bluuebunny/crossref_metadata_2025 huggingface dataset:
The Spatial Dependence of the Poststimulus Undershoot as Revealed by High-Resolution BOLD- and CBV-Weighted fMRI
Authors: Yacoub Essa , Ugurbil Kamil , Harel Noam
Published: October 2005

The hemodynamic response to neural activity consists of changes in blood flow, blood volume and oxygen metabolism. Changes in the vascular state after sensory stimulation have different spatial and temporal characteristics in the brain. This has been shown using imaging techniques, such as BOLD functional magnetic resonance imaging (fMRI), which monitor vascular changes once the stimulus is turned on, and the eventual return to baseline levels, once the stimulus is turned off. The BOLD fMRI signal during sensory stimulation has been well characterized and modeled in terms of the spatial and temporal characteristics of the vascular response. However, the return of the signals to baseline levels after sensory stimulation is not as well characterized. During this period, a poststimulus undershoot in the BOLD signal is observed. This poststimulus undershoot has been modeled and investigated to characterize the physiological mechanisms (cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral oxygen consumption) associated with the response. However, the data in the literature, which lack any spatially dependent information, appear to be contradictory in terms of the mechanisms associated with this poststimulus response. With a high spatial resolution cat model at 9.4 T, we show that CBV changes in the tissue persist once the stimulus is turned off, while CBV changes in the surface vessels quickly return to baseline levels, despite a concurrent undershoot in the BOLD signal in both the tissue and surface vessel areas. In addition, the BOLD data alone indicate that different physiological mechanisms regulate the poststimulus response in the tissue versus the surface vessel regions.
A note on BRST quantization of SU(2) Yang-Mills mechanics
Authors: Fuster A. , van Holten J. W.
Published: October 2005

The quantization of SU(2) Yang-Mills theory reduced to 0+1 space-time dimensions is performed in the BRST framework. We show that in the unitary gauge A0=0 the BRST procedure has difficulties which can be solved by introduction of additional singlet ghost variables. In the Lorenz gauge Ȧ0=0 one has additional unphysical degrees of freedom, but the BRST quantization is free of the problems of the unitary gauge.
Induced matter: Curved N-manifolds encapsulated in Riemann-flat N+1 dimensional space
Authors: Ringermacher Harry I. , Mead Lawrence R.
Published: October 2005

Liko and Wesson have recently introduced a new five-dimensional induced matter solution of the Einstein equations, a negative curvature Robertson-Walker space embedded in a Riemann-flat five-dimensional manifold. We show that this solution is a special case of a more general theorem prescribing the structure of certain N+1 dimensional Riemann-flat spaces which are all solutions of the Einstein equations. These solutions encapsulate N-dimensional curved manifolds. Such spaces are said to “induce matter” in the submanifolds by virtue of their geometric structure alone. We prove that the N-manifold can be any maximally symmetric space.
Quantum spheres for OSpq(1∕2)
Authors: Aizawa N. , Chakrabarti R.
Published: October 2005

Using the corepresentation of the quantum supergroup OSpq(1∕2) a general method for constructing noncommutative spaces covariant under its coaction is developed. In particular, a one-parameter family of covariant algebras, which may be interpreted as noncommutative superspheres, is constructed. It is observed that embedding of the supersphere in the OSpq(1∕2) algebra is possible. This realization admits to the infinitesimal characterization by Koornwinder. A covariant oscillator realization of the supersphere is also presented.
Enhanced magnetism in Fe-filled carbon nanotubes produced by pyrolysis of ferrocene
Authors: Leonhardt A. , Ritschel M. , Elefant D. , Mattern N. , Biedermann K. , Hampel S. , Müller Ch. , Gemming T. , Büchner B.
Published: October 2005

By optimization of the synthesis of ferromagnetic-filled carbon nanotube ensembles on Si substrates (catalytic decomposition of ferrocene) and following annealing at 645°C, marked hysteresis loops can be measured by the alternating-gradient method. Unusually high coercivities and strong anisotropies with an easy magnetic axis parallel to the alignment of the nanotubes are observed from the as-grown samples, whereas an enhanced magnetic saturation moment (up to a factor of 2) and a decreased anisotropy are realized after annealing at 645°C. The increase of the magnetic saturation moment of the Fe-filled carbon nanotube ensembles is caused by the entire transformation within the tubes of the γ-Fe and Fe3C phases to ferromagnetic α-Fe and graphite. X-ray diffraction with different glancing incidence shows that the γ-Fe is predominantly at the tips of the nanotubes, while the iron carbide resides closer to the substrate. However, after the annealing process only α-Fe is found. At an annealing temperature of 675°C the nanotube structures are destroyed and the magnetic characteristics are dramatically altered (viz., the disappearance of anisotropy and reduction in coercivity).
Pore nucleation in mechanically stretched bilayer membranes
Authors: Wang Zun-Jing , Frenkel Daan
Published: October 2005

We report a computer-simulation study of the free-energy barrier for the nucleation of pores in the bilayer membrane under constant stretching lateral pressure. We find that incipient pores are hydrophobic but as the lateral size of the pore nucleus becomes comparable with the molecular length, the pore becomes hydrophilic. In agreement with previous investigations, we find that the dynamical process of growth and closure of hydrophilic pores is controlled by the competition between the surface tension of the membrane and the line tension associated with the rim of the pore. We estimate the line tension of a hydrophilic pore from the shape of the computed free-energy barriers. The line tension thus computed is in a good agreement with available experimental data. We also estimate the line tension of hydrophobic pores at both macroscopic and microscopic levels. The comparison of line tensions at these two different levels indicates that the “microscopic” line tension should be carefully distinguished from the “macroscopic” effiective line tension used in the theoretical analysis of pore nucleation. The overall shape of the free-energy barrier for pore nucleation shows no indication for the existence of a metastable intermediate during pore nucleation.
Hysteresis in gadolinium oxide metal-oxide-semiconductor capacitors
Authors: Hsieh Li-Zen , Ko Hong-Hsi , Kuei Ping-Yu , Chang Liann-Be , Jeng Ming-Jer
Published: October 2005

This investigation explores how oxidation affects the gadolinium oxide capacitor and the corresponding Gd2O3 hysteresis phenomenon. The current-voltage varied with Gd2O3 thickness and a charged capacitance voltage (C-V) curve with a left shift is also observed in experimental results. The breakdown voltages rise with increasing oxidation time, while the corresponding C-V hysteresis gaps decrease with increasing oxidation time.
Electrostatic potential in manganite-based heterojunctions by electron holography
Authors: Tian H. F. , Sun J. R. , Lü H. B. , Jin K. J. , Yang H. X. , Yu H. C. , Li J. Q.
Published: October 2005

Electric potentials at the manganite-based heterojunctions, composed of La0.9Sr0.1MnO3 and 0.01wt% Nb-doped SrTiO3 (p-n junction) and La0.7Ce0.3MnO3 and 0.5wt% Nb-doped SrTiO3 (n-n junction), have been studied by means of off-axis electron holography. The experimental measurements demonstrate that evident electron diffusion from the n-type SrNbxTi1−xO3 to the manganite films occurs in both p-n and n-n heterojunctions. The p-n heterojunction shows a complex potential change across the interface due to the variation of dielectric constant and electronic structure. In situ cooling experimental measurement on n-n junctions reveals an apparent change of potential along with the ferromagnetic phase transition.
Fabrication of Ni nanoparticles and their size-selective self-assembly into chains under external magnetic field
Authors: Singamaneni Srikanth , Bliznyuk Valery
Published: October 2005

In this letter, we report a simple method for the preparation of colloidal solutions of nickel nanoparticles through the ultrasonication of thermally evaporated ultrathin films. Atomic force microscopy imaging revealed that the particles had a narrow size distribution centered at 9.6 nm. Self-assembly of particles into nanochains was observed when the particles in the colloidal solution were subjected to a magnetic field during the solvent evaporation process. In the absence of an external magnetic field, randomly distributed individual nanoparticles were observed. The interplay between isotropic van der Waals forces and anisotropic magnetic forces governs the self-assembly process of the nanoparticles. The nanochains form an electrically percolating network on a solid substrate, which is characterized with linear current-voltage characteristics and a conductivity of 7×10−4Sm−1.
From nucleation to coercivity
Authors: Zhao G. P. , Zhao M. G. , Lim H. S. , Feng Y. P. , Ong C. K.
Published: October 2005

The demagnetization process of an exchange-coupled hard/soft/hard magnetic system and its coercivity mechanism are investigated within a micromagnetic framework. The calculation reveals that the demagnetization is a three-step process: (i) it begins with the nucleation of a transition region, (ii) the subsequent evolution of the domain wall near the interface, and (iii) the irreversible domain-wall motion from the soft phase into hard phase. As the thickness of the soft interlayer decreases, the dominant mechanism of coercivity switches from pinning to nucleation. However, for very thin interlayer, the three-step process occurs at the same applied field.
Schottky barrier formed by network of screw dislocations in SrTiO3
Authors: Guo Xin , Zhang Zaoli , Sigle Wilfried , Wachsman Eric , Waser Rainer
Published: October 2005

A network of screw dislocations was artificially created in SrTiO3, and characterized by transmission electron microscopy (TEM). Slight expansion of the dislocation core was observed by TEM. The composition of the dislocation core was quantified by electron energy loss spectroscopy, which reveals a 13±5% Ti∕O ratio increase but no Sr∕Ti ratio change in the core, demonstrating an oxygen deficiency or oxygen vacancy surplus in the dislocation core. The vacancy surplus was estimated to be about one vacancy every unit cell along the core. The dislocation core is positively charged; therefore, oxygen vacancies and holes are expelled from the dislocation network, forming a double Schottky barrier, which blocks charge carrier transports across the network. The Schottky barrier height at T=823K and PO2=2Pa was determined to be ∼0.48V.
High-power single-mode vertical-cavity surface-emitting lasers
Authors: Samal N. , Johnson S. R. , Ding D. , Samal A. K. , Yu S.-Q. , Zhang Y.-H.
Published: October 2005

This letter reports a design for high-power single-mode operation in vertical-cavity surface-emitting lasers by means of modal gain control using two different sized current apertures to shape the injection-current profile. A smaller current aperture is located several mirror-pairs away from the active region in the p-mirror and a larger current aperture is located in the first n-mirror-pair next to the active region. Both theoretical modeling and experimental test results show substantial improvement in the optical mode behavior using this approach when compared to a traditional single-aperture design. A clear trend of the spectral purity in the modal behavior under continuous wave and pulsed conditions is demonstrated and is in good agreement with theoretical predictions. The best design tested demonstrated a room-temperature continuous wave power output of 7.5mW with a side mode suppression ratio of 20dB.
On Qualculation, Agency, and Otherness
Authors: Callon Michel , Law John
Published: October 2005

In this paper we explore the boundary between calculative and noncalculative action by arguing that these are separate but mutually constitutive. By using the notion of qualculation, a neologism coined by Cochoy, we redefine the notion of calculation to include judgment. We then argue that making qualculability is not trivial: that it takes effort to create calculation and judgment. But it also takes effort to consider nonqualculability. Two strategies for achieving nonqualculability are identified, those of rarefaction and proliferation. Rarefaction, illustrated by the cases of Quaker worship and selfless love or agapè, works by withdrawing all qualculative resources. Conversely, proliferation, illustrated by the attribution of cause and responsibility after railway accidents, and by a major television fund-raiser, the ‘Téléthon’, works to impede calculation by an overload of qualculative resources.
Caught between the Cartographic and the Ethnographic Imagination: The Whereabouts of Amateurs, Professionals, and Nature in Knowing Biodiversity
Authors: Ellis Rebecca , Waterton Claire
Published: October 2005

In this paper we document current research into new forms of public engagement presently taking place in UK biodiversity policy. This involves locating the main participants in such patterns of engagement; namely nature, amateur naturalists, and professional biologists and conservationists. Two interwoven and mutually interdependent perspectives or ‘imaginaries’—the ‘cartographic’ and the ‘ethnographic’—are presented in the paper to explore the shaping and interpretation of such new forms of engagement. However, in this context the interest lies in the ways in which either perspective is foregrounded or backgrounded by the different parties involved. The described shifts and movements of a range of actors and processes being studied demonstrate the fluidity and instability of networks of ‘knowing nature well’, whose stability is often assumed. The tracing of two constants— expertise and exchange—within networks inhabited by nature and by amateur and professional naturalists allows for an exploration of ways in which social/natural inclusions and exclusions occur in new participatory practices designed as part of biodiversity action planning.
The Secret of Yucca Mountain: Reflections on an Object in Extremis
Authors: Bloomfield Brian P , Vurdubakis Theo
Published: October 2005

The processes through which boundaries are made and unmade—conceptually, socially, and materially—have been of enduring interest to a wide range of social scientific disciplines including sociology, anthropology, geography, science studies, etc. The subject matter of this paper—the Yucca Mountain high-level nuclear waste repository in Nye county, Nevada, which is meant to keep such waste safe for 10 000 years—constitutes, we contend, a case study of such processes taken to extremes. This, in turn, makes Yucca Mountain an interesting vantage point from which to (re)view the traditional ontological and epistemological preoccupations characteristic of social science, not so much in terms of abstract theory but rather in terms of concrete practical problems of spatial and temporal organisation.
Locating, Negotiating, and Crossing Boundaries: A Western Desert Land Claim, the Tordesillas Line, and the West Australian Border
Authors: Turnbull David
Published: October 2005

This is a story about the boundaried nature of stories and the storied nature of boundaries. It concerns a modern ‘scientific’ boundary: the West Australian border. In the process of trying to locate Aboriginal boundaries in a native title claim, this border is revealed as problematic and bent, and as rooted in the colonial history of the last 500 years. The tensions between Western and Aboriginal conceptions of boundaries open up a space for the exploration of the hidden social and narratological dimensions of land and knowledge, ownership, and authority.
The Boundary of Animality
Authors: Risan Lars Christian
Published: October 2005

In this paper I explore some limits of the generalized symmetry of actor-network theory. The paper is based on a study on cows, farming technology, and farming science, and is empirically based on an anthropological fieldwork in modern, computerized cowsheds. By exploring differences in interactions between human beings and cows, on the one hand, and between human beings and computers, on the other, I argue that the partly common natural history of human beings and cows, and the lack of such a history in human–computer interactions, makes it impossible to be agnostic about where to find subjectivity in such a place as a cowshed. Animal bodies (including human beings) demand certain kinds of interactions, and thus produce certain distributions of subjectivities. The boundary of animality is not a purely ‘cultural’ distinction, and cannot be deconstructed as such.
Biological imaging by soft x-ray diffraction microscopy
Authors: Shapiro David , Thibault Pierre , Beetz Tobias , Elser Veit , Howells Malcolm , Jacobsen Chris , Kirz Janos , Lima Enju , Miao Huijie , Neiman Aaron M. , Sayre David
Published: October 2005

We have used the method of x-ray diffraction microscopy to image the complex-valued exit wave of an intact and unstained yeast cell. The images of the freeze-dried cell, obtained by using 750-eV x-rays from different angular orientations, portray several of the cell's major internal components to 30-nm resolution. The good agreement among the independently recovered structures demonstrates the accuracy of the imaging technique. To obtain the best possible reconstructions, we have implemented procedures for handling noisy and incomplete diffraction data, and we propose a method for determining the reconstructed resolution. This work represents a previously uncharacterized application of x-ray diffraction microscopy to a specimen of this complexity and provides confidence in the feasibility of the ultimate goal of imaging biological specimens at 10-nm resolution in three dimensions.
Single-particle tracking of murine polyoma virus-like particles on live cells and artificial membranes
Authors: Ewers Helge , Smith Alicia E. , Sbalzarini Ivo F. , Lilie Hauke , Koumoutsakos Petros , Helenius Ari
Published: October 2005

The lateral mobility of individual murine polyoma virus–like particles (VLPs) bound to live cells and artificial lipid bilayers was studied by single fluorescent particle tracking using total internal reflection fluorescence microscopy. The particle trajectories were analyzed in terms of diffusion rates and modes of motion as described by the moment scaling spectrum. Although VLPs bound to their ganglioside receptor in lipid bilayers exhibited only free diffusion, analysis of trajectories on live 3T6 mouse fibroblasts revealed three distinct modes of mobility: rapid random motion, confined movement in small zones (30–60 nm in diameter), and confined movement in zones with a slow drift. After binding to the cell surface, particles typically underwent free diffusion for 5–10 s, and then they were confined in an actin filament-dependent manner without involvement of clathrin-coated pits or caveolae. Depletion of cholesterol dramatically reduced mobility of VLPs independently of actin, whereas inhibition of tyrosine kinases had no effect on confinement. The results suggested that clustering of ganglioside molecules by the multivalent VLPs induced transmembrane coupling that led to confinement of the virus/receptor complex by cortical actin filaments.
Early age-related cognitive impairment in mice lacking cannabinoid CB1 receptors
Authors: Bilkei-Gorzo A. , Racz I. , Valverde O. , Otto M. , Michel K. , Sarstre M. , Zimmer A.
Published: October 2005

The molecular mechanisms contributing to the normal age-related decline of cognitive functions or to pathological learning and memory impairment are largely unknown. We demonstrate here that young mice (6–7 weeks) with a genetic deletion of the cannabinoid CB1 receptor performed as well as WT mice, or often better, in a number of learning and memory paradigms, including animal models of skill-learning, partner recognition, and operant conditioning. In contrast, the performance of mature mice (3–5 months) lacking CB1 receptors was much worse than that of age-matched WT animals. In most tests, these mice performed at the same level as old animals (14–17 months), suggesting that the decline in cognitive functions is accelerated in the absence of CB1 receptors. This rapid decline in CB1-deficient animals is accompanied by a loss of neurons in the CA1 and CA3 regions of the hippocampus.
Antibody vs. HIV in a clash of evolutionary titans
Authors: Burton Dennis R. , Stanfield Robyn L. , Wilson Ian A.
Published: October 2005

HIV has evolved many strategies to avoid neutralizing antibody responses, particularly to conserved regions on the external glycoprotein spikes of the virus. Nevertheless, a small number of antibodies have been evolved by the human immune system to recognize conserved parts of the glycoproteins, and therefore, have broadly neutralizing cross-strain activities. These antibodies constitute important tools in the quest to design immunogens that can elicit broadly neutralizing antibodies in humans and hence contribute to an effective HIV vaccine. Crystallographic analyses of the antibodies, in many cases in an antigen-complexed form, have revealed novel and, in some instances, remarkable structural adaptations to attain virus recognition. Antibodies, like HIV, can evolve relatively rapidly through mutation and selection. It seems that the structures of these broadly neutralizing antibodies bear witness to a heroic struggle between two titans of rapid evolution.
HIV Gag protein conjugated to a Toll-like receptor 7/8 agonist improves the magnitude and quality of Th1 and CD8+T cell responses in nonhuman primates
Authors: Wille-Reece Ulrike , Flynn Barbara J. , Loré Karin , Koup Richard A. , Kedl Ross M. , Mattapallil Joseph J. , Weiss Walter R. , Roederer Mario , Seder Robert A.
Published: October 2005

Induction and maintenance of antibody and T cell responses will be critical for developing a successful vaccine against HIV. A rational approach for generating such responses is to design vaccines or adjuvants that have the capacity to activate specific antigen-presenting cells. In this regard, dendritic cells (DCs) are the most potent antigen-presenting cells for generating primary T cell responses. Here, we report that Toll-like receptor (TLR) agonists and ligands that activate DCsin vitroinfluence the magnitude and quality of the cellular immune response in nonhuman primates (NHPs) when administered with HIV Gag protein. NHPs immunized with HIV Gag protein and a TLR7/8 agonist or a TLR9 ligand [CpG oligodeoxynucleotides (CpG ODN)] had significantly increased Gag-specific T helper 1 and antibody responses, compared with animals immunized with HIV Gag protein alone. Importantly, conjugating the HIV Gag protein to the TLR7/8 agonist (Gag-TLR7/8 conjugate) dramatically enhanced the magnitude and altered the quality of the T helper 1 response, compared with animals immunized with HIV Gag protein and the TLR7/8 agonist or CpG ODN. Furthermore, immunization with the Gag-TLR7/8 conjugate vaccine elicited Gag-specific CD8+T responses. Collectively, our results show that conjugating HIV Gag protein to a TLR7/8 agonist is an effective way to elicit broad-based adaptive immunity in NHPs. This type of vaccine formulation should have utility in preventive or therapeutic vaccines in which humoral and cellular immunity is required.
Method for targeting protein destruction by using a ubiquitin-independent, proteasome-mediated degradation pathway
Authors: Matsuzawa Shu-ichi , Cuddy Michael , Fukushima Toru , Reed John C.
Published: October 2005

With the euchromatic portion of several mammalian genomes now sequenced, emphasis has turned to ascertaining the functions of gene products. A method for targeting destruction of selected proteins in mammalian cells is described, based on the ubiquitin-independent mechanism by which ornithine decarboxylase (ODC) is degraded by the 26S proteasome in collaboration with antizyme (AZ). We show that expressing whole proteins, protein domains, or peptide ligands fused to the N terminus of ODC promotes proteasome-dependent degradation of these chimeric fusion proteins and their interacting cellular target proteins. Moreover, the degradation of the interacting (targeted) protein depends on coexpression of AZ in about half of cases, providing an inducible switch for triggering the degradation process. By using 12 pairs of interacting proteins for testing, direct comparisons with several alternative strategies for achieving targeted protein destruction based on the concept of induced ubiquitination revealed advantages of the ODC/AZ system, which does not require posttranslational attachment of ubiquitin to target proteins. As proof of concept, the ODC/AZ system was used to ablate expression of specific endogenous proteins (e.g., TRAF6; Rb), and was shown to create the expected lesions in cellular pathways that require these proteins. Altogether, these findings reveal a strategy for achieving targeted destruction of cellular proteins, thus providing an additional tool for revealing the cellular phenotypes of gene products.
Social Innovation and Civil Society in Urban Governance: Strategies for an Inclusive City
Authors: Gerometta Julia , Haussermann Hartmut , Longo Giulia
Published: October 2005

Processes of socioeconomic polarisation and social exclusion mark contemporary cities. In many countries, welfare states are in crisis, suffering from post-Fordist transformations. In cities, new ways of governance are needed to overcome the consequences of economic, social and political restructuring. This article seeks to explore the role of civil society in new urban governance arrangements that will hopefully contribute to counter the trends towards social exclusion. While aware of the ambiguity of civil society's role in rebuilding governance relationships, it is argued that, under certain conditions, civil society is found to be a valuable contributor towards more cohesive cities and governance arrangements that promote them. Such conditions involve the existence of a multiscalar democratic governance regime that favours public deliberation and social economy initiatives.
Business Privilege and the Strategic Planning Agenda of the Greater London Authority
Authors: Thornley Andy , Rydin Yvonne , Scanlon Kath , West Karen
Published: October 2005

The establishment of the Greater London Authority (GLA) in 2000 brought a new form of politics to London and new powers to formulate strategic policy. Through an investigation of the access of business interests in the formulation of London's strategic agenda, this article illuminates one aspect of the pressures on city government. It uses the urban regime approach as a framework for analysing the co-operation between the Mayor and business interests in shaping strategic priorities. Although there was a surrounding rhetoric that pointed towards a greater consensus-seeking approach, the business sector was very active in maintaining its privileged access. Strategic priorities were established in the GLA's first year and were then subsequently embodied in the London Plan. Our analysis is based on a detailed examination of this agenda-setting period using material from meetings, written reports and interviews with key actors.
Assessing the Effect of Area Based Initiatives on Local Area Outcomes: Some Thoughts Based on the National Evaluation of the Single Regeneration Budget in England
Authors: Rhodes John , Tyler Peter , Brennan Angela
Published: October 2005

During the past 25 years, there has been an extensive use of Area Based Initiatives (ABIs) to regenerate run-down areas in many countries. However, despite their increased popularity, evidence on their success in helping to turn around depressed areas remains elusive. The evidence base has been constrained by inadequate understanding of the theory of change behind the policy intervention, insufficient development of evaluation theory and method and a lack of information about the impact of the interventions on the key outcomes that they are designed to affect. This article seeks to address the third of these limitations-namely, a focus on the impact of ABIs on key outcomes that reflect the quality of life of the people who live in depressed areas. However, it also considers issues relating to the other two key factors. The article illustrates how the impacts of ABIs on key outcomes might be assessed by drawing upon recent findings that have emerged from an evaluation of one of the largest ABI programmes that has been deployed in England, that of the Single Regeneration Budget.
Predictors of strong sense of coherence and positive attitudes to physical education in adolescents
Authors: Sollerhed Ann-Christin , Ejlertsson Göran , Apitzsch Erwin
Published: October 2005

Aims: The aim of this study was to find variables related to positive attitudes to physical education (PE) and strong sense of coherence (SOC) among adolescents. Methods: The study included three parts: seven physical tests; a questionnaire which included ways of living, attitudes to PE, and subjective health, the 13-question version of SOC; and information on every student's grades. The study group comprised 301 teenagers (131 girls and 170 boys, aged 16—19 years) attending upper secondary school. Positive odds ratio was used in the logistic regression analyses with SOC and attitudes to PE as dependent variables. Results: Variables related to positive attitudes to PE were strong SOC, high physical capacity, high leisure-time physical activity (PA), high grades in PE, and little time spent watching TV. Variables related to strong SOC were positive attitudes to PE, high grades in PE, very good subjective health, and feeling comfortable in school. Highest physical capacity, highest mean grades, and highest grades in PE were found among adolescents who reported exercise four times or more per week. Conclusions: An interrelation between attitudes to PE and SOC was shown. The relation between positive attitudes to PE and high scores in SOC indicated that past experiences of PA and PE could contribute to the development of SOC, and actual levels of SOC could influence the persistent attitudes to PE and be important for lifelong PA. One means of identification of favourable or unfavourable health behaviour among young people might be through PA patterns, and relations between attitudes to PE and SOC.
Long-term sick-listing among women in the public sector and its associations with age, social situation, lifestyle, and work factors: A three-year follow-up study
Authors: Vingård Eva , Lindberg Per , Josephson Malin , Voss Margaretha , Heijbel Bodil , Alfredsson Lars , Stark Stefan , Nygren Åke
Published: October 2005

Background: Since 1997 the number of long-term sick-listed people in Sweden has increased dramatically, especially among women employed in the public sector. Aims: The aim of this study was to investigate associations between age, social situation, lifestyle, work factors, and long-term sick-listing (≥28 days), regardless of diagnosis, during a period of three years among women employed in the public sector. Methods: Exposure information at baseline was recorded by a questionnaire. All new spells of sick-listing ≥28 days were consecutively reported from the employer for three years from baseline. In total 6,246 women from the public sector in Sweden answered the questionnaire (85% response rate); 5,224 were classified as having good or rather good health for working and were included. Of these, 918 persons had spells of sick-listing ≥28 days during follow-up. Results: Univariate and multivariate analyses for calculating relative risks (RR) were carried out. In the Cox regression model age (RR 1.4), strained financial situation (RR 1.3), obesity (RR 1.3), bullying (RR 1.5), physical demands at work higher than own capacity (RR 1.5), and mental demands at work higher than own capacity (1.2) remained risk indicators for long-term sick-listing. Conclusion: This study suggests prevention of some work and lifestyle factors as general measures to reduce long-term sick-listing among women in the public sector.
Defining the Social Economy and its Governance at the Neighbourhood Level: A Methodological Reflection
Authors: Moulaert Frank , Nussbaumer Jacques
Published: October 2005

This largely methodological paper focuses on how to define the social economy and its governance at the local and especially the urban neighbourhood level. A distinction is made between essentialist and holistic definitions. The second section appraises the potential contribution of various current ideas in institutional economics and economic sociology to the definition of the social economy and its governance. It is found that 'old' and 'new' institutionalism in particular offer useful tools, including the holistic methodology as applied by John Commons. The third section elaborates on the analytical elements required for defining the social economy from a holistic perspective, stressing the role of essentialist abstract categories, the role of local culture and articulation between spatial scales. First, we show how the notion of social capital defined through a 'holistic approach' can enrich the definition of the social economy. Secondly, we stress the importance of empirical investigations in feeding into the holistic definitional work. The fourth section concludes the paper by enhancing the necessary dialogue between an abstract-essentialist and a contextualised holistic definition of the social economy at the neighbourhood level.
Spatial Approval Voting
Authors: Laslier Jean-François
Published: October 2005

This article provides a model for analyzing approval voting elections. Within a standard probabilistic spatial voting setting, we show that principal component analysis makes it possible to derive candidates' relative locations from the approval votes. We apply this technique to original experimental data from the French 2002 presidential election.
Lawrence Bragg's role in the development of sound-ranging in World War I
Authors: Van der Kloot William
Published: October 2005

In 1915, when Lawrence Bragg was a 25-year-old Second Lieutenant in the Royal Horse Artillery, seconded to ‘Maps GHQ’, he learned that he and his father had shared the Nobel Prize in physics. Lawrence's equation was crucial for winning the prize and he had been wounded by his father's early dissemination of their work with casual attribution to ‘my son’. Lawrence was responsible for developing methods for pinpointing the position of enemy artillery pieces by recording the boom of their firing with an array of microphones. It was a simple idea but difficult to implement. Step by step, Bragg and the group he assembled solved the problems and developed a system that worked. Sound-ranging was valuable in the British victory at Cambrai in 1917 and vital for that at Amiens in 1918: the ‘black day of the German Army’. He received the MC and the OBE. His Army service manifested both his scientific leadership and administrative skills, which culminated in the demonstrations of the validity of the dream he enunciated in his Nobel lecture: that X-rays could be used to resolve the structure of the most complicated molecules.
History of one defeat: reform of the Julian calendar as envisaged by Isaac Newton
Authors: Belenkiy Ari , Vila Echagüe Eduardo
Published: October 2005

Having been asked in February 1700 by The Royal Society to respond to G. W. Leibniz's letter from Hanover about the decision of the German states to accept a so-called ‘improved calendar’, Isaac Newton, then Master of the Mint, developed a proposal for the reform of the Julian and Ecclesiastical calendars that was later found among his unpublished manuscripts (now grouped as Yahuda MS 24). His calendar, if implemented, would have become for England a viable alternative to the Gregorian. Despite having a different algorithm, its solar part agrees with the latter untilad2400 and is more precise in the long run, within a period of 5000 years. Although Newton's lunar algorithm is more elegant than the Gregorian, his Ecclesiastical calendar remained incomplete. We explain why blank spaces were left and data were changed in several of the manuscripts, discuss the time frame and the order in which Newton wrote different drafts of Yahuda MS 24, analyse their relation with three manuscripts from the Cambridge collection, and suggest a reason for Newton's delay and failure to press for the implementation of his calendar. Newton, as can be discerned from his statistical analysis of Hipparchus's equinox observations, can be credited, historically, with the first application of the technique known today aslinear regression analysisand also with a remarkable guess about the ancient Greek observations of the equinoxes that recently has been confirmed.
A free-surface capturing method for two fluid flows with moving bodies
Authors: Qian L , Causon D.M , Mingham C.G , Ingram D.M
Published: October 2005

A two-fluid solver has been developed for flow problems with both moving solid bodies and free surfaces. The underlying scheme is based on the solution of the incompressible Navier–Stokes equations for a variable density fluid system with a free surface. The cut cell method is used for tracking moving solid boundaries across a stationary background Cartesian grid. The computational domain encompasses fully both fluid regions and the fluid interface is treated as a contact discontinuity in the density field, which is captured automatically without special provision as part of the numerical solution using a time-accurate artificial compressibility method and high resolution Godunov-type scheme. A pressure-splitting algorithm is proposed for the accurate treatment of the normal pressure gradient at the interface in the presence of a gravity term. The Cartesian cut cell technique provides a highly efficient and fully automated process for generating body fitted meshes, which is particularly useful for moving boundary problems. Several test cases have been calculated using the present approach including a moving paddle as a wave generator and the initial stages of entry into still water of rigid wedges. The results compare well with other theoretical results and experimental data. Finally, test cases involving the entry into water and subsequent total immersion of a two-dimensional rigid wedge-shaped body as well as the inverse problem of wedge egress have been calculated to demonstrate the ability of the current method to tackle more general two fluid flows with interface break-up, reconnection, entrapment of one fluid into the other, as well as handling moving bodies of complex geometry.
Antagonistic coevolution with parasites increases the cost of host deleterious mutations
Authors: Buckling Angus , Wei Yan , Massey Ruth C , Brockhurst Michael A , Hochberg Michael E
Published: October 2005

The fitness consequences of deleterious mutations are sometimes greater when individuals are parasitized, hence parasites may result in the more rapid purging of deleterious mutations from host populations. The significance of host deleterious mutations when hosts and parasites antagonistically coevolve (reciprocal evolution of host resistance and parasite infectivity) has not previously been experimentally investigated. We addressed this by coevolving the bacterium
Pseudomonas fluorescens
and a parasitic bacteriophage in laboratory microcosms, using bacteria with high and low mutation loads. Directional coevolution between bacterial resistance and phage infectivity occurred in all populations. Bacterial population fitness, as measured by competition experiments with ancestral genotypes in the absence of phage, declined with time spent coevolving. However, this decline was significantly more rapid in bacteria with high mutation loads, suggesting the cost of bacterial resistance to phage was greater in the presence of deleterious mutations (synergistic epistasis). As such, resistance to phage was more costly to evolve in the presence of a high mutation load. Consistent with these data, bacteria with high mutation loads underwent less rapid directional coevolution with their phage populations, and showed lower levels of resistance to their coevolving phage populations. These data suggest that coevolution with parasites increases the rate at which deleterious mutations are purged from host populations.
Skin function parameters in intensive‐care patients
Authors: Fischer Matthias , Donath Christian , Radke Joachim , Marsch Wolfgang Ch. , Soukup Jens
Published: October 2005

Background/purpose: The study was performed to investigate the transepidermal water loss (TEWL) and pH‐value in patients in intensive care.

Methods: Forty intensive‐care patients (22 men, 18 women) were included in the study. TEWL and pH‐values were measured at admission, and after 24, 96 and 168 h. The areas of measurement were the forehead, the volar forearm, paraumbilical and the ventral thigh. The measurements were made under standardized environmental conditions according to the recommendations of the EMCO Group.

Results: Elevated values were found on the forehead compared with the other skin areas examined. There was no significant change in mean TEWL‐values in any patient in the course of the study. There was also no significant influence of TEWL at the time of admission on the prognosis. The course analysis of the mean pH‐values, however, showed that patients who developed a systemic inflammatory response syndrome (SIRS) or sepsis during the further course had a higher pH‐value over the entire study period.

Conclusion: TEWL and the pH of the skin surface could be measured at bedside in the intensive‐care unit and delivered reproducible results. These parameters appear, however, to be relevant only for subgroups of patients under intensive care.
Digital image enhancement for in vivo laser scanning microscopy
Authors: Gruber Martin J. , Wackernagel Alexandra , Richtig Erika , Koller Silvia , Kerl Helmut , Smolle Josef
Published: October 2005

Background/purpose: In vivo confocal laser scanning microscopy (CLSM) is a new method that provides skin images in horizontal plane at a level of resolution that allows to view microanatomic structures. This study examines whether certain digital image‐processing steps can increase the visibility of various structures in CLSM.

Study design: Fifty images were taken from normal skin of 25 probands, and 39 image enhancement procedures were created. Eight procedures that seemed to provide some quality enhancement were deliberately selected for further evaluation. Subsequently, a collection of random pairs of the original image and an image submitted to any of the eight selected procedures was rated by five independent observers.

Results: In three of the eight procedures tested, the modified image was significantly preferred to the original image (χ2‐test,: P≤0.001). In particular, smoothing, shading correction, delineate and grey‐level normalization in various combinations were helpful in showing the characteristic honeycomb pattern, pigmented basal cell layer, cell borders and the nuclei more clearly.

Conclusion: Digital image processing may help to increase visibility of in vivo CLSM images.
Age and skin structure and function, a quantitative approach (I): blood flow, pH, thickness, and ultrasound echogenicity
Authors: Waller Jeanette M. , Maibach Howard I.
Published: October 2005

Background/purpose: The aging process has been studied with fervor recently, given our shifting demographics. Since age's effects are so manifest in skin's appearance, structure, mechanics, and barrier function, it is not surprising that much effort has been placed in research to better understand them. Quantitative measurements permitted by bioengineering have allowed us to objectively and precisely study aging skin. These overviews piece together the immense amounts of information that have emerged from recent technological advances in dermatological research in order to develop a unified understanding of the quantitative effects of age on the skin.

Methods: We performed a literature on age‐related changes in blood flow, pH, skin thickness, and ultrasound imaging data, searching Pub‐med, Em‐Base, Science Citation Index, and the UCSF dermatological library's collection of books on the topic of aging skin.

Results: Despite the many tools and techniques available for quantitative analysis of skin, age studies are often conflicting, especially in the areas of blood flow and skin thickness. Trends indicate that blood flow may decrease with age, especially in sites exposed to the environment. pH apparently varies little until the age of 70, after which it declines. Skin thickness data are difficult to interpret; while the stratum corneum is generally accepted to maintain its thickness during aging, dermal, epidermal, and whole skin thickness changes are controversial. Ultrasound reveals the appearance of a subepidermal low echogenic band that thickens with age, especially in environmentally exposed areas. Some studies also indicate the presence of an echogenic band in the lower dermis which thins with increased age. However, the whole dermis appears to become more echogenic in elderly people.

Conclusion: Much remains to be done if we are to reach consensus on the effects of age on skin structure and function. Future studies would be benefited by increased standardization of skin sites tested, methodology, and increased sample size.
Fluorescence fibre‐optic confocal microscopy of skin in vivo: microscope and fluorophores
Authors: Suihko Christian , Swindle Lucinda D. , Thomas Steven G. , Serup Jørgen
Published: October 2005

Background/aims: Fibre‐optic confocal imaging in vivo is a new approach in the assessment of human skin. The objective is to describe a novel instrument and its operation and use in combination with fluorophores.

Methods: The Stratum® is a fibre‐optic fluorescence confocal microscope especially developed for the study of skin and mucous membranes. The system is flexible and any body site can be studied with a hand‐held scanner. The light source is a 488 nm argon ion laser. Horizontal (en face) images of the epidermis and outer dermis are produced with cellular resolution. Magnification is approximately 1000 × . Fluorescein sodium is routinely used as fluorophore (intradermal injection or application to the skin surface). This fluorophore is safe for human use in vivo, but other substances (rhodamine B, Acridine Orange, green fluorescent protein, curcumin) have also been studied.

Results: The instrument produces sharp images of epidermal cell layers from the epidermal surface to the sub‐papillary dermis, with sub‐cellular resolution. The scanner is flexible in use. The technique of intradermal fluorophore injection requires some skill.

Conclusions: We consider this fibre‐optic instrument a potentially important tool in skin research for non‐invasive optical biopsy of primarily the epidermis. Present use is focussed on research applications, where the fluorophore distribution in the skin may illustrate morphological changes in the epidermis.
Processing and Sintering of Ultrafine MgO‐ZrO2 and (MgO, Y2O3)‐ZrO2 Powders
Authors: Readey Michael J. , Lee Ran‐Rong , Halloran John W. , Heuer Arthur H.
Published: October 2005

Chemical coprecipitation was used to produce ultrafine and easily sinterable MgO‐stabilized and (MgO, Y2O3) stabilized ZrO2 powders. The sintering behavior is very sensitive to post‐precipitation washing because “hard” agglomerates form when the precipitated gels are washed with water, whereas “soft” agglomerates form when they are washed with ethanol. The soft agglomerates pack uniformly, resulting in homogeneous shrinkage of powder compacts to near‐theoretical density. The hard agglomerates result in compacts which have regions of localized densification and a signifiint fraction of residual porosity.