bluuebunny/crossref_metadata_2025 huggingface dataset:
Adolescents’ transitions to behavioral autonomy after German unification
Authors: Haase Claudia M. , Silbereisen Rainer K. , Reitzle Matthias
Published: August 2007

The present study examined the timing of behavioral autonomy transitions in two same‐aged cohorts of East German adolescents assessed in 1991 and 1996. An earlier timing of autonomy privileges was associated with higher deviant behavior. A later timing of autonomy privileges and responsibilities was linked to structural constraints, specifically, to parental unemployment. Between 1991 and 1996 significant timing differences were observed for some autonomy transitions in the East, implying an adaptation to Western timetables. Our findings illustrate the plasticity of autonomy transitions under conditions of social change.
Bioinformatic analysis of post‐transcriptional regulation by uORF in human and mouse
Authors: Matsui Motomu , Yachie Nozomu , Okada Yuki , Saito Rintaro , Tomita Masaru
Published: August 2007

RNA decay is thought to exert an important influence on gene expression by maintaining a steady‐state level of transcripts and/or by eliminating aberrant transcripts. However, the sequence elements which control such processes have not been determined. Upstream open reading frames (uORFs) in the transcripts of several genes are reported to control translational initiation by stalling ribosomes and thereby promote RNA decay. We therefore performed bioinformatic analysis of the tissue‐wide expression profiles and mRNA half‐life of transcripts containing uORFs in humans and mice to assess the relationship between RNA decay and the presence of uORFs in transcripts. The expression levels of transcripts containing uORF were markedly lower than those not containing uORF. Moreover, the half‐life of the uORF‐containing transcripts was also shorter. These results suggest that uORFs are sequence elements that down‐regulate RNA transcripts via RNA decay mechanisms.
High glucose enhances MMP‐2 production in adventitial fibroblasts via Akt1‐dependent NF‐κB pathway
Authors: Lee Seung Jin , Bae Sun Sik , Kim Koan Hoi , Lee Won Suk , Rhim Byung Yong , Hong Ki Whan , Kim Chi Dae
Published: August 2007

To understand the role of adventitial fibroblasts (AF) in diabetic vascular diseases, the importance of high glucose (HG, 25 mM) on matrix metalloproteinase‐2 (MMP‐2) production in AF was determined. HG enhanced mRNA, protein and gelatinolytic activity of MMP‐2. The enhanced MMP‐2 activity was significantly attenuated not only by a PI3K inhibitor but also by an Akt inhibitor. These HG‐induced MMP‐2 responses were markedly reduced in Akt1‐deficient (1KO) cells. The diminished HG‐induced MMP‐2 responses were completely restored by re‐expression of Akt1. Both the reporter activity and electrophoretic mobility shift assay for activator protein‐1 and nuclear factor‐kappa B (NF‐κB) were enhanced by HG, but NF‐κB were not increased in 1KO cells. Furthermore, HG‐induced MMP‐2 responses were markedly suppressed by NF‐κB decoy oligodeoxynucleotides. Based on these results, it is suggested that HG augments MMP‐2 production via PI3K/Akt1/NF‐κB pathway.
A role for phospholipase A in auxin‐regulated gene expression
Authors: Scherer Günther F.E. , Zahn Marc , Callis Judy , Jones Alan M.
Published: August 2007

Auxin increases phospholipase A2 activity within 2 min (Paul, R., Holk, A. and Scherer, G.F.E. (1998) Fatty acids and lysophospholipids as potential second messengers in auxin action. Rapid activation of phospholipase A2 activity by auxin in suspension‐cultured parsley and soybean cells. Plant J. 16, 601–611) and the phospholipase A inhibitors, ETYA and HELSS, inhibit elongation growth of etiolated Arabidopsis hypoctyls (Holk, A., Rietz, S., Zahn, M., Quader, H. and Scherer, G.F.E. (2002) Molecular identification of cytosolic, patatin‐related phospholipases A from Arabidopsis with potential functions in plant signal transduction. Plant Physiol. 130, 90–101). To identify the mode of action, rapid auxin‐regulated gene expression was tested for sensitivity to these PLA2 inhibitors using seedlings expressing β‐glucuronidase (GUS) under the control of the synthetic auxin‐responsive promoter DR5. ETYA and HELSS inhibited the auxin‐induced increases in GUS activity, the steady‐state level of the corresponding GUS mRNA and the mRNAs encoded by four other auxin‐induced genes, IAA1, IAA5, IAA19 and ARF19. Factors that bind to the auxin response elements of the DR5 promoter and thereby regulate gene expression are regulated by a set of proteins such as Aux/IAA1 whose abundances are, in part, under control of E3 ubiquitin ligase SCF complexes. To investigate this mechanism further, the effect of ETYA on Aux/IAA1 degradation rate was examined using seedlings expressing Aux/IAA1:luciferase fusion proteins. In the presence of cycloheximide and excluding synthesis of IAA1:luciferase, ETYA had no apparent effect on degradation rates of IAA1, either with or without exogenous auxin. Therefore, the E3 ubiquitin ligase SCFTIR1 complex is an unlikely direct target of the PLA inhibitor. When cycloheximide was omitted, however, the inhibitors ETYA and HELSS blocked a sustained auxin‐induced decrease in its steady‐state level, indicating an unknown target capable to regulate Aux/IAA protein levels and, hence, transcription.
Expression and selective up‐regulation of toxin‐related mono ADP‐ribosyltransferases by pathogen‐associated molecular patterns in alveolar epithelial cells
Authors: Balducci Enrico , Micossi Luigi G. , Soldaini Elisabetta , Rappuoli Rino
Published: August 2007

Mono ADP‐ribosyltransferases (ARTs) are a family of enzymes related to bacterial toxins that possess adenosine diphosphate ribosyltransferase activity. We have assessed that A549 constitutively expressed ART1 on the cell surface and shown that lipotheicoic acid (LTA) and flagellin, but not lipopolysaccharide (LPS), peptidoglycan (PG) and poly (I:C), up‐regulate ART1 in a time and dose dependent manner. These agonists did not alter the expression of ART3 and ART5 genes. Indeed, LTA and flagellin stimulation increased the level of ART1 protein and transcript while ART4 gene was activated after stimulation of cells with LPS, LTA, PAM and PG via TLR2 and TLR4 receptors. These results show that human ARTs possess a differential capacity to respond to bacteria cell wall components and might play a crucial role in innate immune response in airways.
Efficacy of levamisole on experimental endometriosis
Authors: Ocal G. , Kokcu A. , Cetinkaya M.B. , Tosun M. , Kefeli M. , Kandemir B.
Published: August 2007

Objective: To investigate the efficacy of levamisole on experimental endometriosis. Methods: After the implantation of endometrial tissue on abdominal peritoneum, 40 rats were randomized to 1 of 4 equal intervention groups. Levamisole (2 mg/rat) was applied subcutaneously to group “L” once a week. Depot medroxyprogesterone acetate (3 mg/kg) was applied intramuscularly to group “M” twice at 4‐week intervals. Leuprolide (0.075 mg/kg) was applied subcutaneously to group “G” twice at 4‐week intervals. Saline (0.1 cm3/rat) was applied subcutaneously to group “C” once a week for 8 weeks. The efficacy of levamisole was determined by volume measurement and characterizing the histological structure of the implants. Result: Volume increase of the implants in group C (P < 0.05), and volume decrease in groups M, G, and L was found (P < 0.05, P < 0.01, and P < 0.01, respectively.) Stromal tissue and glandular activity were not different between groups L and G. Conclusion: Levamisole was found to be as effective as leuprolide in regression of the volume of endometriotic implants.
Different by design
Authors: Martin W. Mike , Fruchter Renate , Cavallin Humberto , Heylighen Ann
Published: August 2007

It is generally known that architectural practice relies heavily on the interactions between architects and other professionals. However, during their formal education, most students attending architecture schools, and engineering schools for that matter, get very little (if any) exposure to decision making in conditions that involve expertise and/or worldviews beyond those reflected and valued by their own discipline. In the past 10 years, a project-based learning initiative was developed between the University of California, Berkeley, and Stanford University in an international context involving several other universities around the world. Throughout this experience, we have identified several issues that have shown to be crucial to these interactions. This paper elaborates on three key issues: improvement of communication skills, empowerment through developing strategies of leadership, and recognition of own and others' worldviews. We also make the case to include experiential educational situations that can introduce these aspects into the academic curricula of architecture and engineering schools.
Estimation of slip distribution using an inverse method based on spectral decomposition of Green's function utilizing Global Positioning System (GPS) data
Authors: Jin Honglin , Kato Teruyuki , Hori Muneo
Published: August 2007

An inverse method based on the spectral decomposition of the Green's function was employed for estimating a slip distribution. We conducted numerical simulations along the Philippine Sea plate (PH) boundary in southwest Japan using this method to examine how to determine the essential parameters which are the number of deformation function modes and their coefficients. Japanese GPS Earth Observation Network (GEONET) Global Positioning System (GPS) data were used for three years covering 1997–1999 to estimate interseismic back slip distribution in this region. The estimated maximum back slip rate is about 7 cm/yr, which is consistent with the Philippine Sea plate convergence rate. Areas of strong coupling are confined between depths of 10 and 30 km and three areas of strong coupling were delineated. These results are consistent with other studies that have estimated locations of coupling distribution.
Calibration of the Interaction Soil Biosphere Atmosphere land‐surface scheme on a small tropical high‐mountain basin (Cordillera Real, Bolivia)
Authors: Caballero Yvan , Chevallier Pierre , Boone Aaron , Noilhan Joël , Habets Florence
Published: August 2007

In a continuing effort to test the behavior of Meteo France's land‐surface scheme, Interaction Soil Biosphere Atmosphere (ISBA), under a wide range of hydrometeorological conditions, the scheme was applied to a small tropical high‐mountain river basin of the Cordillera Real in Bolivia. The surface scheme simulates the key hydrological processes, such as evaporation, infiltration, surface runoff, and snow and soil ice freeze‐thaw processes, which are essential for accurately simulating the hydrological behavior of the river basin in this type of location. The 12.5 km2 nonglacierized subbasin has been divided into homogeneous surface units with irregular shapes, on the basis of their elevation and soil surface characteristics. The ISBA scheme was applied to each unit and the water fluxes were transferred from one unit to another using a system dynamics modeling approach. The method was applied step by step, improving its efficiency based on several hypotheses. This special application of the ISBA scheme, combining the high‐mountain conditions and the tropical seasonality is discussed.
Gradient methods applied to simulated ULF data: The effects of the ionospheric damping factor
Authors: Kawano H. , Lee D.‐H.
Published: August 2007

The gradient methods have widely been used to identify the field‐line resonance (FLR) signature in the ULF range in data from two latitudinally separated ground magnetometers. However, there are also cases in which ULF waves exist in the data but the gradient methods do not identify an FLR signature; in such cases, it is unclear if FLR is actually nonexistent or if some other factors bias the gradient‐method output. As a step toward finding a way to distinguish these two, in this paper we apply, for the first time, the gradient methods to MHD‐simulation results to examine the gradient methods. As a first step, we have confirmed that there are cases in which the gradient methods successfully identify FLR. We have then applied the gradient methods to the results of two simulation runs with different ionospheric reflection coefficients for the impinging wave (100 and 60%). As a result, we have found that the overhead ionospheric reflection coefficient (controlled by the ionospheric conductivity) affects the proper spacing of the two ground magnetometers; an improper spacing is a possible reason for the gradient method's being unsuccessful. We have also found that, when the ionosphere is not a perfect reflector, which is the case in reality, a non‐FLR wave component biases the gradient‐method output; the non‐FLR component appears to arise from the coupling of an FLR component and a cavity‐mode component where the two frequencies match. This coupling is another possible reason that the gradient methods are unsuccessful.
Statistical description of the bulge‐type auroral substorm in the far ultraviolet
Authors: Gjerloev J. W. , Hoffman R. A. , Sigwarth J. B. , Frank L. A.
Published: August 2007

Using global auroral images at ultraviolet wavelengths during 116 substorms, we have obtained quantitative measures of key features of the bulge aurora and oval aurora: their temporal variations, their locations, rates, and characteristics of gross expansion and decay, and the variability of these parameters. The expansion period identified solely from images varied primarily from 10 to 40 minutes, with an average of 30.9 minutes. To avoid mixing expansion data with recovery data, we normalized the time of each substorm to one unit from onset to maximum expansion. The average onset location was 22.6 magnetic local time (MLT) and 66.8° invariant latitude (ILat), in good agreement with previous analyses. We found that the bulge aurora rapidly expanded out of the onset location approximately equally to the west (surge) and to the east, so that the average center of the bulge remained close to the onset MLT. This is also the case for average location of the maximum expansion in latitude of the bulge. Thus the bulge is offset about 1 1/2 hours west of midnight. By half the expansion period the bulge has usually expanded poleward sufficiently to reveal a brightened portion of the original auroral oval. This brightening expands less than 1 hour MLT to the west, but rapidly to the east, farther than the east end of the bulge. Thus the two auroras are offset in MLT. The bulge expansion is fastest initially but slows for the second half of the expansion period. The ends of the bulge continue a small expansion poleward during early recovery when the center of the bulge slowly retreats. The large spreads of substorm expansion times, the onset locations and in the locations in ΔMLT and ΔILat of the key features of these auroras, argue strongly for the need to normalize the time of expansion and location of key features of the substorm for any kind of superposed epoch analysis to be meaningful.
Modeling the propagation characteristics of chorus using CRRES suprathermal electron fluxes
Authors: Bortnik J. , Thorne R. M. , Meredith N. P.
Published: August 2007

In the present paper, phase space density functions of the form f(v) = AN/vn are fitted to statistical distributions of suprathermal electron fluxes (E = 0.213–16.5 keV) from the CRRES satellite, parameterized by L‐shell, Magnetic Local Time (MLT), and geomagnetic activity. The fitted distributions are used in conjunction with ray tracing to calculate the Landau damping rates of an ensemble of rays representing whistler‐mode chorus waves. The modeled propagation characteristics are compared with observations of chorus wave power from the CRRES satellite, as a function of L‐shell, MLT, and magnetic latitude, in various frequency bands, and under various geomagnetic conditions. It is shown that the model results are remarkably consistent with many aspects of the observed wave distributions, including frequency, L‐shell, MLT, and latitudinal dependence. In addition, the MLT distribution of wave power becomes characteristically asymmetric during active geomagnetic conditions, with small propagation lengths on the nightside which increase with MLT and maximize on the dayside. This asymmetry is shown to be directly related to the dynamics of the Landau resonant suprathermal electrons which drift around the Earth whilst undergoing scattering and loss due to a variety of plasma waves. Consequently, the suprathermal electrons play an important role in radiation belt dynamics, by controlling the distribution of chorus, which in turn contributes to the acceleration and loss of relativistic electrons in the recovery phase of storms.
Three‐dimensional P wave velocity model for the San Francisco Bay region, California
Authors: Thurber Clifford H. , Brocher Thomas M. , Zhang Haijiang , Langenheim Victoria E.
Published: August 2007

A new three‐dimensional P wave velocity model for the greater San Francisco Bay region has been derived using the double‐difference seismic tomography method, using data from about 5,500 chemical explosions or air gun blasts and approximately 6,000 earthquakes. The model region covers 140 km NE‐SW by 240 km NW‐SE, extending from 20 km south of Monterey to Santa Rosa and reaching from the Pacific coast to the edge of the Great Valley. Our model provides the first regional view of a number of basement highs that are imaged in the uppermost few kilometers of the model, and images a number of velocity anomaly lows associated with known Mesozoic and Cenozoic basins in the study area. High velocity (Vp > 6.5 km/s) features at ∼15‐km depth beneath part of the edge of the Great Valley and along the San Francisco peninsula are interpreted as ophiolite bodies. The relocated earthquakes provide a clear picture of the geometry of the major faults in the region, illuminating fault dips that are generally consistent with previous studies. Ninety‐five percent of the earthquakes have depths between 2.3 and 15.2 km, and the corresponding seismic velocities at the hypocenters range from 4.8 km/s (presumably corresponding to Franciscan basement or Mesozoic sedimentary rocks of the Great Valley Sequence) to 6.8 km/s. The top of the seismogenic zone is thus largely controlled by basement depth, but the base of the seismogenic zone is not restricted to seismic velocities of ≤6.3 km/s in this region, as had been previously proposed.
Simulating spatial and temporal evolution of multiple wing cracks around faults in crystalline basement rocks
Authors: Willson Jonathan P. , Lunn Rebecca J. , Shipton Zoe K.
Published: August 2007

Fault zones are structurally highly spatially heterogeneous and hence extremely complex. Observations of fluid flow through fault zones over several scales show that this structural complexity is reflected in the hydrogeological properties of faults. Information on faults at depth is scarce, hence, it is highly valuable to understand the controls on spatial and temporal fault zone development. In this paper we increase our understanding of fault damage zone development in crystalline rocks by dynamically simulating the growth of single and multiple splay fractures produced from failure on a pre‐existing fault. We present a new simulation model, MOPEDZ (Modeling Of Permeability Evolution in the Damage Zone surrounding faults), that simulates fault evolution through solution of Navier's equation with a combined Mohr‐Coulomb and tensile failure criteria. Simulations suggest that location, frequency, mode of failure and orientation of splay fractures are significantly affected both by the orientation of the fault with respect to the maximum principal compressive stress and the conditions of differential stress. Model predictions compare well with published field outcrop data, confirming that this model produces realistic damage zone geometries.
Forecast errors in dust vertical distributions over Rome (Italy): Multiple particle size representation and cloud contributions
Authors: Kishcha P. , Alpert P. , Shtivelman A. , Krichak S. O. , Joseph J. H. , Kallos G. , Katsafados P. , Spyrou C. , Gobbi G. P. , Barnaba F. , Nickovic S. , Pérez C. , Baldasano J. M.
Published: August 2007

In this study, forecast errors in dust vertical distributions were analyzed. This was carried out by using quantitative comparisons between dust vertical profiles retrieved from lidar measurements over Rome, Italy, performed from 2001 to 2003, and those predicted by models. Three models were used: the four‐particle‐size Dust Regional Atmospheric Model (DREAM), the older one‐particle‐size version of the SKIRON model from the University of Athens (UOA), and the pre‐2006 one‐particle‐size Tel Aviv University (TAU) model. SKIRON and DREAM are initialized on a daily basis using the dust concentration from the previous forecast cycle, while the TAU model initialization is based on the Total Ozone Mapping Spectrometer aerosol index (TOMS AI). The quantitative comparison shows that (1) the use of four‐particle‐size bins in the dust modeling instead of only one‐particle‐size bins improves dust forecasts; (2) cloud presence could contribute to noticeable dust forecast errors in SKIRON and DREAM; and (3) as far as the TAU model is concerned, its forecast errors were mainly caused by technical problems with TOMS measurements from the Earth Probe satellite. As a result, dust forecast errors in the TAU model could be significant even under cloudless conditions. The DREAM versus lidar quantitative comparisons at different altitudes show that the model predictions are more accurate in the middle part of dust layers than in the top and bottom parts of dust layers.
Nonmethane hydrocarbons in the transported and local air masses at a clean remote site on Hainan Island, south China
Authors: Tang Jian‐Hui , Chan Lo‐Yin , Chan Chuen‐Yu , Li Yok‐Sheung , Chang Chih‐Chung , Liu Shaw‐Chen , Li Yi‐De
Published: August 2007

Nonmethane hydrocarbons (NMHCs) were investigated in a clean remote tropical rain forest site of Jianfengling Natural Reserve in Hainan Island in spring, autumn and early winter of 2004. The aim was to characterize air pollution transported from east Asia and SE Asian subcontinent on this relatively undeveloped region of south China. Ethane, ethyne, isoprene and ethene are the most abundant hydrocarbons. The relative contributions of pollution transport from urban and industrial zones of east Asia and agricultural zones of SE Asia are discussed with the help of backward air trajectories. The air masses from the SE Asian biomass burning region contained higher concentrations of ethane and ethyne while air masses traveling through coastal east China contained higher concentrations of ethene and toluene in addition to ethane and ethyne. It was found that anthropogenic emissions transported from the SE and south China developed and developing regions in autumn had a higher input than biomass burning emission from SE Asia in spring. Local biogenic emission was deduced to be the major source of isoprene. Hydrocarbon concentration ratios were found to be good indicators for identification of inflow air masses from different source regions.
Evaluation of Moderate‐Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo‐Gangetic Basin
Authors: Jethva Hiren , Satheesh S. K. , Srinivasan J.
Published: August 2007

We have compared the spectral aerosol optical depth (AOD, τλ) and aerosol fine mode fraction (AFMF) of Collection 004 (C004) derived from Moderate‐Resolution Imaging Spectroradiometer (MODIS) on board National Aeronautics and Space Administration's (NASA) Terra and Aqua platforms with that obtained from Aerosol Robotic Network (AERONET) at Kanpur (26.45°N, 80.35°E), India for the period 2001–2005. The spatially‐averaged (0.5° × 0.5° centered at AERONET sunphotometer) MODIS Level‐2 aerosol parameters (10 km at nadir) were compared with the temporally averaged AERONET‐measured AOD (within ± 30 minutes of MODIS overpass). We found that MODIS systematically overestimated AOD during the pre‐monsoon season (March to June, known to be influenced by dust aerosols). The errors in AOD at 0.66 μm were correlated with the apparent reflectance at 2.1 μm (ρ*2.1) which MODIS C004 uses to estimate the surface reflectance in the visible channels (ρ0.47 = ρ*2.1/4, ρ0.66 = ρ*2.1/2). The large errors in AOD (Δτ0.66 > 0.3) are found to be associated with the higher values of ρ*2.1 (0.18 to 0.25), where the uncertainty in the ratios of reflectance is large (Δρ0.66 ± 0.04, Δρ0.47 ± 0.02). This could have resulted in lower surface reflectance, higher aerosol path radiance and thus lead to overestimation in AOD. While MODIS‐derived AFMF has binary distribution (1 or 0) with too low (AFMF < 0.2) during dust‐loading period, and ∼1 for the rest of the retrievals, AERONET showed range of values (0.4 to 0.9). The errors in τ0.66 were also high in the scattering angle range 110°–140°, where the optical effects of nonspherical dust particles are different from that of spherical particles.
Recalculation of 11‐year total ozone of Brewer spectrophotometer 115
Authors: Lam K. S. , Savastiouk V. , Fung W. Y. , Chan T. K. , Lamb K.
Published: August 2007

Ground‐based total ozone (O3) has been measured by Brewer 115 at Hong Kong (Cape D'Aguilar, 22°13′N, 114°15′E, 64 m above mean sea level). Long‐term observations between 1995 and 2005 show that the sensitivity of outdoor spectrophotometers exhibit long‐term drift. Despite the undesirable sensitivity shift, high‐quality total ozone observations can still be achieved so long as the spectrophotometer is well maintained and calibrated regularly, and appropriate corrections applied to the data. The recalculated ground‐based total ozone also shows good agreement with the satellite (Total Ozone Mapping Spectrometer (TOMS) version 8) data and Brewer 61 (Chengkung: 23°05′, 121°21′). The procedures and experience of a total ozone trend analysis using multiple linear regression that account for upper level temperatures, QBO, AOD, sun spot activities, and El Niño were reported for future reference. It can be concluded that no ozone depletion was observed over Hong Kong in this time period.
Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau
Authors: Densmore Alexander L. , Ellis Michael A. , Li Yong , Zhou Rongjun , Hancock Gregory S. , Richardson Nicholas
Published: August 2007

The steep, high‐relief eastern margin of the Tibetan Plateau has undergone rapid Cenozoic cooling and denudation yet shows little evidence for large‐magnitude shortening or accommodation generation in the foreland basin. We address this paradox by using a variety of geomorphic observations to place constraints on the kinematics and slip rates of several large faults that parallel the plateau margin. The Beichuan and Pengguan faults are active, dominantly dextral‐slip structures that can be traced continuously for up to 200 km along the plateau margin. Both faults offset fluvial fill terraces that yield inheritance‐corrected, cosmogenic 10Be exposure ages of <15 kyr, indicating latest Pleistocene activity. The Pengguan fault appears to have been active in the Holocene at two sites along strike. Latest Quaternary apparent throw rates on both faults are variable along strike but are typically <1 mm yr−1. Rates of strike‐slip displacement are likely to be several times higher, probably ∼1–10 mm yr−1 but remain poorly constrained. Late Quaternary folding and dextral strike‐slip has also occurred along the western margin of the Sichuan Basin, particularly associated with the present‐day mountain front. These observations support models for the formation and maintenance of the eastern plateau margin that do not involve major upper crustal shortening. They also suggest that activity on the margin‐parallel faults in eastern Tibet may represent a significant seismic hazard to the densely populated Sichuan Basin.
A watershed scale numerical model of the impact of land use change on bed material transport in suburban Maryland, USA
Authors: Lewicki Mikolaj , Pizzuto James E. , Moglen Glenn E. , Allmendinger Nicholas E.
Published: August 2007

We predict changes in bed elevation and grain size composition caused by urbanization from 1952 to 1996 in the channel network of the Good Hope Tributary watershed. We developed methods for predicting the influence of urbanization on (1) the 1.5‐year peak discharge, (2) the annual sediment supply to the network, and (3) sediment production caused by channel enlargement. The model was calibrated to reproduce bed material yield estimated from a sediment budget. Development caused channel width to increase by a factor of 1.7, and discharge, upland sediment supply, and bed material yield approximately doubled. The longitudinal profile became smoother, and the bed coarsened. After 1996, model boundary conditions were held constant and the simulation continued through 2042. The bed continued to coarsen, and the yield of bed material gradually declined. Sediment production did not approach a steady state value, suggesting that geomorphic recovery from urbanization may require more than 50 years.
Modeling integrated water user decisions in intermittent supply systems
Authors: Rosenberg David E. , Tarawneh Tarek , Abdel‐Khaleq Rania , Lund Jay R.
Published: August 2007

We apply systems analysis to estimate household water use in an intermittent supply system considering numerous interdependent water user behaviors. Some 39 household actions include conservation; improving local storage or water quality; and accessing sources having variable costs, availabilities, reliabilities, and qualities. A stochastic optimization program with recourse decisions identifies the infrastructure investments and short‐term coping actions a customer can adopt to cost‐effectively respond to a probability distribution of piped water availability. Monte Carlo simulations show effects for a population of customers. Model calibration reproduces the distribution of billed residential water use in Amman, Jordan. Parametric analyses suggest economic and demand responses to increased availability and alternative pricing. It also suggests potential market penetration for conservation actions, associated water savings, and subsidies to entice further adoption. We discuss new insights to size, target, and finance conservation.
On biodiversity in river networks: A trade‐off metapopulation model and comparative analysis
Authors: Muneepeerakul R. , Levin S. A. , Rinaldo A. , Rodriguez‐Iturbe I.
Published: August 2007

A discrete, structured metapopulation model is coupled with the strictly hierarchical competition‐colonization trade‐off model, in which competitively superior species have lower fecundity rates and thus lower colonizing ability, to study the resulting biodiversity patterns in river networks. These patterns are then compared with those resulting from the neutral dynamics, in which every species has the same fecundity rate and is competitively equivalent at a per capita level. Significant differences exist between riparian biodiversity patterns and those predicted by theories developed for two‐dimensional landscapes. We find that dispersal directionality and network structure promote species that produce a large number of propagules at a species level; such species are considered competitively superior in the neutral model and inferior in the trade‐off model. As a result, the two key characteristics of riparian systems, dispersal directionality and network structure, lead to lower and higher overall γ diversity in the former and the latter models, respectively. The network structure, through the containment effect due to limited cross‐basin dispersal, always leads to higher between‐community, β diversity. The spatial distribution of local, α diversity becomes heterogeneous and thus important under directional dispersal and network structure. A higher degree of dividedness results in higher γ diversity for communities obeying both neutral and trade‐off models, but the increase is more dramatic in the latter.
Near‐coastal satellite altimetry: Sea surface height variability in the North Sea–Baltic Sea area
Authors: Madsen K. S. , Høyer J. L. , Tscherning C. C.
Published: August 2007

The radiometer wet tropospheric correction is a limiting factor of the application of near‐coastal altimetry observations in the North Sea – Baltic Sea area. Using an ECMWF model based correction instead, we increase the return rate from 70% to 95%, with observations as close as 10 km from the coast. The altimetry and 39 coastal tide gauges are referenced to the same state of the art regional geoid. The two data sets are highly correlated and reveal a consistent mean dynamic topography and two distinct correlation regimes separated by the Danish islands. The combination of the two data sets in a simple statistical model is shown to estimate the sea surface height with the same error level as state of the art operational models, indicating the potential for near‐coastal applications of satellite altimetry observations.
Temporal controls on global dust emissions: The role of surface gustiness
Authors: Engelstaedter S. , Washington R.
Published: August 2007

Topographic depressions serve as the key spatial control on large global dust sources. In contrast, the temporal control on these hotspots has remained elusive. We provide the first global observational evidence that the annual cycle of emissions from dust hotspots is determined by an erosivity feature in the form of wind gustiness. We use TOMS AI and an aridity index to define 131 global dust hotspots. The correlation between the annual cycle of hotspot dust and the annual cycle of gustiness is 70% stronger than the corresponding correlation with wind. The mean significant correlation with wind (n = 106 hotspots) is 0.37 (σ = 0.24) and the mean of significant correlation (n = 118 hotspots) with gustiness is 0.63 (σ = 0.12). Whereas most model simulations of dust have relied on the broadscale wind, gustiness holds overwhelmingly more power in explaining the annual cycle of dust emissions from global dust hotspots.
Atmospheric driving forces for the Agulhas Current in the subtropics
Authors: Fetter A. , Lutjeharms J. R. E. , Matano R. P.
Published: August 2007

The Agulhas Current is the western boundary current of the South Indian Ocean and is thought to play an important role in the global overturning circulation. In this study, we investigate the contribution from the wind stress field over each ocean basin of the southern hemisphere to the variability of Agulhas Current transport. We ran a series of experiments using the Modular Ocean Model 2. The model grid extends from 20°S to 70°S and has a horizontal resolution of ° with 25 levels in the vertical. The first experiment was forced with monthly means of the wind stress field from the project ERA 40 from ECMWF. In three other sensitivity experiments, the model was forced with the climatological mean over the whole domain plus the monthly wind stress anomalies (Jan/1979–Dec/2001) over one of the three ocean basins to whit: the South Atlantic, the South Indian and the South Pacific. The results show that inter‐annual variations in the Agulhas Current transport are due largely to the wind field over the South Indian Ocean, whereas annual variations are driven by the wind field over both the South Atlantic and South Indian oceans. The annual signal from the South Atlantic is shown to move equatorward along the southeastern coast of Africa through coastally trapped waves.
Highly localized cooling in daytime mesopause temperature over the dip equator during counter electrojet events: First results
Authors: Vineeth C. , Pant Tarun Kumar , Devasia C. V. , Sridharan R.
Published: August 2007

The first observations of lowering of mesopause temperature during Counter Electrojet (CEJ) events over a narrow region of ∼ ±150 km centered at around magnetic equator are presented. The daytime mesopause temperature is measured over Trivandrum (8.5°N; 77°E; dip lat. 0.5°N), India using the ground based Multiwavelength Dayglow Photometer. The unique meridional scanning capability of the instrument is extensively used in this study. A lowering of temperature by as much as ∼25 K has been observed during certain CEJ events, which includes a few partial CEJs. The gravity wave tidal interaction through vertically upward wind is proposed to be manifesting as lowering in the mesopause temperature and also as CEJ. These observations are ‘new’ and address to the issues concerning the vertical coupling processes prevailing in the equatorial Mesosphere Lower Thermosphere Ionosphere (MLTI) region.
Magnetochronology of the Feiliang Paleolithic site in the Nihewan Basin and implications for early human adaptability to high northern latitudes in East Asia
Authors: Deng Chenglong , Xie Fei , Liu Caicai , Ao Hong , Pan Yongxin , Zhu Rixiang
Published: August 2007

We present a new magnetostratigraphic dating of the Feiliang Paleolithic site in the Nihewan Basin, northern China. Partially‐oxidized magnetite and hematite were identified as the main carriers for the characteristic remanent magnetizations of the fluvio‐lacustrine sediments. Paleomagnetic results suggest that the sequence recorded the very early Brunhes chron and the upper Matuyama chron, including the Jaramillo subchron. The Feiliang artifact layer was determined to be within the pre‐Jaramillo Matuyama chron, with an estimated age of ca. 1.2 Ma. Our finding, coupled with previously published magnetochronology, strongly indicates a prominent early human flourishing in the high northern latitudes of East Asia during or just prior to the Mid‐Pleistocene climate transition.
Methane seeps and mud volcanoes in Italy: Gas origin, fractionation and emission to the atmosphere
Authors: Etiope Giuseppe , Martinelli Giovanni , Caracausi Antonio , Italiano Francesco
Published: August 2007

Molecular composition, CH4 isotopes and gas flux of all main terrestrial mud volcanoes and other methane seeps in Italy are being assessed for the first time. Whereas 74% of the Italian gas reservoirs are biogenic, about 80% of the seeps release thermogenic gas. Dry‐seep gas generally maintains the reservoir C1/(C2 + C3) “Bernard” ratio while mud volcanoes show molecular fractionation likely occurring during advective migration. Accordingly, a simple and direct use of the “Bernard” parameter might be misleading when applied to mud volcanoes as it could not always reflect the reservoir composition. Methane flux into the atmosphere from macro‐seep areas is in the order of 102–106 t km−2y−1. Microseepage is widespread throughout large areas and, on a regional scale, it provides the main methane output. A first emission estimate for the total hydrocarbon‐prone area of Italy suggests levels of 105 t y−1, comparable to national sources from fossil fuel industry.
Effects of precipitation‐bias corrections on surface hydrology over northern latitudes
Authors: Tian Xiangjun , Dai Aiguo , Yang Daqing , Xie Zhenghui
Published: August 2007

Under‐catch errors in precipitation gauge records can be as large as 50–100% during the cold season at high latitudes. To quantify the impacts of these errors on hydrometeorological fields, a comprehensive land surface model, namely the Community Land Model version 3 (CLM3), is run forced with (COF) and without (CON) precipitation‐bias corrections and other identical atmospheric forcing from 1973 to 2004. It is found that the enhanced snowfall induced by the bias corrections increases snow accumulation on the ground (by 6–18 cm for December to February), which in turn increases May to July runoff by 0.4–0.6 mm day−1 and streamflow by 5–25% for most major rivers in the northern latitudes (north of 45°N). The precipitation‐bias corrections also improve the model‐simulated mean annual cycle and temporal variations of streamflow for the major northern rivers during 1973–2004. As a result, the simulation of the freshwater discharge into the Arctic Ocean is also improved. Only small and statistically insignificant changes are found in soil moisture content, surface evaporation, and sensible heat flux between the CON and COF runs. Nevertheless, the results still suggest that it is important to use bias‐corrected precipitation in terrestrial water balance analyses and land surface modeling.
Rapid motion capture of mode-specific quantum wave packets selectively generated by phase-controlled optical pulses
Authors: Horikoshi Kengo , Misawa Kazuhiko , Lang Roy
Published: August 2007

Rapid motion capture of phase-controlled wave packets was realized using a sensitive wave-packet spectrometer, which was previously developed by the present authors. Two-dimensional Fourier-transformed spectrograms obtained by the wave-packet spectrometer provide us full information about the wave-packet motion on both excited- and ground-state potential surfaces. Vibrational wave packet associated with a twisting mode in a DTTCI molecule was observed to be dependent on the pulse chirp, and was generated in the excited state preferably with negatively chirped excitation. The result indicates that the excited-state wave packet can be driven along a favorable configuration coordinate by using phase-controlled femtosecond pulses. The present method is essential to adaptive coherent-control application.
Quantum molecular dynamics of hydrogen bonded complexes of rigid molecules using the semiclassical initial value representation in Cartesian coordinates
Authors: Issack Bilkiss B. , Roy Pierre-Nicholas
Published: August 2007

Semiclassical initial value representation calculations are performed for the constrained water dimer in Cartesian coordinates. The study represents the first application of a previously reported method [Issak and Roy, J. Chem. Phys. 123, 084103 (2005); 126, 024111 (2007)] to a molecular cluster. Bound state energies are calculated for a dimer of rigid water molecules (H2O)2 as well as its deuterated form (D2O)2. The results show that the approach fares well with respect to accuracy in capturing quantum effects in intermolecular interactions.
Layer-by-layer growth of polar MgO(111) ultrathin films
Authors: Xue Mingshan , Guo Qinlin
Published: August 2007

By alternate deposition of Mg and exposure of O2, layer-by-layer growth, polar MgO(111) ultrathin films with Mg-terminated or O-terminated surfaces have been successfully fabricated on Mo(110) substrate. The surface geometric structure and electronic structures of the polar MgO(111) films were investigated using surface analysis techniques including low-energy electron diffraction and photoelectron emission and electron energy loss spectroscopies. The results indicate that the O-terminated surface is of an insulating character, while for Mg-terminated surface, a prominent new surface state at 2–3eV and appreciable density of states near Fermi level have been observed. The polar oxide films provide ideal model surfaces for further investigation of support-particle system.
Anomalous tunneling effect on photoluminescence of asymmetric coupled double InGaN∕GaN quantum wells
Authors: Wang Y. , Pei X. J. , Xing Z. G. , Guo L. W. , Jia H. Q. , Chen H. , Zhou J. M.
Published: August 2007

Tunneling-assisted carrier transfer in coupled double InGaN∕GaN quantum wells (QWs) has been studied by temperature-dependent photoluminescence (PL) at varied excitation density. It is found that the carriers captured by the wide (“deep”) well are efficiently transferred to the adjacent narrow (“shallow”) one by resonant tunneling, which results in anomalous temperature dependence of PL intensity and significantly enhanced luminescent efficiency for the narrow well. This is disparate from those conventional tunneling-assisted behaviors in coupled double QWs constructed by zinc-blende materials without polarization effect, where the carriers are always tunneling from the narrow (“shallow”) well to the wide (“deep”) one.
How tight is the Lieb-Oxford bound?
Authors: Odashima Mariana M. , Capelle K.
Published: August 2007

Density-functional theory requires ever better exchange-correlation (xc) functionals for the ever more precise description of many-body effects on electronic structure. Universal constraints on the xc energy are important ingredients in the construction of improved functionals. Here we investigate one such universal property of xc functionals: the Lieb-Oxford lower bound on the exchange-correlation energy, Exc[n]⩾−C∫d3rn4∕3, where C⩽CLO=1.68. To this end, we perform a survey of available exact or near-exact data on xc energies of atoms, ions, molecules, solids, and some model Hamiltonians (the electron liquid, Hooke’s atom, and the Hubbard model). All physically realistic density distributions investigated are consistent with the tighter limit C⩽1. For large classes of systems one can obtain class-specific (but not fully universal) similar bounds. The Lieb-Oxford bound with CLO=1.68 is a key ingredient in the construction of modern xc functionals, and a substantial change in the prefactor C will have consequences for the performance of these functionals.
Band structures, magnetic properties, and enhanced magnetoresistance in the high pressure phase of Gd and Y doped two-dimensional perovskite Sr2CoO4 compounds
Authors: Wang X. L. , Takayama-Muromachi E. , Dou S. X. , Cheng Z. X.
Published: August 2007

The authors present their studies on the band structures and on the magnetic and magnetotransport properties of the high pressure phase of Sr2−xRExCoO4 [rare earth (RE)=Gd and Y, x=0.1–0.5] compounds which were synthesized by a high pressure and high temperature technique. The authors found that as x increases, the magnetoresistance {(ρH−ρ0)∕ρ0} increases up to −17% at 5K and 7T, which is 2.5 times higher than that for undoped Sr2CoO4, although the ferromagnetic transition drops from 255to200K for the Gd doping with x=0.3. The saturation moments at low temperature are significantly enhanced for the Gd doped Sr2CoO4. Observation of a close correlation between resistance and field revealed a strong spin-dependent tunneling magnetoresistance. First-principles band structure calculations indicate that high spin polarization is present for both undoped and doped compounds.
Magnetic field effects on the manganite junction with different electronic processes
Authors: Wang D. J. , Sun J. R. , Xie Y. W. , Lü W. M. , Liang S. , Zhao T. Y. , Shen B. G.
Published: August 2007

A manganite junction with two distinguishable electronic processes has been fabricated and its rectifying properties are experimentally studied. The current-voltage characteristics of the junctions are found to be dominated by leakage current and thermal current under low and high bias voltages, respectively. The responses of these two processes to magnetic field are found to be different, and the magnetoresistance (MR) of the junction arises mainly from the modification of magnetic field to leakage current. Although the MR shows a monotonic decrease with bias voltage (V), the MR-V dependence is different for the two processes. An approximately linear, yet slow, decrease of MR with V is observed for the leakage process, while an exponential reduction for the thermal one. These results show that the electronic processes undergoing in the junction can be identified based on the analysis of the MR-V relations.
Inter-Landau level scattering and LO-phonon emission in terahertz quantum cascade laser
Authors: Péré-Laperne N. , de Vaulchier L. A. , Guldner Y. , Bastard G. , Scalari G. , Giovannini M. , Faist J. , Vasanelli A. , Dhillon S. , Sirtori C.
Published: August 2007

A terahertz quantum cascade laser (QCL) structure based on a bound to continuum and LO-phonon extraction stage is studied under a strong magnetic field. Two series of power oscillations as a function of magnetic field are observed. Comprehensive simulations of the lifetimes allow the first series to be assigned to interface roughness (elastic) and the second to LO-phonon scattering (inelastic) of hot carriers in an excited Landau level, previously unobserved in terahertz QCL. The authors demonstrate that for the latter, the thermal electron distribution in the upper laser state leads to a breaking of the population inversion and hence laser action.