bluuebunny/crossref_metadata_2025 huggingface dataset:
Retrieval of snow surface microwave emissivity from the advanced microwave sounding unit
Authors: Yan Banghua , Weng Fuzhong , Meng Huan
Published: October 2008

Satellite data assimilation in numerical weather prediction systems requires information on microwave snow surface emissivity in a wide wavelength range. However, the existing models perform poorly for stratified snow or aged snow especially at high frequencies such that they are inapplicable for various snow types. The brightness temperatures at the window channels of the advanced microwave sounding unit (AMSU) are characterized strongly by surface emissivity and are thus used in this study to retrieve snow surface emissivity from 23.8 to 150 GHz under both clear and cloudy conditions. This algorithm uses an iteration scheme associated with a two‐stream radiative transfer model. The accuracy of the AMSU‐retrieved snow emissivity using this algorithm is first assessed against a set of satellite‐observed emissivity under clear skies and a set of simulated emissivity under cloudy conditions. The algorithm is then assessed by its application to seven consecutive snow events observed at Hagerstown, Maryland, in February 2003 and to a set of mountainous snowpacks observed at the Local Scale Observation Site of the Cold Land Processes Field Experiment in northern Colorado in February and March of 2002 and 2003. Results show that the AMSU‐retrieved snow emissivity spectra are consistent with the snow emissivity model simulations of the snow events in both Maryland and Colorado. Furthermore, the impact of the AMSU‐retrieved snow emissivity on global satellite data assimilation systems is investigated by applying the algorithm to the National Centers for Environmental Prediction (NCEP) Gridpoint Statistical Interpolation (GSI) system. Compared to the existing analytic land emissivity model used in the GSI system, the retrieved emissivity significantly improves the use of the AMSU sounding data in the NCEP GSI system. Therefore, the AMSU‐based snow emissivity retrieval algorithm has demonstrated its potential use in the global satellite data assimilation systems.
Seasonal patterns of tropical forest leaf area index and CO2 exchange
Authors: Doughty Christopher E. , Goulden Michael L.
Published: October 2008

We used in situ and satellite measurements to investigate the seasonal patterns of leaf area index (LAI) and gross ecosystem CO2 exchange (GEE) by an evergreen tropical forest. The forest experienced a dry season from June through November. The rates of light‐saturated CO2 uptake (GEE) were comparatively high from December through March and low from May through July. In situ measurements showed that LAI varied seasonally, with a minimum from May through September. Leaf production and leaf abscission were reduced from December through April. Leaf abscission increased in May, which reduced LAI. High rates of leaf abscission and production occurred from July through September associated with leaf turnover. Leaf abscission decreased abruptly in October, while production continued, which rapidly increased LAI. Leaf phenology was not directly correlated with changes in soil water. The seasonal cycle of in situ LAI differed markedly from the seasonal cycles of in situ normalized difference vegetation index (NDVI) and the Moderate Resolution Imaging Spectroradiometer (MODIS) MOD15 LAI product. We hypothesize that the NDVI and MOD15 seasonality at the site is driven partly by seasonal changes in leaf age and leaf reflectance. We developed three simple models to investigate the causes of GEE seasonality. The first two models showed that the seasonal changes in LAI alone, and the effects of leaf age on leaf‐level photosynthesis alone, could not account for the observed GEE seasonality. The third model showed that the combined effect of seasonal changes in LAI and seasonal changes in leaf age and leaf photosynthesis was sufficient to account for the observed GEE seasonality.
Tremor Activity Monitoring in Northern Cascadia
Authors: Kao Honn , Thompson Philip J. , Shan Shao‐Ju , Rogers Garry , Dragert Herb
Published: October 2008

The Cascadia margin is characterized by a young (<8‐million‐year‐old) subducting slab stretching from British Columbia, Canada, to northern California, marking the convergent boundary between the North America plate and the oceanic Juan de Fuca and Explorer plates (Figure 1). Geodetic measurements over the past two decades have established that the shallow portion (depth <15 kilometers) of the interface between the subducting Juan de Fuca plate and the overriding North America plate is strongly coupled. The inevitable “unlocking” process can and will generate a megathrust earthquake with a magnitude as large as 9, as confirmed by the studies of paleoearthquakes in the region. Paleoseismic and tsunami data have indicated that the last Cascadia megathrust event (magnitude ∼9) occurred in 1700 [e.g., Satake et al., 2003].
Antarctic Treaty Summit to Focus on Global Science Policy Lessons
Authors: Berkman Paul Arthur , Walton David W. H. , Weiler C. Susan
Published: October 2008

The Antarctic Treaty Summit, which will coincide with the fiftieth anniversary of the treaty's signing, will be held at the Smithsonian Institution's National Museum of Natural History, in Washington, D.C., from 30 November to 3 December 2009. The summit will provide an open international forum for scientists, legislators, lawyers, administrators, educators, students, corporate executives, historians, and other members of global civil society to explore science policy achievements from the first 50 years of the Antarctic Treaty. In addition, the summit will complement official government celebrations of the Antarctic Treaty anniversary that do not include public participation.
Can Groundwater Meet Africa's Demand for Water as Climates Change?: Groundwater and Climate in Africa: An International Conference; Kampala, Uganda, 24–28 June 2008
Authors: Taylor Richard , Tindimugaya Callist , Aureli Alice
Published: October 2008

The impact of climate variability and change on groundwater resources remains poorly understood and is one of the most persistent knowledge gaps identified by the Intergovernmental Panel on Climate Change (IPCC) in both its Third (2001) and Fourth (2007) Assessment Reports. The common exclusion of groundwater from current monitoring and evaluation of the impacts of climate variability and change is of particular concern in Africa, where approximately half of its nearly 1 billion inhabitants rely upon groundwater for their daily water supply. Furthermore, future adaptations in response to climate change and rapid population growth are expected to intensify dependence upon ground water in Africa as communities seek to improve access to safe water and adequate sanitation pursuant to the U.N. Millennium Development Goals, which include sustaining food security and promoting agricultural and industrial development.
Non‐linear alignment of El Niño to the 11‐yr solar cycle
Authors: White Warren B. , Liu Zhengyu
Published: October 2008

El Nino/La Nina episodes represent warm/cool phases of 2‐ to 7‐yr period El Nino‐Southern Oscillation (ENSO) in the tropical Pacific ocean‐atmosphere system. Modeling studies find ENSO self‐excited or driven by ambient noise. Here we find most El Nino and La Nina episodes from 1900–2005 grouped into non‐commuting pairs that repeat every ∼11 yrs, aligned with rising and falling transition phases of the ∼11‐yr period quasi‐decadal oscillation (QDO). These alignments arise from non‐linear phase locking of 3rd and 5th harmonics near 3.6‐ and 2.2‐yr to the 1st harmonic near 11‐yr period. Here we find these alignments replicated in both coupled general circulation model and conceptual model driven by 11‐yr solar forcing, wherein the solar‐forced 1st harmonic initiates a non‐linear cascade of higher odd harmonics that are phase‐locked with the same alignments as observed. These solar‐forced 3rd and 5th harmonics explain ∼52% of inter‐annual variance in the Nino‐3 temperature index from 1900–2005.
Planforms of self‐consistently generated plates in 3D spherical geometry
Authors: van Heck H. J. , Tackley P. J.
Published: October 2008

In the past decade, several studies have documented the effectiveness of plastic yielding in causing a basic approximation of plate tectonic behavior in mantle convection models with strongly temperature dependent viscosity, strong enough to form a rigid lid in the absence of yielding. The vast majority of such research to date has been in either two‐dimensional, or three‐dimensional cartesian geometry. In the present study, mantle convection calculations are performed to investigate the planform of self‐consistent tectonic plates in three‐dimensional spherical geometry. The results are compared to those of similar calculations where a three dimensional cartesian geometry is used. We found that when yield stress of the lithosphere is low (∼20 MPa) a “great circle”‐subduction zone forms. At low‐intermediate yield stresses (∼100 MPa) plates, spreading centers and subduction zones formed and were destroyed over time. At high‐intermediate yield stresses (∼200 MPa) two plates form, separated by a great circle boundary that is a spreading centre on one side and a subduction zone on the other side. At high yield stresses (∼400 MPa) a rigid lid was observed. The great circle subduction zone and the rigid lid are stable over time while at intermediate yield stresses some episodic behavior is observed. The spherical cases showed a higher, more Earth‐like, toroidal‐poloidal ratio of the surface velocity field than the cartesian cases.
Nuclear magnetic resonance relaxation measurements as a means of monitoring iron mineralization processes
Authors: Keating Kristina , Knight Rosemary , Tufano Katharine J.
Published: October 2008

In this laboratory study, we assessed the measurement of nuclear magnetic resonance (NMR) relaxation times as a means of monitoring iron mineralization processes. We conducted experiments in which columns containing ferrihydrite‐coated quartz sand reacted with aqueous Fe(II) solutions to form goethite, lepidocrocite and magnetite. An observed increase in the volume of water relaxing with long relaxation times in the NMR relaxation time distribution corresponds to the formation of goethite and lepidocrocite; a decrease in the average (mean log) relaxation time, and a broadening of the relaxation time distribution, corresponds to the formation of magnetite. These results indicate that NMR relaxation times are sensitive to changes in iron mineralogy and illustrate the potential use of NMR for monitoring iron mineralization processes.
DMSP/GPS observations of intense ion upflow in the midnight polar ionosphere associated with the SED plume during a super geomagnetic storm
Authors: Yuan Zhi‐Gang , Deng Xiao‐Hua , Wang Jing‐Fang
Published: October 2008

We report observations from the GPS TEC and DMSP F‐15 satellite showing that a very strong upward field‐aligned (FA) plasma velocity and flux at F‐region heights in the auroral zone/polar cap boundary during a passage of the polar tongue of ionization (TOI) full of storm‐enhanced density (SED) materials occurred in the event of the super geomagnetic storm on Nov. 20, 2003. The upward FA ion velocities in excess of 460 m/s are obtained from observations of the DMSP F‐15 satellite. With enhancements of the plasma density caused by the TOI, FA ion fluxes are estimated to about 1.2 × 1014 ions m−2s−1, which are comparable to those observed by the ground‐based radar in the polar cusp. Therefore, during the super geomagnetic storm a s SED can cause a TOI plume at F region altitudes, which leads to a strong upward ion flux reaching 1–2 orders of magnitude larger than that of the typical flux at midnight auroral zone/polar cap boundary. Through estimations of the influence of those upflow ions associated with SED plumes on the development of the super storm, our result suggests that the midnight auroral zone/polar cap boundary becomes an important source to directly provide rich O+ to the ring current during super geomagnetic storms.
Evidence of deuterium excess in water vapor as an indicator of ocean surface conditions
Authors: Uemura Ryu , Matsui Yohei , Yoshimura Kei , Motoyama Hideaki , Yoshida Naohiro
Published: October 2008

Stable isotopes of water are important climatic tracers used to understand atmospheric moisture cycling and to reconstruct paleoclimate. The combined use of hydrogen and oxygen isotopes in water provides an additional parameter, deuterium excess (d), which might reflect ocean surface conditions in moisture source regions for precipitation. The d records from polar ice cores covering glacial‐interglacial cycles were used to reconstruct ocean surface temperatures at the moisture source, enabling elimination of source effects from the conventional isotope thermometer. However, observations of the essential relationship between d in vapor and ocean surface conditions are very limited. To date, theoretical values predicted using simple and atmospheric general circulation models (GCM) have not been validated against the data. Here, we show the isotope ratios of atmospheric water vapor near the ocean surface in middle and high latitudes of the Southern Ocean. Our observations show that d negatively correlates with relative humidity (h) above the ocean and correlates with sea surface temperature (SST). Despite the fact that the GCMs would underestimate the absolute value of observed d, the observations and simulation results are consistent for slopes between d versus h and d versus SST, suggesting that d is a reliable index to h and SST over the ocean surface.
Atlases of Minnesota Water Sustainability: Creation from Models, Analytical Methods, and Database of Watershed Characteristics
Authors: Nieber John , Kanivetsky Roman , Peterson Heidi , Lahoud Francisco , Mulla David , Shmagin Boris
Published: October 2008

Confident assessment of the numbers of regional water balance and water resources for Atlases of MN Water Sustainability (AMNWS) has to be based on the best science, advanced knowledge and modern technology. Creating a watershed characteristic database is the first and most significant step in the analysis of time spatial distributions of Minnesota’s water balance components. The database spatially associates hydrologic data (annual discharge, monthly proportion, and yield) with topographical, soil and vadoze zone, ecological and hydrogeological conditions and properties. USGS stream flow data for 129 gauging stations surrounding MN was manipulated within ArcGIS. Characteristics of the 129 watersheds (drainage areas 100-10000 square miles) were summarized to create a matrix database (1947-1971 (79 watersheds), 1955-1979 (93), and 1976-2006 (74). Model as formal integrator of knowledge plays a central role for hydrological process in the landscape environment study. The use of cyber model of landscape (Krcho, 1978) and watershed as part of it (Shmagin, 1997) provides research tasks for data analyses. Six research tasks implied 17 initial matrixes incorporated the existing longtime hydrological data (from 25 to 109 years). Special part of database includes temperatures and precipitation (from 56 to 106 years) for 90 meteorological stations for MN and surrounding states (from US Historical Climatology Network: http://cdiac.ornl.gov/epubs/ndp/ushcn/usa_monthly.html). The data analysis (multivariate exploratory techniques) operates with two kinds of data: time series and maps that are integrated with use of GIS. Statistic was used with this database to transform initial matrixes of watershed characteristics into linear components and residual matrixes, establishing characteristics interconnections. To combine the results of data analysis of layered quantities and qualitative information onto a map of water resources with defined unit boundaries requires the fuzzy logic approach for regionalization (Shmagin and Chen, 2006). For AMNWS future developments, the watershed characteristics database can be upgraded to include monitoring of the surface and ground water regimes.
The Art of Creating Culinary Innovations
Authors: Stierand Marc , Lynch Paul
Published: October 2008

The life worlds of innovating chefs are identified as important aspects towards a better understanding of culinary innovation. Hence, the concept of personal culinary innovation is proposed as a verifiable way to identify innovators in the field. Current studies, however, interchangeably use the term invention and innovation and fail to address central dimensions such as artistic aspiration, continuous and discontinuous conditions, learning and networking, adoption and diffusion as well as perceived newness and change. As a result, improving the dialogue between chefs and scholars is believed to be the key to better research in the field.
Lagrangian and Hamiltonian two-scale reduction
Authors: Giannoulis Johannes , Herrmann Michael , Mielke Alexander
Published: October 2008

Studying spatially extended Hamiltonian systems with coherent microstructure, it is an important and challenging problem to identify reduced Hamiltonian models that describe the effective dynamics on large spatial and temporal scales. Such models require macroscopically varying, deterministic initial data which can possess a well-organized microstructure. This paper concerns the question how reasonable macroscopic Lagrangian and Hamiltonian structures can be derived from the microscopic system. In the first part we develop a general approach by considering noncanonical Hamiltonian structures on the tangent bundle. This approach can be applied to all Hamiltonian lattices [or Hamiltonian partial differential equations (PDEs)] and involves three building blocks: (i) the embedding of the microscopic system, (ii) an invertible two-scale transformation that encodes the underlying scaling of space and time, and (iii) an elementary model reduction that is based on a principle of consistent expansions. The result is always a reduced Hamiltonian PDE that governs the macroscopic dynamics, provided that the initial data are chosen consistently with the underlying two-scale ansatz. In the second part we exemplify the reduction approach and derive various reduced PDE models for the atomic chain. The reduced equations are either related to long-wave motion or describe macroscopic modulations of oscillatory microstructures.
Determination of liquid crystal orientation in holographic polymer dispersed liquid crystals by linear and nonlinear optics
Authors: Yemtsova M. , Kirilyuk A. , van Etteger A. F. , Rasing Th.
Published: October 2008

The liquid crystal alignment imposed during the fabrication process of one-dimensional transmission gratings, holographically formed in a polymer dispersed liquid crystal, is determined by linear optical birefringence as well as rotational second harmonic generation. For a mixture consisting of nematic liquid crystal E7, a pentafunctional acrylate monomer, and a photoinitiator, the director orientation inside the liquid-crystal-rich layer is found to be approximately along the grating direction. We suggest that this molecular orientation is the consequence of the strong flow during the grating formation.
Temperature and isotope effects on water cluster ions with path integral molecular dynamics based on the fourth order Trotter expansion
Authors: Suzuki Kimichi , Shiga Motoyuki , Tachikawa Masanori
Published: October 2008

Path integral molecular dynamics simulation based on the fourth order Trotter expansion has been performed to elucidate the geometrical isotope effect of water dimer anions, H3O2−, D3O2−, and T3O2−, at different temperatures from 50 to 600 K. At low temperatures below 200 K the hydrogen-bonded hydrogen nucleus is near the center of two oxygen atoms with mostly O⋯X⋯O geometry (where X=H, D, or T), while at high temperatures above 400 K, hydrogen becomes more delocalized, showing the coexistence between O⋯X–O and O–X⋯O. The OO distance tends to be shorter as the isotopomer is heavier at low temperatures, while this ordering becomes opposite at high temperatures. It is concluded that the coupling between the OO stretching mode and proton transfer modes is a key to understand such a temperature dependence of a hydrogen-bonded structure.
In situ characterization of strontium surface segregation in epitaxial La0.7Sr0.3MnO3 thin films as a function of oxygen partial pressure
Authors: Fister Tim T. , Fong Dillon D. , Eastman Jeffrey A. , Baldo Peter M. , Highland Matthew J. , Fuoss Paul H. , Balasubramaniam Kavaipatti R. , Meador Joanna C. , Salvador Paul A.
Published: October 2008

Using in situ synchrotron measurements of total reflection x-ray fluorescence, we find evidence of strontium surface segregation in (001)-oriented La0.7Sr0.3MnO3 thin films over a wide range of temperatures (25–900 °C) and oxygen partial pressures (pO2=0.15–150 Torr). The strontium surface concentration is observed to increase with decreasing pO2, suggesting that the surface oxygen vacancy concentration plays a significant role in controlling the degree of segregation. Interestingly, the enthalpy of segregation becomes less exothermic with increasing pO2, varying from −9.5 to −2.0 kJ/mol. In contrast, the La0.7Sr0.3MnO3 film thickness and epitaxial strain state have little impact on segregation behavior.
Adsorption of inert gases including element 118 on noble metal and inert surfaces from ab initio Dirac–Coulomb atomic calculations
Authors: Pershina V. , Borschevsky A. , Eliav E. , Kaldor U.
Published: October 2008

The interaction of the inert gases Rn and element 118 with various surfaces has been studied on the basis of fully relativistic ab initio Dirac–Coulomb CCSD(T) calculations of atomic properties. The calculated polarizability of element 118, 46.3 a.u., is the largest in group 18, the ionization potential is the lowest at 8.91 eV, and the estimated atomic radius is the largest, 4.55 a.u. These extreme values reflect, in addition to the general trends in the Periodic Table, the relativistic expansion and destabilization of the outer valence 7p3/2 orbital. Van der Waals coefficients C3 and adsorption enthalpies ΔHads of Ne through element 118 on noble metals and inert surfaces, such as quartz, ice, Teflon, and graphite, were calculated in a physisorption model using the atomic properties obtained. The C3 coefficients were shown to steadily increase in group 18, while the increase in ΔHads from Ne to Rn does not continue to element 118: The large atomic radius of the latter element is responsible for a decrease in the interaction energy. We therefore predict that experimental distinction between Rn and 118 by adsorption on these types of surfaces will not be feasible. A possible candidate for separating the two elements is charcoal; further study is needed to test this possibility.
Dicyanovinyl-quinquethiophenes with varying alkyl chain lengths: Investigation of their performance in organic devices
Authors: Schulze Kerstin , Riede Moritz , Brier Eduard , Reinold Egon , Bäuerle Peter , Leo Karl
Published: October 2008

We compare between two derivatives of dicyanovinyl-quinquethiophenes with different alkyl side chain lengths. Both materials show comparable open circuit voltages Voc in organic solar cells with fullerene C60 as acceptor, as expected since they have the same highest occupied molecular orbital energy. However, differences in the current-voltage-characteristics, particularly in the fill factor, are observed. We analyze both derivatives in hole-only devices and find a difference in the hole injection between the doped hole transport layer and the oligothiophenes. Additionally, we determine the hole mobility of the two materials and explain the different behaviors of the two materials in solar cells.
Additivity and distinguishability of random unitary channels
Authors: Rosgen Bill
Published: October 2008

A random unitary channel is one that is given by a convex combination of unitary channels. It is shown that the conjectures on the additivity of the minimum output entropy and the multiplicativity of the maximum output p-norm can be equivalently restated in terms of random unitary channels. This is done by constructing a random unitary approximation to a general quantum channel. This approximation can be constructed efficiently, and so it is also applied to the computational problem of distinguishing quantum circuits. It is shown that the problem of distinguishing random unitary circuits is as hard as the problem of distinguishing general mixed-state circuits, which is complete for the class of problems having quantum interactive proof systems.
Photonic crystal high-efficiency multispectral thermal emitters
Authors: El-Kady I. , Farfan G. B. , Rammohan R. , Taha M. M. Reda
Published: October 2008

We demonstrate through numerical simulation the modification of the thermal emission spectrum by a metallic photonic crystal (PhC). Here the radiation is funneled into a narrow emission band in contrast to the broad spectrum associated with a Planckian-distribution. A detailed quantitative evaluation of the spectral, power, and angular efficiencies of a PhC thermal emitter and its portability across IR spectral bands is provided. We show that an optimized tungsten PhC possesses a predominant narrow-band forward emission profile with an emitter efficiency that is more than double that of an ideal blackbody and ∼65–75% more power-efficient across the IR spectrum.
Global endwall effects on centrifugally stable flows
Authors: Avila Marc , Grimes Matt , Lopez Juan M. , Marques Francisco
Published: October 2008

We investigate the stability of a fluid confined between two cylinders that rotate at same constant angular speed. In the case of infinite cylinders, or endwalls rotating with the cylinders, the flow is in solid-body rotation and hence linearly stable for any rotation speed. However, when the endwalls are stationary, a large-scale circulation is driven by radially inward boundary layer flow on the endwalls. For sufficiently high angular speeds, this circulation becomes unstable to azimuthal waves. As the length-to-gap aspect ratio of the system is increased, a wealth of instabilities is revealed. It is particularly interesting that for all these instabilities the associated energy is localized in the equatorial region, as far from the endwalls as possible. This shows that care must be taken when assuming localized endwall effects in simplified models.
1 V saturated Pb(Zr,Ti)O3 films with (111) orientation using lattice-matched (111)SrRuO3/(111)Pt bottom electrode prepared by pulsed metal organic chemical vapor deposition
Authors: Kuwabara Hiroki , Menou Nicolas , Funakubo Hiroshi
Published: October 2008

Pb ( Zr 0.35 Ti 0.65 ) O 3 films measuring 33 nm thick, were prepared on (111)SrRuO3/(111)Pt/TiO2/SiO2/(100)Si substrates at 540 °C using pulsed metal organic chemical vapor deposition. (111)-oriented films consisting of columnar grains possessed local epitaxial relationships with the underling (111)-oriented SrRuO3 layer. Their polarization (electric field characteristics), which had better symmetry than those on (111)Ir//TiO2/SiO2/(100)Si substrates, were saturated below 1 V with a large remanent polarization, but were not noticeably degraded upon decreasing film thickness. These results demonstrate that film thickness can be scaled down for low voltage operations using lattice matched interface between a Pb(Zr0.35Ti0.65)O3 film and SrRuO3 bottom electrode.
Interface engineering for molecular alignment and device performance of quaterrylene thin films
Authors: Hayakawa Ryoma , Petit Matthieu , Chikyow Toyohiro , Wakayama Yutaka
Published: October 2008

We investigated the impact of interface modification by an octadecyltrichlorosilane self-assembled monolayer (OTS-SAM) on growth mode and transistor performance of quaterrylene thin films. Interface modification by OTS-SAM contributed effectively to stress-free film growth and highly molecular ordering, particularly in the initial layers, dramatically improving transistor performance. We found that the structural features in a few layers were key factors for determining the overall thin film growth mode and ameliorating carrier transport in organic field-effect transistors (OFETs). These results clearly demonstrated the effectiveness of interface engineering in the OFETs.
Giant electric-field-induced magnetization in a magnetoelectric composite at high frequency
Authors: Zhou Jian-Ping , Guo Yang-Yang , Xi Zengzhe , Liu Peng , Lin Shuyu , Liu Gang , Zhang Huai-Wu
Published: October 2008

Electric-field-induced magnetization (EIM) characteristics are investigated in a small 0.68[Pb(Mg1/3Nb2/3)O3]0.32PbTiO3/Terfenol-D bilayered composite by using double coils in a wide frequency range of 10–700 kHz. The EIM behaviors are strongly dependent on driving electric field frequency, bias magnetic field, and angle θ between the bias magnetic field and polarization direction. The magnetoelectric coefficient at electromechanical resonance frequency of 185 kHz reaches up to 3.1×10−7 s/m, which is ∼60 times higher than the values at nonresonance frequency. The EIM variations with the bias magnetic field exhibit hysteresis, forming EIM hysteresis loops caused by the magnetostrictive hysteresis from Terfenol-D.
Dust acoustic vortices in an inhomogeneous quantum magnetoplasma with dissipation and sheared dust flows
Authors: Masood W. , Mirza Arshad M. , Nargis Shahida
Published: October 2008

Linear and nonlinear properties of quantum dust acoustic waves are studied in a nonuniform, dissipative quantum plasma with sheared dust flow parallel to the ambient magnetic field, using the quantum hydrodynamic model. It is shown that the shear dust flow parallel to the external magnetic field can drive the quantum dust-acoustic wave unstable provided it has a negative slope. Stationary solutions of the nonlinear equations that govern the quantum dust-acoustic waves are also obtained. It is found that electrostatic monopolar, dipolar, and vortex street-type solutions can appear in such a plasma. It is observed that the inclusion of dust, quantum statistical, and Bohm potential terms significantly modify the scale lengths of these nonlinear structures. The relevance of the present investigation with regard to the dense astrophysical environments is also pointed out.
Super-radiance of excitons in a single ZnO nanostructure
Authors: Ding C. R. , Lin W. , Chen B. C. , Zhao F. L. , Dong J. W. , Shi M. , Wang H. Z. , Hsu Y. F. , Djurišić A. B.
Published: October 2008

Super-radiance of excitons in a single ZnO tetrapod nanostructure has been observed. The emitted pulses exhibited very short duration, and the emission peak intensity exhibited exponential increase with the increased pump density. Multiple narrow emission peaks with short peak spacing have been observed in the emission spectra of a single ZnO tetrapod nanostructure.
Electron irradiation of AlGaN∕GaN and AlN∕GaN heterojunctions
Authors: Polyakov A. Y. , Smirnov N. B. , Govorkov A. V. , Markov A. V. , Pearton S. J. , Dabiran A. M. , Wowchak A. M. , Cui B. , Osinsky A. V. , Chow P. P. , Kolin N. G. , Boiko V. M. , Merkurisov D. I.
Published: October 2008

The effects of 10MeV electron irradiation on AlGaN∕GaN and AlN∕GaN heterojunctions grown by molecular beam epitaxy are reported. The irradiation increases the resistivity of the GaN buffer due to compensation by radiation defects with levels near Ec−1eV and decreases the mobility of the two-dimensional electron gas (2DEG) near the AlGaN∕GaN (or AlN∕GaN) interface. The bulk carrier removal rate in the GaN buffer is the same for both types of structures and similar to carrier removal rates for undoped n-GaN films. In structures with a density of residual donors of ∼1015cm−3, irradiation with electron doses of ∼5×1015cm−2 renders the buffer semi-insulating. The 50% degradation of the 2DEG conductivity happens at several times higher doses (close to 3×1016cm−2 versus 6.5×1015cm−2) for AlN∕GaN than for AlGaN∕GaN structures, most likely because of the lower thickness of the AlN barrier.
Integrating Multiple Perspectives in Social Multicriteria Evaluation of Flood-Mitigation Alternatives: The Case of Malborghetto-Valbruna
Authors: Scolobig Anna , Broto Vanesa Castán , Zabala Aiora
Published: October 2008

There is an increasing demand for a new paradigm to improve flood-mitigation decision processes that calls for risk-reduction strategies at several levels. This demand may gain ground only if dialogue is encouraged among different perspectives, disciplines, and knowledge types. The aim of this paper is to explore new methods to improve flood-mitigation decision processes. A growing body of evidence suggests that the involvement of the local actors is a key aspect in successful decision making. Following this premise, we analyze a recent case of controversy in flood mitigation in Malborghetto-Valbruna (Northern Italy), using social multicriteria evaluation (SMCE) and social actors' narrative analysis. Six alternatives are defined and the different positions adopted by the local actors are described. The different narratives of the actors are also analyzed to allow the identification of improvement routes for a more accurate SMCE of flood-mitigation alternatives. Thus, this case study suggests that the analysis of narratives is a useful tool to complement SMCE.
A farm-scale, bio-economic model for assessing investments in recycled water for irrigation
Authors: Brennan L. E. , Lisson S. N. , Poulton P. L. , Carberry P. S. , Bristow K. L. , Khan S.
Published: October 2008

Demand for water in Australia is increasing along with growing pressure to maximise the efficiency of irrigation water use and seek additional and alternative irrigation supplies. The scarcity of water supplies coupled with the need for urban communities to dispose of large quantities of treated recycled water from sewage treatment plants has led to increasing interest from urban and rural communities in the reticulation of this water for irrigating adjacent crop-production areas. Proposals to use recycled water inevitably lead to a complex range of issues that need to be addressed, including:

costs and benefits of supplying an additional source of water to current or new cropping systems;
optimum irrigation design and management, particularly where there are multiple sources of irrigation water;
management of overflow from on-farm water storages; and
environmental implications with regard to salinity, runoff, drainage, nitrate leaching, and environmental flows.

Simulation models can capture many of the key factors and processes influencing irrigated crop production systems, and can play a useful role in exploring these issues. In this paper, we have described an approach that couples agricultural production system and economic models in a way that enables analysis of the likely benefits and risks of investing in recycled water, although the analysis is equally relevant to any assessment of the value of an additional source of irrigation water, particularly saline water. The approach has been illustrated with a case study of a mixed-crop farm in the Darling Downs region of Queensland, Australia, in which the farm-scale crop production, economic, and environmental implications of investing in recycled water were considered.
Time-resolved and two-photon emission imaging microscopy of live cells with inert platinum complexes
Authors: Botchway Stanley W. , Charnley Mirren , Haycock John W. , Parker Anthony W. , Rochester David L. , Weinstein Julia A. , Williams J. A. Gareth
Published: October 2008

This work explores time-resolved emission imaging microscopy (TREM) for noninvasive imaging and mapping of live cells on a hitherto uncharted microsecond time scale. Simple robust molecules for this purpose have long been sought. We have developed highly emissive, synthetically versatile, and photostable platinum(II) complexes that make TREM a practicable reality. [PtLCl], {HL = 1,3-di(2-pyridyl)benzene and derivatives}, are charge-neutral, small molecules that have low cytotoxicity and accumulate intracellularly within a remarkably short incubation time of 5 min, apparently under diffusion control. Their microsecond lifetimes and emission quantum yields of up to 70% are exceptionally high for transition metal complexes and permit the application of TREM to be demonstrated in a range of live cell types—normal human dermal fibroblast, neoplastic C8161 and CHO cells. [PtLCl] are thus likely to be suitable emission labels for any eukaryotic cell types. The high photostability of [PtLCl] under intense prolonged irradiation has allowed the development of tissue-friendly NIR two-photon excitation (TPE) in conjunction with transition metal complexes in live cells. A combination of confocal one-photon excitation, nonlinear TPE, and microsecond time-resolved imaging has revealed (
i
) preferential localization of the complexes to intracellular nucleic acid structures, in particular the nucleoli and (
ii
) the possibility of measuring intracellular emission lifetimes in the microsecond range. The combination of TREM, TPE, and Pt(II) complexes will be a powerful tool for investigating intracellular processes
in vivo
, because the long lifetimes allow discrimination from autofluorescence and open up the use of commonplace technology.
Dyggve–Melchior–Clausen syndrome: Chondrodysplasia resulting from defects in intracellular vesicle traffic
Authors: Osipovich Anna B. , Jennings Jennifer L. , Lin Qing , Link Andrew J. , Ruley H. Earl
Published: October 2008

Dyggve–Melchior–Clausen syndrome and Smith-McCort dysplasia are recessive spondyloepimetaphyseal dysplasias caused by loss-of-function mutations in dymeclin (
Dym
), a gene with previously unknown function. Here we report that
Dym
-deficient mice display defects in endochondral bone formation similar to that of Dyggve–Melchior–Clausen syndrome and Smith-McCort dysplasia, demonstrating functional conservation between the two species.
Dym
-mutant cells display multiple defects in vesicle traffic, as evidenced by enhanced dispersal of Golgi markers in interphase cells, delayed Golgi reassembly after brefeldin A treatment, delayed retrograde traffic of an endoplasmic reticulum-targeted Shiga toxin B subunit, and altered furin trafficking; and the Dym protein associates with multiple cellular proteins involved in vesicular traffic. These results establish dymeclin as a novel protein involved in Golgi organization and intracellular vesicle traffic and clarify the molecular basis for chondrodysplasia in mice and men.
Three-dimensional brain growth abnormalities in childhood-onset schizophrenia visualized by using tensor-based morphometry
Authors: Gogtay Nitin , Lu Allen , Leow Alex D. , Klunder Andrea D. , Lee Agatha D. , Chavez Alex , Greenstein Deanna , Giedd Jay N. , Toga Arthur W. , Rapoport Judith L. , Thompson Paul M.
Published: October 2008

Earlier studies revealed progressive cortical gray matter (GM) loss in childhood-onset schizophrenia (COS) across both lateral and medial surfaces of the developing brain. Here, we use tensor-based morphometry to visualize white matter (WM) growth abnormalities in COS throughout the brain. Using high-dimensional elastic image registration, we compared 3D maps of local WM growth rates in COS patients and healthy children over a 5-year period, based on analyzing longitudinal brain MRIs from 12 COS patients and 12 healthy controls matched for age, gender, and scan interval. COS patients showed up to 2.2% slower growth rates per year than healthy controls in WM (
P
= 0.02, all
P
values corrected). The greatest differences were in the right hemisphere (
P
= 0.006). This asymmetry was attributable to a right slower than left hemisphere growth rate mapped in COS patients (
P
= 0.037) but not in healthy controls. WM growth rates reached 2.6% per year in healthy controls (
P
= 0.0002). COS patients showed only a 1.3% per year trend for growth in the left hemisphere (
P
= 0.066). In COS, WM growth rates were associated with improvement in the Children's Global Assessment Scale (
R
= 0.64,
P
= 0.029). Growth rates were reduced throughout the brain in COS, but this process appeared to progress in a front-to-back (frontal-parietal) fashion, and this effect was not attributable to lower IQ. Growth rates were correlated with functional prognosis and were visualized as detailed 3D maps. Finally, these findings also confirm that the progressive GM deficits seen in schizophrenia are not the result of WM overgrowth.
A Schiff base connectivity switch in sensory rhodopsin signaling
Authors: Sineshchekov Oleg A. , Sasaki Jun , Phillips Brian J. , Spudich John L.
Published: October 2008

Sensory rhodopsin I (SRI) in
Halobacterium salinarum
acts as a receptor for single-quantum attractant and two-quantum repellent phototaxis, transmitting light stimuli via its bound transducer HtrI. Signal-inverting mutations in the SRI–HtrI complex reverse the single-quantum response from attractant to repellent. Fast intramolecular charge movements reported here reveal that the unphotolyzed SRI–HtrI complex exists in two conformational states, which differ by their connection of the retinylidene Schiff base in the SRI photoactive site to inner or outer half-channels. In single-quantum photochemical reactions, the conformer with the Schiff base connected to the cytoplasmic (CP) half-channel generates an attractant signal, whereas the conformer with the Schiff base connected to the extracellular (EC) half-channel generates a repellent signal. In the wild-type complex the conformer equilibrium is poised strongly in favor of that with CP-accessible Schiff base. Signal-inverting mutations shift the equilibrium in favor of the EC-accessible Schiff base form, and suppressor mutations shift the equilibrium back toward the CP-accessible Schiff base form, restoring the wild-type phenotype. Our data show that the sign of the behavioral response directly correlates with the state of the connectivity switch, not with the direction of proton movements or changes in acceptor pK
a
. These findings identify a shared fundamental process in the mechanisms of transport and signaling by the rhodopsin family. Furthermore, the effects of mutations in the HtrI subunit of the complex on SRI Schiff base connectivity indicate that the two proteins are tightly coupled to form a single unit that undergoes a concerted conformational transition.
DNA variation and symbiotic associations in phenotypically diverse sea urchin
Strongylocentrotus intermedius
Authors: Balakirev Evgeniy S. , Pavlyuchkov Vladimir A. , Ayala Francisco J.
Published: October 2008

Strongylocentrotus intermedius
(A. Agassiz, 1863) is an economically important sea urchin inhabiting the northwest Pacific region of Asia. The northern Primorye (Sea of Japan) populations of
S. intermedius
consist of two sympatric morphological forms, “usual” (U) and “gray” (G). The two forms are significantly different in morphology and preferred bathymetric distribution, the G form prevailing in deeper-water settlements. We have analyzed the genetic composition of the
S. intermedius
forms using the nucleotide sequences of the mitochondrial gene encoding the cytochrome
c
oxidase subunit I and the nuclear gene encoding bindin to evaluate the possibility of cryptic species within
S. intermedius
. We have examined the presence of symbiont microorganisms by means of 16S rRNA sequences. The nucleotide sequence divergence between the morphological forms is low: 0.74% and 0.70% for cytochrome
c
oxidase subunit I and nuclear gene encoding bindin, respectively, which is significantly below average intrageneric sequence divergence among
Strongylocentrotus
species. We thus have found no genetic evidence of cryptic species within
S. intermedius
. Phylogenetic analysis shows that the bacteria symbionts of
S. intermedius
belong to the phylum
Bacteroidetes
, but the U and G forms predominantly harbor highly divergent bacterial lineages belonging to two different taxonomic classes,
Flavobacteria
and
Sphingobacteria
. We propose that the U and G forms of
S. intermedius
represent distinct ecomorphological adaptations to contrasting shallow- and deep-water marine environments and might be considered incipient species. We also propose that the symbiotic bacteria likely play an important role in the evolution of morphological divergence of
S. intermedius
.
PERK-dependent regulation of lipogenesis during mouse mammary gland development and adipocyte differentiation
Authors: Bobrovnikova-Marjon Ekaterina , Hatzivassiliou Georgia , Grigoriadou Christina , Romero Margarita , Cavener Douglas R. , Thompson Craig B. , Diehl J. Alan
Published: October 2008

The role of the endoplasmic reticulum stress-regulated kinase, PERK, in mammary gland function was assessed through generation of a targeted deletion in mammary epithelium. Characterization revealed that PERK is required for functional maturation of milk-secreting mammary epithelial cells. PERK-dependent signaling contributes to lipogenic differentiation in mammary epithelium, and
perk
deletion inhibits the sustained expression of lipogenic enzymes FAS, ACL, and SCD1. As a result, mammary tissue has reduced lipid content and the milk produced has altered lipid composition, resulting in attenuated pup growth. Consistent with PERK-dependent regulation of the lipogenic pathway, loss of PERK inhibits expression of FAS, ACL, and SCD1 in immortalized murine embryonic fibroblasts when cultured under conditions favoring adipocyte differentiation. These findings implicate PERK as a physiologically relevant regulator of the lipogenic pathway.
Evolution of the ssrA degradation tag in
Mycoplasma
: Specificity switch to a different protease
Authors: Gur Eyal , Sauer Robert T.
Published: October 2008

Stalled ribosomes in bacteria are rescued by the tmRNA system. In this process, the nascent polypeptide is modified by the addition of a short C-terminal sequence called the ssrA tag, which is encoded by tmRNA and allows normal termination and release of ribosomal subunits. In most bacteria, ssrA-tagged proteins are degraded by the AAA+ protease, ClpXP. However, in bacterial species of the genus
Mycoplasma
, genes for ClpXP and many other proteins were lost through reductive evolution. Interestingly,
Mycoplasma
ssrA tag sequences are very different from the tags in other bacteria. We report that ssrA-tagged proteins in
Mesoplasma florum
, a
Mycoplasma
species, are efficiently recognized and degraded by the AAA+ Lon protease. Thus, retaining degradation of ssrA-tagged translation products was apparently important enough during speciation of
Mycoplasma
to drive adaptation of the ssrA tag to a different protease. These results emphasize the importance of coupling proteolysis with tmRNA-mediated tagging and ribosome rescue.
An empirical explanation of the flash-lag effect
Authors: Wojtach William T. , Sung Kyongje , Truong Sandra , Purves Dale
Published: October 2008

When a flash of light is presented in physical alignment with a moving object, the flash is perceived to lag behind the position of the object. This phenomenon, known as the flash-lag effect, has been of particular interest to vision scientists because of the challenge it presents to understanding how the visual system generates perceptions of objects in motion. Although various explanations have been offered, the significance of this effect remains a matter of debate. Here, we show that: (
i
) contrary to previous reports based on limited data, the flash-lag effect is an increasing nonlinear function of image speed; and (
ii
) this function is accurately predicted by the frequency of occurrence of image speeds generated by the perspective transformation of moving objects. These results support the conclusion that perceptions of the relative position of a moving object are determined by accumulated experience with image speeds, in this way allowing for visual behavior in response to real-world sources whose speeds and positions cannot be perceived directly.