bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrification of wind‐blown sand on Mars and its implications for atmospheric chemistry
Authors: Kok Jasper F. , Renno Nilton O.
Published: March 2009

Wind‐blown sand, or ‘saltation,’ creates sand dunes, erodes geological features, and could be a significant source of dust aerosols on Mars. Moreover, the electrification of sand and dust in saltation, dust storms, and dust devils could produce electric discharges and affect atmospheric chemistry. We present the first calculations of electric fields in martian saltation, using a numerical model of saltation that includes sand electrification, plasma physics, and the adsorption of ions and electrons onto particulates. Our results indicate that electric discharges do not occur in martian saltation. Moreover, we find that the production of hydrogen peroxide and the dissociation of methane by electric fields are less significant than previously thought. Both these species are highly relevant to studies of past and present life on Mars.
Full‐wave reflection of lightning long‐wave radio pulses from the ionospheric D region: Numerical model
Authors: Jacobson Abram R. , Shao Xuan‐Min , Holzworth Robert
Published: March 2009

A model is developed for calculating ionospheric reflection of electromagnetic pulses emitted by lightning, with most energy in the long‐wave spectral region (f ∼ 3–100 kHz). The building block of the calculation is a differential equation full‐wave solution of Maxwell's equations for the complex reflection of individual plane waves incident from below, by the anisotropic, dissipative, diffuse dielectric profile of the lower ionosphere. This full‐wave solution is then put into a summation over plane waves in an angular direct Fourier transform to obtain the reflection properties of curved wavefronts. This step models also the diffraction effects of long‐wave ionospheric reflections observed at short or medium range (∼200–500 km). The calculation can be done with any arbitrary but smooth dielectric profile versus altitude. For an initial test, this article uses the classic D region exponential profiles of electron density and collision rate given by Volland. With even these simple profiles, our model of full‐wave reflection of curved wavefronts captures some of the basic attributes of observed reflected waveforms recorded with the Los Alamos Sferic Array. A follow‐on article will present a detailed comparison with data in order to retrieve ionospheric parameters.
Climatic effects of 30 years of landscape change over the Greater Phoenix, Arizona, region: 1. Surface energy budget changes
Authors: Georgescu M. , Miguez‐Macho G. , Steyaert L. T. , Weaver C. P.
Published: March 2009

This paper is part 1 of a two‐part study that evaluates the climatic effects of recent landscape change for one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, Arizona, region. The region's landscape evolution over an approximate 30‐year period since the early 1970s is documented on the basis of analyses of Landsat images and land use/land cover (LULC) data sets derived from aerial photography (1973) and Landsat (1992 and 2001). High‐resolution, Regional Atmospheric Modeling System (RAMS), simulations (2‐km grid spacing) are used in conjunction with consistently defined land cover data sets and associated biophysical parameters for the circa 1973, circa 1992, and circa 2001 time periods to quantify the impacts of intensive land use changes on the July surface temperatures and the surface radiation and energy budgets for the Greater Phoenix region. The main findings are as follows: since the early 1970s the region's landscape has been altered by a significant increase in urban/suburban land area, primarily at the expense of decreasing plots of irrigated agriculture and secondarily by the conversion of seminatural shrubland. Mean regional temperatures for the circa 2001 landscape were 0.12°C warmer than the circa 1973 landscape, with maximum temperature differences, located over regions of greatest urbanization, in excess of 1°C. The significant reduction in irrigated agriculture, for the circa 2001 relative to the circa 1973 landscape, resulted in dew point temperature decreases in excess of 1°C. The effect of distinct land use conversion themes (e.g., conversion from irrigated agriculture to urban land) was also examined to evaluate how the most important conversion themes have each contributed to the region's changing climate. The two urbanization themes studied (from an initial landscape of irrigated agriculture and seminatural shrubland) have the greatest positive effect on near‐surface temperature, increasing maximum daily temperatures by 1°C. Overall, sensible heat flux differences between the circa 2001 and circa 1973 landscapes result in a 1 W m−2 increase in domain‐wide sensible heating, and a similar order of magnitude decrease in latent heating, highlighting the importance of surface repartitioning in establishing near‐surface temperature trends. In part 2 of this study, we address the role of the surface budget changes on the mesoscale dynamics/thermodynamics, in context of the large‐scale environment.
Climatic effects of 30 years of landscape change over the Greater Phoenix, Arizona, region: 2. Dynamical and thermodynamical response
Authors: Georgescu M. , Miguez‐Macho G. , Steyaert L. T. , Weaver C. P.
Published: March 2009

This paper is part 2 of a two‐part study evaluating the climatic effect of one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, Arizona, region. Part 1, using a set of sensitivity experiments, estimated the potential impact of observed landscape evolution, since the dawn of the Landsat satellite era on the near surface climate, with a primary focus on the alteration of the surface radiation and energy budgets and through use of high‐resolution, 2km grid spacing, Regional Atmospheric Modeling System (RAMS) simulations with circa 1973, circa 1992, and circa 2001 landscape data sets. In this paper, part 2, we address the role of the previously discussed surface budget changes and subsequent repartitioning of energy on the mesoscale dynamics and thermodynamics of the region, the effect on convective rainfall, and their association with the large‐scale North American Monsoon System (NAMS). Our results show that contrasts in surface heating resulting from landscape change are responsible for the development of preferentially located mesoscale circulations, on most days, which were stronger for the 2001 compared to the 1973 landscape, due to increased planetary boundary layer (PBL) heating via enhanced turbulent heat flux. The effect of these stronger circulations was to warm and dry the lower part of the PBL and moisten the upper part of the PBL for the 2001 relative to the 1973 landscape. The precise physical pathway(s) whereby precipitation enhancement is initiated with evolving landscape, since the early 1970s, reveals a complicated interplay among scales (from the turbulent to the synoptic scale) that warrants future research. Precipitation recycling, however, was found to be an important driver in the overall sustenance of rainfall enhancement. Although this study was not designed to investigate other radiative forcing factors such as greenhouse gas emissions and aerosols, the results of our sensitivity experiments do suggest that regional land use change is an important element of climate change in semiarid environments characterized by large urban areas with scarce water resources.
Historical Selection
Authors: Kagan Jerome
Published: March 2009

This paper discusses a select list of six historical conditions, some long-lasting, some of shorter duration that have influenced the research of many psychologists. The conditions are: (a) the emergence of industrialization and increased numbers of European immigrants to the United States, (b) the historical commitment to a material basis for all natural phenomena, (c) the Cold War and computers, (d) the entry of mothers into the workforce, (e) the reliance on the analysis of variance and regression, and (f) the unique position of physics among the empirical sciences.
Characterization of the HSiNHNSi system in its electronic ground state
Authors: Lind Maria C. , Pickard Frank C. , Ingels Justin B. , Paul Ankan , Yamaguchi Yukio , Schaefer Henry F.
Published: March 2009

The electronic ground states (X̃Σ+1) of HSiN, HNSi, and the transition state connecting the two isomers were systematically studied using configuration interaction with single and double (CISD) excitations, coupled cluster with single and double (CCSD) excitations, CCSD with perturbative triple corrections [CCSD(T)], multireference complete active space self-consistent field (CASSCF), and internally contracted multireference configuration interaction (ICMRCI) methods. The correlation-consistent polarized valence (cc-pVXZ), augmented correlation-consistent polarized valence (aug-cc-pVXZ) (X=T,Q,5), correlation-consistent polarized core-valence (cc-pCVYZ), and augmented correlation-consistent polarized core-valence (aug-cc-pCVYZ) (Y=T,Q) basis sets were used. Via focal point analyses, we confirmed the HNSi isomer as the global minimum on the ground state HSiNHNSi zero-point vibrational energy corrected surface and is predicted to lie 64.7kcalmol−1 (22640cm−1, 2.81eV) below the HSiN isomer. The barrier height for the forward isomerization reaction (HSiN→HNSi) is predicted to be 9.7kcalmol−1, while the barrier height for the reverse process (HNSi→HSiN) is determined to be 74.4kcalmol−1. The dipole moments of the HSiN and HNSi isomers are predicted to be 4.36 and 0.26D, respectively. The theoretical vibrational isotopic shifts for the HSiN/DSiN and HNSi/DNSi isotopomers are in strong agreement with the available experimental values. The dissociation energy for HSiN [HSiN(X̃Σ+1)→H(S2)+SiN(XΣ+2)] is predicted to be D0=59.6kcalmol−1, whereas the dissociation energy for HNSi [HNSi(X̃Σ+1)→H(S2)+NSi(XΣ+2)] is predicted to be D0=125.0kcalmol−1 at the CCSD(T)/aug-cc-pCVQZ level of theory. Anharmonic vibrational frequencies computed using second order vibrational perturbation theory are in good agreement with available matrix isolation experimental data for both HSiN and HNSi isomers root mean squared derivation (RMSD=9cm−1).
Effects of exchange coupling between cap layer and oxide layer on the recording performance in perpendicular media
Authors: Zhang Kezhao , Choe Gunn , Duan Shanlin
Published: March 2009

To understand the effects of exchange coupling between the CoCr-alloy cap layer and the CoCrPt-oxide layer in perpendicular media, we measured switching dynamics and recording performances of a series of media with various exchange-coupling layer thicknesses on a high-precision spinstand. This study shows that the cap and the oxide layers have different switching dynamics and sufficiently strong exchange coupling is necessary for adequate thermal stability. Exchange coupling improves the signal-to-noise ratio (SNR) through improved writability and reduced noise from the cap. In the strong coupling region, overwrite and write widths can be varied without loss in SNR.
Enhanced magneto-optical Kerr effect in magnetic multilayers containing double-negative metamaterials
Authors: Dong Yunxia , Zhang Xiangdong
Published: March 2009

The magneto-optical Kerr effects in magnetic multilayered structures containing double-negative metamaterials are investigated by using 4×4 transfer-matrix method. The azimuth rotations and the figure of merit of the magneto-optical effects are calculated as a function of the thickness, permeability, and permittivity of the layers. It is shown that the magneto-optical effects are not only enhanced largely for the present system in comparison with those in the magnetic multilayered structures containing general metal materials but a giant Kerr rotation near 90° is also observed when the thickness of the sample is far less than the resonant wavelength. The physical origination for such a phenomenon is also analyzed. This means that we can obtain large magneto-optical Kerr effects at very thin magnetic film by using the double-negative metamaterials, which benefit the application in magnetic-optical recording.
Nonlinear electron-acoustic waves in quantum plasma
Authors: Sah O. P. , Manta J.
Published: March 2009

The nonlinear wave structure of electron-acoustic waves (EAWs) is investigated in a three component unmagnetized dense quantum plasma consisting of two distinct groups of electrons (one inertial cold electron, and other inertialess hot electrons) and immobile ions. By employing one dimensional quantum hydrodynamic model and standard reductive perturbation technique, a Korteweg–de-Vries equation governing the dynamics of EAWs is derived. Both compressive and rarefactive solitons along with periodical potential structures are found to exist for various ranges of dimensionless quantum parameter H. The quantum mechanical effects are also examined numerically on the profiles of the amplitude and the width of electron-acoustic solitary waves. It is observed that both the amplitude and the width of electron-acoustic solitary waves are significantly affected by the parameter H. The relevance of the present investigation to the astrophysical ultradense plasmas is also discussed.
Solid-liquid coexistence of polydisperse fluids via simulation
Authors: Wilding Nigel B.
Published: March 2009

We describe a simulation method for the accurate study of the equilibrium freezing properties of polydisperse fluids under the experimentally relevant condition of fixed polydispersity. The approach is based on the phase switch Monte Carlo method of Wilding and Bruce [Phys. Rev. Lett. 85, 5138 (2000)]. This we have generalized to deal with particle size polydispersity by incorporating updates which alter the diameter σ of a particle, under the control of a distribution of chemical potential differences μ̃(σ). Within the resulting isobaric semi-grand-canonical ensemble, we detail how to adapt μ̃(σ) and the applied pressure such as to study coexistence, while ensuring that the ensemble averaged density distribution ρ(σ) matches a fixed functional form. Results are presented for the effects of small degrees of polydispersity on the solid-liquid transition of soft spheres.
Radiochromic film imaging spectroscopy of laser-accelerated proton beams
Authors: Nürnberg F. , Schollmeier M. , Brambrink E. , Blažević A. , Carroll D. C. , Flippo K. , Gautier D. C. , Geißel M. , Harres K. , Hegelich B. M. , Lundh O. , Markey K. , McKenna P. , Neely D. , Schreiber J. , Roth M.
Published: March 2009

This article reports on an experimental method to fully reconstruct laser-accelerated proton beam parameters called radiochromic film imaging spectroscopy (RIS). RIS allows for the characterization of proton beams concerning real and virtual source size, envelope- and microdivergence, normalized transverse emittance, phase space, and proton spectrum. This technique requires particular targets and a high resolution proton detector. Therefore thin gold foils with a microgrooved rear side were manufactured and characterized. Calibrated GafChromic radiochromic film (RCF) types MD-55, HS, and HD-810 in stack configuration were used as spatial and energy resolved film detectors. The principle of the RCF imaging spectroscopy was demonstrated at four different laser systems. This can be a method to characterize a laser system with respect to its proton-acceleration capability. In addition, an algorithm to calculate the spatial and energy resolved proton distribution has been developed and tested to get a better idea of laser-accelerated proton beams and their energy deposition with respect to further applications.
Microstructure and transport properties of ZnO:Mn diluted magnetic semiconductor thin films
Authors: Yang Z. , Beyermann W. P. , Katz M. B. , Ezekoye O. K. , Zuo Z. , Pu Y. , Shi J. , Pan X. Q. , Liu J. L.
Published: March 2009

Microstructural studies using transmission electron microscopy were performed on a ZnO:Mn diluted magnetic semiconductor thin film. The high-resolution imaging and electron diffraction reveal that the ZnO:Mn thin film has a high structural quality and is free of clustering/segregated phases. High-angle annular dark field imaging and x-ray diffraction patterns further support the absence of phase segregation in the film. Magnetotransport was studied on the ZnO:Mn samples, and from these measurements, the temperature dependence of the resistivity and magnetoresistance, electron carrier concentration, and anomalous Hall coefficient of the sample is discussed. The anomalous Hall coefficient depends on the resistivity, and from this relation, the presence of the quadratic dependence term supports the intrinsic spin-obit origin of the anomalous Hall effect in the ZnO:Mn thin film.
Ferroelectric phase transitions in three-component short-period superlattices studied by ultraviolet Raman spectroscopy
Authors: Tenne D. A. , Lee H. N. , Katiyar R. S. , Xi X. X.
Published: March 2009

Vibrational spectra of three-component BaTiO3/SrTiO3/CaTiO3 short-period superlattices grown by pulsed laser deposition with atomic-layer control have been investigated by ultraviolet Raman spectroscopy. Monitoring the intensity of the first-order phonon peaks in Raman spectra as a function of temperature allowed the determination of the ferroelectric phase transition temperature Tc. Raman spectra indicate that all superlattices remain in the tetragonal ferroelectric phase with out-of-plane polarization in the entire temperature range below Tc. The dependence of Tc on the relative thicknesses of ferroelectric (BaTiO3) to nonferroelectric materials (SrTiO3 and CaTiO3) has been studied. The highest Tc was found in superlattices having the largest relative amount of BaTiO3, provided that the superlattice maintains its coherency with the substrate. Strain relaxation leads to a significant decrease in the ferroelectric phase transition temperature.
Classification of bound exciton complexes in bulk ZnO by magnetophotoluminescence spectroscopy
Authors: Ding L. , Li B. K. , He H. T. , Ge W. K. , Wang J. N. , Ning J. Q. , Dai X. M. , Ling C. C. , Xu S. J.
Published: March 2009

A series of bound exciton transitions of a bulk ZnO sample has been studied by high resolution magnetophotoluminescence spectra. Ten sharp intense bound exciton emissions are classified into three groups according to their dependences on magnetic field, angle, and circular polarization of the emission lines. The charge states of the defect centers and exciton types are identified. The effective g factors of the electrons and holes are determined.
Telegraph noise due to domain wall motion driven by spin current in perpendicular magnetized nanopillars
Authors: Cucchiara J. , Henry Y. , Ravelosona D. , Lacour D. , Fullerton E. E. , Katine J. A. , Mangin S.
Published: March 2009

Telegraph noise induced by stochastic domain wall nucleation, pinning, and annihilation in the presence of spin transfer torque is observed in nanopillar spin valves with perpendicular anisotropy. By measuring the dwell times corresponding to domain wall pinning and to domain wall nucleation, the telegraph noise is found to be consistent with thermal activation over an effective potential barrier.
Magnetization dynamics and Gilbert damping in ultrathin Co48Fe32B20 films with out-of-plane anisotropy
Authors: Malinowski G. , Kuiper K. C. , Lavrijsen R. , Swagten H. J. M. , Koopmans B.
Published: March 2009

Time resolved magneto-optical Kerr measurements are carried out to study the precessional dynamics of ferromagnetic thin films with out-of-plane anisotropy. A combined analysis of parameters, such as coercive fields, magnetic anisotropy, and Gilbert damping α, is reported. Using a macrospin approximation and the Landau–Lifshitz–Gilbert equation, the effective anisotropy and α are obtained. A large damping varying with the applied field as well as with the thickness of the ferromagnetic layer is reported. Simulations using a distribution in the effective anisotropy allow us to reproduce the field evolution of α. Moreover, its thickness dependence correlates with the spin pumping effect.
Crystallization of amorphous Si film by microwave annealing with SiC susceptors
Authors: Fong S. C. , Wang C. Y. , Chang T. H. , Chin T. S.
Published: March 2009

Crystalline silicon film is extremely important for low-cost, high performance Si-based devices, such as thin film transistors and solar cells. This study employs an elliptical microwave applicator to process the material placing near the field maximum. It is demonstrated that microwave irradiation incorporating with SiC susceptors is able to crystallize amorphous silicon film on glass substrate at a low temperature below 600 °C in a short period of 600 s. The reasons for such a fast processing time and a low annealing temperature are not clear.
A two-plate lateral photonic crystal with controllable negative refraction
Authors: Pogrebnyak Victor A.
Published: March 2009

We propose a two-plate lateral photonic crystal (LPC) with controllable negative refraction. Our experiment and analysis demonstrate that the electromagnetic wave can be negatively refracted between two parallel periodic metal plates. The negative refraction is provided by lateral periodicity of the two-plate structure. The lateral mechanism reduces the interaction between the wave and the periodic medium as compared with bulk photonic crystals. The simplicity of the LPC allows for easy control of its parameters. Variation of spacing between the plates controls negative refraction by varying the focal length of a proposed lateral photonic crystal.
Optimized optical generation and detection of superlattice acoustic phonons
Authors: Pascual Winter M. F. , Fainstein A. , Jusserand B. , Perrin B. , Lemaître A.
Published: March 2009

We present a device for the optimization of the folded acoustic phonon signal in femtosecond pump-probe experiments through the spatial decoupling of the generation and detection processes in two different GaAs/AlAs superlattices separated by a thick GaAs layer. A thickness gradient in one of them allows a fine tuning of the generation and detection spectral responses. In the optimal overlap condition, a clear enhancement of the signal is observed at a time delay that matches the travel time of acoustic phonons through the intermediate layer. This nanostructure provides a sensitive tool for studying terahertz phonon propagation over long distances.
Fiscal Decentralisation, Efficiency, and Growth
Authors: Rodríguez-Pose Andrés , Tijmstra Sylvia A R , Bwire Adala
Published: March 2009

Much of the recent worldwide trend towards devolution has been driven by the belief that fiscal decentralisation is likely to have a positive effect on government efficiency and economic growth. It is generally assumed that the transfer of powers and resources to lower tiers of government allows for a better matching of public policies to local needs and thus for a better allocation of resources. These factors, in turn, are expected to lead to an improvement in regional economic performance, if subnational authorities shift resources from current to capital expenditures in search of a better response to local needs. In this paper we test these assumptions empirically by analysing the evolution of subnational expenditure categories and regional growth in Germany, India, Mexico, Spain, and the USA. We find that, contrary to expectations, decentralisation has coincided in the sample countries with a relative increase in current expenditures at the expense of capital expenditures, which has been associated with lower levels of economic growth in countries where devolution has been driven from above (India and Mexico), but not in Spain, where it has been driven from below. We hypothesise that the differences in legitimacy between the central or federal government and subnational governments in top-down and bottom-up processes of devolution may be at the origin of the diverse capacity to deliver greater allocative and productive efficiency and, eventually, greater economic growth by devolved governments.
Disordered Land-Rent Competition in China's Periurbanization: Case Study of Beiqijia Township, Beijing
Authors: Zhu Jieming , Hu Tingting
Published: March 2009

Land development for nonagricultural uses in China's periurban areas has been driven by the rapid urbanization which has made the areas an intense mixture of urban and rural activities. The taking of land-rent differentials derived from land-use change is also a strong driving force for land conversion. In addition to formal land developments, informal and quasi-formal land developments have been induced by the institution of incomplete and ambiguously delineated collective land rights which facilitate disordered land-rent competition. Urban land uses permeate extensively into the agricultural territory of villages. Spatially uncoordinated land conversion and disorganized physical development result in substandard, inferior, and deteriorating habitations. Land utilization becomes suboptimal, and land values depreciate in a worsening environment. Land rents dissipate as a result. This mode of periurbanization is deemed unsustainable for a low-income developing country with high population density and scarce land resources.
Urban Implications of Cultural Policy Networks: The Case of the Mount Vernon Cultural District in Baltimore
Authors: Ponzini Davide
Published: March 2009

The intersection of urban and cultural policies has recently been at the center of international debate. The cultural planning approach argued that cultural policies can generally display positive effects in contemporary cities. The economic literature put forth spatial organization models of cultural institutions and producers, sometimes confirming policy makers' expectations. Concerning the urban implications of cultural policies, many authors tended to be more skeptical and made several critical observations that can be better disclosed by analyzing cultural networks in urban policy making. Drawing on an extended case of Baltimore's Mount Vernon Cultural District, I show that these critical factors are relevant but not determinant since they do not explain how and why cultural policy networks intervene in urban policy making. The analysis of Mount Vernon showed how a self-interested network promoted revitalization by framing a specific area as a ‘common campus’ and by integrating public, private, and nonprofit on this spatial basis. I suggest considering the implications of cultural networks in further urban research and policy making.
Fetal ethanol exposure increases ethanol intake by making it smell and taste better
Authors: Youngentob Steven L. , Glendinning John I.
Published: March 2009

Human epidemiologic studies reveal that fetal ethanol exposure is highly predictive of adolescent ethanol avidity and abuse. Little is known about how fetal exposure produces these effects. It is hypothesized that fetal ethanol exposure results in stimulus-induced chemosensory plasticity. Here, we asked whether gestational ethanol exposure increases postnatal ethanol avidity in rats by altering its taste and odor. Experimental rats were exposed to ethanol in utero via the dam's diet, whereas control rats were either pair-fed an iso-caloric diet or given food ad libitum. We found that fetal ethanol exposure increased the taste-mediated acceptability of both ethanol and quinine hydrochloride (bitter), but not sucrose (sweet). Importantly, a significant proportion of the increased ethanol acceptability could be attributed directly to the attenuated aversion to ethanol's quinine-like taste quality. Fetal ethanol exposure also enhanced ethanol intake and the behavioral response to ethanol odor. Notably, the elevated intake of ethanol was also causally linked to the enhanced odor response. Our results demonstrate that fetal exposure specifically increases ethanol avidity by, in part, making it taste and smell better. More generally, they establish an epigenetic chemosensory mechanism by which maternal patterns of drug use can be transferred to offspring. Given that many licit (e.g., tobacco products) and illicit (e.g., marijuana) drugs have noteworthy chemosensory components, our findings have broad implications for the relationship between maternal patterns of drug use, child development, and postnatal vulnerability.
S-nitrosylation of XIAP compromises neuronal survival in Parkinson's disease
Authors: Tsang Anthony H. K. , Lee Yun-IL , Ko Han Seok , Savitt Joseph M. , Pletnikova Olga , Troncoso Juan C. , Dawson Valina L. , Dawson Ted M. , Chung Kenny K. K.
Published: March 2009

Inhibitors of apoptosis (IAPs) are a family of highly-conserved proteins that regulate cell survival through binding to caspases, the final executioners of apoptosis. X-linked IAP (XIAP) is the most widely expressed IAP and plays an important function in regulating cell survival. XIAP contains 3 baculoviral IAP repeats (BIRs) followed by a RING finger domain at the C terminal. The BIR domains of XIAP possess anticaspase activities, whereas the RING finger domain enables XIAP to function as an E3 ubiquitin ligase in the ubiquitin and proteasomal system. Our previous study showed that parkin, a protein that is important for the survival of dopaminergic neurons in Parkinson's disease (PD), is S-nitrosylated both in vitro and in vivo in PD patients. S-nitrosylation of parkin compromises its ubiquitin E3 ligase activity and its protective function, which suggests that nitrosative stress is an important factor in regulating neuronal survival during the pathogenesis of PD. In this study we show that XIAP is S-nitrosylated in vitro and in vivo in an animal model of PD and in PD patients. Nitric oxide modifies mainly cysteine residues within the BIR domains. In contrast to parkin, S-nitrosylation of XIAP does not affect its E3 ligase activity, but instead directly compromises its anticaspase-3 and antiapoptotic function. Our results confirm that nitrosative stress contributes to PD pathogenesis through the impairment of prosurvival proteins such as parkin and XIAP through different mechanisms, indicating that abnormal S-nitrosylation plays an important role in the process of neurodegeneration.
Response of small intestinal epithelial cells to acute disruption of cell division through CDC25 deletion
Authors: Lee Gwanghee , White Lynn S. , Hurov Kristen E. , Stappenbeck Thaddeus S. , Piwnica-Worms Helen
Published: March 2009

The CDC25 protein phosphatases (CDC25A, B, and C) drive cell cycle transitions by activating key components of the cell cycle engine. CDC25A and CDC25B are frequently overproduced in human cancers. Disruption of
Cdc25B
or
Cdc25C
individually or in combination has no effect on mouse viability. Here we report that CDC25A is the only family member to provide an essential function during early embryonic development, and that other family members compensate for its loss in adult mice. In contrast, conditional disruption of the entire family is lethal in adults due to a loss of small intestinal epithelial cell proliferation in crypts of Lieberkühn.
Cdc25
loss induced Wnt signaling, and overall crypt structures were preserved. In the face of continuous Wnt signaling, nearly all crypt epithelial progenitors differentiated into multiple cell lineages, including crypt base columnar cells, a proposed stem cell. A small population of Musashi/Dcamkl-1/nuclear β-catenin–positive epithelial cells was retained in these crypts. These findings have implications for the development of novel, less cytotoxic cancer chemotherapeutic drugs that specifically target the cell cycle.
Structural Funds and Gender Equality: The Impact of Gender Mainstreaming in Western Scotland
Authors: Campbell Jim , Fitzgerald Rona , McSorley Leaza
Published: March 2009

The introduction of the Gender Equality Duty (GED) on 6 April 2007 represented the most significant change to sex equality legislation since the equal pay and anti-discrimination Acts of the 1970s. The GED is a form of legally enforceable gender mainstreaming that requires public authorities to build gender equality into all of their activities. Gender mainstreaming represents the latest approach in the search for equality. It is a holistic strategy that requires making equality considerations a central feature of policy-making. While gender mainstreaming may be new terrain for a number of policy makers, the experience of managing Structural Funds in Scotland provides a practical example of gender mainstreaming in action. On the positive side, there are examples of how projects from infrastructure to business development have integrated gender in all aspects of the policy and planning cycle and in service delivery. On the negative side, there still appears to be a lack of understanding of what gender mainstreaming is all about. Gender is seen as being about women and there is confusion between mainstreaming as the method, and the overall objective of achieving gender equality. The challenge for the GED is to underline the role of gender as a key variable in the success or failure of public policy interventions.
A Framework for Assessing Regeneration, Business Strategies and Urban Competitiveness
Authors: Singhal Shaleen , Berry Jim , McGreal Stanley
Published: March 2009

Certain cities have competitive advantage and capture the opportunities for growth and development while others continue to negotiate their position in an increasingly competitive global economy. The less competitive cities are struggling to employ effective urban regeneration strategies and property-led business strategies. This paper is concerned with developing an integrated framework for urban competitiveness with linkages to regeneration and business strategies. The methodology employed examines the literature on various regeneration and property-led business strategies being adopted in urban centres to formulate two parallel frameworks for urban regeneration and business. The key outcome of this paper is an integrated evaluation framework for urban competitiveness linked to the regeneration and business strategies.
Multidetector computed tomography for characterization of calcium deposits in reperfused myocardial infarction
Authors: Carlsson M. , Ursell P. C. , Saloner D. , Saeed M.
Published: March 2009

Background: Calcium overload is a major cause of reperfusion myocardial injury. Multidetector computed tomography (MDCT) has been previously used in visualizing coronary artery calcium, but not calcium deposits in reperfused infarction.

Purpose: To assess the ability of MDCT to 1) noninvasively visualize and characterize calcium deposits in reperfused infarcts, and 2) monitor regional wall swelling, regional systolic wall thickening, and infarct resorption.

Material and Methods: Reperfused myocardial infarcts were created in seven pigs by 2-hour occlusion of the left anterior descending coronary artery (LAD) after coronary catheterization. A 64-slice MDCT scanner was used for non-contrast images to depict calcium deposits. Furthermore, cine and delayed contrast-enhanced (DE) MDCT imaging were acquired to assess the chronological changes (2–4 hours, 1 week, and 8 weeks) in regional wall swelling, systolic wall thickening, and infarct size.

Results: Non-contrast MDCT images depicted calcium deposits as “hot-spots.” Attenuation of calcium deposits was greater (89±6 Hounsfield units [HU]) than remote myocardium (36±3 HU; P<0.05). Calcium deposits were not evident at 2–4 hours and were substantially smaller at 8 weeks compared to 1 week. Correlations were found between the extent of calcium deposits, ejection fraction ( R=0.81), and infarction size ( R=0.70). Cine MCDT images demonstrated transient wall swelling (edema formation and resorption) at 2–4 hours and differences in regional systolic wall thickening among infarcted, peri-infarcted, and remote myocardium. Calcium-specific von Kossa stain confirmed the presence of calcium deposits in infarcted myocardium.

Conclusion: 64-slice MDCT has the potential to demonstrate the progression and regression of calcium deposits, interstitial edema, and infarction. The presence of calcium deposits was transient and associated with reperfused recent infarction. The extent of calcium deposits was positively correlated with infarction size and negatively with global left-ventricular function.
Chest abnormalities in juvenile-onset mixed connective tissue disease: Assessment with high-resolution computed tomography and pulmonary function tests
Authors: Aaløkken T. M. , Lilleby V. , Søyseth V. , Mynarek G. , Pripp A. H. , Johansen B. , Førre Ø. , Kolbenstvedt A.
Published: March 2009

Background: Mixed connective tissue disease (MCTD) is associated with several chest manifestations. Only a few studies have focused on chest manifestations in juvenile-onset MCTD (jMCTD), and the true prevalence of pulmonary abnormalities on high-resolution computed tomography (HRCT) in these patients is unknown.

Purpose: To investigate the occurrence of pulmonary abnormalities in jMCTD with particular reference to interstitial lung disease (ILD), and to evaluate a possible association between pulmonary findings and disease-related variables.

Material and Methods: Twenty-four childhood-onset MCTD patients with median disease duration of 10.5 years (range 1–21 years) were investigated in a cross-sectional study by means of HRCT, pulmonary function tests (PFT), and clinical assessment.

Results: Discrete ILD was identified in six patients (25%). Median extent of ILD was 2.0%, and all except one of the patients had very mild disease in which 5% or less of the parenchyma was affected. The CT features of fibrosis were mainly microcystic and fine intralobular. The most frequently abnormal PFT was carbon monoxide uptake from the lung, which was abnormal in 33% of the patients. PFT and disease duration were not significantly associated with HRCT findings of ILD.

Conclusion: The prevalence of ILD in childhood-onset MCTD patients was lower than previously believed. In most of the patients with ILD, the findings were subtle and without clinical correlation. The results suggest a low extent of ILD in childhood-onset MCTD, even after long-term disease duration.
Population Genetics of Fungal and Oomycete Effectors Involved in Gene-for-Gene Interactions
Authors: Stukenbrock Eva H. , McDonald Bruce A.
Published: March 2009

Antagonistic coevolution between plants and pathogens has generated a broad array of attack and defense mechanisms. In the classical avirulence (Avr) gene-for-gene model, the pathogen gene evolves to escape host recognition while the host resistance (R) gene evolves to track the evolving pathogen elicitor. In the case of host-specific toxins (HST), the evolutionary arms race may be inverted, with the gene encoding the pathogen toxin evolving to maintain recognition of the host sensitivity target while the host sensitivity gene evolves to escape binding with the toxin. Pathogen effector genes, including those encoding Avr elicitors and HST, often show elevated levels of polymorphism reflecting the coevolutionary arms race between host and pathogen. However, selection can also eliminate variation in the coevolved gene and its neighboring regions when advantageous alleles are swept to fixation. The distribution and diversity of corresponding host genes will have a major impact on the distribution and diversity of effectors in the pathogen population. Population genetic analyses including both hosts and their pathogens provide an essential tool to understand the diversity and dynamics of effector genes. Here, we summarize current knowledge about the population genetics of fungal and oomycete effector genes, focusing on recent studies that have used both spatial and temporal collections to assess the diversity and distribution of alleles and to monitor changes in allele frequencies over time. These studies illustrate that effector genes exhibit a significant degree of diversity at both small and large sampling scales, suggesting that local selection plays an important role in their evolution. They also illustrate that Avr elicitors and HST may be recognizing the same R genes in plants, leading to evolutionary outcomes that differ for necrotrophs and biotrophs while affecting the evolution of the corresponding R genes. Under this scenario, the optimal number of R genes in a plant genome may be determined by the relative abundance of necrotrophic and biotrophic pathogens in the plant's environment.
Induction of Distinct Defense-Associated Protein Patterns in Aphanomyces euteiches (Oomycota)–Elicited and –Inoculated Medicago truncatula Cell-Suspension Cultures: A Proteome and Phosphoproteome Approach
Authors: Trapphoff Tom , Beutner Clara , Niehaus Karsten , Colditz Frank
Published: March 2009

A comprehensive proteomic approach was applied to investigate molecular events occurring upon inoculation of Medicago truncatula cell-suspension cultures with the oomycete root pathogen Aphanomyces euteiches. Establishment of an inoculation assay in the cell cultures allowed a direct comparison between proteins induced by elicitation with a crude culture extract of the oomycete and by inoculation with A. euteiches zoospores representing the natural infection carrier. Oxidative burst assays revealed responsiveness of the cell cultures for perception of elicitation and inoculation signals. The plant “elicitation proteome” resembles the “inoculation proteome” in early incubation stages and includes proteins induced following initial oxidative burst and defense reactions, but also proteins involved in the antioxidative system. However, approximately 2 days after incubation, the inoculation proteome differs drastically from the proteome of elicited cultures, where a cessation of responses assignable to A. euteiches elicitation occurred. The specific protein induction patterns of zoospore-inoculated cells appeared consistent with the protein induction identified in recent studies for an A. euteiches infection in planta and consist of three functional groups: i) pathogenesis-related proteins, ii) proteins associated with secondary phenylpropanoid or phytoalexin metabolism, and, particularly, iii) proteins assigned to carbohydrate metabolism and energy-related cellular processes. Phosphoproteomic analyses revealed consistent and specific activation of these defense-related pathways already at very early timepoints of inoculation, providing evidence that the identified protein profiles are representative for an established A. euteiches infection of M. truncatula.
Insights into the Defense-Related Events Occurring in Plant Cells Following Perception of Surfactin-Type Lipopeptide from Bacillus subtilis
Authors: Jourdan E. , Henry G. , Duby F. , Dommes J. , Barthélemy J. P. , Thonart P. , Ongena M.
Published: March 2009

Multiple strains of Bacillus subtilis were demonstrated to stimulate plant defense responses, and cyclic lipopeptides may be involved in the elicitation of this induced systemic resistance phenomenon. Here, we further investigated molecular events underlying the interaction between such lipopeptides and plant cells. Addition of surfactin but not fengycin or iturin in the micromolar range to tobacco cell suspensions induced defense-related early events such as extracellular medium alkalinization coupled with ion fluxes and reactive oxygen species production. Surfactin also stimulated the defense enzymes phenylalanine ammonia lyase and lipoxygenase and modified the pattern of phenolics produced by the elicited cells. The occurrence of these surfactin-elicited early events is closely related to Ca2+ influx and dynamic changes in protein phosphorylation but is not associated with any marked phytotoxicity or adverse effect on the integrity and growth potential of the treated tobacco cells. Reduced activity of some homologues also indicates that surfactin perception is dictated by structural clues in both the acyl moiety and cyclic peptide part. Our results suggest that these molecules could interact without irreversible pore formation but in a way sufficient to induce disturbance or transient channeling in the plasma membrane that can, in turn, activate a biochemical cascade of molecular events leading to defensive responses. The present study sheds new light not only on defense-related events induced following recognition of amphiphilic lipopeptides from Bacillus spp. but also more globally on the way elicitors from beneficial bacteria can be perceived by host plant cells.
Efficacy of Seed Treatment Chemicals for Black Root Rot, Caused by Thielaviopsis basicola, on Cotton
Authors: Toksoz Harun , Rothrock Craig S. , Kirkpatrick Terrence L.
Published: March 2009

The efficacy of triazole and host resistance–inducing seed treatment chemicals was examined for black root rot on cotton caused by Thielaviopsis basicola in both artificially and naturally infested soils with and without nematodes. In naturally infested soil, myclobutanil was effective in reducing root and hypocotyl discoloration over a wide range of soil population densities. Treatments containing high rates (42 g a.i./100 kg seed) of myclobutanil provided greater reductions in disease than low rates (21 g a.i./100 kg seed) in some experiments. Acibenzolar-S-methyl applied to the seed reduced black root rot or colonization by T. basicola on seedlings in artificially infested soils. Rates of acibenzolar-S-methyl did not differ in efficacy. In controlled studies, root colonization by T. basicola was significantly lower when seeds were treated with both myclobutanil and acibenzolar-S-methyl than with either chemical alone. In naturally infested soil under low (24 CFU/g soil) and high (154 CFU/g soil) populations of T. basicola, a combination of myclobutanil and acibenzolar-S-methyl at the high rate resulted in the lowest root discoloration and colonization. The nematicide seed treatment abamectin improved the control of black root rot in the presence of Meloidogyne incognita. The semi-selective medium TB-CEN allowed the importance of T. basicola to be evaluated in the presence of other pathogens that contribute to the seedling disease complex on cotton by quantifying the isolation frequency and percent colonization of T. basicola.
Detection of Virulence to Resistance Gene Sr36 Within the TTKS Race Lineage of Puccinia graminis f. sp. tritici
Authors: Jin Y. , Szabo L. J. , Rouse M. N. , Fetch T. , Pretorius Z. A. , Wanyera R. , Njau P.
Published: March 2009

The stem rust resistance gene Sr36 confers a near-immune resistance reaction to many races of Puccinia graminis f. sp. tritici and is highly effective against race TTKSK (syn. Ug99), which possesses unusually broad virulence combinations. Because this gene is widely used in United States soft winter wheat germplasm and cultivars, it has been considered to be an important source of resistance to TTKSK. In 2007, moderately susceptible infection responses were observed on wheat lines and cultivars carrying Sr36 in a field screening nursery for stem rust at Njoro, Kenya. We derived 18 single-pustule isolates from stem rust samples collected from the 2007 Njoro nursery. The isolates were evaluated for virulence on 20 North American stem rust differential lines and on wheat lines and cultivars carrying Sr36, Sr31+Sr36, and Sr24+Sr31. Of the 18 isolates, 10 produced infection types 3+ to 4 on line W2691SrTt-1 (monogenic for Sr36) and other lines that carry Sr36 and belonged to a new virulence phenotype that was not detected in previous years. These isolates were identified as race TTTSK. The remaining eight isolates were identified as races TTKSK (five isolates) and TTKST (three isolates), with avirulence and virulence, respectively, to Sr24. Thirteen simple sequence repeat (SSR) markers were used to examine the genetic relationships among the three races in the TTKS lineage. All isolates in the lineage shared an identical SSR genotype and were clearly different from North American races. In all, 16 wheat cultivars and 60 elite breeding lines, postulated to possess Sr36, were susceptible to race TTTSK. The occurrence of race TTTSK with combined virulence on Sr31 and Sr36 has further broadened the virulence spectrum of the TTKS lineage and rendered an important source of resistance ineffective.