bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of YSZ–SDC Solid Solution in a Nanocrystalline Heterophase System and Its Effect on the Electrical Conductivity
Authors: Price Matthew , Dong Junhang , Gu Xuehong , Speakman Scott A. , Payzant E. Andrew , Nenoff Tina M.
Published: June 2005

The stability of an yttria‐stabilized zirconia and samaria‐doped ceria (YSZ–SDC) nanocrystalline heterophase system was studied with in situ high‐temperature X‐ray diffraction during a simulated sintering program. Formation of YSZ–SDC solid solution in the nanocrystalline system was found to start at a low temperature between 900° and 950°C. The analysis of lattice parameters as a function of temperature suggested that YSZ and SDC species diffused mutually during the formation of solid solution. The electrical conductivity of the YSZ–SDC solid solution was significantly lower than that of the YSZ and SDC.
On the Effect of Local Grain‐Boundary Chemistry on the Macroscopic Mechanical Properties of a High‐Purity Y2O3‐Al2O3‐Containing Silicon Nitride Ceramic: Role of Oxygen
Authors: Ziegler A. , McNaney J. M. , Hoffmann M. J. , Ritchie R. O.
Published: June 2005

The effects of grain‐boundary chemistry on the mechanical properties of high‐purity silicon nitride ceramics have been investigated, specifically involving the role of oxygen, present along the grain boundaries, in influencing the fracture behavior. To avoid complications from inadvertently introduced impurities, studies were performed on a high‐purity Si3N4 processed using two‐step gas‐pressure‐HIP sintering. Varying the grain‐boundary oxygen content, which was achieved by control of oxidizing heat treatments and sintering additives, was found to result in a transition in fracture mechanism, from transgranular to intergranular fracture, with an associated increase in fracture toughness. This phenomenon is correlated to an oxygen‐induced change in grain‐boundary chemistry and possibly to a concomitant structural transformation along the interface. The incorporation of oxygen appears to affect fracture by “weakening” the interface, thus facilitating debonding and crack advance along the boundaries, and hence to toughening by grain bridging. It is concluded that if the oxygen content in the thin grain‐boundary films exceeds a lower limit, which is ∼0.87 equiv% oxygen content, then the interfacial structure and bonding characteristics favor intergranular debonding during crack propagation; otherwise, transgranular fracture ensues.
Effects of Substrate Orientation and Metal Film Thickness on the Intrinsic Strength, Intrinsic Fracture Energy, and Total Fracture Energy of Tantalum–Sapphire Interfaces
Authors: Wang Xuemei , Gupta Vijay , Basu Soumendra N.
Published: June 2005

Parameters that characterize interface fracture are defined, and procedures to measure them are discussed. The interface strength σo is measured by using a novel laser spallation experiment, which uses a laser‐induced stress wave to separate the interface. The intrinsic (Go) and total (Gc) fracture energies are measured using a double cantilever beam experiment performed at ambient and cryogenic temperatures, respectively. These experiments are used to obtain relationships between Gc and Go, and between σo and Go, for interfaces between sputter‐deposited polycrystalline Ta coatings and sapphire substrates. The intrinsic toughness and strength were modified by changing the orientation of the sapphire surface (basal and prismatic), while Gc was varied by changing the test temperature (ambient and cryogenic) and the thickness (1–3 μm) of the ductile Ta layer. Besides providing values that have interest in their own right, the work presented here provides a general framework for designing interfaces in bonded structures and serves as a basis to develop atomistic and continuum interface fracture models.
In Situ Monitoring of C–S–H Gel Processing by Magnetic Susceptibility and Turbidity Measurements
Authors: Wang Zhihong , Sun Liming , Hou Yunfen , Tang Erzhuo
Published: June 2005

The magnetic susceptibility and turbidity of calcium silicate hydrate (C–S–H) gel hydrothermally synthesized under various conditions were studied. The experimental results indicate that C–S–H gel with diatomite and lime has an optimum time for hydrothermal synthesis, in terms of susceptibility (χm) and turbidity (τ). C–S–H gel hydrothermally synthesized for the optimum time has higher susceptibility and lower turbidity, i.e., the gel exhibits high dispersibility (fineness) and numerous structural defects, properties that provide a better strengthening effect for cements. Susceptibility and turbidity have obvious characteristics and can be used as indexes of quality control for the synthesis of C–S–H gel.
Stress Rate Dependence of Fracture Strength in Pre‐Cracked Silicon Nitride Ceramics Doped with Ytterbium Oxide
Authors: Pan Yi , Huang Jow‐Lay , Li Chun‐Te , Lo Wen‐Tse
Published: June 2005

High‐temperature dynamic fatigue behavior has been investigated in 6 wt% ytterbium oxide and 2 wt% alumina‐doped silicon nitride ceramics by nitrogen gas pressure sintering. The specimens were pre‐cracked by Vickers indentation to prevent creep damage and to ensure dynamic fatigue dominating. The tests were performed in four‐point flexure in air at temperatures of 1000°, 1200°, 1300°, and 1400°C and by varying the loading rate from 1, 0.5, 0.1–0.01 mm/min at each temperature. The analyses were conducted by plotting fatigue stress against loading rate at each testing temperature in double logarithm coordinates. The material was found to be the least susceptible (the highest slow crack exponent number N) to slow crack growth at 1200°C, as reflected by the comparison of the plot slopes for the four testing temperatures. The explanation and analyses take into consideration the grain‐boundary phase crystallization, crack healing, and oxidation during testing evidenced by X‐ray diffraction and transmission electron microscopy. The fracture surfaces were characterized by three well‐defined zones, namely zone I, II, and III, referring to the pre‐cracked area, slow crack growth area, and fast fracture area, respectively.
Recent Materials Characterizations of [2D] and [3D] Thin Film Ferroelectric Structures
Authors: Scott J. F. , Morrison F. D. , Miyake M. , Zubko P. , Lou Xiaojie , Kugler V. M. , Rios S. , Zhang Ming , Tatsuta T. , Tsuji O. , Leedham T. J.
Published: June 2005

A review is given of ceramic and single‐crystal thin film ferroelectric oxides, emphasizing perovskite phases, together with some new developments on hafnia films. It is shown that single‐crystal barium titanate films behave as bulk down to at least 77 nm, with no finite size effects, no phase transition temperature shifts, and no dielectric peak broadening or change from first‐ to second‐order transitions, suggesting that the gradient defect model of Bratkovsky and Levanyuk correctly describes such effects as extrinsic in experimental studies of equally thin ceramic thin films. In ceramic barium–strontium titanate (BST) thin films, it is shown that there is also no intrinsic broadening or shifts in phase transitions, with sharp, unshifted, bulk‐like transitions observed only as re‐entrant upon warming from cryogenic temperatures; this shows that phase transitions in ceramic thin films are dominated by kinetics and not thermodynamics and are definitely not equilibrium measurements. At high fields (>1 GV/m), the films exhibit space charge‐limited conduction; no variable‐range hopping is observed, contrary to recent studies on SrTiO3. Some novel, unconventional switching processes are discussed, comparing the “perimeter effect” (non‐equilibrium, ballistic) with Molotskii's equilibrium model. Theory and experiment are described for [3D] nanotubes, nanorods, and nano‐ribbons (or micro‐ribbons). The layered‐structure‐perovskite–pyrochlore conversion in bismuth titanate is described together with the PbO+TiO2 phase separation in lead zirconate titanate during electrical breakdown, as are novel HfO2 precursors that demonstrate enhanced temperature crystallization from the amorphous state and hence commercial advantages for front‐end processing.
For the Sake of the Team: Unity and Disunity in a Multiparty Major League Baseball Negotiation
Authors: Crump Larry
Published: June 2005

“Divide and conquer” is a well‐known expression although the literature on distributive negotiation offers little theory in support of this technique. This article develops theory to explain increases or decreases in unity and disunity among negotiation groups comprising multiple parties in organizational settings. Specifically, this study analyzes the negotiations surrounding the purchase of the Seattle Mariners baseball team in 1992 by a group that included Japanese investors. The study identifies reframing as a technique that can be used strategically to create disunity between cooperating parties on the same side in a negotiation. This article also develops a theory about techniques that can enhance unity between cooperating parties and can protect against disunity that may be generated by the opposition. Dividing and unifying techniques are both components of a larger negotiation theory that seeks to evaluate actions designed to affect the degree of unity between parties working together in distributive settings.
Metaphors for Navigating Negotiations
Authors: Smith Thomas H.
Published: June 2005

A metaphor operates covertly to gain tacit agreement on direction, means, and ends without full description or rationale. It constrains a discussion, focusing on certain concerns while masking others. Becoming consciously aware of the metaphors commonly used during negotiation offers valuable insights into meanings not overtly discussed. This awareness helps reveal intentions and implicit evaluations while also illuminating obvious areas for mutual gain. It suggests ways to reinforce rapport, to persevere in negotiating, to reflect and query usefully, and to explore and propose different options. Drawing on the large body of applied metaphor research, including conceptual metaphor theory, several structural properties of metaphor are explained. Their usefulness in detecting metaphors, elaborating how metaphors map issues being discussed, and unpacking meaning is illustrated using excerpts from a negotiation case transcript. This article argues that when a negotiator becomes conscious of such metaphors, more options become available for intelligent exploration.
The Secrets of Successful Mediators
Authors: Goldberg Stephen B.
Published: June 2005

A survey of thirty experienced mediators showed that three‐quarters of them regarded achieving rapport with the parties as central to their success in bringing about settlements. This article discusses how mediators achieve and make use of that rapport. The article also considers the implications for mediator training of the finding that achieving rapport with the parties is a key factor in successful mediation.
Using Tomorrow's Headlines for Today's Training: Creating Pseudo‐reality in Conflict Resolution Simulation Games
Authors: Ebner Noam , Efron Yael
Published: June 2005

This article introduces the “pseudo‐reality” method of constructing and conducting conflict resolution training workshops. This method focuses on creating a backdrop against which participants engage in building negotiation and mediation skills using real‐life events and facts — but only to the extent that these events and facts promote the learning process. By creating pseudo‐reality, trainers can overcome strong preconceptions or biases that can interfere with the learning process while at the same time preserving the advantages of working within a familiar, realistic environment. This method is meant to be used when the main goal of a workshop is skill building rather than imparting substantive knowledge of a specific conflict. The article illustrates this method by describing its use at a workshop conducted recently in Cyprus, in which the Israeli–Palestinian conflict served as a backdrop for conflict resolution skill building. Finally, the article describes a model designed to help conflict resolution trainers create pseudo‐reality in their own workshops.
What We Have Learned About Teaching Multiparty Negotiation
Authors: Susskind Lawrence , Mnookin Robert , Rozdeiczer Lukasz , Fuller Boyd
Published: June 2005

This article grows out of our experience teaching an advanced course on multiparty negotiation. The main question underlying the course is: “How can experts in two‐party negotiations make themselves effective multiparty negotiators?” In this article, we describe what and how we taught, what we think worked, and what we decided to change after the first year of teaching.
The functional role of cysteines adjacent to the NRY motif of the human MT1 melatonin receptor
Authors: Kokkola Tarja , Salo Outi M. H. , Poso Antti , Laitinen Jarmo T.
Published: June 2005

Abstract:  All G protein‐coupled melatonin receptors have two conserved cysteines in the interphase between transmembrane helix III and the second intracellular loop, in the region assumed important in receptor/G protein coupling. The cysteines are also potential targets of receptor S‐nitrosylation. The effects of site‐directed mutagenesis of these cysteines in the human MT1 melatonin receptor were investigated. The cysteines were mutated into serines either individually or as a pair and stable Chinese hamster ovary cell lines expressing the wild‐type and mutant MT1 receptors were created. Receptor expression level, subcellular localization, ligand binding and G protein activation of the cell lines were analyzed. Serine substitution of C127 (Cys3.52) did not affect the ligand binding affinity and agonist potency but had an influence on receptor trafficking and G protein activation capacity. Serine substitution of C130 (Cys3.55) resulted in a decrease in the potency of melatonin to activate G proteins. When both cysteines were mutated into serines, normal MT1 receptor binding and activation were abolished. Computer modeling revealed that the mutations did not change the structure of the ligand binding pocket. Cysteine S‐nitrosylation had no influence on G protein activation through MT1 receptors. Taken together, these data show that the two conserved cysteines in the end of transmembrane domain III of the MT1 melatonin receptor, especially C130 (Cys3.55), are needed for normal G protein activation and receptor trafficking.
Legally regulating intergenerationally transmitted debt
Authors: Burns Fiona R
Published: June 2005

This article considers the phenomenon of intergenerationally transmitted debt in Australia from the legal perspective. It will be argued that generally while confident and capable elders ought to be able to deal with their assets how they think fit, elders may suffer from vulnerabilities which prevent them from protecting their interests. The legal regulation of guarantees is presently a unco‐ordinated and complex amalgam of case law, statute and finance industry self‐regulatory codes which do not accord elders any special protection. This article suggests that it may be necessary to take some steps to protect vulnerable elders while still recognising their rights to exercise autonomy over assets.
Guardianship for adults in Japan: Legal reforms and advances in practice
Authors: Arai Makoto , Homma Akira
Published: June 2005

Major law reforms in Japan established a new system of guardianship for adults that took effect from early 2000, coinciding with the introduction of Japan's new long‐term care insurance scheme. The new legislation created a new form of advisership, alongside reforms to existing curatorship and guardianship, and introduced voluntary guardianship. Replacing the traditional system based on incompetence and quasi‐incompetence, the new system is based on respecting the autonomy of a principal as far as possible, in common with developments in other countries. After setting the context of the reforms, this paper gives with an account of the reform process and then outlines the structure of the new provisions and reports on their early operation. In concluding, some observations are made on the application of the adult guardianship to consent to medical treatment on the part of patients with dementia, an issue that remains unresolved.
Generational justice in aged care policy in Australia and the United Kingdom
Authors: Howe Anna , Healy Judith
Published: June 2005

This paper traces the emergence of the theme of generational justice in aged care policy in Australia and the United Kingdom. Debate about the balance to be struck between inter‐ and intragenerational funding in the two countries took somewhat different courses before and after the crossover in the political persuasion of national governments that occurred in 1996–1997, but both continue to grapple with the question as to whether housing assets of the elderly are a resource for private, intergenerational transfers, or a source of intragenerational funding for aged care.
The development of advance care directives in New South Wales
Authors: Squires Barbara , Barr Felicity
Published: June 2005

Advance Care Directives (ACDs) are becoming an increasingly popular way for people to state their wishes about the treatment they do or do not want at the end of their lives. This paper records some of the background to their introduction in NSW and reflects on the motivations and backgrounds of those who have been involved in developments to date. These developments came in response to changes in social attitudes and shifted the focus in advance planning for later life from financial and property decisions to encompass personal and medical treatment preferences. The relevant legislation in NSW is the Guardianship Act 1987, which governs substitute medical consent for adults who are unable to consent to their own treatment and enables competent adults to appoint an enduring guardian to be their substitute decision maker for personal and medical decisions. Although proclaimed in 1989, its provisions are still not well understood by the medical profession, much less by the general public. Action is underway on many fronts to increase awareness of all the ways in which people can plan ahead to have their wishes respected if they lose their mental competence.
Issues in applying advance directives to psychiatric care in the United States
Authors: Srebnik Debra
Published: June 2005

Created while competent, psychiatric advance directives (PADs) are legal documents that specify treatment preferences and may also include designation of a surrogate decision maker for use during later periods of acute illness in which competent decision making is impaired. The paper begins with an overview of the potentially therapeutic effects of PADs and then addresses four areas in which legislation and methods of implementing PADs need to consider implications of therapeutic jurisprudence: competence to create PADs, when to activate them, whether revocation should be permitted during incapacity and circumstances for overriding PADs. The paper draws on the research carried out in the US by the author and sponsored by the National Institute of Mental Health. The ways in which issues have been resolved in practice in the US point to applications in other jurisdictions.
The Australian experience of advance directives and possible future directions
Authors: Stewart Cameron
Published: June 2005

This paper analyses the role that advance directives can play in the formation of advanced care planning. Following on from a review of the legal history of advance directives in Australia, including the common law and statutory regimes, it is argued that schemes for advance directives have not yet proven to be successful. It is proposed that what is needed is a more integrated approach, whereby advance directives are but one mechanism used in a wider concept of advanced care planning. This integrated approach should employ a variety of mechanisms including proxy decision‐making, structured concepts of best interests and clearly defined dispute resolution processes.
The changing balance of government and family in care for the elderly in Sweden and other European countries
Authors: Sundström Gerdt , Johansson Lennarth
Published: June 2005

Patterns of care for the elderly have changed dramatically in Sweden over the post‐war years, and new trends have emerged in the last decade. Relatively fewer elderly are institutionalised or use public Home Help and more are helped by family members. The family structure of the elderly in Sweden is more favourable today than before for providing help: more elders are married (or cohabit) and stay married longer and more of them have children and other kin than previously. Although old parents and their offspring very seldom live together, they often do not live far apart. Social services increasingly target elders who are short on kin, very frail and live alone, a pattern that is common in European countries. Both carers and cared‐for elderly persons want shared responsibility, that state and family together provide for frail elders. Paradoxically, more elders are cared for longer and more by their families, but eventually also a larger proportion of elders than before use public services; in particular, more elderly persons now use institutional care for some period before the end of their life than previously. This paper draws on evidence across 50 years of shifting patterns in Swedish old age care and makes comparisons with living arrangements and patterns of care in several western European countries.

‘Cast me not off in the time of old age; forsake me not when my strength faileth’.

Text on a gravestone from 1702 at Fiskebäck chapel, Sweden, from the King James Bible, Psalm 71 Verse 9.
Older people's assets: a contested site1
Authors: Tilse Cheryl , Wilson Jill , Setterlund Deborah , Rosenman Linda
Published: June 2005

The management of the financial assets of older people is increasingly important in the current policy context. Competing interests from the state, the market and the family regarding the appropriate use of these assets suggest that non‐professional managers are assisting older people in a complex environment. This paper, based on a national prevalence study and an in‐depth study, explores the nature and extent of asset management on behalf of older people. It examines the role of legal provision for substitute decision‐making in these processes and concludes that the current provision is insufficient to protect older people from financial abuse and support carers to manage assets well. This paper proposes that more broadly based interventions are required in a complex environment of competing interests. Such interventions include attitudinal change, improved financial literacy, information and support for older people and informal asset managers and improved monitoring and support for substitute decision makers.
Tachykinin‐related peptide precursors in two cockroach species
Authors: Predel Reinhard , Neupert Susanne , Roth Steffen , Derst Christian , Nässel Dick R.
Published: June 2005

Tachykinins and tachykinin‐related peptides (TKRPs) play major roles in signaling in the nervous system and intestine of both invertebrates and vertebrates. Here we have identified cDNAs encoding precursors of multiple TKRPs from the cockroaches Leucophaea maderae and Periplaneta americana. All nine LemTKRPs that had been chemically isolated in earlier experiments could be identified on the precursor of L. maderae. Four previously unidentified LemTKRPs were found in addition on the precursor. The P. americana cDNA displayed an open reading frame very similar to that of L. maderae with 13 different TKRPs. MALDI‐TOF mass spectra from tissues of both species confirms the presence of all the TKRPs encoded on the precursor plus two additional peptides that are cleavage products of the N‐terminally extended TKRPs. A tissue‐specific distribution of TKRPs was observed in earlier experiments at isolation from brain and midgut of L. maderae. Our data do not suggest a differential gene expression but a different efficacy in processing of LemTKRP‐2 and Lem/PeaTKRP‐3 in the brain and intestine, respectively. This results in a gut‐specific accumulation of these extended peptides, whereas in the brain their cleavage products, LemTKRP‐1 and LemTKRP‐311−19, are most abundant. Mass spectrometric analysis demonstrated the occurrence of the different TKRPs in single glomeruli of the tritocerebrum and in cells of the optical lobe.
Diego and friends play again
Authors: Mihály József , Matusek Tamás , Pataki Csilla
Published: June 2005

The formation of properly differentiated organs often requires the planar coordination of cell polarization within the tissues. Such planar cell polarization (PCP) events are best studied in Drosophila, where many of the key players, known as PCP genes, have already been identified. Genetic analysis of the PCP genes suggests that the establishment of polarity consists of three major steps. The first step involves the generation of a global polarity cue; this in turn promotes the second step, the redistribution of the core PCP proteins, leading to the formation of asymmetrically localized signaling centers. During the third step, these complexes control tissue‐specific cellular responses through the activation of cell type specific effector genes. Here we discuss some of the most recent advances that have provided valuable new insight into each of the three major steps of planar cell polarization.
Future Mortality: A Bumpy Road to Shangri-La?
Authors: Tuljapurkar Shripad
Published: June 2005

Americans are getting fatter, and it is known that increased obesity may increase the risk of death. Olshansky
et al.
have argued that this increase in obesity will likely slow, or even reverse, increases in life expectancy in the United States and perhaps save U.S. Social Security as a result. We discuss historical changes in the mortality rate and the reasons why other analyses argue that life expectancies will continue to increase. We also discuss the limitations of using single risk factors such as obesity as predictors of mortality risk. Finally, we explore the relation between risk factors and the long-term historical increase in human life expectancy.
Synapses Form in Skeletal Muscles Lacking Neuregulin Receptors
Authors: Escher P. , Lacazette E. , Courtet M. , Blindenbacher A. , Landmann L. , Bezakova G. , Lloyd K. C. , Mueller U. , Brenner H. R.
Published: June 2005

The formation of the neuromuscular junction (NMJ) is directed by reciprocal interactions between motor neurons and muscle fibers. Neuregulin (NRG) and Agrin from motor nerve terminals are both implicated. Here, we demonstrate that NMJs can form in the absence of the NRG receptors ErbB2 and ErbB4 in mouse muscle. Postsynaptic differentiation is, however, induced by Agrin. We therefore conclude that NRG signaling to muscle is not required for NMJ formation. The effects of NRG signaling to muscle may be mediated indirectly through Schwann cells.
Allometry of Alarm Calls: Black-Capped Chickadees Encode Information About Predator Size
Authors: Templeton Christopher N. , Greene Erick , Davis Kate
Published: June 2005

Many animals produce alarm signals when they detect a potential predator, but we still know little about the information contained in these signals. Using presentations of 15 species of live predators, we show that acoustic features of the mobbing calls of black-capped chickadees (Poecile atricapilla) vary with the size of the predator. Companion playback experiments revealed that chickadees detect this information and that the intensity of mobbing behavior is related to the size and threat of the potential predator. This study demonstrates an unsuspected level of complexity and sophistication in avian alarm calls.
Cleaning the Air and Improving Health with Hydrogen Fuel-Cell Vehicles
Authors: Jacobson M. Z. , Colella W. G. , Golden D. M.
Published: June 2005

Converting all U.S. onroad vehicles to hydrogen fuel-cell vehicles (HFCVs) may improve air quality, health, and climate significantly, whether the hydrogen is produced by steam reforming of natural gas, wind electrolysis, or coal gasification. Most benefits would result from eliminating current vehicle exhaust. Wind and natural gas HFCVs offer the greatest potential health benefits and could save 3700 to 6400 U.S. lives annually. Wind HFCVs should benefit climate most. An all-HFCV fleet would hardly affect tropospheric water vapor concentrations. Conversion to coal HFCVs may improve health but would damage climate more than fossil/electric hybrids. The real cost of hydrogen from wind electrolysis may be below that of U.S. gasoline.
Deep-Sea Temperature and Circulation Changes at the Paleocene-Eocene Thermal Maximum
Authors: Tripati Aradhna , Elderfield Henry
Published: June 2005

A rapid increase in greenhouse gas levels is thought to have fueled global warming at the Paleocene-Eocene Thermal Maximum (PETM). Foraminiferal magnesium/calcium ratios indicate that bottom waters warmed by 4° to 5°C, similar to tropical and subtropical surface ocean waters, implying no amplification of warming in high-latitude regions of deep-water formation under ice-free conditions. Intermediate waters warmed before the carbon isotope excursion, in association with downwelling in the North Pacific and reduced Southern Ocean convection, supporting changing circulation as the trigger for methane hydrate release. A switch to deep convection in the North Pacific at the PETM onset could have amplified and sustained warming.
Elementary Response of Olfactory Receptor Neurons to Odorants
Authors: Bhandawat Vikas , Reisert Johannes , Yau King-Wai
Published: June 2005

Signaling by heterotrimeric GTP-binding proteins (G proteins) drives numerous cellular processes. The number of G protein molecules activated by a single membrane receptor is a determinant of signal amplification, although in most cases this parameter remains unknown. In retinal rod photoreceptors, a long-lived photoisomerized rhodopsin molecule activates many G protein molecules (transducins), yielding substantial amplification and a large elementary (single-photon) response, before rhodopsin activity is terminated. Here we report that the elementary response in olfactory transduction is extremely small. A ligand-bound odorant receptor has a low probability of activating even one G protein molecule because the odorant dwell-time is very brief. Thus, signal amplification in olfactory transduction appears fundamentally different from that of phototransduction.
GDF11 Controls the Timing of Progenitor Cell Competence in Developing Retina
Authors: Kim Joon , Wu Hsiao-Huei , Lander Arthur D. , Lyons Karen M. , Matzuk Martin M. , Calof Anne L.
Published: June 2005

The orderly generation of cell types in the developing retina is thought to be regulated by changes in the competence of multipotent progenitors. Here, we show that a secreted factor, growth and differentiation factor 11 (GDF11), controls the numbers of retinal ganglion cells (RGCs), as well as amacrine and photoreceptor cells, that form during development. GDF11 does not affect proliferation of progenitors—a major mode of GDF11 action in other tissues—but instead controls duration of expression of
Math5
, a gene that confers competence for RGC genesis, in progenitor cells. Thus, GDF11 governs the temporal windows during which multipotent progenitors retain competence to produce distinct neural progeny.
Larger Islands House More Bacterial Taxa
Authors: Bell Thomas , Ager Duane , Song Ji-Inn , Newman Jonathan A. , Thompson Ian P. , Lilley Andrew K. , van der Gast Christopher J.
Published: June 2005

The power law that describes the relationship between species richness and area size is one of the few generalizations in ecology, but recent studies show that this relationship differs for microbes. We demonstrate that the natural bacterial communities inhabiting small aquatic islands (treeholes) do indeed follow the species-area law. The result requires a re-evaluation of the current understanding of how natural microbial communities operate and implies that analogous processes structure both microbial communities and communities of larger organisms.
Landmarks on the Road to Modern Analysis
Authors: Grabiner Judith V.
Published: June 2005

The Calculus Gallery
. Masterpieces from Newton to Lebesgue.
By William Dunham
. Princeton University Press, Princeton, NJ, 2005. 252 pp. $29.95, £18.95. ISBN 0-691-09565-5.

Using modern terms and notations, the author presents the growth of calculus through a sample of the contributions of 13 mathematicians who have shaped its development.
Sound Velocities of Hot Dense Iron: Birch's Law Revisited
Authors: Lin Jung-Fu , Sturhahn Wolfgang , Zhao Jiyong , Shen Guoyin , Mao Ho-kwang , Hemley Russell J.
Published: June 2005

Sound velocities of hexagonal close-packed iron (hcp-Fe) were measured at pressures up to 73 gigapascals and at temperatures up to 1700 kelvin with nuclear inelastic x-ray scattering in a laser-heated diamond anvil cell. The compressional-wave velocities (
V
P
) and shear-wave velocities (
V
S
) of hcp-Fe decreased significantly with increasing temperature under moderately high pressures.
V
P
and
V
S
under high pressures and temperatures thus cannot be fitted to a linear relation, Birch's law, which has been used to extrapolate measured sound velocities to densities of iron in Earth's interior. This result means that there are more light elements in Earth's core than have been inferred from linear extrapolation at room temperature.
Tyrosinase Reactivity in a Model Complex: An Alternative Hydroxylation Mechanism
Authors: Mirica Liviu M. , Vance Michael , Rudd Deanne Jackson , Hedman Britt , Hodgson Keith O. , Solomon Edward I. , Stack T. Daniel P.
Published: June 2005

The binuclear copper enzyme tyrosinase activates O
2
to form a μ-η
2
:η
2
-peroxodicopper(II) complex, which oxidizes phenols to catechols. Here, a synthetic μ-η
2
:η
2
-peroxodicopper(II) complex, with an absorption spectrum similar to that of the enzymatic active oxidant, is reported to rapidly hydroxylate phenolates at –80°C. Upon phenolate addition at extreme temperature in solution (–120°C), a reactive intermediate consistent with a bis-μ-oxodicopper(III)-phenolate complex, with the O–O bond fully cleaved, is observed experimentally. The subsequent hydroxylation step has the hallmarks of an electrophilic aromatic substitution mechanism, similar to tyrosinase. Overall, the evidence for sequential O–O bond cleavage and C–O bond formation in this synthetic complex suggests an alternative intimate mechanism to the concerted or late stage O–O bond scission generally accepted for the phenol hydroxylation reaction performed by tyrosinase.
Dependence of Olfactory Bulb Neurogenesis on Prokineticin 2 Signaling
Authors: Ng Kwan L. , Li Jia-Da , Cheng Michelle Y. , Leslie Frances M. , Lee Alex G. , Zhou Qun-Yong
Published: June 2005

Neurogenesis persists in the olfactory bulb (OB) of the adult mammalian brain. New interneurons are continually added to the OB from the subventricular zone (SVZ) via the rostral migratory stream (RMS). Here we show that secreted prokineticin 2 (PK2) functions as a chemoattractant for SVZ-derived neuronal progenitors. Within the OB, PK2 may also act as a detachment signal for chain-migrating progenitors arriving from the RMS. PK2 deficiency in mice leads to a marked reduction in OB size, loss of normal OB architecture, and the accumulation of neuronal progenitors in the RMS. These findings define an essential role for G protein–coupled PK2 signaling in postnatal and adult OB neurogenesis.
Probing Performance Gaps
Authors: Lewis Debra
Published: June 2005

Gender Differences in Mathematics
. An Integrative Psychological Approach.
Ann M. Gallagher and James C. Kaufman, Eds.
. Cambridge University Press, Cambridge, 2005. 367 pp. $70, £40. ISBN 0-521-82605-5. Paper, $25.99, £16.99. ISBN 0-521-53344-9.

The contributors explore the question of why females consistently score lower than males on standardized tests of mathematics although such performance differences are not found in the classroom.
Focus Issue: Going for the Gut
Authors: Adler Elizabeth M.
Published: June 2005

This week’s issues of
Science
and
Science’s STKE
cover various aspects of gastrointestinal function and malfunction. Topics include the regulation of feeding behavior, host interactions with the organisms that colonize the gut, signaling pathways involved in gut barrier function and self-renewal, and factors associated with gastrointestinal inflammatory disorders and the pathogenesis of gastrointestinal cancers.
Signaling the Junctions in Gut Epithelium
Authors: Hollande Frédéric , Shulkes Arthur , Baldwin Graham S.
Published: June 2005

This Perspective summarizes recent developments in our understanding of the signaling pathways involved in the regulation of epithelial cell adhesion in the gut. The role of phosphatidylinositol 3-kinase signaling in the modulation of adherens junctions, and the connections between tight junctions and nuclear transcription factors, are discussed. The effect of gastrins on adherens and tight junctions is presented as an example of the regulation of adhesion by growth factors. The consequences of dysregulation of adherens junctions and tight junctions for human pathology are also considered.
How and Why Are Channels in Transporters?
Authors: Vandenberg Robert J. , Ryan Renae M.
Published: June 2005

Traditionally, transporters and ion channels have been thought of as structurally and functionally distinct proteins. However, neurotransmitter transporters can be both. Vandenberg and Ryan discuss recent developments in understanding how and why these transporters contain ion channels.
Regulation of Mitochondrial Dynamics: Another Process Modulated by Ca
2+
Signals?
Authors: Yoon Yisang
Published: June 2005

This Perspective describes signaling mechanisms that may be involved in regulating mitochondrial dynamics and discusses the possible role of changes in mitochondrial morphology and location in mitochondrial function.
Functional ankle control of rock climbers
Authors: Schweizer A , Bircher H-P , Kaelin X , Ochsner P E
Published: June 2005

Objective:To evaluate whether rock climbing type exercise would be of value in rehabilitating ankle injuries to improve ankle stability and coordination.

Methods:A group of 25 rock climbers was compared with a group of 26 soccer players. All were male, uninjured, and exercised three to four times a week. Active ankle stability was evaluated by one leg stand stabilometry (measurement of migration of the centre of gravity) and measurements of maximum strength of ankle isokinetic concentric flexion and extension (Cybex).

Results:The rock climbers showed significantly better results in the stabilometry and greater absolute and relative maximum strength of flexion in the ankle. The soccer players showed greater absolute but not relative strength in extension.

Conclusion:Rock climbing, because of its slow and controlled near static movements, may be of value in the treatment of functional ankle instability. However, it has still to be confirmed whether it is superior to the usual rehabilitation exercises such as use of the wobble board.
Risk of cervical injuries in mixed martial arts
Authors: Kochhar T , Back D L , Mann B , Skinner J
Published: June 2005

Background:Mixed martial arts have rapidly succeeded boxing as the world’s most popular full contact sport, and the incidence of injury is recognised to be high.

Objective:To assess qualitatively and quantitatively the potential risk for participants to sustain cervical spine and associated soft tissue injuries.

Methods:Four commonly performed manoeuvres with possible risks to the cervical spine were analysed with respect to their kinematics, and biomechanical models were constructed.

Results:Motion analysis of two manoeuvres revealed strong correlations with rear end motor vehicle impact injuries, and kinematics of the remaining two suggested a strong risk of injury. Mathematical models of the biomechanics showed that the forces involved are of the same order as those involved in whiplash injuries and of the same magnitude as compression injuries of the cervical spine.

Conclusions:This study shows that there is a significant risk of whiplash injuries in this sport, and there are no safety regulations to address these concerns.
Lactate threshold responses to a season of professional British youth soccer
Authors: McMillan K , Helgerud J , Grant S J , Newell J , Wilson J , Macdonald R , Hoff J
Published: June 2005

Objective:To examine the changes in aerobic endurance performance of professional youth soccer players throughout the soccer season.

Methods:Nine youth soccer players were tested at six different time points throughout the soccer season by sub-maximal blood lactate assessment, using an incremental treadmill protocol. Whole blood lactate concentration and heart frequency (Hf) were determined at each exercise stage. Running velocities at the first lactate inflection point (v-Tlac) and at a blood lactate concentration of 4 mmol l−1(v-4mM) were determined.

Results:Running velocity at the two lactate thresholds increased from the start of pre-season training to the early weeks of the competitive season, from 11.67 (0.29) to 12.96 (0.28) km h−1forv-Tlac, and from 13.62 (0.25) to 14.67 (0.24) km h−1forv-4mM (p<0.001). However,v-Tlacandv-4mM when expressed relative to maximum heart frequency (Hfmax) remained unchanged. The Hf to blood lactate concentration relationship was unchanged after the pre-season training period. The two expressions of lactate threshold did not reveal differences between each other.

Conclusion:Running velocity atv-Tlacandv-4mM increased significantly over the pre-season period, butv-Tlacandv-4mM were unchanged when expressed relative to Hfmax. This finding may indicate that increased endurance performance may be mainly attributable to alterations in Vo2max. Although lactate assessment of soccer players is useful for determining endurance training adaptations in soccer players, additional assessment of the other two determinants of endurance performance (Vo2maxand running economy) may provide more useful information for determining physiological adaptations resulting from soccer training and training interventions.
Neovascularisation and pain in jumper’s knee: a prospective clinical and sonographic study in elite junior volleyball players
Authors: Gisslén K , Alfredson H
Published: June 2005

Background:The nature of tendon neovascularisation associated with pain over time has not been studied.

Objective:To prospectively study the patellar tendons in elite junior volleyball players.

Methods:The patellar tendons in all students at the Swedish National Centre for high school volleyball were evaluated clinically and by ultrasonography (US) and Power Doppler (PD) sonography.

Results:Altogether 120 patellar tendons were followed for 7 months. At inclusion, jumper’s knee was diagnosed clinically in 17 patellar tendons. There were structural changes on US in 14 tendons, in 13 of which PD sonography showed neovascularisation. There were 70 clinically normal tendons with normal US and PD sonography, 24 clinically normal tendons with abnormal US but normal PD sonography, and nine clinically normal tendons with abnormal US and neovascularisation on PD sonography. At 7 month follow up, jumper’s knee was diagnosed clinically and by US in 19 patellar tendons, in 17 of which there was neovascularisation. Three of nine clinically normal tendons with structural changes and neovascularisation at inclusion developed jumper’s knee. Two of 24 tendons clinically normal at inclusion, with abnormal US but normal PD sonography, developed jumper’s knee with abnormal US and neovascularisation on PD sonography. A total of 20 clinically normal tendons with normal US and PD sonography at inclusion developed structural tendon changes and 12 of these also developed neovascularisation.

Conclusions:The clinical diagnosis of jumper’s knee is most often associated with neovascularisation in the area with structural tendon changes. The finding of neovessels might indicate a deterioration of the condition.
A comparison of the physiological profiles of elite Gaelic footballers, hurlers, and soccer players: Table 1
Authors: McIntyre M C
Published: June 2005

Background:Gaelic football, soccer, and hurling are prominent field games in Ireland and involve participants undertaking a variety of playing tasks and skills which place various physiological demands on the participants. The aim of this study was to evaluate and compare the mid-season physiological profiles of elite players.

Methods:Physiological assessment was carried out on 29 inter-county Gaelic footballers, 30 inter-county hurlers, and 21 League of Ireland soccer players.

Results:Significant differences were reported for % body fat (p<0.05), aerobic capacity (p<0.05), flexibility (p<0.05), upper body strength (p<0.05), upper body strength endurance (p<0.05), abdominal endurance (p<0.05), and speed endurance (p<0.05), while there were no differences recorded for height, weight, or speed levels. A relatively heterogeneous body size is evident for all three sports. Soccer players had lower body fat levels, greater aerobic capacity, greater strength endurance, and greater flexibility compared to both Gaelic footballers and hurlers, possibly due to specific training and conditioning programmes or physical adaptation to match play The greater strength of both Gaelic footballers and hurlers and the superior speed endurance levels of Gaelic footballers also reflect the physical nature of the sports. Similar speed levels amongst all three sports reflect the importance of speed for performance.

Conclusions:The various physiological attributes for Gaelic football, soccer, and hurling reflect the physical requirements for success and participation in each of these field games.
Injury history as a risk factor for incident injury in youth soccer
Authors: Kucera K L , Marshall S W , Kirkendall D T , Marchak P M , Garrett W E
Published: June 2005

Objectives:To determine if athletes with a self reported history of previous injury have a higher incident injury rate than athletes without a self reported injury history.

Methods:A prospective cohort study of Classic League soccer players playing at the level under 12 through under 18. Injury history forms were mailed to all registering Classic League soccer players in the North Carolina Youth Soccer Association during 1997–2000 (n  =  7000); 1483 (19%) returned the baseline questionnaire and were followed up for injuries.

Results:There were 5139 player-seasons of follow up and an estimated 171 957 athlete-exposures. More than half self reported an injury history (59.7%). Overall, the unadjusted incidence rate was 4.6 (95% confidence interval (CI) 4.3 to 4.9) incident injuries per 1000 athlete-exposures. Multivariate generalised Poisson regression modelling indicated that players with one previous injury had a twofold greater risk of incident injury (IRR  =  2.6; 95% CI 2.0 to 3.3), and those with two or more previous injuries had a threefold greater risk of incident injury (IRR  =  3.0; 95% CI 2.3 to 3.8) compared with athletes with no previous injuries.

Conclusions:Injury history was associated with an increased injury rate. This suggests that, even in these youth soccer players, those with an injury history may be at higher risk.