bluuebunny/crossref_metadata_2025 huggingface dataset:
Creating Sustainable Communities - A Means to Enhance Social Mobility?
Authors: Bell Simon , Lane Amanda
Published: December 2009

The purpose of this paper is to describe the origins, composition and outputs of the development in the UK of a generic course: Creating Sustainable Communities (CSC). The paper describes the origins and inception of CSC in work undertaken within coastal communities in the Mediterranean. Developed in order to encourage participation in self-review of sustainability for diverse social groupings in Coastal Area Management Programmes in Cyprus, Malta, Algeria, Slovenia and Lebanon (2000-2006), CSC was subsequently developed in collaboration between Dr Simon Bell and the UK Homes and Communities Academy (HCA - formerly the Academy for Sustainable Communities (ASC)) and linked to the HCA Foundation Degree in Sustainable Communities. By 2007, the course had been refined as a generic module for application in a number of presentational forms: within Higher Education, Continuing Professional Development and community development. CSC provides a powerful means for communities of all kinds to assess their current situation, reflect on how sustainability can be projected onto this reality, measure how sustainable the community is, has been and can be in its own terms and, finally, develop meaningful action plans for agreed change agendas. Such agendas are intended to lead to the enhancement of all aspects of the community and, we argue, can improve the social mobility of all members of the collective. Background to the Course: The Development of the ‘Imagine’ Methodology The Creating Sustainable Communities (CSC)
Spatial Dimensions of Social Mobility
Authors: Williams Dominic
Published: December 2009

Historical urban development patterns in the UK concentrated the poor in private rented housing close to industrial areas. This housing was replaced by social rented housing, which remained behind after de-industrialisation and was later allocated by need rather than by ability to pay. Thus, worklessness and deprivation have become co-dependent. However, social mobility is also driven by economic growth, with deprived neighbourhoods in high growth cities having more mobility or #x2018;churn#x2019; than those in low growth cities and regions.
Revolutionising Local Politics? Radical Experiments in Burkina Faso, Ghana and Uganda in the 1980s
Authors: Dickovick J. Tyler
Published: December 2009

This article compares three African countries whose attempts to transform local governance in the 1980s were among the most dramatic, particularly in rural areas: Burkina Faso under Thomas Sankara (1983–1987), Ghana in the early years of the Jerry Rawlings presidency (1981–1992), and Uganda under Yoweri Museveni (1985–present). Despite surface similarities, especially in the establishment of local ‘people's defence councils’ or ‘resistance councils’, the three experiments had quite different outcomes, as a function both of antecedent conditions in state–society relations and of regimes' choices. A structured comparative-historical argument highlights differing state strategies vis-à-vis important social forces, especially traditional chiefs. Regimes' choices betweenconfrontation,coexistence, and theconstructionof new relations with social forces resulted in different degrees of local political change. The ‘revolutionary’ local experiments provide insight into a general theory of African politics, in which states' transformational powers in rural areas remain circumscribed by entrenched local forces.
Violent Conflicts and Sustainable Development in Bayelsa State
Authors: Ibaba Ibaba
                      S.
Published: December 2009

Although the literature on the Niger Delta has highlighted the impact of the violence raging in the region, the analysis appears to have under-emphasised the effects of violent conflicts on sustainable development in the region. This study sets out to fill this gap. To achieve this, an empirical investigation involving 30 communities was conducted. The study shows that violent conflicts have undermined environmental quality through pollution and unsustainable exploitation of resources. The destruction of lives and property, the stagnation of infrastructure and agricultural development, and the insecurity caused by violence are noted to have constrained productivity, wealth creation and poverty reduction. Governance based on accountability, transparency, and the pursuit of the public good or common interest is seen as the most likely means to end the violence and secure sustainable development in the state.
Violence and National Development in Nigeria: The Political Economy of Youth Restiveness in the Niger Delta
Authors: Arowosegbe Jeremiah O.
Published: December 2009

One element in the contradictions underpinning Nigeria's development crisis is the marginalisation of the youth. This article examines the factors that influence youth restiveness in Nigeria's Niger Delta region. It discusses the impact of conservative elite politics and the oil-centric political economy characterised by the impoverishment, neglect and the repression of the oil-producing communities on the youth in the region. The article raises pertinent questions on the violence–development dialectic, drawing upon the context, dynamics, explanations and impact of youth violence in Nigeria's oil-rich Niger Delta. It examines the contradictions and injustices existing against the ethnic minorities of the oil-bearing communities in the region, from the centralisation of oil revenues by the federal centre and how these have generated marginalisation and violent conflict in the region. Detailing the repressive responses by the Nigerian state and the forms of violence that have occurred in the region between 1999 and 2007, the article discusses the implications of youth violence in the oil-rich Niger Delta for national development in Nigeria. It provides a context for understanding the connection between youth involvement in violent conflict and its deleterious impact on Nigeria's development. Tapping into issues of ethnicity and high-stake elite politics, it locates violent youth behaviour in the politics of exclusion and proffers suggestions for restoring the trust of marginalised youth as a necessary step toward development and peace in Nigeria.
Reinventing Knowledge Systems: With an Application to Recent Systemic Changes in East and South Asia
Authors: von Tunzelmann Nick
Published: December 2009

The paper is built around a critique of the recent book by McNeely and Wolverton, entitled Reinventing Knowledge. The paper first contests the concepts of ‘knowledge’ and ‘institutions’, before arguing that the ‘systems’ within which knowledge is embedded are in reality growing more and more complex. The huge scale and scope of the present‐day Internet in our view invalidate their rather one‐dimensional view of knowledge accumulation and their downplayed interpretation of the impact of the Internet. Our historical studies indicate that the Internet ‘revolution’ lies at the core of the ‘Third Industrial Revolution’ the advanced industrial nations are currently experiencing, which seems likely to transform the worlds that such nations are facing, not just in certain technologies or products, but in broader domains of the organization of production and innovation, their management and governance. The final section of the paper assesses the recent ‘growth dynamics’ in Eastern and Southern Asia and finds mostly confirmation of the points already made, in societies that eagerly await them.
Information Technology and the Economics of Storing, Spreading and Generating Knowledge
Authors: Earl Peter E.
Published: December 2009

This paper examines the future for the growth and transmission of knowledge with a particular focus on the collision between the zero‐marginal‐cost economics of online publishing and the finite attention spans of those who download content. The paper tries to show that while it is likely that the information revolution will produce much greater equality of access to knowledge, its impacts on the efficiency with which people pick up capabilities or generate new knowledge remain debatable.
Pathological Knowledge‐Based Economies: Towards a Knowledge‐Based Economy Perspective on the Current Crisis
Authors: Engelbrecht Hans‐Jürgen
Published: December 2009

The crisis that started on Wall Street in mid‐2007 and that has turned into a global financial and economic crisis is also a crisis of knowledge‐based economies (KBEs). In fact, it is related to intrinsic features of such economies. The central point argued in this paper is the need for a specific knowledge‐based economy perspective on the crisis that takes human nature seriously, i.e. that incorporates psychological factors like Keynes’ ‘animal spirits’. Such a perspective is a pre‐requisite for designing institutions that might be able to reduce the likelihood of the development of severe pathologies of KBEs in future. It also suggests the need for a new kind of welfare economics.
Student Appropriation of Writing Lessons through Hybrid Composing Practices: Direct, Diffuse, and Indirect Use of Teacher-Offered Writing Tools in an ESL Classroom
Authors: Ranker Jason
Published: December 2009

This is a qualitative case study (conducted in an urban, public school classroom in the United States) of the collaborative composing processes of two groups of first-grade students designated as English Language Learners (ELLs) as they wrote in a writing workshop context. I focused on a specific type of the students' hybrid composing practices: those that featured them combining elements of their cultural and linguistic repertoires with writing tools offered by the teacher's lessons. These hybrid composing practices served as a medium for the students to appropriate (Wertsch, 1998) the teacher-offered writing tools into their composing repertoires. I identified three types, or degrees, of student appropriation of lesson elements: direct, diffuse, and indirect. During direct appropriation, students incorporated elements from the writing lesson during the composing period immediately after the lesson. In cases of a diffuse or indirect relationship between the lesson and situated composing, students used lessons from previous days in unpredictable ways, used a broader theme or idea from the lesson, or transformed the purposes of the writing period to explore practices not anticipated by the lesson. Several pedagogical implications related to ELL-designated students' uses of hybrid composing practices in workshop settings are also discussed.
Adolescent Literacy—Reviewing Adolescent Literacy Reports: Key Components and Critical Questions
Authors: Faggella-Luby Michael N. , Ware Sharon M. , Capozzoli Ashley
Published: December 2009

There is growing concern that adolescent learners are not adequately prepared to meet the literacy challenges of school and life. To address this concern, a proliferation of reports related to adolescent literacy has attempted to synthesize and translate related research for a variety of stakeholders including educators, administrators, and policy makers. Such reports are essential to recommend components of successful programs and practices but are potentially overwhelming in scope and volume for practitioners. The purpose of this essay review is to identify key components and pressing critical questions from a variety of adolescent literacy reports that will direct improvement in reading for older students. This article serves as a primary review, presenting common threads across the reports related to core instruction for all students, supplemental instruction for adolescent struggling readers, the infrastructure necessary to support improved outcomes, and critical questions for moving forward as a field. Following this core review, three responses highlight perspectives from research, practice, and policy. First, Elizabeth Moje invites readers to consider the historical and sociocultural dimensions of the topic, discussing both overlooked research that has been conducted, and overlooked topics that have yet to be addressed by research. Next, Lori Digisi provides a practitioner's viewpoint, looking at literacy practices and results in her state, district, and school. Finally, Kris Gutierrez calls for the development of a broad federal literacy policy, one that is inclusive of individuals across the lifespan and is sensitive to the needs of students from non-dominant communities.
Any l-state solutions of the Klein–Gordon equation for the modified Rosen–Morse potential with centrifugal term
Authors: Qiang Wen-Chao , -Li Kai , Chen Wen-Li , Wang Xi-ming
Published: December 2009

We present the analytical solutions of the Klein–Gordon equation with the modified Rosen–Morse potential within the framework of an approximation to the centrifugal potential for any l state. The explicit expressions of bound state energy spectra and eigenfunctions are obtained. We also numerically solved the Klein–Gordon equation without any approximation to the centrifugal term for the same potential and compared the numerical energy levels with those of the approximate analytical results. It is found that the approximate analytical results of energy eigenvalues are in good agreement with those numerically obtained.
Standard cosmological evolution in the f(R) model to Kaluza–Klein cosmology
Authors: Aghmohammadi A , Saaidi Kh , Abolhassani M R , Vajdi A
Published: December 2009

In this paper, using f(R) theory of gravity we explicitly calculate cosmological evolution in the presence of a perfect fluid source in four- and five-dimensional space–time in which this cosmological evolution in self-creation is presented by Reddy et al (2009 Int. J. Theor. Phys.
48 10). An exact cosmological model is presented using a relation between Einstein's gravity field equation components due to a metric with the same component from f(R) theory of gravity. Some physics and kinematical properties of the model are also discussed.
Entanglement swapping in the two-photon Jaynes–Cummings model
Authors: dSouza A D , Cardoso W B , Avelar A T , Baseia B
Published: December 2009

In the present work, we study the entanglement swapping via the two-photon process without explicitly using the Bell-state measurement. We employ the appropriate ‘full two-photon Hamiltonian approach’ instead of the ‘effective Hamiltonian approach’ used in recent schemes. We obtain entanglement swapping with 94.7% fidelity for maximally entangled states by conveniently choosing the atom–field interaction time. The success probability is also considered.
Displacement formulae for noncommutative operators
Authors: Hsu Bailey C , Huele Jean-François S Van
Published: December 2009

We present analytical expressions for displacements that involve noncommutative operators. We generalize the standard displacement formula D

a

f(x)=f(x-a) by considering successively the displacement effect of momentum operators in noncommutative quantum mechanics [p

i
,p

j
]=iθ
ij
, d-dimensional radial momentum operators p

r

(d)=- iℏ(∂
r
+(d−1)/2) and spin-dependent operators. The noncommutativity results in three characteristic effects: the appearance of phase factors, space-modulated displacements and staggered spin-dependent displacements.
Soliton solutions and Bäcklund transformation for the generalized inhomogeneous coupled nonlinear Schrödinger equations via symbolic computation
Authors: Wang Pan , Tian Bo , Liu Wen-Jun , Liu Ying , Qu Qi-Xing
Published: December 2009

The generalized inhomogeneous coupled nonlinear Schrödinger (CNLS) equations are under investigation in this paper. Based on the Hirota method, the bilinear form and analytic one-, two- and N-soliton solutions are obtained, of which some properties are discussed simultaneously. Furthermore, with symbolic computation, the Bäcklund transformation and some sample soliton solutions for the inhomogeneous CNLS equations are given.
Darboux transformation and new periodic wave solutions of generalized derivative nonlinear Schrödinger equation
Authors: Tian Shou-fu , Zhang Tian-tian , Zhang Hong-qing
Published: December 2009

In this paper, three new kinds of N-fold Darboux transformations with multiparameters for the spectral problem associated with the generalized derivative nonlinear Schrödinger (GDNS) equation are structured with the help of different gauge transformations. With these transformations, some new (2N-1)-soliton periodic wave solutions for the GDNS equation are obtained by taking positon spectral (λ> 0), negaton spectral (λ<0) and complexiton spectral solutions. This method can also be applied to other nonlinear evolution equations.
Electromagnetic wave reflection from right- and left-handed anisotropic materials
Authors: Hillion P
Published: December 2009

The propagation of electromagnetic plane waves in anisotropic media is analyzed when permittivity and permeability tensors are simultaneously diagonalizable with components ε
j
, μ
j
, j=1,2,3, being positive or negative according to whether the material is right or left handed. The behavior of transverse electric, transverse magnetic (TE, TM) fields in biaxial media is carefully analyzed. In uniaxial materials with ε1=ε2, μ1=μ2, analytical expressions are obtained for the components of two harmonic plane waves propagating with different refractive indexes. These results are used to discuss the reflection of a harmonic plane wave, impinging from an isotropic medium on the plane boundary of biaxial and uniaxial anisotropic half space material. In each case, the two possibilities—right- and left-handed materials—are discussed in parallel. The main novelty of this work lies in the definition of left-handed anisotropic media.
Study of a bounded Coulomb potential
Authors: Ateser Engin , Ciftci Hakan , Yalcin Zeynel
Published: December 2009

In this paper, we have studied a new bounded Coulombic potential for the Schrödinger equation with the asymptotic iteration method (AIM). We have calculated energy eigenvalues for different potential parameters.
Improving the wavefunction of the Schwinger multichannel method for positron scattering—II: Application for elastic and inelastic e+-H2 scattering
Authors: Lino Jorge L S
Published: December 2009

In the present paper, we propose a development to the Schwinger multichannel (SMC) method (Germano J S E and Lima M A P 1993 Phys. Rev. 47 3976) for the elastic and inelastic scattering of positrons by targets of arbitrary geometry. The essence of this work is based on the fact that the main limitation of the SMC method for positron scattering lies in what makes it a general method, i.e. the expansion of the scattering function is done in an L2 basis (Cartesian Gaussian functions) and this is very effective for short-range potentials. Our effort is to improve the SMC method through the use of plane waves as trial functions (SMC-PW) (Lino J L S 2007 Phys. Scr. 76 521). In order to do this, we have to evaluate reliable codes involving matrix elements of the type , which is done here by direct numerical quadrature. Calculated elastic differential and inelastic integral cross sections for positron–H2 collisions are reported. For the elastic scattering, we discuss a mechanism for the Buckingham polarization model using an adjustable energy-dependent parameter at intermediate energies in the range 50–200 eV. We also present a preliminary study on the excitation of the X 1Σ+
g→B 1Σ+
u transitions in H2. Our calculations for inelastic scattering cover the impact range of 13.5–30 eV investigated by Arretche and Lima (2006 Phys. Rev. A 74 042713) using the traditional SMC method. Our inelastic and elastic cross sections are found to be in reasonable agreement with other theoretical studies and experimental data.
The Hulthén potential in D-dimensions
Authors: Agboola D
Published: December 2009

An approximate solution of the Schrödinger equation with the Hulthén potential is obtained in D-dimensions with an exponential approximation of the centrifugal term. A solution to the corresponding hyperradial equation is given by using the conventional Nikiforov–Uvarov method. The normalization constants for the Hulthén potential are also computed. The expectation values ⟨r
−2⟩, ⟨V(r)⟩ are also obtained by using the Hellmann–Feynman theorem.
Particle collision frequency and particle density at equilibrium. I
Authors: Peev N S
Published: December 2009

The subject of the present paper is the formation of multiatomic particles such as clusters and nanoparticles. The probability for collision of two particles in an amorphous medium at equilibrium is derived and the particle frequency of collision per unit volume per unit time has been evaluated. Within the frame of given assumptions and approximations, the equilibrium density of two- and three-atomic particles in the medium has been assessed. This approach may be significant in the investigation of the process of new phase nuclei formation. The existence of a limit value of the particle size for coalescence is supposed by this approach.
van der Waals three-body force shell model (VTSM) for the lattice dynamical studies of thallous bromide
Authors: Tiwari Sarvesh K , Pandey L K , Shukla Lal Ji , Upadhyaya K S
Published: December 2009

The van der Waals three-body force shell model (VTSM) has been developed by modifying the three-body force shell model (TSM) for the lattice dynamics of ionic crystals with cesium chloride (CsCl) structure. This new model incorporates van der Waals interactions along with long-range Coulomb interactions, three-body interactions and short-range second neighbour interactions in the framework of a rigid shell model (RSM). In the present paper, VTSM has been used to study the lattice dynamics of thallous bromide (TlBr), from which adequacy of VTSM has been established. A comparative study of the dynamical behaviour of TlBr has also been done between the present model and TSM, the model over which modification has been made to obtain the present model VTSM. Good agreement has been observed between the theoretical and experimental results, which give confidence that it is an appropriate model for the complete description of ionic crystals with CsCl structure.
The Faraday effect in a semiconductor rectangular quantum wire
Authors: Jabrailova G G , Ismailov T G
Published: December 2009

We theoretically study the interband Faraday rotation (FR) in a rectangular quantum wire (QWR) with infinite barriers in a transverse magnetic field. The FR is calculated as a function of an incident light energy for different values of magnetic field and wire size. It is shown that on the FR curve, the resonance peaks appear and they split at large magnetic fields. The selection rules are derived. Numerical results are presented for GaAs/AlGaAs rectangular QWR.
The magnetism and photoluminescence of nickel-doped SnO2 nano-powders
Authors: Liu C M , Fang L M , Zu X T , Zhou W L
Published: December 2009

The magnetism and photoluminescence (PL) of nickel-doped SnO2 nano-powders were studied in detail. A weak room temperature hysteresis is obtained in the pure SnO2 nano-powders, which means that no extra transition metal ions are needed for obtaining magnetism in SnO2 nano-powders. Furthermore, it is found that the measured magnetic moment per nickel ion is reduced with the doping content increasing. The ratio of ferromagnetic ordering moments to the measured magnetic moment is quickly decreased by nickel doping. This may be contributing to the anti-ferromagnetic interaction caused by nickel doping. The PL signal is split into two emission bands with annealing temperature increasing above 200 °C, which may be due to the reduction of twofold-coordinated tin oxygen-deficient centers. The ultraviolet emission band is separated into two peaks at higher doping content.
Structural studies of calcium phosphate doped with titanium and zirconium obtained by high-energy mechanical alloying
Authors: Silva C C , Sombra A S B
Published: December 2009

In this paper, we present a new variation of the solid-state procedure on the synthesis of bioceramics with titanium (CapTi) and zirconium (CapZr), considering that zirconium (ZrO2) and titanium oxide (TiO2) are strengthening agents, due to their superb force and fracture toughness. The high efficiency of the calcination process opens a new way of producing commercial amounts of nanocrystalline bioceramics. In this work, a new variation of the solid-state procedure method was used to produce nanocrystalline powders of titanium and zirconium, using two different experimental chemical routes: CapTi: Ca(H2PO4)2+TiO2 and CapZr: Ca(H2PO4)2+ZrO2. The powders were submitted to calcination processes (CapTic and CapZrc) at 800, 900 and 1000 °C. The calcium titanium phosphate phase, CaTi4P6O24, was obtained in the CapTic reaction and the calcium zirconium phosphate, CaZr4P6O24, was obtained in the CapZrc reaction. The obtained ceramics were characterized by x-ray powder diffraction (XRD), infrared (IR) spectroscopy, Raman scattering spectroscopy (RSS) and scanning electron microscopy (SEM) analysis. This method was compared with the milling process (CapTim and CapZrm), where in the last process the melting is not necessary and the powder obtained is nanocrystalline. The calcium titanium phosphate phase, CaTi4P6O24, was obtained in the reaction CapTim, but in CapZrm the formation of any calcium phosphate phase even after 15 h of dry mechanical alloying was not observed.
Comment on ‘Calculations of electron angular distribution in resonant Auger decay for Na, Ba, Hg and Kr*’
Authors: Kleiman U , Lohmann B
Published: December 2009

We make a comment on the discrepancy between the numerical results for the angular anisotropy parameter α2 for the L3M1M4, 5 Auger transitions of Kr, Xe, Ba and Hg which have been obtained by Elizarov and Tupitsyn (2004 Phys. Scr. 70 139) and beforehand by ourselves (Kleiman and Lohmann 2000 J. Phys. B: At. Mol. Opt. Phys. 33 2653). By comparing the results obtained not only for the angular anisotropy parameter α2 but also for the dynamic spin polarization parameter ξ2, where the latter agree considerably better, it is most likely that the discrepancies are mainly due to some of the phase differences because the parameter α2 depends on the cosine of the phase differences whereas the parameter ξ2 depends on the sine.
Mutual Dependence of Mob1 and the Chromosomal Passenger Complex for Localization during Mitosis
Authors: Wilmeth Lori Jo , Shrestha Sanjay , Montaño Gilbert , Rashe Jennifer , Shuster Charles Bradley
Published: December 2009

The spatial and temporal coordination of chromosome segregation with cytokinesis is essential to ensure that each daughter cell receives the correct complement of chromosomal and cytoplasmic material. In yeast, mitotic exit and cytokinesis are coordinated by signaling cascades whose terminal components include a nuclear Dbf2-related family kinase and a noncatalytic subunit, Mps one binding (Mob) 1. There are five human Mob1 isoforms, all of which display redundant localization patterns at the spindle poles and kinetochores in early mitosis, and the spindle midzone during cytokinesis. Mob1 shares similar localization patterns to Polo-like kinase (Plk1) and the chromosomal passenger complex (CPC), and although depletion of Plk1 resulted in a loss of Mob1 from the spindle poles, Mob1 recruitment to kinetochores was unaffected. Conversely, disruption of CPC signaling resulted in a loss of Mob1 from kinetochores without disrupting recruitment to the spindle poles. In Mob1-depleted cells, the relocalization of the CPC and mitotic kinesin-like protein (MKLP) 2 to the spindle midzone was delayed during early anaphase, and as a consequence, the midzone recruitment of MKLP1 also was affected. Together, these results suggest that Mob1 and the other mammalian orthologues of the mitotic exit network regulate mitotic progression by facilitating the timely mobilization of the CPC to the spindle midzone.
The Exo70 Subunit of the Exocyst Is an Effector for Both Cdc42 and Rho3 Function in Polarized Exocytosis
Authors: Wu Hao , Turner Courtney , Gardner Jimmy , Temple Brenda , Brennwald Patrick
Published: December 2009

The Rho3 and Cdc42 members of the Rho GTPase family are important regulators of exocytosis in yeast. However, the precise mechanism by which they regulate this process is controversial. Here, we present evidence that the Exo70 component of the exocyst complex is a direct effector of both Rho3 and Cdc42. We identify gain-of-function mutants in EXO70 that potently suppress mutants in RHO3 and CDC42 defective for exocytic function. We show that Exo70 has the biochemical properties expected of a direct effector for both Rho3 and Cdc42. Surprisingly, we find that C-terminal prenylation of these GTPases both promotes the interaction and influences the sites of binding within Exo70. Finally, we demonstrate that the phenotypes associated with novel loss-of-function mutants in EXO70, are entirely consistent with Exo70 as an effector for both Rho3 and Cdc42 function in secretion. These data suggest that interaction with the Exo70 component of the exocyst is a key event in spatial regulation of exocytosis by Rho GTPases.
Myosin II Is Essential for the Spatiotemporal Organization of Traction Forces during Cell Motility
Authors: Meili Ruedi , Alonso-Latorre Baldomero , del Álamo Juan C. , Firtel Richard A. , Lasheras Juan C.
Published: December 2009

Amoeboid motility requires spatiotemporal coordination of biochemical pathways regulating force generation and consists of the quasi-periodic repetition of a motility cycle driven by actin polymerization and actomyosin contraction. Using new analytical tools and statistical methods, we provide, for the first time, a statistically significant quantification of the spatial distribution of the traction forces generated at each phase of the cycle (protrusion, contraction, retraction, and relaxation). We show that cells are constantly under tensional stress and that wild-type cells develop two opposing “pole” forces pulling the front and back toward the center whose strength is modulated up and down periodically in each cycle. We demonstrate that nonmuscular myosin II complex (MyoII) cross-linking and motor functions have different roles in controlling the spatiotemporal distribution of traction forces, the changes in cell shape, and the duration of all the phases. We show that the time required to complete each phase is dramatically increased in cells with altered MyoII motor function, demonstrating that it is required not only for contraction but also for protrusion. Concomitant loss of MyoII actin cross-linking leads to a force redistribution throughout the cell perimeter pulling inward toward the center. However, it does not reduce significantly the magnitude of the traction forces, uncovering a non–MyoII-mediated mechanism for the contractility of the cell.
Biology of Maize Kernel Infection by Fusarium verticillioides
Authors: Duncan Keith E. , Howard Richard J.
Published: December 2009

Fusarium kernel rot disease starburst symptomatology was characterized fully for the first time. Two maize lines were hand pollinated and inoculated, using a fluorescent protein-expressing transformant of the fungal pathogen Fusarium verticillioides, by introduction of a conidial suspension through the silk channel of intact ears. Microscopy was used to identify the infection court and document initial stages of kernel colonization and subsequent manifestation of macroscopic symptoms. The fungus entered kernels of susceptible line AD38 via an open stylar canal and spread extracellularly and over the kernel through the nucellus region, sporadically entering pericarp and filling the long thick-walled mesocarp cells. Hyphae spread within pericarp from cell to cell via pits, colonizing files of host cells by growing both up and down the kernel in a radial pattern that preceded macroscopic symptom development. The starburst symptom developed subsequently, and mirrored colonization exactly, when there was extensive dissolution of the thick walls of pericarp cells. Line HT1 exhibited a closed stylar canal phenotype and was not susceptible—except when the pericarp surface was breached mechanically. We hypothesize the passive movement of conidia along the surface of silks, perhaps via capillarity, as a possible mechanism for pathogen access to the infection court.
Discriminating Mutations of HC-Pro ofZucchini yellow mosaic viruswith Differential Effects on Small RNA Pathways Involved in Viral Pathogenicity and Symptom Development
Authors: Wu Hui-Wen , Lin Shih-Shun , Chen Kuan-Chun , Yeh Shyi-Dong , Chua Nam-Hai
Published: December 2009

Helper component-proteinase (HC-Pro), the gene-silencing suppressor of Potyvirus spp., interferes with microRNA (miRNA) and short-interfering RNA (siRNA) pathways. Our previous studies showed that three mutations of highly conserved amino acids of HC-Pro, R180I (mutation A), F205L (B), and E396N (C), of Zucchini yellow mosaic virus (ZYMV) affect symptom severity and viral pathogenicity. The mutant ZYMV GAC (ZGAC) with double mutations, R180I/E396N, induces transient leaf mottling in host plants followed by recovery. This mutant confers complete cross protection against subsequent infection by the parental ZYMV (ZG) strain. Here, we sought to obtain molecular evidence on the roles of the three highly conserved amino acids of HC-Pro in miRNA and siRNA pathways using transgenic Arabidopsis plants expressing comparable levels of wild-type and mutant HC-Pro proteins. We demonstrated that amino acid residues 180, 205, and 396 of HC-Pro are critical for suppression of miRNA, trans-acting siRNA (ta-siRNA), and virus-induced gene silencing (VIGS) pathways but not for sense-post transcriptional gene silencing (s-PTGS). Because the HC-Pro double mutant (R180I/E396N) does not interfere with miRNA and ta-siRNA pathways, the ZGAC mutant virus elicits only attenuated symptoms. Furthermore, the recovery seen on ZGAC-infected plants likely results from the weak VIGS suppression by the HC-Pro double AC mutant. Thus, through manipulating these three conserved amino acids on HC-Pro, symptom severity of diseases caused by Potyvirus spp. can be modulated to generate useful cross protectants for field application. Although some of our mutated HC-Pro proteins do not interfere with miRNA and ta-siRNA pathways, they still retain the ability to suppress s-PTGS.
Basal Host Resistance of Barley to Powdery Mildew: Connecting Quantitative Trait Loci and Candidate Genes
Authors: Aghnoum Reza , Marcel Thierry C. , Johrde Annika , Pecchioni Nicola , Schweizer Patrick , Niks Rients E.
Published: December 2009

The basal resistance of barley to powdery mildew (Blumeria graminis f. sp. hordei) is a quantitatively inherited trait that is based on nonhypersensitive mechanisms of defense. A functional genomic approach indicates that many plant candidate genes are involved in the defense against formation of fungal haustoria. It is not known which of these candidate genes have allelic variation that contributes to the natural variation in powdery mildew resistance, because many of them may be highly conserved within the barley species and may act downstream of the basal resistance reaction. Twenty-two expressed sequence tag or cDNA clone sequences that are likely to play a role in the barley–Blumeria interaction based on transcriptional profiling, gene silencing, or overexpression data, as well as mlo, Ror1, and Ror2, were mapped and considered candidate genes for contribution to basal resistance. We mapped the quantitative trait loci (QTL) for powdery mildew resistance in six mapping populations of barley at seedling and adult plant stages and developed an improved high-density integrated genetic map containing 6,990 markers for comparing QTL and candidate gene positions over mapping populations. We mapped 12 QTL at seedling stage and 13 QTL at adult plant stage, of which four were in common between the two developmental stages. Six of the candidate genes showed coincidence in their map positions with the QTL identified for basal resistance to powdery mildew. This co-localization justifies giving priority to those six candidate genes to validate them as being responsible for the phenotypic effects of the QTL for basal resistance.
A Kelch Repeat Protein, Cokel1p, Associates with Microtubules and Is Involved in Appressorium Development in Colletotrichum orbiculare
Authors: Sakaguchi Ayumu , Miyaji Toshihiko , Tsuji Gento , Kubo Yasuyuki
Published: December 2009

Kelch repeat proteins are conserved in diverse organisms and some are known to mediate fundamental cellular functions. We isolated the gene CoKEL1, encoding a novel kelch repeat protein, from Colletotrichum orbiculare. Analysis of a cokel1 mutant indicated that CoKEL1 is involved in proper appressorium development and cell wall synthesis. Appressoria produced by cokel1 disruption mutants showed irregular shape and impairment of turgor generation and the mutant appressoria rarely penetrated to form infection hyphae in host epidermal cells. Accordingly, cokel1 mutants had reduced pathogenicity on host leaves compared with the wild type. Furthermore, the cokel1 mutant was more sensitive to cell-wall-degrading enzymes and showed altered labeling with the cell wall stain Calcofluor white. Cokel1p was localized on cortical and spindle microtubules in vegetative hyphae. These results suggest that Cokel1p is a microtubule-associated protein involved in infection-related morphogenesis and pathogenicity. This is the first report that a kelch repeat protein is required for the pathogenicity of a fungal plant pathogen.
A Novel Protein Com1 Is Required for Normal Conidium Morphology and Full Virulence in Magnaporthe oryzae
Authors: Yang Jun , Zhao Xiaoyan , Sun Jing , Kang Zhensheng , Ding Shengli , Xu Jin-Rong , Peng You-Liang
Published: December 2009

In Magnaporthe oryzae, pyriform conidia are the primary inoculum and the main source for disease dissemination in the field. In this study, we identified and characterized the COM1 gene that was disrupted in three insertional mutants producing slender conidia. COM1 encodes a putative transcription regulator unique to filamentous ascomycetes. The com1 disruption and deletion mutants had similar defects in conidium morphology and were significantly reduced in virulence on rice and barley seedlings. Microscopic examination revealed that the Δcom1 mutants were defective in appressorium turgor generation, penetration, and infectious growth. COM1 was expressed constitutively in M. oryzae. The Com1 protein had putative helix-loop-helix structures and three predicted nuclear localization signal sequences. In transformants expressing COM1335-613–enhanced green fluorescent protein fusion constructs, fluorescence signals were observed in the nucleus. Our data indicated that the COM1 gene may encode a novel transcription regulator that regulates conidial development and invasive growth in M. oryzae.
How hazardous is the Sahara Desert crossing for migratory birds? Indications from satellite tracking of raptors
Authors: Strandberg Roine , Klaassen Raymond H. G. , Hake Mikael , Alerstam Thomas
Published: December 2009

We investigated the risk associated with crossing the Sahara Desert for migrating birds by evaluating more than 90 journeys across this desert by four species of raptors (osprey
Pandion haliaetus
, honey buzzard
Pernis apivorus
, marsh harrier
Circus aeruginosus
and Eurasian hobby
Falco subbuteo
) recorded by satellite telemetry. Forty per cent of the crossings included events of aberrant behaviours, such as abrupt course changes, slow travel speeds, interruptions, aborted crossings followed by retreats from the desert and failed crossings due to death, indicating difficulties for the migrants. The mortality during the Sahara crossing was 31 per cent per crossing attempt for juveniles (first autumn migration), compared with only 2 per cent for adults (autumn and spring combined). Mortality associated with the Sahara passage made up a substantial fraction (up to about half for juveniles) of the total annual mortality, demonstrating that this passage has a profound influence on survival and fitness of migrants. Aberrant behaviours resulted in late arrival at the breeding grounds and an increased probability of breeding failure (carry-over effects). This study also demonstrates that satellite tracking can be a powerful method to reveal when and where birds are exposed to enhanced risk and mortality during their annual cycles.
Visual stabilization dynamics are enhanced by standing flight velocity
Authors: Theobald Jamie C. , Ringach Dario L. , Frye Mark A.
Published: December 2009

A flying insect must travel to find food, mates and sites for oviposition, but for a small animal in a turbulent world this means dealing with frequent unplanned deviations from course. We measured a fly's sensory-motor impulse response to perturbations in optic flow. After an abrupt change in its apparent visual position, a fly generates a compensatory dynamical steering response in the opposite direction. The response dynamics, however, may be influenced by superimposed background velocity generated by the animal's flight direction. Here we show that constant forward velocity has no effect on the steering responses to orthogonal sideslip perturbations, whereas constant parallel sideslip substantially shortens the lags and relaxation times of the linear dynamical responses. This implies that for flies stabilizing in sideslip, the control effort is strongly affected by the direction of background motion.
Bioinspired engineering study of Plantae vascules for self-healing composite structures
Authors: Trask R. S. , Bond I. P.
Published: December 2009

This paper presents the first conceptual study into creating a Plantae-inspired vascular network within a fibre-reinforced polymer composite laminate, which provides an ongoing self-healing functionality without incurring a mass penalty. Through the application of a ‘lost-wax’ technique, orthogonal hollow vascules, inspired by the ‘ray cell’ structures found in ring porous hardwoods, were successfully introduced within a carbon fibre-reinforced epoxy polymer composite laminate. The influence on fibre architecture and mechanical behaviour of single vascules (located on the laminate centreline) when aligned parallel and transverse to the local host ply was characterized experimentally using a compression-after-impact test methodology. Ultrasonic C-scanning and high-resolution micro-CT X-ray was undertaken to identify the influence of and interaction between the internal vasculature and impact damage. The results clearly show that damage morphology is influenced by vascule orientation and that a 10 J low-velocity impact damage event is sufficient to breach the vasculature; a prerequisite for any subsequent self-healing function. The residual compressive strength after a 10 J impact was found to be dependent upon vascule orientation. In general, residual compressive strength decreased to 70 per cent of undamaged strength when vasculature was aligned parallel to the local host ply and a value of 63 per cent when aligned transverse. This bioinspired engineering study has illustrated the potential that a vasculature concept has to offer in terms of providing a self-healing function with minimum mass penalty, without initiating premature failure within a composite structure.
An eigenstrain-based model for residual stress arising from transient local surface heating
Authors: Bromley J. M. , Saimoto A. , Alizadeh H. , Smith D. J. , Truman C. E.
Published: December 2009

We present a model for approximating residual stresses arising from thermally induced plasticity and apply it to a simple two-dimensional (plane strain) test problem of transient heating. The model uses stress fields derived from simple eigenstrains to perturb an initially elastic-only solution in a way that mimics plastic flow. The plane strain condition of the test problem gives rise to plastic strains in the
out-of-plane
direction, owing to constraints on thermal expansion. However, the model is able to cope with the challenges this poses and also encapsulates the time-dependent nature of the problem. We show that the model agrees well with finite-element simulations under moderate strength heat sources provided that appropriate plastic flow rules are used. There exists sufficient generality in the model to allow its extension to more realistic scenarios.
Boundary integral equations for general laminated plates with coupled stretching–bending deformation
Authors: Hwu Chyanbin
Published: December 2009

The boundary integral equations for the stretching–bending coupling analysis of general laminated plates are derived in this paper with the aid of the reciprocal theorem of Betti and Raleigh. No restriction is placed on the location of the point load or moment, and so it can be an internal or external point or a smooth or non-smooth boundary point. The fundamental solutions derived from Green’s function for an infinite laminated plate subjected to concentrated forces/moments are presented in the complex matrix form. Through the use of some identities converting complex form to real form, the free term coefficients, which are important for the boundary integral equations, are obtained explicitly and expressed in the real form. Alternative formulae for calculating the free term coefficients are also derived using five rigid body movements. By using the explicit real expressions obtained recently for the Stroh-like formalism of coupled stretching–bending analysis, the free term coefficients are further reduced to the cases of isotropic plates and are then compared with known expressions published in the literature. Since stretching and bending decouple for isotropic plates, comparison is made separately for the in-plane problem and plate bending problem, and it is shown that the boundary integral equations derived in this paper agree with previous results for these two special cases.
The longitudinal static stability of an aerodynamically alleviated marine vehicle, a mathematical model
Authors: Collu Maurizio , Patel Minoo H. , Trarieux Florent
Published: December 2009

An assessment of the relative speeds and payload capacities of airborne and waterborne vehicles highlights a gap that can be usefully filled by a new vehicle concept, utilizing both hydrodynamic and aerodynamic forces. A high-speed marine vehicle equipped with aerodynamic surfaces is one such concept. In 1904, Bryan & Williams (Bryan & Williams 1904
Proc. R. Soc. Lond.
73
, 100–116 (doi:10.1098/rspl.1904.0017)) published an article on the longitudinal dynamics of aerial gliders, and this approach remains the foundation of all the mathematical models studying the dynamics of airborne vehicles. In 1932, Perring & Glauert (Perring & Glauert 1932 Reports and Memoranda no. 1493) presented a mathematical approach to study the dynamics of seaplanes experiencing the planing effect. From this work, planing theory has developed. The authors propose a unified mathematical model to study the longitudinal stability of a high-speed planing marine vehicle with aerodynamic surfaces. A kinematics framework is developed. Then, taking into account the aerodynamic, hydrostatic and hydrodynamic forces, the full equations of motion, using a small perturbation assumption, are derived and solved specifically for this concept. This technique reveals a new static stability criterion that can be used to characterize the longitudinal stability of high-speed planing vehicles with aerodynamic surfaces.
Solar change and climate: an update in the light of the current exceptional solar minimum
Authors: Lockwood Mike
Published: December 2009

Solar outputs during the current solar minimum are setting record low values for the space age. Evidence is here reviewed that this is part of a decline in solar activity from a grand solar maximum and that the Sun has returned to a state that last prevailed in 1924. Recent research into what this means, and does not mean, for climate change is reviewed.