ISBN 0-670-89976-3.

Waldrop tells the story of the MIT psychologist who inspired and laid the groundwork for the discipline of computer science and the networking and computer technology we now take for granted.
Lysophospholipids--Receptor Revelations
Authors: Hla Timothy , Lee Menq-Jer , Ancellin Nicolas , Paik Ji H. , Kluk Michael J.
Published: July 2002

Upon cell activation, membrane phospholipids are metabolized into potent lysophospholipid (LP) mediators, such as sphingosine 1-phosphate and lysophosphatidic acid. LPs fulfill signaling roles in organisms as diverse as yeast and humans. The recent discovery of G protein–coupled receptors for LPs in higher eukaryotes, and their involvement in regulating diverse processes such as angiogenesis, cardiac development, neuronal survival, and immunity, has stimulated growing interest in these lipid mediators. LP receptor biology has generated insights into fundamental cellular mechanisms and may provide therapeutic targets for drug development.
Distinct Effects of T-bet in T
H
1 Lineage Commitment and IFN-γ Production in CD4 and CD8 T Cells
Authors: Szabo Susanne J. , Sullivan Brandon M. , Stemmann Claudia , Satoskar Abhay R. , Sleckman Barry P. , Glimcher Laurie H.
Published: July 2002

T-bet is a member of the T-box family of transcription factors that appears to regulate lineage commitment in CD4 T helper (T
H
) lymphocytes in part by activating the hallmark T
H
1 cytokine, interferon-γ (IFN-γ). IFN-γ is also produced by natural killer (NK) cells and most prominently by CD8 cytotoxic T cells, and is vital for the control of microbial pathogens. Although T-bet is expressed in all these cell types, it is required for control of IFN-γ production in CD4 and NK cells, but not in CD8 cells. This difference is also apparent in the function of these cell subsets. Thus, the regulation of a single cytokine, IFN-γ, is controlled by distinct transcriptional mechanisms within the T cell lineage.
Regulation of Life-Span by Germ-Line Stem Cells in
Caenorhabditis elegans
Authors: Arantes-Oliveira Nuno , Apfeld Javier , Dillin Andrew , Kenyon Cynthia
Published: July 2002

The germ line of the nematode
Caenorhabditis elegans
influences life-span; when the germ-line precursor cells are removed, life-span is increased dramatically. We find that neither sperm, nor oocytes, nor meiotic precursor cells are responsible for this effect. Rather life-span is influenced by the proliferating germ-line stem cells. These cells, as well as a downstream transcriptional regulator, act in the adult to influence aging, indicating that the aging process remains plastic during adulthood. We propose that the germ-line stem cells affect life-span by influencing the production of, or the response to, a steroid hormone that promotes longevity.
A Grand Old Synthesizer's Overview
Authors: Schilthuizen Menno
Published: July 2002

What Evolution Is
. Ernst Mayr. Basic Books, New York, 2001. 336 pp. $26, C$39.50. ISBN 0-465-04425-5.

Written for a broad, popular audience, Mayr's overview of topics that have interested him during his long, productive, and very influential career provides a primer on evolution and a spirited defense of Darwinian explanations in biology.
Requirement of a Macromolecular Signaling Complex for β Adrenergic Receptor Modulation of the KCNQ1-KCNE1 Potassium Channel
Authors: Marx Steven O. , Kurokawa Junko , Reiken Steven , Motoike Howard , D'Armiento Jeanine , Marks Andrew R. , Kass Robert S.
Published: July 2002

Sympathetic nervous system (SNS) regulation of cardiac action potential duration (APD) is mediated by β adrenergic receptor (βAR) activation, which increases the slow outward potassium ion current (
I
KS
). Mutations in two human
I
KS
channel subunits, hKCNQ1 and hKCNE1, prolong APD and cause inherited cardiac arrhythmias known as LQTS (long QT syndrome). We show that βAR modulation of
I
KS
requires targeting of adenosine 3′,5′-monophosphate (cAMP)–dependent protein kinase (PKA) and protein phosphatase 1 (PP1) to hKCNQ1 through the targeting protein yotiao. Yotiao binds to hKCNQ1 by a leucine zipper motif, which is disrupted by an LQTS mutation (hKCNQ1-G589D). Identification of the hKCNQ1 macromolecular complex provides a mechanism for SNS modulation of cardiac APD through
I
KS
.
Positive Mass Balance of the Ross Ice Streams, West Antarctica
Authors: Joughin Ian , Tulaczyk Slawek
Published: July 2002

We have used ice-flow velocity measurements from synthetic aperture radar to reassess the mass balance of the Ross Ice Streams, West Antarctica. We find strong evidence for ice-sheet growth (+26.8 gigatons per year), in contrast to earlier estimates indicating a mass deficit (−20.9 gigatons per year). Average thickening is equal to ∼25% of the accumulation rate, with most of this growth occurring on Ice Stream C. Whillans Ice Stream, which was thought to have a significantly negative mass balance, is close to balance, reflecting its continuing slowdown. The overall positive mass balance may signal an end to the Holocene retreat of these ice streams.
Synthesis and Structure of Formally Hexavalent Palladium Complexes
Authors: Chen Wanzhi , Shimada Shigeru , Tanaka Masato
Published: July 2002

Formally hexavalent palladium complexes have been isolated and structurally characterized for the first time. Thermal condensation reaction of three molecules of 1,2-C
6
H
4
(SiH
2
)
2
Pd
II
(R
2
PCH
2
CH
2
PR
2
) (where R is defined as a methyl or ethyl) provided trinuclear palladium complexes. Single-crystal x-ray analysis revealed that each of the central palladium atoms of the complexes is ligated by six silicon atoms and is hexavalent, whereas the other palladium atoms are divalent.
A Scientific Kokopelli
Authors: Edgar Bob
Published: July 2002

My Life in Science
. Sydney Brenner, Errol C. Friedberg, and Eleanor Lawrence, Eds. BioMed Central, London, 2001. 197 pp. Paper, $21, £14.99. ISBN 0-9540278-0-9.

This enjoyable, informative, and accessible account of the life and research of one of the most influential biologists of the 20th century was prepared from a video-taped autobiography that Brenner told to Lewis Wolpert.
Growing Trees from Molecular Data
Authors: Meyer Axel
Published: July 2002

Phylogenetic Trees Made Easy
A How-To Manual for Molecular Biologists. Barry G. Hall. Sinauer Associates, Sunderland, MA, 2001. 191 pp. Paper, $24.95, £18.99. ISBN 0-87893-311-5.

Hall offers researchers and students a practical introduction to the methods for aligning protein and nucleic sequences and for constructing phylogenetic trees from such data.
Production of α-1,3-Galactosyltransferase Knockout Pigs by Nuclear Transfer Cloning
Authors: Lai Liangxue , Kolber-Simonds Donna , Park Kwang-Wook , Cheong Hee-Tae , Greenstein Julia L. , Im Gi-Sun , Samuel Melissa , Bonk Aaron , Rieke August , Day Billy N. , Murphy Clifton N. , Carter David B. , Hawley Robert J. , Prather Randall S.
Published: July 2002

The presence of galactose α-1,3-galactose residues on the surface of pig cells is a major obstacle to successful xenotransplantation. Here, we report the production of four live pigs in which one allele of the α-1,3-galactosyltransferase locus has been knocked out. These pigs were produced by nuclear transfer technology; clonal fetal fibroblast cell lines were used as nuclear donors for embryos reconstructed with enucleated pig oocytes.
A Draft Sequence of the Rice Genome (
Oryza sativa
L. ssp.
japonica
)
Authors: Goff Stephen A. , Ricke Darrell , Lan Tien-Hung , Presting Gernot , Wang Ronglin , Dunn Molly , Glazebrook Jane , Sessions Allen , Oeller Paul , Varma Hemant , Hadley David , Hutchison Don , Martin Chris , Katagiri Fumiaki , Lange B. Markus , Moughamer Todd , Xia Yu , Budworth Paul , Zhong Jingping , Miguel Trini , Paszkowski Uta , Zhang Shiping , Colbert Michelle , Sun Wei-lin , Chen Lili , Cooper Bret , Park Sylvia , Wood Todd Charles , Mao Long , Quail Peter , Wing Rod , Dean Ralph , Yu Yeisoo , Zharkikh Andrey , Shen Richard , Sahasrabudhe Sudhir , Thomas Alun , Cannings Rob , Gutin Alexander , Pruss Dmitry , Reid Julia , Tavtigian Sean , Mitchell Jeff , Eldredge Glenn , Scholl Terri , Miller Rose Mary , Bhatnagar Satish , Adey Nils , Rubano Todd , Tusneem Nadeem , Robinson Rosann , Feldhaus Jane , Macalma Teresita , Oliphant Arnold , Briggs Steven
Published: July 2002

The genome of the japonica subspecies of rice, an important cereal and model monocot, was sequenced and assembled by whole-genome shotgun sequencing. The assembled sequence covers 93% of the 420-megabase genome. Gene predictions on the assembled sequence suggest that the genome contains 32,000 to 50,000 genes. Homologs of 98% of the known maize, wheat, and barley proteins are found in rice. Synteny and gene homology between rice and the other cereal genomes are extensive, whereas synteny with
Arabidopsis
is limited. Assignment of candidate rice orthologs to
Arabidopsis
genes is possible in many cases. The rice genome sequence provides a foundation for the improvement of cereals, our most important crops.
Transcription Control by E1A and MAP Kinase Pathway via Sur2 Mediator Subunit
Authors: Stevens Jennitte L. , Cantin Greg T. , Wang Gang , Shevchenko Andrej , Shevchenko Anna , Berk Arnold J.
Published: July 2002

Sur2 is a metazoan Mediator subunit that interacts with the adenovirus E1A protein and functions in a mitogen-activated protein kinase pathway required for vulva development in
Caenorhabditis elegans
. We generated
sur2
−/−
embryonic stem cells to analyze its function as a mammalian Mediator component. Our results show that Sur2 forms a subcomplex of the Mediator with two other subunits, TRAP/Med100 and 95. Knock-out of Sur2 prevents activation by E1A-CR3 and the mitogen-activated protein kinase–regulated ETS transcription factor Elk-1, but not by multiple other transcription factors. These results imply that specific activation domains stimulate transcription by binding to distinct Mediator subunits. Activation by E1A and Elk-1 requires recruitment of Mediator to a promoter by binding to its Sur2 subunit.
A New Source of Basaltic Meteorites Inferred from Northwest Africa 011
Authors: Yamaguchi Akira , Clayton Robert N. , Mayeda Toshiko K. , Ebihara Mitsuru , Oura Yasuji , Miura Yayoi N. , Haramura Hiroshi , Misawa Keiji , Kojima Hideyasu , Nagao Keisuke
Published: July 2002

Eucrites are a class of basaltic meteorites that share common mineralogical, isotopic, and chemical properties and are thought to have been derived from the same parent body, possibly asteroid 4 Vesta. The texture, mineralogy, and noble gas data of the recently recovered meteorite, Northwest Africa (NWA) 011, are similar to those of basaltic eucrites. However, the oxygen isotopic composition of NWA011 is different from that of other eucrites, indicating that NWA011 may be derived from a different parent body. The presence of basaltic meteorites with variable oxygen isotopic composition suggests the occurrence of multiple basaltic meteorite parent bodies, perhaps similar to 4 Vesta, in the early solar system.
Archaefructaceae, a New Basal Angiosperm Family
Authors: Sun Ge , Ji Qiang , Dilcher David L. , Zheng Shaolin , Nixon Kevin C. , Wang Xinfu
Published: July 2002

Archaefructaceae is proposed as a new basal angiosperm family of herbaceous aquatic plants. This family consists of the fossils
Archaefructus liaoningensis
and
A
.
sinensis
sp. nov. Complete plants from roots to fertile shoots are known. Their age is a minimum of 124.6 million years from the Yixian Formation, Liaoning, China. They are a sister clade to all angiosperms when their characters are included in a combined three-gene molecular and morphological analysis. Their reproductive axes lack petals and sepals and bear stamens in pairs below conduplicate carpels.
Induction of Cachexia in Mice by Systemically Administered Myostatin
Authors: Zimmers Teresa A. , Davies Monique V. , Koniaris Leonidas G. , Haynes Paul , Esquela Aurora F. , Tomkinson Kathy N. , McPherron Alexandra C. , Wolfman Neil M. , Lee Se-Jin
Published: July 2002

Mice and cattle with genetic deficiencies in myostatin exhibit dramatic increases in skeletal muscle mass, suggesting that myostatin normally suppresses muscle growth. Whether this increased muscling results from prenatal or postnatal lack of myostatin activity is unknown. Here we show that myostatin circulates in the blood of adult mice in a latent form that can be activated by acid treatment. Systemic overexpression of myostatin in adult mice was found to induce profound muscle and fat loss analogous to that seen in human cachexia syndromes. These data indicate that myostatin acts systemically in adult animals and may be a useful pharmacologic target in clinical settings such as cachexia, where muscle growth is desired.
Theoretical Study of the Validity of the Born-Oppenheimer Approximation in the Cl + H
2
→ HCl + H Reaction
Authors: Alexander Millard H. , Capecchi Gabriella , Werner Hans-Joachim
Published: July 2002

Reactivity of the excited spin-orbit state of Cl with H
2
to yield ground-state HCl products is forbidden by the Born-Oppenheimer (BO) approximation. We used new ab initio potential energy surfaces and exact quantum scattering calculations to explore the extent of electronic nonadiabaticity in this reaction. In direct contrast to recent experiments, we predict that the BO-allowed reaction of the ground spin-orbit state will be much more efficient than the BO-forbidden reaction of the excited spin-orbit state. Also, Coriolis coupling opens up an electronically nonadiabatic inelastic channel, which competes substantially with reaction.
Rapid Bottom Melting Widespread near Antarctic Ice Sheet Grounding Lines
Authors: Rignot Eric , Jacobs Stanley S.
Published: July 2002

As continental ice from Antarctica reaches the grounding line and begins to float, its underside melts into the ocean. Results obtained with satellite radar interferometry reveal that bottom melt rates experienced by large outlet glaciers near their grounding lines are far higher than generally assumed. The melting rate is positively correlated with thermal forcing, increasing by 1 meter per year for each 0.1°C rise in ocean temperature. Where deep water has direct access to grounding lines, glaciers and ice shelves are vulnerable to ongoing increases in ocean temperature.
Magneto-Opto-Electronic Bistability in a Phenalenyl-Based Neutral Radical
Authors: Itkis M. E. , Chi X. , Cordes A. W. , Haddon R. C.
Published: July 2002

A new organic molecular conductor, based on a spiro-biphenalenyl neutral radical, simultaneously exhibits bistability in three physical channels: electrical, optical, and magnetic. In the paramagnetic state, the unpaired electrons are located in the exterior phenalenyl units of the dimer, whereas in the diamagnetic state the electrons migrate to the interior phenalenyl units and spin pair as a π-dimer. Against all expectations, the conductivity increases by two orders of magnitude in the diamagnetic state, and the band gap decreases. This type of multifunctional material has the potential to be used as the basis for new types of electronic devices, where multiple physical channels are used for writing, reading, and transferring information.
C-Cadherin Ectodomain Structure and Implications for Cell Adhesion Mechanisms
Authors: Boggon Titus J. , Murray John , Chappuis-Flament Sophie , Wong Ellen , Gumbiner Barry M. , Shapiro Lawrence
Published: July 2002

Cadherins are transmembrane proteins that mediate adhesion between cells in the solid tissues of animals. Here we present the 3.1 angstrom resolution crystal structure of the whole, functional extracellular domain from C-cadherin, a representative “classical” cadherin. The structure suggests a molecular mechanism for adhesion between cells by classical cadherins, and it provides a new framework for understanding both cis (same cell) and trans (juxtaposed cell) cadherin interactions. The trans adhesive interface is a twofold symmetric interaction defined by a conserved tryptophan side chain at the membrane-distal end of a cadherin molecule from one cell, which inserts into a hydrophobic pocket at the membrane-distal end of a cadherin molecule from the opposing cell.
Signal Transduction by the TGF-β Superfamily
Authors: Attisano Liliana , Wrana Jeffrey L.
Published: July 2002

Transforming growth factor–β (TGF-β) superfamily members regulate a plethora of developmental processes, and disruption of their activity has been implicated in a variety of human diseases ranging from cancer to chondrodysplasias and pulmonary hypertension. Intense investigations have revealed that SMAD proteins constitute the basic components of the core intracellular signaling cascade and that SMADs function by carrying signals from the cell surface directly to the nucleus. Recent insights have revealed how SMAD proteins themselves are regulated and how appropriate subcellular localization of SMADs and TGF-β transmembrane receptors is controlled. Current research efforts investigating the contribution of SMAD-independent pathways promise to reveal advances to enhance our understanding of the signaling cascade.
Mechanochemistry
Authors: Gilman John J.
Published: July 2002

Some chemical reactions, such as the detonation of explosives, can be initiated by mechanical forces. In his Perspective, Gilman discusses the microscopic story behind such reactions. Unlike liquids or gases, solids can experience shear forces, and these in turn can cause bending of atomic bonds in molecules. The energy levels of these bent molecules can change in such a way as to lead to bond breaking and rearrangement.
Orogenic Evolution of the Ural Mountains: Results from an Integrated Seismic Experiment
Authors: Berzin R. , Oncken O. , Knapp J. H. , Pérez-Estaún A. , Hismatulin T. , Yunusov N. , Lipilin A.
Published: July 2002

Results of the URSEIS '95 integrated seismic experiment document the lithospheric structure of an intact Paleozoic collisional orogen in the Ural Mountains. Hybrid-source seismic reflection and refraction data provide images of a crustal-scale collisional fabric and a pronounced crustal root preserved since Paleozoic time. Mantle reflections are observed at depths of more than 150 kilometers, possibly representing the base of the lithosphere. The Urals do not conform to existing models of postorogenic evolution involving large-scale extension, which may be a consequence of an incomplete or arrested collisional process that has led to the preservation of the largest continental landmass.
Observations of Near-Zero Ozone Concentrations Over the Convective Pacific: Effects on Air Chemistry
Authors: Kley D. , Crutzen P. J. , Smit H. G. J. , Vömel H. , Oltmans S. J. , Grassl H. , Ramanathan V.
Published: July 2002

A series of measurements over the equatorial Pacific in March 1993 showed that the volume mixing ratios of ozone were frequently well below 10 nanomoles per mole both in the marine boundary layer (MBL) and between 10 kilometers and the tropopause. These latter unexpected results emphasize the enormous variability of tropical tropospheric ozone and hydroxyl concentrations, which determine the oxidizing efficiency of the troposphere. They also imply a convective short circuit of marine gaseous emissions, such as dimethyl sulfide, between the MBL and the uppermost troposphere, leading, for instance, to sulfate particle formation.
Impaired Defense of Intestinal Mucosa in Mice Lacking Intestinal Trefoil Factor
Authors: Mashimo Hiroshi , Wu Deng-Chyang , Podolsky Daniel K. , Fishman Mark C.
Published: July 2002

The mechanisms that maintain the epithelial integrity of the gastrointestinal tract remain largely undefined. The gene encoding intestinal trefoil factor (ITF), a protein secreted throughout the small intestine and colon, was rendered nonfunctional in mice by targeted disruption. Mice lacking ITF had impaired mucosal healing and died from extensive colitis after oral administration of dextran sulfate sodium, an agent that causes mild epithelial injury in wild-type mice. ITF-deficient mice manifested poor epithelial regeneration after injury. These findings reveal a central role for ITF in the maintenance and repair of the intestinal mucosa.