bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term changes of epiphytic lichen species composition over landscape gradients: an 18 year time series
Authors: LIŠKA Jiří , HERBEN Tomáš
Published: August 2008

The study aimed to determine how the response of the epiphytic lichen vegetation to sulphur air pollution is affected by interaction with other factors (distance from pollution sources, habitat, altitude, initial eutrophication of the tree bark). It was based on a series of four successive recordings taken over a period of 18 years with increasing pollution levels and on the same set of 139 solitary trees. Relationships between habitat variables and lichen community composition are assessed using canonical correspondence analysis. The data set comprised 69 lichen species. Ordination of initial species composition on trees revealed two major gradients: eutrophication and acidity.

The species composition significantly changed with time, with a general decrease of the total number of lichen species per tree. In general, species sensitive to air pollution decreased, while tolerant species increased in number. Change over time differed depending on the position of the tree within the landscape (relative to one major source of pollution, the town of Tábor, whereas the distance to the other source, Sezimovo Ústí, was not significant) and on the initial species composition found on the tree. Trees under the effect of eutrophication changed their species composition less, indicating that the effect of eutrophication (mainly increased bark pH) may ameliorate the effects of air pollution; a local effect of eutrophication also seems to play an important role. Distance to pollution sources had only a small impact on the rate of change and perhaps other local conditions (sheltered or humid position, altitude) play a role in this interaction. There was a decrease of the overall heterogeneity of the data set over time. This means that the gradients in species composition attributable to these variables became less important over time. Therefore, one of the effects of air pollution is also a general homogenization of the lichen vegetation of the solitary trees.
New species and additional records of foliicolous lichenized fungi from Bolivia
Authors: FLAKUS Adam , LÜCKING Robert
Published: August 2008

Six new species of foliicolous lichenized fungi are described as new to science from Bolivian lowland Amazon forest: Asterothyrium vezdae Flakus & Lücking (Asterothyriaceae), Keratosphaera multiseptata Flakus & Lücking (Pseudoperisporiaceae), Phylloblastia bielczykiae Flakus & Lücking (Verrucariaceae), Porina boliviana Flakus & Lücking (Porinaceae), Tapellaria intermedia Flakus & Lücking (Pilocarpaceae) and Trichothelium subargenteum Flakus & Lücking (Porinaceae). In addition, new records of 70 lichen species in Bolivia are listed. Of these, 52 are new to Bolivia.
Sticta alpinotropica, a new saxicolous lichen species from the alpine zone of Mt Wilhelm, Papua New Guinea
Authors: APTROOT André
Published: August 2008

The lichen species Sticta alpinotropica is described new to science from Papua New Guinea. It grows on rock between 3900 and 4200 m elevation in an alpine environment virtually on the equator. Although it is locally abundant, it is known only from one small mountain top.
Caloplaca subalpina and C. thracopontica, two new saxicolous species from the Caloplaca cerina group ( Teloschistales)
Authors: VONDRÁK Jan , ŠOUN Jaroslav , HROUZEK Pavel , ŘÍHA Pavel , KUBÁSEK Jiří , PALICE Zdeněk , SØCHTING Ulrik
Published: August 2008

Caloplaca subalpina Vondrák, Šoun & Palice and C. thracopontica Vondrák & Šoun are described here as new to science. The former is a sorediate, often sterile, saxicolous species inhabiting subalpine base-rich overhanging rocks in European mountains; the latter grows on maritime cliffs of the Black Sea and is conspicuous by the lobules and pustules which are usually present on its thallus and by its apothecia which are typically large and abundant. The placing of the two species in the C. cerina group was confirmed by molecular studies using nrDNA ITS sequences. The chemosyndromes of both new species correspond to chemosyndrome A, which is in accordance with their position in the C. cerina group. A key to the saxicolous species of the C. cerina group is provided.
Ameliella, a new genus of lichen-forming fungi from north-west Europe and western Canada
Authors: FRYDAY Alan M. , COPPINS Brian J.
Published: August 2008

Ameliella Fryday & Coppins gen. nov. is proposed to accommodate two inconspicuous, undescribed species, A. andreaeicola and A. grisea, collected from high altitude in the Scottish Highlands. Outside the Scottish Highlands, Ameliella andreaeicola is known from single collections from Norway and Canada, and A. grisea from a single collection from Norway. The new genus appears to have some affinity with Miriquidica.
Guest Editorial
Authors: BAUER KEITH A.
Published: August 2008

In the advent of the 21st century there can be no doubt that we have entered uncharted territory as we continue to employ diverse information and communication technologies (ICT) within healthcare. This is simply a matter of fact, at least for the Western world. But, as a question of value, what are the ethical and social ramifications of this healthcare trek? What assessments can we render on this murky, barely explored topography? A utopian answer is that ICT would deliver us to a technologic garden of healthcare delights. Here, health-related information and services abound and healthcare professionals and patients, under the protection of an electronic, global umbrella, operate in perfect harmony for the good of patients.
Bioethics, Business Ethics, and Science: Bioinformatics and the Future of Healthcare
Authors: GOODMAN KENNETH W. , CAVA ANITA
Published: August 2008

The intersection of ethics, computing, and genetics plots a space not yet adequately mapped, despite its importance, indeed, its rapidly growing importance. Its subdomains are well-enough known: “Genethics,” or the study of ethical issues in genetics and genomics, is part of core curricula everywhere. Ethics and computing is an established subfield. Computing and genetics—bioinformatics—has in little more than a decade progressed from subsubspecialty to the sine qua non of contemporary biomedical research, and it bids fair to transform clinical practice. We must prepare for the complete digitization of the genomes of individual patients and the storage of millions of these genomes in very large databases.
“The Cure Is in Hand”? The Brave New World of Handheld Computers in Medicine
Authors: DE VILLE KENNETH
Published: August 2008

According to a 2001 market report, titled “The Cure Is in Hand,” handheld computers, or personal digital assistants (PDAs), will “dramatically change the way that physicians practice medicine.” Such enthusiasm has resulted in an extraordinarily rapid diffusion of PDAs into a wide range of clinical settings. One report states that 47% of internists use PDAs once a day with rates of daily usage reaching 70% for resident physicians. Another study found clinical usage as high as 85% in teaching hospitals. The rapidly expanding employment of PDAs, however, has been uneven. Some clinicians have explored the devices’ benefits more thoroughly than their colleagues. Similarly, a number of potentially valuable uses of the handheld computer have been ignored or remain insufficiently developed by the medical community and the health delivery system at large.
An Analysis of Factors Underlying E-Health Disparities
Authors: BAUR CYNTHIA
Published: August 2008

The potential public and individual health consequences of unequal access to digital technologies have been recognized in the United States for at least a decade. Unequal access to the Internet and related technologies has been characterized as a “digital divide”; naturalistic trends toward broader access across the population and targeted intervention to increase access are described as progress toward “digital inclusion.” The problem of the digital divide has been characterized as one of healthcare justice. The idea that everyone should have access to the telecommunications grid—telephone and computer—is a central tenet of the U.S. universal service policy. With the diffusion of broadband technologies, the issue of digital access includes not only access to the Internet but also access to new levels of service, such as broadband, to support a wide range of emerging applications.
An Architecture for Privacy in a Networked Health Information Environment
Authors: DIAMOND CAROL , GOLDSTEIN MELISSA , LANSKY DAVID , VERHULST STEFAAN
Published: August 2008

As we move toward the creation of a networked health information environment, the potential of privacy intrusions increases, with potentially devastating impact on quality and access to healthcare. This paper describes the risks we face and proposes a framework to minimize those risks. In particular, it proposes nine principles to protect privacy in an information age.
The occurrence of ionospheric signatures of plasmaspheric plumes over different longitudinal sectors
Authors: Yizengaw E. , Dewar J. , MacNeil J. , Moldwin M. B. , Galvan D. , Sanny J. , Berube D. , Sandel B.
Published: August 2008

Plasmaspheric plumes have ionospheric signatures and are observed as storm‐enhanced density (SED) in global positioning system (GPS) total electron content (TEC). These ionospheric signatures have been primarily observed over the American sector and in a few limited examples over the European sector. This study examines the longitudinal occurrence frequency of plasmaspheric plumes. We analyzed all images from the Imager for Magnetopause‐to‐Aurora Global Exploration (IMAGE) Extreme Ultraviolet Imager (EUV) databases for the first half of 2001 and identified a total of 31 distinct plume intervals observed during different storm events. Out of the total IMAGE EUV plumes that we identified, 12 were projected over North America, 10 over Asia, and the remaining 9 were over Europe and the Atlantic Ocean. Using ground‐based GPS TEC from MIT's Madrigal database, we searched for corresponding SED/TEC plumes at different longitudinal sector and found 12 ionospheric SED plume signatures over North America, 4 over Europe, and 2 over Asia. This indicates that the observation probability of an ionospheric SED plume when a plasmaspheric plume is seen is 100% in the American sector, 50% in the European sector, and 20% in the Asian sector. This could be due to the fact that the plumes may be either positioned beyond the limit of the ground‐based GPS field of view, which happens mainly when there is less plasmaspheric erosion, or are too weak to be detected by the sparse number of GPS receivers over Asia. The in situ plasma densities from the available coincident defense metrological satellite program (DMSP) satellites were also used to study the characteristics of SED/TEC plume at DMSP orbiting altitude (i.e., ∼870 km). The TOPographic EXplorer (TOPEX) altimeter TEC also is used to identify the conjugate SED/plume signature over the Southern Hemisphere.
Faulting processes controlled by the nonuniform thermal structure of the crust and uppermost mantle beneath the northeastern Japanese island arc
Authors: Shibazaki Bunichiro , Garatani Kazuteru , Iwasaki Takaya , Tanaka Akiko , Iio Yoshihisa
Published: August 2008

We performed a finite element analysis, taking into account nonlinear viscoelasticity and plasticity, to construct a two‐dimensional model of the deformation and faulting processes that occur in the deeper parts of the seismogenic zone beneath northeastern Japan. Our finite element code was developed on the basis of the GeoFEM parallel finite element code using plug‐ins to adopt several nonlinear functions. An extensive onshore‐offshore wide‐angle seismic expedition conducted across northeastern Japan in 1997 revealed a detailed image of the deep crust and uppermost mantle structures. In modeling the deformation and faulting beneath the Ou Backbone Range and Dewa Hill, northeastern Japan, we consider a realistic crust and uppermost mantle structure revealed by the 1997 seismic expedition and the existence of the two hot regions revealed by geothermal observations in a compressional tectonic setting. The numerical results reveal that shortening deformation due to nonlinear viscous flow occurs in the hot region in the lower crust and the uppermost mantle, resulting in shear faulting in the upper crust. Our model reproduces three reverse fault zones that are consistent with those observed. We investigate the stress accumulation process over a period approximately corresponding to the earthquake recurrence interval by prohibiting plastic faulting and found that the stress is loaded along the fault zone at magnitudes much lower than the absolute stress level. The results indicate that the loading processes of large inland earthquakes in northeastern Japan are determined by the nonuniform thermal structure in the deeper crust and uppermost mantle.
Arctic waters and marginal ice zones: 2. An investigation of arctic atmospheric infrared absorption for advanced very high resolution radiometer sea surface temperature estimates
Authors: Vincent R. F. , Marsden R. F. , Minnett P. J. , Buckley J. R.
Published: August 2008

The derivation of sea surface temperatures (SST) from satellite radiometric data is well established in temperate latitudes. Water vapor is typically the greatest clear sky absorber of infrared (IR) energy between the emitting surface and spaceborne sensor, necessitating a corrective term for SST calculation. Algorithms developed for advanced very high resolution radiometers (AVHRR) use the difference in brightness temperatures between Channel 4 (10.3 to 11.3 μm) and Channel 5 (11.5 to 12.5 μm), or T45, to estimate the amount of IR absorption in the atmosphere. While relatively accurate in temperate latitudes, this approach is not applicable to Arctic waters, typically overestimating the SST by 2 to 3 K as a result of high T45 values that are not indicative of IR absorption by water vapor. The high T45 values in the Arctic may be attributable to atmospheric ice crystals. The attenuation of IR energy increases sharply across Channel 4 and 5 for ice crystals, the amount of which is a function of crystal size, shape and orientation. In the development of the Composite Arctic Sea Surface Temperature Algorithm in the North Water polynya (NOW), it was demonstrated that when T45 exceeded a threshold of 2 K the surface temperature could not be estimated owing to the presence of a clear sky absorptive feature. Observations from the NOW study led to the assessment that areas where T45 > 2K were covered by ice fog. This is a significant finding since these regions must be identified to achieve an accurate mapping of the surface temperature.
Dynamics of leaf area for climate and weather models
Authors: Dickinson Robert E. , Tian Yuhong , Liu Qing , Zhou Liming
Published: August 2008

Leaf area is the most relevant scalar variable for describing the dynamics of vegetation on seasonal time scales, and hence is required as part of the land‐surface component of a meteorological model. A mathematical scheme for the dynamic vegetation component of such a model is formulated and reduced to a toy model for seasonal leaf dynamics. Leaf growth is seen as a temperature‐initiated instability of the ecosystem that drives it away from its state of winter dormancy; the onset of dormancy in autumn consists of cold temperatures breaking the summer‐time attractor; the temperature‐dependent controls are represented by a “ramp‐up” function. Results from ensemble simulations driven by a stochastic temperature model show that leaf variability statistics have a very strong seasonality, such that variability is largely confined to spring and autumn. These variability windows promote non‐Gaussian and nonstationary statistics that occur when the stable attractor of one season has flipped to the stable attractor of the other season. During such periods of high variability, any dynamic vegetation model will be most unreliable without observational constraints because of its unstable trajectory.
Measurement of low‐altitude CO over the Indian subcontinent by MOPITT
Authors: Kar J. , Jones D. B. A. , Drummond James R. , Attié J. L. , Liu J. , Zou J. , Nichitiu F. , Seymour M. D. , Edwards D. P. , Deeter M. N. , Gille J. C. , Richter A.
Published: August 2008

We show that the dayside MOPITT retrievals in the lower troposphere can provide useful information on surface sources of atmospheric CO over the Indian subcontinent. We find that MOPITT retrievals at 850 hPa show localized enhancements over the Indian subcontinent, which correlate with similar enhancements seen in the tropospheric NO2 columns from the SCIAMACHY instrument. In particular, high concentrations of CO over the Indo‐Gangetic basin and some prominent cities are captured in the lower‐tropospheric retrievals in spring. MOPITT averaging kernels (normalized to take into account the absorber amounts in the layers) indicate that the retrievals are sensitive to CO in the lower troposphere. In winter, MOPITT retrievals at 850 hPa can detect the strongest source areas over the eastern states of Bihar and West Bengal, thus confirming the so‐called “Bihar pollution pool,” which was detected earlier in the aerosol measurements by the multiangle imaging spectroradiometer (MISR) aboard Terra. The pollution features are consistent with the spatial distribution of CO emissions in India, as reflected in the GEOS‐Chem simulation of CO. Furthermore, these lower‐tropospheric features in the simulation are still present after smoothing the modeled fields using the MOPITT averaging kernels and a priori profile, demonstrating that the retrievals do have sensitivity in the lower troposphere. This work indicates that although MOPITT retrievals are often most sensitive to CO in the middle and upper troposphere, they do provide information on lower‐tropospheric CO in selected continental regions with strong thermal contrast and could be useful for pollution studies.
The frequency and dynamics of stratospheric sudden warmings in the 21st century
Authors: Charlton‐Perez A. J. , Polvani L. M. , Austin J. , Li F.
Published: August 2008

Changes to stratospheric sudden warmings (SSWs) over the coming century, as predicted by the Geophysical Fluid Dynamics Laboratory (GFDL) chemistry climate model [Atmospheric Model With Transport and Chemistry (AMTRAC)], are investigated in detail. Two sets of integrations, each a three‐member ensemble, are analyzed. The first set is driven with observed climate forcings between 1960 and 2004; the second is driven with climate forcings from a coupled model run, including trace gas concentrations representing a midrange estimate of future anthropogenic emissions between 1990 and 2099. A small positive trend in the frequency of SSWs is found. This trend, amounting to 1 event/decade over a century, is statistically significant at the 90% confidence level and is consistent over the two sets of model integrations. Comparison of the model SSW climatology between the late 20th and 21st centuries shows that the increase is largest toward the end of the winter season. In contrast, the dynamical properties are not significantly altered in the coming century, despite the increase in SSW frequency. Owing to the intrinsic complexity of our model, the direct cause of the predicted trend in SSW frequency remains an open question.
Observations and simulations of a large‐amplitude mountain wave breaking over the Antarctic Peninsula
Authors: Plougonven R. , Hertzog A. , Teitelbaum H.
Published: August 2008

A case study of a large‐amplitude orographic gravity wave occurring over the Antarctic Peninsula is presented, based on observations from the Vorcore balloon campaign and on mesoscale numerical simulations. The Vorcore campaign (September 2005 to February 2006) consisted in the flight of 27 superpressure balloons in the core of the Southern Hemisphere stratospheric polar vortex at altitudes of 16–19 km, from September 2005 to February 2006. On 7 October 2005, one of the balloons exploded as it was flying above the Antarctic Peninsula. The observations collected by another balloon that was flying during the same time period above the peninsula suggest the presence of a very intense gravity wave (peak‐to‐peak amplitude of the order of 25–30 m s−1 in zonal and meridional velocity disturbances). The wave packet is likely undersampled in the balloon observations because of its high intrinsic frequency, but the balloon data set is complemented with high‐resolution numerical simulations carried out with the Weather Research and Forecast Model. The simulations are validated by comparison with the balloon measurements and show that the wave was breaking in the lower stratosphere at the time and height where the balloon exploded. The simulations highlight several consequences of the mountain wave on the stratosphere: forcing of the mean flow, generation of secondary inertia‐gravity waves, and turbulence and mixing. In particular, the momentum fluxes are calculated and are found to compare well with the estimates from balloon measurements. The large values found are likely extreme values, which raises the issue of their representativity. To discuss this, the balloon measurements are used in conjunction with operational analyses to estimate the frequency of such large‐amplitude gravity waves, i.e., to provide an estimate of their intermittency.
Extreme uplift of the Rwenzori Mountains in the East African Rift, Uganda: Structural framework and possible role of glaciations
Authors: Ring Uwe
Published: August 2008

The >5‐km‐high Rwenzori Mountains in the East African Rift form a promontory on the rift shoulder and are an extreme expression of rift‐mountain uplift. This study reports the pattern and the kinematics of major faults in the Rwenzori region. The fault pattern is characterized by a first set of N/NNE‐striking normal faults that are offset by mainly NE‐ to E‐striking faults. Fault‐slip data indicate a change in the extension direction from ENE/E to SE. The latter direction is in accord with earthquake focal data and borehole breakouts. Major faults with displacements >6 km occur at the boundaries of the Rwenzori Mountains; within the range minor faults with offsets ≤2 km have been mapped. Flexural isostatic rebound of the footwall of large‐displacement back‐to‐back normal faults bounding the Rwenzori horst and additional footwall uplift of a young crosscutting normal fault probably caused cumulative (surface) uplift of ∼3–4 km. I propose that the change in the kinematics of the rift faults and the largely contemporaneous onset of glaciation in the Rwenzori Mountains in the Middle Pleistocene were important for enhanced rock uplift. Glacial erosion rates were 1.5–4 mm/a and eroded 1–2 km of material off the top of the Rwenzoris. Glacial erosion and the retreat of the glaciers during interglacial periods caused removal of loads leading to isostatic rebound, which reduced horizontal stresses promoting normal faulting and enhanced rock uplift, thereby elevating the remaining terrain, transforming it into one with high peaks and deeply incised valleys.
Structure of Tendaho Graben and Manda Hararo Rift: Implications for the evolution of the southern Red Sea propagator in Central Afar
Authors: Acocella V. , Abebe B. , Korme T. , Barberi F.
Published: August 2008

The Red Sea and Aden rifts (or propagators) meet in Afar. Here we use remote sensing and field analyses to define the geology and structure of the southern part of the Red Sea propagator in Central Afar. This consists of the NW‐SE trending Tendaho Graben (TG) and the younger and active NW‐SE trending Manda Hararo Rift (MHR), partly within TG. Tectonic and volcanic activity within TG developed mostly between ∼1.8 and ∼0.6 Ma, with a stretching factor β ∼ 1.1, an extension rate ∼3.6 mm/yr and the fissural eruption of part (∼7000 km3/Ma) of the Afar Stratoid sequence (mainly basaltic lava flows and ignimbrites). MHR, before terminating southward, has a β ∼ 1.04 and an extension rate ∼1.2 mm/yr, and is associated with the emission of ∼600 km3/Ma of basalts in the last ∼0.2 Ma. These data suggest that after the exceptional amount of magma erupted between ∼1.8 and ∼0.6 Ma, magmatic and tectonic activity significantly decreased along the southern part of the Red Sea propagator in the last ∼0.2 Ma. This decrease coincides with the on‐land development and migration of the more active (inferred extension rate in the order of ∼10 mm/yr, as proposed in previous studies) Aden propagator, suggesting that spreading in Central Afar mainly occurred along one active propagator at any one time.
Parameter conditioning with a noisy Monte Carlo genetic algorithm for estimating effective soil hydraulic properties from space
Authors: Ines Amor V. M. , Mohanty Binayak P.
Published: August 2008

The estimation of effective soil hydraulic parameters and their uncertainties is a critical step in all large‐scale hydrologic and climatic model applications. Here a scale‐dependent (top‐down) parameter estimation (inverse modeling) scheme called the noisy Monte Carlo genetic algorithm (NMCGA) was developed and tested for estimating these effective soil hydraulic parameters and their uncertainties. We tested our method using three case studies involving a synthetic pixel (pure and mixed) where all modeling conditions are known, and with actual airborne remote sensing (RS) footprints and a satellite RS footprint. In the synthetic case studies under pure (one soil texture) and mixed‐pixel (multiple soil textures) conditions, NMCGA performed well in estimating the effective soil hydraulic parameters even with pixel complexities contributed by various soil types and land management practices (rain‐fed/irrigated). With the airborne and satellite remote sensing cases, NMCGA also performed well for estimating effective soil hydraulic properties so that when applied in forward stochastic simulation modeling it can mimic large‐scale soil moisture dynamics. The results also suggest a possible scaling down of the effective soil water retention curve θ(h) at the larger satellite remote sensing pixel compared with the airborne remote sensing pixel. However, it did not generally imply that all effective soil hydraulic parameters should scale down like the soil water retention curve. The reduction of the soil hydraulic parameters was most profound in the saturated soil moisture content (θsat) as we relaxed progressively the soil hydraulic parameter search spaces in our satellite remote sensing studies. Overall, the NMCGA framework was found to be very promising in the inverse modeling of remotely sensed near‐surface soil moisture for estimating the effective soil hydraulic parameters and their uncertainties at the remote sensing footprint/climate model grid.
Lateral momentum flux and the spatial evolution of flow within a confluence mixing interface
Authors: Rhoads Bruce L. , Sukhodolov Alexander N.
Published: August 2008

Mixing interfaces at confluences have been viewed as analogous to shallow mixing layers in which lateral fluxes of momentum generally are viewed as unimportant. This investigation examines the spatial evolution of flow along a confluence mixing interface, focusing on lateral fluxes of momentum. Cross‐stream profiles of depth‐averaged mean velocities indicate that flow within the mixing interface has wake characteristics near the upstream junction corner, mixing‐layer properties within the confluence, and attributes of a weak jet within the downstream channel. Convective acceleration of downstream velocity along the path of the mixing interface is influenced by lateral fluxes of momentum from the converging mean flow. These fluxes exceed turbulence lateral momentum fluxes by one to two orders of magnitude. Flow in the mixing interface is unstable, but lateral expansion of coherent turbulent vortices over distance is limited, possibly due to the inhibiting effects of the converging flow. Similar low‐frequency oscillations in near‐surface velocity fluctuations occur within the stagnation zone and along the mixing interface, suggesting that the dynamics of the stagnation‐zone wake may influence low‐frequency characteristics of flow in the downstream portion of the mixing interface. Patterns of turbulence kinetic energy (k) are influenced by lateral momentum fluxes, which progressively shift the zone of maximum k toward the outer bank. Overall the study shows that lateral momentum fluxes are important in the spatial evolution of flow within confluence mixing interfaces and need to be accounted for in theoretical treatments of these interfaces.
Modeling spectra of the north and south Jovian X‐ray auroras
Authors: Kharchenko V. , Bhardwaj Anil , Dalgarno A. , Schultz D. R. , Stancil P. C.
Published: August 2008

Spectra of Jovian X‐ray auroras observed from the North and South poles with the Chandra X‐ray telescope are analyzed and compared with predicted spectra of the charge‐exchange mechanism. To determine the theoretical spectra of Jovian X‐ray auroras, we model numerically the collisionally induced evolution of energy and charge distributions of Oq+ and Sq+ ions, precipitating into the Jovian atmosphere. Monte Carlo simulations of the energy and charge relaxation of the precipitating ions are carried out with updated cross‐sections of the ion stripping, electron capture, and gas‐ionization collisions. X‐ray and Extreme Ultraviolet (EUV) spectra of cascading radiation induced by individual energetic sulfur and oxygen ions are calculated, and relative intensities of X‐ray emission lines are determined. Synthetic spectra of X‐ray and EUV photons are computed at different initial kinetic energies and compositions of ion‐precipitating fluxes. Theoretical spectra with adjustable initial energies and relative fraction of sulfur and oxygen ions are shown to be in good agreement with the spectra of X rays detected from the South and North polar regions. The abundances and initial energies of the precipitating ions are inferred by comparing synthetic and observed X‐ray spectra. Comparisons are performed independently for the North and South pole emissions. Abundances of the precipitating sulfur ions are found to be four to five times smaller than those of oxygen ions, and averaged ion energies are determined to lie between 1 and 2 MeV/amu. Slightly different ion flux compositions are found to describe the observed spectra of X‐ray emission from the North and South poles.
Seasonal dependence and solar wind control of transpolar arc luminosity
Authors: Kullen A. , Cumnock J. A. , Karlsson T.
Published: August 2008

The influence of the solar wind and the interplanetary magnetic field (IMF) on the luminosity of transpolar arcs (TPAs) is examined by taking into account seasonal effects. The study focuses on those transpolar arcs that appear after an IMF By sign change during steady northward IMF. It includes 21 northern hemisphere events identified in a previous study from global UV images taken by the Polar spacecraft between 1996 and 2000. Sorting the TPA events by sign of the Earth dipole tilt we find that the TPAs which appear in the dark hemisphere are on average much weaker than TPAs in the sunlit hemisphere. For the dark hemisphere events, no clear correlation between solar wind parameters and TPA luminosity is found. However, in the sunlit hemisphere, a clear dependence on solar wind and IMF conditions is seen. The TPA brightness is strongly influenced by IMF magnitude, northward IMF Bz and solar wind speed. A weak, negative correlation with the ion density is found. The TPA luminosity in the sunlit hemisphere is much more strongly controlled by the magnetic energy flux than by the kinetic energy flux of the solar wind. This explains the absence of transpolar arcs for the two By sign change cases for positive dipole tilts with lowest magnetic energy flux values. The strong influence of the Earth dipole tilt on the transpolar arc luminosity appears due to the dependence of the ionospheric conductivity on solar EUV emissions.
Q‐bursts: A comparison of experimental and computed ELF waveforms
Authors: Nickolaenko A. P. , Hayakawa M. , Ogawa Toshio , Komatsu Masayuki
Published: August 2008

Experimental waveforms of natural ELF transient signals (Q‐bursts) are compared with computations based on the analytical time domain solution. The computations were performed for the uniform Earth‐ionosphere cavity model with a linear frequency dependence of the ELF propagation constant. The vertical electric field was recorded in the frequency band from 1 Hz to 11 kHz by a ball antenna in fair weather conditions at Kochi (geographic coordinates: 33.3°N and 133.4°E) during the period of 2003–2004. Waveforms of discrete pulses were compared, each showing a high similarity. This confirms the validity of the model and the consistency of the source‐observer distance found experimentally, directly in the time domain.
Increased tyrosine phosphorylation of PSD-95 by Src family kinases after brain ischaemia
Authors: Du Cai-Ping , Gao Jin , Tai Jian-Min , Liu Yong , Qi Jing , Wang Wei , Hou Xiao-Yu
Published: August 2008

PSD (postsynaptic density)-95, a scaffold protein that tethers NMDA (N-methyl-D-aspartate) receptors to signal molecules, is implicated in pathological events resulting from excitotoxicity. The present study demonstrates that brain ischaemia and reperfusion increase the tyrosine phosphorylation of PSD-95 in the rat hippocampus. PP2, a specific inhibitor of SrcPTKs (Src family protein tyrosine kinases), prevents the ischaemia-induced increases not only in the tyrosine phosphorylation of PSD-95, but also in the interaction between PSD-95 and Src kinases. PSD-95 is phosphorylated either by purified Src/Fyn kinases in vitro or by co-expression of constitutively active Src/Fyn in COS7 cells. The results suggest that SrcPTKs are involved in PSD-95 phosphorylation. The single Tyr523 mutation to phenylalanine (Y523F) reduces the Src/Fyn-mediated phosphorylation of PSD-95 in COS7 cells and in vitro. As shown with a rabbit polyclonal antibody against phospho-PSD-95 (Tyr523), Tyr523 phosphorylation is responsible for the increased tyrosine phosphorylation of PSD-95 induced by ischaemia in the rat hippocampus. In cultured hippocampal neurons, overexpression of PSD-95 Y523F, but not PSD-95 Y533F, abolishes the facilitating effect of PSD-95 on the glutamate- or NMDA-mediated currents, implying that PSD-95 Tyr523 phosphorylation contributes to the post-ischaemic over-activation of NMDA receptors. Thus the present study reveals an additional mechanism for the regulation of PSD-95 by tyrosine phosphorylation. This mechanism may be of pathological significance since it is associated with excitotoxicity in the ischaemic brain.
Novel haem co-ordination variants of flavocytochrome P450 BM3
Authors: Girvan Hazel M. , Toogood Helen S. , Littleford Rachael E. , Seward Harriet E. , Smith W. Ewen , Ekanem Idorenyin S. , Leys David , Cheesman Myles R. , Munro Andrew W.
Published: August 2008

Bacillus megaterium flavocytochrome P450 BM3 is a catalytically self-sufficient fatty acid hydroxylase formed by fusion of soluble NADPH–cytochrome P450 reductase and P450 domains. Selected mutations at residue 264 in the haem (P450) domain of the enzyme lead to novel amino acid sixth (distal) co-ordination ligands to the haem iron. The catalytic, spectroscopic and thermodynamic properties of the A264M, A264Q and A264C variants were determined in both the intact flavocytochromes and haem domains of P450 BM3. Crystal structures of the mutant haem domains demonstrate axial ligation of P450 haem iron by methionine and glutamine ligands trans to the cysteine thiolate, creating novel haem iron ligand sets in the A264M/Q variants. In contrast, the crystal structure of the A264C variant reveals no direct interaction between the introduced cysteine side chain and the haem, although EPR data indicate Cys264 interactions with haem iron in solution. The A264M haem potential is elevated by comparison with wild-type haem domain, and substrate binding to the A264Q haem domain results in a ∼360 mV increase in potential. All mutant haem domains occupy the conformation adopted by the substrate-bound form of wild-type BM3, despite the absence of added substrate. The A264M mutant (which has higher dodecanoate affinity than wild-type BM3) co-purifies with a structurally resolved lipid. These data demonstrate that a single mutation at Ala264 is enough to perturb the conformational equilibrium between substrate-free and substrate-bound P450 BM3, and provide firm structural and spectroscopic data for novel haem iron ligand sets unprecedented in Nature.
Stimulation by lithium of the interaction between the transcription factor CREB and its co-activator TORC
Authors: Heinrich Annette , Böer Ulrike , Tzvetkov Mladen , Oetjen Elke , Knepel Willhart
Published: August 2008

Lithium salts are clinically important drugs used to treat bipolar mood disorder. The mechanisms accounting for the clinical efficacy are not completely understood. Chronic treatment with lithium is required to establish mood stabilization, suggesting the involvement of neuronal plasticity processes. CREB (cAMP-response-element-binding protein) is a transcription factor known to mediate neuronal adaptation. Recently, the CREB-co-activator TORC (transducer of regulated CREB) has been identified as a novel target of lithium and shown to confer an enhancement of cAMP-induced CREB-directed gene transcription by lithium. TORC is sequestered in the cytoplasm and its nuclear translocation controls CREB activity. In the present study, the effect of lithium on TORC function was investigated. Lithium affected neither the nuclear translocation of TORC nor TORC1 transcriptional activity, but increased the promoter occupancy by TORC1 as revealed by chromatin immunoprecipitation assay. In a mammalian two-hybrid assay, as well as in a cell-free GST (glutathione transferase) pull-down assay, lithium enhanced the CREB–TORC1 interaction. Magnesium ions strongly inhibited the interaction between GST–CREB and TORC1 and this effect was reversed by lithium. Thus our results suggest that, once TORC has entered the nucleus, lithium as a cation stimulates directly the binding of TORC to CREB, leading to an increase in cAMP-induced CREB target-gene transcription. This novel mechanism of lithium action is likely to contribute to the clinical mood-stabilizing effect of lithium salts.
Considerations for Persons With Mild Traumatic Brain Injury
Authors: Myers Paula J. , Henry James A. , Zaugg Tara L.
Published: August 2008

The intensified use of explosive devices and mines in warfare and excessive noise of weapons has created an extraordinary amount of auditory dysfunction, traumatic brain injury (TBI), and mental health complaints among soldiers from the global war on terrorism. Mild TBI, particularly for those with closed head injuries, may not be immediately obvious. Audiologists must be prepared to identify those at risk for mild TBI or mental health problems, justify the need for screening and/or clinical referral for further evaluation of TBI and/or posttraumatic stress disorder (PTSD), and adapt audiologic clinical assessment and management practices to this population. An interdisciplinary comprehensive evaluation of peripheral, central, and vestibular components of the auditory system should be employed in patients with mild TBI to ensure that auditory dysfunction is accurately diagnosed so appropriate rehabilitation can be provided.
Expand Your Practice: Add (Central) Auditory Processing Services
Authors: Brannen Susan J.
Published: August 2008

Two documents of the American Speech-Language-Hearing Association (ASHA) can assist the audiologist in expanding his or her practice to include services for (Central) Auditory Processing Disorder, (C)APD. The purpose of this article is to acquaint the reader with the critical aspects of (C)APD services and how to utilize the documents identified. Issues that continue to prevail within the audiology community are acknowledged. There are necessary tenets to (C)APD services that must be addressed, if these services are to be efficacious as well as ethical. The pertinent documents are reviewed in a step-by-step method. As a result, the practitioner could presumably expand his or her practice in an effective manner. Including these services may appear formidable, but the benefit to the client could suggest greater communication competence and social well-being.
Silicon surface passivation by atomic layer deposited Al2O3
Authors: Hoex B. , Schmidt J. , Pohl P. , van de Sanden M. C. M. , Kessels W. M. M.
Published: August 2008

Thin Al2O3 films with a thickness of 7–30 nm synthesized by plasma-assisted atomic layer deposition (ALD) were used for surface passivation of crystalline silicon (c-Si) of different doping concentrations. The level of surface passivation in this study was determined by techniques based on photoconductance, photoluminescence, and infrared emission. Effective surface recombination velocities of 2 and 6 cm/s were obtained on 1.9 Ω cm n-type and 2.0 Ω cm p-type c-Si, respectively. An effective surface recombination velocity below 1 cm/s was unambiguously obtained for nearly intrinsic c-Si passivated by Al2O3. A high density of negative fixed charges was detected in the Al2O3 films and its impact on the level of surface passivation was demonstrated experimentally. The negative fixed charge density results in a flat injection level dependence of the effective lifetime on p-type c-Si and explains the excellent passivation of highly B-doped c-Si by Al2O3. Furthermore, a brief comparison is presented between the surface passivations achieved for thermal and plasma-assisted ALD Al2O3 films prepared in the same ALD reactor.
Strain relaxation induced microphotoluminescence characteristics of a single InGaN-based nanopillar fabricated by focused ion beam milling
Authors: Yu Peichen , Chiu C. H. , Wu Yuh-Renn , Yen H. H. , Chen J. R. , Kao C. C. , Yang Han-Wei , Kuo H. C. , Lu T. C. , Yeh W. Y. , Wang S. C.
Published: August 2008

A freestanding nanopillar with a diameter of 300nm and a height of 2μm is demonstrated by focused ion beam milling. The measured microphotoluminescence (μ-PL) from the embedded InGaN∕GaN multiple quantum wells shows a blueshift of 68meV in energy with a broadened full width at half maximum, ∼200meV. Calculations based on the valence force field method suggest that the spatial variation of the strain tensors in the nanopillar results in the observed energy shift and spectrum broadening. Moreover, the power-dependent μ-PL measurement suggests that the strain-relaxed emission region exhibits a higher radiative recombination rate than that of the strained region, indicating potential for realizing high-efficiency nanodevices in the UV/blue wavelength range.
Nanoscale epitaxial lateral overgrowth of GaN-based light-emitting diodes on a SiO2 nanorod-array patterned sapphire template
Authors: Chiu C. H. , Yen H. H. , Chao C. L. , Li Z. Y. , Yu Peichen , Kuo H. C. , Lu T. C. , Wang S. C. , Lau K. M. , Cheng S. J.
Published: August 2008

High efficiency GaN-based light-emitting diodes (LEDs) are demonstrated by a nanoscale epitaxial lateral overgrowth (NELO) method on a SiO2 nanorod-array patterned sapphire substrate (NAPSS). The transmission electron microscopy images suggest that the voids between SiO2 nanorods and the stacking faults introduced during the NELO of GaN can effectively suppress the threading dislocation density. The output power and external quantum efficiency of the fabricated LED were enhanced by 52% and 56%, respectively, compared to those of a conventional LED. The improvements originated from both the enhanced light extraction assisted by the NAPSS and the reduced dislocation densities using the NELO method.
Reconciling semiclassical and Bohmian mechanics. VI. Multidimensional dynamics
Authors: Poirier Bill
Published: August 2008

In previous articles [J. Chem. Phys. 121, 4501 (2004); J. Chem. Phys. 124, 034115 (2006); J. Chem. Phys. 124, 034116 (2006); J. Phys. Chem. A 111, 10400 (2007); J. Chem. Phys. 128, 164115 (2008)] an exact quantum, bipolar wave decomposition, ψ=ψ++ψ−, was presented for one-dimensional stationary state and time-dependent wavepacket dynamics calculations, such that the components ψ± approach their semiclassical WKB analogs in the large action limit. The corresponding bipolar quantum trajectories are classical-like and well behaved, even when ψ has many nodes or is wildly oscillatory. In this paper, both the stationary state and wavepacket dynamics theories are generalized for multidimensional systems and applied to several benchmark problems, including collinear H+H2.
Mechanism of charge generation in p-type doped layer in the connection unit of tandem-type organic light-emitting devices
Authors: Gao X. D. , Zhou J. , Xie Z. T. , Ding B. F. , Qian Y. C. , Ding X. M. , Hou X. Y.
Published: August 2008

A p-type doped organic layer combined with a hole-blocking layer has been experimentally demonstrated to serve as the charge generation unit in tandem-type organic light-emitting devices. The p-type layer functions as the source of both holes and electrons. Charge separation is explained by the tunneling model that the hole-blocking layer reduces the energy barrier for the electrons generated in the p-type layer to tunnel through into one light-emitting unit, while the holes generated in the p-type layer can transport to the other light-emitting unit easily under operation voltage.
Epitaxial nanotwinned Cu films with high strength and high conductivity
Authors: Anderoglu O. , Misra A. , Wang H. , Ronning F. , Hundley M. F. , Zhang X.
Published: August 2008

We report on the synthesis of epitaxial (single-crystal-like), nanotwinned Cu films via magnetron sputtering. Increasing the deposition rate from 1 to 4 nm/s decreased the average twin lamellae spacing from 16 to 7 nm. These epitaxial nanotwinned Cu films exhibit significantly higher ratio of hardness to room temperature electrical resistivity than columnar grain (nanocrystalline), textured, nanotwinned Cu films.
Diffusive transport in graphene: The role of interband correlation
Authors: Liu S. Y. , Lei X. L. , Horing Norman J. M.
Published: August 2008

We present a kinetic equation approach to investigate dc transport properties of graphene in the diffusive regime considering long-range electron-impurity scattering. In our study, the effects of interband correlation (or polarization) on conductivity are taken into account. We find that the conductivity contains not only the usual term inversely proportional to impurity density Ni but also an anomalous term that is linear in Ni. This leads to a minimum in the density dependence of conductivity when the electron density Ne is equal to a finite critical value Nc. The effects of various scattering potentials on the conductivity minimum are also analyzed. Using typical experimental parameters, we find that for random-phase-approximation–screened electron-impurity scattering, the minimum conductivity is about 4.42e2/h when Ne≈0.11Ni, and the conductivity varies almost linearly with the electron density for Ne>Ni.
Toward spectroscopic accuracy for organic free radicals: Molecular structure, vibrational spectrum, and magnetic properties of F2NO
Authors: Puzzarini Cristina , Barone Vincenzo
Published: August 2008

The structure, harmonic frequencies, and hyperfine couplings of F2NO have been computed by the coupled cluster ansatz using a hierarchical series of basis sets and, in some cases, extrapolation procedures to reach the complete basis set limit. Methods rooted into the density functional theory have been used to estimate anharmonic and environmental effects. The remarkable agreement with experimental hyperfine coupling constants and most of vibrational frequencies confirms the reliability of the computational approach and suggests that one of the observed frequencies probably refers to a different species.