bluuebunny/crossref_metadata_2025 huggingface dataset:
Lattice vibration of Sr3TaGa3Si2O14 single crystal
Authors: Li Yingfeng , Lu Guiwu , Yang Hong , Lan Jianhui , Zhang Jun , Huang Wenqi , Zhao Kun , Wang Zengmei , Yuan Duorong
Published: September 2006

Based on the space group theory, the normal vibrational modes of Sr3TaGa3Si2O14 (STGS) single crystal were predicted, and the Raman scattering intensities of non‐polar and polar modes were calculated. The lattice vibration modes of STGS crystal were studied by density functional theory (DFT) using the Dmol3 module in Material Studio program package. A Sr3TaGa2SiO12 cluster was constructed, and its vibrational frequencies were calculated using GAUSSIAN98 quantum chemistry suite. Excellent agreement has been achieved between theory prediction and Raman spectroscopy experiment results. The layer structure of STGS crystal was identified, and its small anisotropy and piezoelectric modulus are ascribed to the weak distortion of decahedral unit. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of flexoelectricity on the propagation of nonlinear strain waves in solids
Authors: Mirzade Fikret Kh.
Published: September 2006

A system of equations is formulated to describe the self‐consistent behavior of elastic displacement fields and the concentration field of nonequilibrium point atomic defects (vacancies, interstitial atoms) in irradiated crystals with a symmetry center (germanium, silicon). In accordance with the values of the defect relaxation times, the model equations are derived, describing the propagation of nonlinear 1D longitudinal strain waves, with regard to the flexoelectric effect. The effect is due to the dielectric polarization induced by nonuniform elastic deformations of the lattice. For a particular relationship between the coefficients of these equations, i.e., between the parameters of the subsystem of defects and those of the nonlinear elastic medium, the exact solutions are obtained, which describe both the shock‐wave structures of low‐intensity and the evolution of solitary strain waves. The contributions of the strain‐defect interaction and the flexoelectric effect to the linear and nonlinear elastic modulus and the dispersion and dissipation properties of the medium are estimated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prediction of size disorder induced resonant tunneling in large scale nanodot arrays
Authors: Chen J. , Lu J. J. , Shen W. Z.
Published: September 2006

We have successfully investigated the effect of size fluctuation on the resonant tunneling characteristics of nanodots arrays. The approach was realized with taking into account the induced electron energy level disorder under the framework of the generalized Breit–Wigner formula. It is found that the dot size fluctuation has played an important role in both the tunneling current profile and number of the resonant peaks. By the aid of the statistical concept to characterize the size fluctuation in large scale nanodots systems, we have shown a clear picture for the dependence of the resonant peak number and peak to valley ratio on the degree of disorder and spatial configuration in the nanodots. The whole investigation will give a general prediction of the origin of resonant tunneling phenomena observed in large scale nanodot systems. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of dilution and disorder on magnetism in diluted spin systems
Authors: Tang Guixin , Nolting Wolfgang
Published: September 2006

The influence of configurational disorder on the magnetic properties of diluted Heisenberg spin systems is studied with regard to the ferromagnetic stability of diluted magnetic semiconductors. The equation of motion of the magnon Green's function is decoupled by Tyablikov approximation. With supercell approach, the concentrations of magnetic ions are determined by the size of the supercell in which there is only one magnetic ion per supercell in our method. In order to distinguish the influence of dilution and disorder, there are two kinds of supercells being used: the diluted and ordered case and the diluted and disordered case. The configurational averaging of magnon Green function due to disorder is treated in the augmented space formalism. The random exchange integrals between two supercells are treated as a matrix. The obtained magnon spectral densities are used to calculate the temperature dependence of magnetization and Curie temperature. The results are shown as following: (i) dilution leads to increasing the averaged distance of two magnetic ions, further decreases the effective exchange integrals and is main reason to reduce Curie temperature; (ii) spatial position disorder of magnetic ions results in the dispersions of the exchange integrals between two supercells and slightly changes ferromagnetic transition temperature; (iii) the exponential damping of distance dependence obviously reduces Curie temperature and should be set carefully in any phenomenological model. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exact analytical solutions to the Kratzer potential by the asymptotic iteration method
Authors: Bayrak O. , Boztosun I. , Ciftci H.
Published: September 2006

For any n and l values, we present a simple exact analytical solution of the radial Schrödinger equation for the Kratzer potential within the framework of the asymptotic iteration method (AIM). The exact bound‐state energy eigenvalues (Enl) and corresponding eigenfunctions (Rnl) are calculated for various values of n and l quantum numbers for CO, NO, O2, and I2 diatomic molecules. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Survival curve estimation for informatively coarsened discrete event‐time data
Authors: Shardell Michelle , Scharfstein Daniel O. , Bozzette Samuel A.
Published: September 2006

Interval‐censored, or more generally, coarsened event‐time data arise when study participants are observed at irregular time periods and experience the event of interest in between study observations. Such data are often analysed assuming non‐informative censoring, which can produce biased results if the assumption is wrong. This paper extends the standard approach for estimating survivor functions to allow informatively interval‐censored data by incorporating various assumptions about the censoring mechanism into the model. We include a Bayesian extension in which final estimates are produced by mixing over a distribution of assumed censoring mechanisms. We illustrate these methods with a natural history study of HIV‐infected individuals using assumptions elicited from an AIDS expert. Copyright © 2006 John Wiley & Sons, Ltd.
Bayesian sensitivity analysis for unmeasured confounding in observational studies
Authors: McCandless Lawrence C. , Gustafson Paul , Levy Adrian
Published: September 2006

We consider Bayesian sensitivity analysis for unmeasured confounding in observational studies where the association between a binary exposure, binary response, measured confounders and a single binary unmeasured confounder can be formulated using logistic regression models. A model for unmeasured confounding is presented along with a family of prior distributions that model beliefs about a possible unknown unmeasured confounder. Simulation from the posterior distribution is accomplished using Markov chain Monte Carlo. Because the model for unmeasured confounding is not identifiable, standard large‐sample theory for Bayesian analysis is not applicable. Consequently, the impact of different choices of prior distributions on the coverage probability of credible intervals is unknown. Using simulations, we investigate the coverage probability when averaged with respect to various distributions over the parameter space. The results indicate that credible intervals will have approximately nominal coverage probability, on average, when the prior distribution used for sensitivity analysis approximates the sampling distribution of model parameters in a hypothetical sequence of observational studies. We motivate the method in a study of the effectiveness of beta blocker therapy for treatment of heart failure. Copyright © 2006 John Wiley & Sons, Ltd.
Recent advances in TGFβ‐regulated transcription during carcinogenesis
Authors: Buck Anita , Ellenrieder Volker
Published: September 2006

The multifunctional activities of transforming growth factor‐beta (TGFβ) endow it with both tumor suppressor and tumor promoting activities, depending on the stage of carcinogenesis and the cellular activation state. In early tumor stages, TGFβ inhibits epithelial cell growth through induction of apoptosis and transcriptional regulation of cell cycle controlling genes. During tumor progression, however, many cancer cells escape from TGFβ‐induced growth inhibition and, instead, respond to TGFβ with increased malignancy. TGFβ stimulates tumor promotion particularly in those tumor cells in which Smad‐signaling remains functional and through transcriptional regulation of gene expression. Thus, loss of sensitivity to growth inhibition by TGFβ is not synonymous with complete loss of TGFβ signaling. Rather, it suggests that tumor cells gain advantage by selective inactivation of TGFβ tumor suppressor activities while retaining its tumor promoting functions. In this review we focus on novel aspects in TGFβ signaling and transcription and in particular on the role of Smad‐interacting transcription factors. We also summarize recent advances in both cytoplasmic and nuclear crosstalk mechanisms between Smad and non‐Smad signaling pathways and how this interaction results in the fine‐tuning of Smad‐mediated transcription during cancer progression. This knowledge will help to better understand the molecular mechanisms responsible for the switch of TGFβ from a tumor suppressor to a tumor promotor.
Moving on: Molecular mechanisms in TGFβ‐induced epithelial cell migration
Authors: Giehl Klaudia , Menke Andre
Published: September 2006

TGFβ, particularly TGFβ1‐3, has been shown to promote epithelial dedifferentiation or epithelial‐mesenchymal transition (EMT). While inhibition of epithelial cell proliferation in response to TGFβ is mainly mediated by the well‐characterised Smad‐pathway and subsequent regulation of gene transcription, the molecular mechanisms leading to TGFβ‐induced migration, invasion and metastasis of epithelial tumour cells are less clear. Recent results from several groups suggest that the gain of tumourigenic activity by TGFβ includes signalling by mitogen‐activated protein kinases (MAP kinases), phosphatidylinositol 3‐kinase (PI3‐K) and Rho‐GTPases. Activation of the MAP kinases extracellular signal‐regulated kinase (ERK) 1 and 2, p38 as well as c‐jun N‐terminal kinase (JNK) has been identified as important steps in TGFβ‐induced, Smad4‐independent signal transduction in epithelial cells. A role of activated ERK and JNK and their association with focal complexes in TGFβ‐induced cell migration and actin cytoskeleton reorganisation of carcinoma cells has been identified recently. In this review we will focus on new data about the molecular mechanisms involved in the TGFβ‐induced Smad‐independent regulation of epithelial cell migration.
US Law: Some Research Hints
Authors: Norman Paul
Published: September 2006

Paul Norman passes on the benefit of his many years' experience of researching US law at the Institute of Advanced Legal Studies.
Life at a Large US Law Firm
Authors: Batchen Joan
Published: September 2006

Joan Batchen, who is Firmwide Library Services Manager for Kirkland & Ellis LLP, describes the entrepreneurial nature of the organization and outlines the services offered by the library and information services within this context.
The American Collection at Middle Temple Library
Authors: Hayward Vanessa
Published: September 2006

Vanessa Hayward, Librarian and Keeper of the Records at Middle Temple, charts the history of one of the most important collections of American law in this country.
One Site Fits All? Opening the Door on Legal Portals
Authors: Wallis Chris
Published: September 2006

Chris Wallis provides a useful guide to developments in the legal portal market and continues our series of articles on portals begun in the last issue with an article by Jill Halford.
Selecting and Implementing Content Management Software for Intranets and Web Sites
Authors: White Martin
Published: September 2006

The majority of websites and intranets are built by creating static HTML pages with software such as FrontPage and Dreamweaver. The effective use of these products requires staff with a combination of technical, design and content management skills, and these are not easy to find, even for large organisations. Over the last few years content management software has become increasingly popular as a way of being able to ensure that the content on web sites and intranets can be updated as quickly as necessary without the need for everyone who wants to publish to be trained in a software product such as Front Page.
An Overview of German Academic and Legal Research Libraries
Authors: Read Katherine
Published: September 2006

Katherine Read identifies some of the main issues which made a particular impression on her during her CILIP sponsored visit to Germany. Particular highlights include a feature on a virtual library of legal resources and a look at some of the current copyright issues under discussion.
ROUSSEAU AND THE REPRESENTANTS: THE POLITICS OF THE LETTRES ECRITES DE LA MONTAGNE
Authors: WHATMORE RICHARD
Published: September 2006

Rousseau's Lettres écrites de la montagne have traditionally been cited as evidence of the influence on his thinking of Genevan traditions of democratic republican political argument, on the grounds that the Lettres were written on behalf of those members of the citizens and bourgeois in the city who were critical of the growing powers of the magistracy, the co-called représentants. This essay proposes a different reading. It argues that the Lettres confirmed long-standing Genevan suspicions about Rousseau's politics and theology which were held both by the représentants and the magistrates. The reason was that Rousseau had composed the Lettres as a critique both of représentant plans for democratic reform and of magisterial usurpation of the sovereign rights of the citizens. The Lettres underscored Rousseau's commitment to the distinction between sovereignty and government outlined in the Contrat social. Rousseau believed that Geneva deserved to be a model for European states because the distinction between sovereignty and government characteristic of its constitution had such clear historical roots. He also recognized that growing uncertainty concerning the relative powers of the General Council, the smaller executive committees of leading magistrates, and the Consistory had created a political impasse. Accordingly the Lettres argued for a new political settlement, that would redefine the constitutional relationship between citizens and magistrates, as well as between church and the state. Rousseau emerges as a dedicated enemy of democratic political innovation in Geneva, and an advocate of renewed Reformation which would make religion the foundation of an anti-commercial morality. Rousseau's singular and heterodox perspective on Geneva and its history is outlined in the essay, which places Rousseau's Lettres in the broader local context of republican and magisterial reform politics.
POLITICAL THEOLOGY AND THE NAZI STATE: CARL SCHMITT'S CONCEPT OF THE INSTITUTION
Authors: BATES DAVID
Published: September 2006

The fundamental importance of theology in the work of Carl Schmitt has been the subject of much recent literature on this controversial figure. However, there has been little consensus on the precise nature of Schmitt's own political theology—that is, on what links there are between his religious or metaphysical concepts and his ideas concerning the nature of political organization and action. This is especially the case with his works of the Nazi era, which are now being studied with the same kind of critical attention given to his more influential Weimar works. In this essay I focus on the important turn Schmitt made in the early years of the Third Reich, from “decisionism” to what he called “institutional thinking,” in order to reveal the theological basis for his understanding of the new regime. I will then argue that Schmitt's institutional approach had in fact always been central to his earlier, better-known writings on law and the state. Schmitt's concept of the institution, which had roots in French legal theory, grounded a political theology that was in the end less a metaphysical approach to the state than one that drew on the concrete example of the legal institutional order of the Catholic Church.
SCIENTISM AND ITS DISCONTENTS: THE INDO-MUSLIM “FASCISM” OF INAYATULLAH KHAN AL-MASHRIQI
Authors: DAECHSEL MARKUS
Published: September 2006

This essay offers a detailed reconstruction of the thought of Inayatullah Khan al-Mashriqi, a camp-follower of fascism in inter-war India who sought to reformulate Islam as a “Religion of Science” according to the precepts of Darwinian evolutionism. Mashriqi has so far been neglected because his political impact was only short-term and did not contribute to the larger story of decolonization in India and Pakistan. But far from being marginal, Mashriqi's philosophical ruminations actually provide a window for a much-needed re-evaluation of the meaning of colonial modernity. While there was much in Mashriqi's writing that conforms to the usual picture of anti-colonial nation-building—his obsession with the truth of science, for instance, and his emphasis on disciplinary political methodologies—the by now standardized critique of such features in the “postcolonial” literature no longer suffices. Behind a façade of continuities with nineteenth-century “Enlightenment” traditions stood a much darker vision of modernity that no longer had any recourse to the certainties of a grand narrative of modernization. Instead, it was a vision that fluctuated between mystical exuberance and deep pessimism. The only sense of certainty was provided by a radical notion of emotional authenticity and a related belief in quasi-religious leadership figures. The larger conclusion to be drawn from the dualistic and contradictory structure of Mashriqi's “fascism” is that the intellectual history of inter-war South Asia needs to be given relative autonomy from the standard nationalism–modernization narrative, for rather than the continuation of an earlier modernity, it should be interpreted as the starting point of a new and much darker formation that arguably continues into the present.
High‐Level Gene Expression for Recombinant Penicillin Acylase Production Using the araB Promoter System in Escherichia coli
Authors: Narayanan Niju , Xu Yali , Chou C. Perry
Published: September 2006

The pac gene encoding penicillin acylase (PAC) was overexpressed under the regulation of the araB promoter (ParaB, also known as PBAD) in Escherichia coli(E. coli). The current ParaB expression system exhibited minimum leaking pac expression in the absence of arabinose as well as fast and high‐level pac expression upon induction with arabinose in a wide concentration range. The production of PAC was limited by the accumulation of PAC precursors (i.e., proPAC in both soluble and insoluble forms) and various negative cellular responses, such as growth arrest and cell lysis. The culture performance could be improved by degP coexpression and the individual contribution of DegP protease and chaperone activities to the enhancement on the production of PAC was characterized. The study highlights the importance of identifying the step(s) limiting high‐level gene expression and subsequent design and construction of the host/vector system for enhancing recombinant protein production in E. coli.
High Concentration Cultivation of Bifidobacteriumbifidum in a Submerged Membrane Bioreactor
Authors: Kwon Soun‐Gyu , Son Ju‐Wan , Kim Hye‐Jung , Park Chang‐Su , Lee Jung‐Kul , Ji Geun Eog , Oh Deok‐Kun
Published: September 2006

In batch cultures, after 25 h, the maximum cell mass of Bifidobacterium bifidum BGN4 was 4.5 g/L, and the maximum cell count was 3.0 × 109 cfu/mL at pH 6.0 and 50 g/L sucrose. To increase the viable counts of bifidobacteria, cell retentive culture was applied using a submerged membrane bioreactor with suction and gas sparging. The maximum mass, count, and productivity of the cells after 36 h were 12.0 g/L, 2.2 × 1010 cfu/mL, and 6.1 × 108 cfu/mL·h, respectively, at the feeding (dilution) rate of 120 mL/h (0.06 h−1) in the feeding medium. The accumulated levels of organic acids and ammonium ions at the end of the cultivation were 1.5 and 1.0 g/L, respectively. The viable counts and volumetric productivity of the cells after the cell retentive culture were 7.3‐ and 5.1‐fold higher, respectively, than the values obtained during batch culture. These high viable counts and volumetric productivities were obtained by maintaining lower concentrations of organic acids and ammonium ions so that the growth of B. bifidum BGN4 was not inhibited. The submerged membrane bioreactor produced the highest viable counts of B. bifidum without membrane fouling and cell damage.
New insights on intraplate volcanism in French Polynesia from wavelet analysis of GRACE, CHAMP, and sea surface data
Authors: Panet I. , Chambodut A. , Diament M. , Holschneider M. , Jamet O.
Published: September 2006

In this paper, we discuss the origin of superswell volcanism on the basis of representation and analysis of recent gravity and magnetic satellite data with wavelets in spherical geometry. We computed a refined gravity field in the south central Pacific based on the GRACE satellite GGM02S global gravity field and the KMS02 altimetric grid, and a magnetic anomaly field based on CHAMP data. The magnetic anomalies are marked by the magnetic lineation of the seafloor spreading and by a strong anomaly in the Tuamotu region, which we interpret as evidence for crustal thickening. We interpret our gravity field through a continuous wavelet analysis that allows to get a first idea of the internal density distribution. We also compute the continuous wavelet analysis of the bathymetric contribution to discriminate between deep and superficial sources. According to the gravity signature of the different chains as revealed by our analysis, various processes are at the origin of the volcanism in French Polynesia. As evidence, we show a large‐scale anomaly over the Society Islands that we interpret as the gravity signature of a deeply anchored mantle plume. The gravity signature of the Cook‐Austral chain indicates a complex origin which may involve deep processes. Finally, we discuss the particular location of the Marquesas chain as suggesting that the origin of the volcanism may interfere with secondary convection rolls or may be controlled by lithospheric weakness due to the regional stress field, or else related to the presence of the nearby Tuamotu plateau.
Representative hydraulic conductivities in saturated groundwater flow
Authors: Sanchez‐Vila Xavier , Guadagnini Alberto , Carrera Jesus
Published: September 2006

Heterogeneity is the single most salient feature of hydrogeology. An enormous amount of work has been devoted during the last 30 years to addressing this issue. Our objective is to synthesize and to offer a critical appraisal of results related to the problem of finding representative hydraulic conductivities. By representative hydraulic conductivity we mean a parameter controlling the average behavior of groundwater flow within an aquifer at a given scale. Three related concepts are defined: effective hydraulic conductivity, which relates the ensemble averages of flux and head gradient; equivalent conductivity, which relates the spatial averages of flux and head gradient within a given volume of an aquifer; and interpreted conductivity, which is the one derived from interpretation of field data. Most theoretical results are related to effective conductivity, and their application to real world scenarios relies on ergodic assumptions. Fortunately, a number of results are available suggesting that conventional hydraulic test interpretations yield (interpreted) hydraulic conductivity values that can be closely linked to equivalent and/or effective hydraulic conductivities. Complex spatial distributions of geologic hydrofacies and flow conditions have a strong impact upon the existence and the actual values of representative parameters. Therefore it is not surprising that a large body of literature provides particular solutions for simplified boundary conditions and geological settings, which are, nevertheless, useful for many practical applications. Still, frequent observations of scale effects imply that efforts should be directed at characterizing well‐connected stochastic random fields and at evaluating the corresponding representative hydraulic conductivities.
Impact of human‐induced desertification on the intensification of Sahel dust emission and export over the last decades
Authors: Moulin Cyril , Chiapello Isabelle
Published: September 2006

Human‐induced soil degradation in Sahel is a major concern for regional climate change. A significant increase in long‐range atmospheric dust transport due to human activities would indeed modify the radiative budget and the water cycle over both Africa and the tropical Atlantic. Here we use two independent long‐term datasets, i.e., surface concentration measurements at Barbados between 1965 and 2000 and maps of TOMS dust optical thickness between 1979 and 2000, to evidence an increase of a factor of two of background dust loads over the Atlantic since the mid 60's, independently of any climatic phenomenon. Satellite imagery suggests that this trend can be attributed to an intensification of dust emissions in a Sahel region centered on southern Mali. The desertification caused by the doubling of the population in Sahel over the last 40 years likely explains the observed intensification of the Atlantic dust export.
Dust flux within dust devils: Preliminary laboratory simulations
Authors: Neakrase Lynn D. V. , Greeley Ronald , Iversen James D. , Balme M. R. , Eddlemon Eric E.
Published: September 2006

Laboratory simulations using the Arizona State University Vortex Generator (ASUVG) were run to simulate dust flux in dust devils. These tests used particles 2 μm in diameter and 2600 kg m−3 in density, and the results were compared with data from natural dust devils on Earth and Mars. Typically, the cores of dust devils (regardless of planetary environment) have a pressure drop of ∼0.2–1.5 percent of ambient atmospheric pressure. Core pressure drops in our experiments ranged from ∼0.01 to 5.00 percent of ambient pressure (10 mbar Mars cases and 1000 mbar for Earth cases). Flux experiments were run at vortex tangential wind velocities of 1 to 42 m s−1; typically ∼35–50 percent above threshold values for the particles used. Dust flux was determined by time averaged measurements of mass loss for a given vortex size. Dust fluxes of ∼10−3 kg m−2 s−1 were obtained, similar to estimates for flux for dust devils on Earth and Mars, regardless of core size. Vortex strength appears to be closely related to the strength of the pressure drop in the core (ΔP) and is less determined by size of the vortex. This is critical in scaling the laboratory results to natural dust devils.
Rise and decline of active chlorine in the stratosphere
Authors: Solomon Philip , Barrett James , Mooney Thomas , Connor Brian , Parrish Alan , Siskind David E.
Published: September 2006

Our ground‐based millimeter‐wave measurements of chlorine monoxide (ClO) in the ozone layer above Hawaii since 1992, together with a few measurements from the same site using an earlier version of the same instrument during the 1980's, provide a unique data set for the determination of the long‐term trend of active chlorine in the middle stratosphere. The trend shows a rapid rise of 58% from 1982 to a broad maximum in 1994–1997 and a substantial decline of 1.5%/year from the maximum through late 2004. About 1/3 of the decline may be due to changes in methane. Both the rise and the decline are consistent with that expected from the rise and decline of total chlorine in the troposphere, which reached a maximum in 1992–1993, then declined sharply after implementation of international agreements to phase out chlorofluorocarbon (CFC) production starting with the Montreal Protocol.
Fire‐climate interactions in forests of the American Pacific coast
Authors: Trouet Valerie , Taylor Alan H. , Carleton Andrew M. , Skinner Carl N.
Published: September 2006

We investigate relationships between climate and wildfire activity between 1929 and 2004 in Pacific coast forests of the United States. Self‐Organizing Mapping (SOM) of annual area burned in National Forests (NF) in California, Oregon, and Washington identifies three contiguous NF groups and a fourth group of NF traversed by major highways. Large fire years in all groups are dry compared to small fire years. A sub‐hemispheric circulation pattern of a strong trough over the North Pacific and a ridge over the West Coast is characteristic of large fire years in all groups. This pattern resembles the Pacific North American (PNA) teleconnection and positive phase of the Pacific Decadal Oscillation (PDO). A reverse PNA and negative PDO phase characterizes small fire years. Despite the effect of fire suppression management between 1929 and 2004, forest area burned is linked to climatic variations related to large‐scale atmospheric circulation patterns.
Effect of temperature and atmospheric pressure on methane (CH4) ebullition from near‐surface peats
Authors: Kellner E. , Baird A. J. , Oosterwoud M. , Harrison K. , Waddington J. M.
Published: September 2006

Recent studies suggest that ebullition of biogenic gas bubbles is an important process of CH4 transfer from northern peatlands into the atmosphere and, as such, needs to be better described by models of peat carbon dynamics. We develop and test a simple ebullition model in which a threshold gas volume in the peat has to be exceeded before ebullition occurs. The model assumes that the gas volume varies because of gas production and variations in pressure and temperature. We incubated peat cores in the laboratory for 190 days and measured their volumetric gas contents and the ebullition flux. The laboratory results support the threshold concept and, considering the simplicity of the model, the calculated ebullition compared well with measured fluxes during the final 120 days with an r2 of 0.66. An improved, more realistic description would also include temporal and spatial variations in gas production and bubble retention terms.
Rain‐yield per flash calculated from TRMM PR and LIS data and its relationship to the contribution of tall convective rain
Authors: Takayabu Yukari N.
Published: September 2006

Rain‐yields per flash (RPF) over the entire tropics were calculated from 3 years of data collected by a Lightning Imaging Sensor (LIS) and a Precipitation Radar (PR) housed onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. The results confirm that RPF is a reliable indicator of precipitation regimes, with a marked land–ocean contrast and intermediate values over monsoonal regions and continental oceans. Mean RPF values averaged over the entire TRMM region are 3.94 × 108 kg fl−1 over land and 1.96 × 109 kg fl−1 over oceans. A good (−0.55) correlation between RPF and the Tall Convective Rain Contribution with a threshold of −20degC (TCRC–20C) was found especially over land. This result indicates that large amounts of tall convective rain are fundamentally associated with intense updrafts that are able to sustain vigorous lightning activity. The correlation is weaker over ocean, except for that over continental oceans.
SAR imaging and hydrodynamic analysis of ocean bottom topographic waves
Authors: Zheng Quanan , Li Li , Guo Xiaogang , Ge Yong , Zhu Dayong , Li Chunyan
Published: September 2006

The satellite synthetic aperture radar (SAR) images display wave‐like patterns of the ocean bottom topographic features at the south outlet of Taiwan Strait (TS). Field measurements indicate that the most TS water body is vertically stratified. However, SAR imaging models available were developed for homogeneous waters. Hence explaining SAR imaging mechanisms of bottom features in a stratified ocean is beyond the scope of those models. In order to explore these mechanisms and to determine the quantitative relations between the SAR imagery and the bottom features, a two‐dimensional, three‐layer ocean model with sinusoidal bottom topographic features is developed. Analytical solutions and inferences of the momentum equations of the ocean model lead to the following conditions. (1) In the lower layer, the topography‐induced waves (topographic waves hereafter) exist in the form of stationary waves, which satisfy a lower boundary resonance condition σ = kC0, here σ is an angular frequency of the stationary waves, k is a wavenumber of bottom topographic corrugation, and C0 is a background current speed. (2) As internal waves, the topographic waves may propagate vertically to the upper layer with an unchanged wavenumber k, if a frequency relation N3 < σ < N2 is satisfied, here N2 and N3 are the Brunt‐Wäisälä frequencies of middle layer and upper layer, respectively. (3) The topographic waves are extremely amplified if an upper layer resonance condition is satisfied. The SAR image of topographic waves is derived on the basis of current‐modulated small wave spectra. The results indicate that the topographic waves on SAR images have the same wavelength of bottom topographic corrugation, and the imagery brightness peaks are either inphase or antiphase with respect to the topographic corrugation, depending on a sign of a coupling factor. These theoretical predictions are verified by field observations. The results of this study provide a physical basis for quantitative interpretation of SAR images of bottom topographic waves in the stratified ocean.
Northern hemisphere Martian gullies and mantled terrain: Implications for near‐surface water migration in Mars' recent past
Authors: Bridges Nathan T. , Lackner Claire N.
Published: September 2006

We report on a systematic study of gullies and mantled terrain in the northern hemisphere of Mars. Consistent with previous work, the mantled terrain is generally located on poleward‐facing slopes, and gullies are found at all orientations. New results are as follows: (1) The range of orientations of mantled terrain increases toward the pole, (2) near‐polar gullies are commonly less morphologically developed compared to ones in the temperate latitudes, (3) gullies toward the pole are better preserved than those closer to the equator, and (4) these studies are conducted in the northern hemisphere, whereas most previous work investigated the south. No gully model in the literature cleanly fits all these observations (nor any other gully observations reported in other papers). However, the likely effects of obliquity and precession variations on snow formation, preservation, and melting are consistent with many of the results.
Thermal conductivity measurements of particulate materials: 3. Natural samples and mixtures of particle sizes
Authors: Presley Marsha A. , Craddock Robert A.
Published: September 2006

A line‐heat source apparatus was used to measure thermal conductivities of natural fluvial and eolian particulate sediments under low pressures of a carbon dioxide atmosphere. These measurements were compared to a previous compilation of the dependence of thermal conductivity on particle size to determine a thermal conductivity‐derived particle size for each sample. Actual particle‐size distributions were determined via physical separation through brass sieves. Comparison of the two analyses indicates that the thermal conductivity reflects the larger particles within the samples. In each sample at least 85–95% of the particles by weight are smaller than or equal to the thermal conductivity‐derived particle size. At atmospheric pressures less than about 2–3 torr, samples that contain a large amount of small particles (≤125 μm or 4 Φ) exhibit lower thermal conductivities relative to those for the larger particles within the sample. Nonetheless, 90% of the sample by weight still consists of particles that are smaller than or equal to this lower thermal conductivity‐derived particle size. These results allow further refinement in the interpretation of geomorphologic processes acting on the Martian surface. High‐energy fluvial environments should produce poorer‐sorted and coarser‐grained deposits than lower energy eolian environments. Hence these results will provide additional information that may help identify coarser‐grained fluvial deposits and may help differentiate whether channel dunes are original fluvial sediments that are at most reworked by wind or whether they represent a later overprint of sediment with a separate origin.
Dcr2 targets Ire1 and downregulates the unfolded protein response in Saccharomyces cerevisiae
Authors: Guo Jinbai , Polymenis Michael
Published: September 2006

Accumulation of unfolded proteins in the endoplasmic reticulum triggers the unfolded protein response (UPR). How the UPR is downregulated is not well understood. Inositol requirement 1 (Ire1) is an endoplasmic reticulum transmembrane UPR sensor in Saccharomyces cerevisiae. When the UPR is triggered, Ire1 is autophosphorylated, on Ser 840 and Ser 841, inducing the cytosolic endonuclease activity of Ire1, thereby initiating the splicing and translational de‐repression of HAC1 mRNA. Homologous to Atf/Creb1 (Hac1) activates UPR transcription. Here, we report that the dose‐dependent cell‐cycle regulator 2 (Dcr2) phosphatase functionally and physically interacts with Ire1. We identified genetic interactions between DCR2 and genes, including IRE1, which are involved in secretory processes. Overexpression of DCR2, but not of a catalytically inactive DCR2 allele, significantly delays HAC1 splicing and sensitizes cells to the UPR. Furthermore, Dcr2 physically interacts in vivo with Ire1‐S840E,S841E, which mimics phosphorylated Ire1, and Dcr2 de‐phosphorylates Ire1 in vitro. Our results are consistent with de‐phosphorylation of Ire1 being a mechanism for antagonizing UPR signalling.
Isolation of neural crest‐derived stem cells from rat embryonic mandibular processes
Authors: Zhang Jianping , Duan Xiaoyan , Zhang Huali , Deng Zhihong , Zhou Zeyuan , Wen Ning , Smith Anthony J. , Zhao Wenming , Jin Yan
Published: September 2006

Background information. Substantial evidence indicates the existence of NCSCs (neural crest‐derived stem cells) in embryonic mandibular processes; however, they have not been fully investigated or isolated. The aim of the present study was to isolate stem cells from mandibular process during embryonic development by MACS (magnetic‐activated cell sorting). The findings show that the cells are multipotent and self‐renewing.

Results. LNGFR (low‐affinity nerve‐growth‐factor receptor)+ cells were isolated from rat embryonic mandibular processes by MACS. The cells were grown in clonal culture by limiting dilution to assess their developmental potential. Clone analysis indicated that, first, LNGFR+ cells are multipotent, being able to generate at least neurons and Schwann cells, similar to peripheral neural crest stem cells. Secondly, multipotent LNGFR+ cells generate multipotent progenies, indicating that they are capable of self‐renewal and therefore are stem cells. Thirdly, manipulation of the medium supplementation alters the fate of the isolated LNGFR+ cells.

Conclusions. These results indicate that LNGFR antibodies label NCSCs with high specificity and purity, and suggest that positive selection using these antibodies may become the method of choice for obtaining multipotent cells from rat embryonic mandibular processes for tissue engineering or regenerative therapeutic use.
Identification of Rho GTPases implicated in terminal differentiation of muscle cells in ascidia
Authors: Coisy‐Quivy Marjorie , Sanguesa‐Ferrer Juan , Weill Mylène , Johnson David Scott , Donnay Jean‐Marc , Hipskind Robert , Fort Philippe , Philips Alexandre
Published: September 2006

Background information. Members of the Rho GTPase family mediate changes in the actin cytoskeleton and are also implicated in developmental processes, including myogenesis. Nevertheless, a comprehensive analysis of these proteins during myofibrillogenesis has never been performed in any organism.

Results. Using the ascidian model to identify the role of Rho GTPases on myofibrillogenesis, we show that transcripts for all Rho GTPases are detected in muscle cells of the embryo. We find that activation of RhoA, TC10 and Cdc42 (cell division cycle 42) disturbs the polarity of muscle cells, whereas that of other Rho GTPases induced cell positioning defects. Moreover, dominant negative version of five Rho GTPases, RhoA, Rac2, RCL2 (Rac‐ and Cdc42‐like 2), TC10 and WRCH (Wnt‐1 responsive Cdc42 homologue), impaired the formation of mature myofibrils.

Conclusions. Taken together, our results show that several Rho GTPase‐dependent pathways are required to control the spatial localization of muscle cells in the embryo and to coordinate myofibril assembly. This stresses the importance of analysing the entire Rho family when studying a new biological process.
Industry Evolution and Cross-Sectoral Skill Transfers: A Comparative Analysis of the Video Game Industry in Japan, the United States, and the United Kingdom
Authors: Izushi Hiro , Aoyama Yuko
Published: September 2006

In this paper we explore the interrelationship between technological progress and the formation of industry-specific skills by analysing the evolution of the video-game industry in three countries: Japan, the United States, and the United Kingdom. We argue that the cross-sectoral transfer of skills occurs differently depending on national contexts, such as the social legitimacy and strength of preexisting industries, the socioeconomic status of entrepreneurs or pioneer firms in an emerging industry, and the sociocultural cohesiveness between the preexisting and emerging industries. Each country draws on a different set of creative resources, which results in a unique trajectory. Whereas Japan's video-game industry emerged out of corporate sponsorships in arcades, toys, and consumer electronics industries and drew skills from the comic book and animated-film sectors, the video-game industry in the United States evolved from arcades and personal computers. In the United Kingdom the video-game industry developed bottom-up, through a process of skills formation in the youth culture of ‘bedroom coders' that nurtured self-taught programmers in their teens throughout the country.
The Sociospatial Dynamics of Creativity and Production in Tanzanian Industry: Urban Furniture Manufacturers in a Liberalizing Economy
Authors: Murphy James T
Published: September 2006

The author examines the design, production, and marketing activities of furniture makers in Mwanza, Tanzania and assesses the degree to which innovative and creative competencies and capabilities are emerging within this industry. A conceptual framework from evolutionary economics is applied, and emphasis is placed on situating the social and spatial characteristics of production, innovation, and knowledge creation within the selection environment or context created by Tanzania's economic liberalization process. Specifically, the cognitive, innovative, and organizational competencies and capabilities of furniture makers are detailed and their emergence is explained in relation to the markets, institutions, and spatial structures concomitant with neoliberal reform. The findings demonstrate how liberalization has, in effect, selected for less creative, smaller scale, and largely informal manufacturers while discouraging the development of more innovative, larger scale, and/or formal firms. In a broad sense, the results of the study raise questions about whether or not structural adjustment policies are contributing to the development of viable, globally oriented, and indigenously owned manufacturing firms in African cities like Mwanza.
Advertising and Creativity, a Governance Approach: A Case Study of Creative Agencies in London
Authors: Pratt Andy C
Published: September 2006

The author explores the processes of restructuring in the UK advertising industry. His core concern is with changes in advertising practice in creative advertising agencies. He explores how creativity is manifest as ‘peer regard’, and shows how there has been a shift of power between creative and media-buying functions as a result of the demise of the commission system in the last twenty-five years. A changing governance of advertising practice, that involves both formal regulation and economic governance in and across firms, is highlighted. It is argued that creativity is better seen as an effect rather than as a cause of particular advertising practices. The author concludes that the ‘creative governance’ of the UK advertising industry has favoured a close-knit and colocated community of firms. A future change in this form of governance could change this pattern.
It's not Just a Question of Taste: Gentrification, the Neighbourhood, and Cultural Capital
Authors: Bridge Gary
Published: September 2006

In this paper I explore elements of the relationship between deployments of cultural capital and neighbourhood change. Based on research in a gentrified neighbourhood of Bristol, England, I argue that for gentrifier households with children the need to reproduce (institutional) cultural capital in the education market can conflict with the desire to display (objectified) cultural capital via the gentrification aesthetic in the inner-urban neighbourhood. In the trade-off between aesthetics and education, education wins, resulting in a much more conventional suburban, exurban housing/neighbourhood career for onward-moving gentrifiers. I conclude by suggesting a more diffuse, provincial form of gentrification in which the different strands of cultural capital can conflict in urban space (rather than the smooth reproduction of cultural capital assumed by the idea of a gentrification habitus). It confirms that the intergenerational reproduction of an (urban) new middle class is likely to be confined to large metropolitan areas.
Creativity, Connections and Innovation: A Study of Linkages in the Montréal Region
Authors: Stolarick Kevin , Florida Richard
Published: September 2006

The importance of creativity as a driving force in regional economic growth and prosperity has been previously documented; however, the mechanisms of this relationship are less well understood. Earlier research suggests, but does not demonstrate, that high levels of density and creative-class employment create conditions under which innovations generated by the interactions between individuals are more likely to occur. The authors examine the specific interactions among the creative, technical, business, and design communities of the Montréal region. It is demonstrated that such connections are possible and can have a positive impact on the innovative and total business activity across the region. A set of mechanisms through which creativity helps to achieve regional growth and prosperity benefits is demonstrated through specific examples.