bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sensitized airway smooth muscle plasticity and hyperreactivity: a reviewThis article is one of a selection of papers published in the Special Issue on Recent Advances in Asthma Research.
Authors: Stephens N. L. , Cheng Z.-Q. , Fust A. 
Published: September 2007

To help elucidate the mechanisms underlying asthmatic bronchospasm, the goal of our research has been to determine whether airway smooth muscle (ASM) hyperreactivity was the responsible factor. We reported that in a canine model of asthma, the shortening capacity (ΔLmax) and velocity (Vo) of in vitro sensitized muscle were significantly increased. This increase was of sufficient magnitude to account for 75% narrowing of the in vivo airway, but maximal isometric force was unchanged. This last feature has been reported by others. Under lightly loaded conditions, ASM completes 75% of its isotonic shortening within the first 2 s. Furthermore, 90% of the increased shortening of ragweed pollen-sensitized ASM (SASM), compared with control (CASM), is complete within the first 2 s. The study of shortening beyond this period will apparently not yield much useful information, and studies of isotonic shortening should be focused on this interval. Although both CASM and SASM showed plasticity and adaptation with respect to isometric force, neither muscle type showed a difference in the force developed in these phases. During isotonic shortening, no evidence of plasticity was seen, but the equilibrated SASM showed increased ΔLmaxand Voof shortening. Molecular mechanisms of changes in Vocould result from changes in the kinetics of the myosin heavy chain ATPase. Motility assay, however, showed no changes between CASM and SASM in the ability of the purified myosin molecule (SF1) to translocate a marker actin filament. On the other hand, we found that the state of activation of the ATPase by phosphorylation of smooth muscle myosin light chain (molecular mass 20 000 Da) was greater in the SASM. This would account for the increased Vo. Investigating the signalling pathway, we found that whereas [Ca2+]iincreased in both isometric and isotonic contraction, there was no significant difference between CASM and SASM. The content and activity of calmodulin were also not different between the 2 muscles. Nevertheless, we did find that content and total activity of smooth muscle myosin light chain kinase (smMLCK) and the abundance of its message were greater; this would explain the increased MLC20 phosphorylation. The binding affinity between Ca2+and calmodulin and between 4 Ca2+calmodulin and smMLCK remains to be studied. We conclude that SASM shows increased isotonic shortening capacity and velocity. It also shows increased content and total activity of smMLCK, which is consistent with the increased shortening. Plasticity produced by oscillation is not seen in the shortening muscle, although it is seen with respect to force development. It did not modulate the behaviour of the sensitized muscle.
Level of toll-like receptor agonist exposure differentially determines chemokine production in humansThis article is one of a selection of papers published in the Special Issue on Recent Advances in Asthma Research.
Authors: Lissitsyn Yuriy , Becker Allan B. , Kozyrskyj Anita L. , HayGlass Kent T. 
Published: September 2007

Toll-like receptor (TLR) agonists, ubiquitously present in the environment, are key players in activating synthesis of cytokines and chemokines that control normal and pathophysiological processes, including multiple inflammatory diseases. TLR2 and TLR4 respond to bacterial cell wall products. We examined the impact of TLR activation on human immune capacity using stimuli ranging from the low levels seen in most environments to the high concentrations widely used for in vitro studies. Peripheral blood mononuclear cells from 117 healthy children were activated with lipopolysaccharide (TLR4 ligand) or peptidoglycan (TLR2 ligand) over a million-fold range of concentrations. Resulting interleukin-6, CCL2, and CCL22 production were quantified by ELISA. The intensity of cytokine production elicited was linearly related to the intensity of the stimulus up to maximal responses. In marked contrast, chemokine production was not linearly related to agonist concentration. Responses rose with increasing stimulation, and then were markedly reduced (40%–100%, p < 0.0001) in response to the high levels of TLR stimulation most commonly cited. Thus, the levels of TLR4 and TLR2 agonists typically used for in vitro interrogation of immune capacity yield results clearly distinct from those obtained using commonly occurring environmental levels of TLR ligands. These findings demonstrate the importance of utilizing TLR ligands at concentrations more closely mimicking environmental levels when assessing immune capacity.
Resistance of fibrogenic responses to glucocorticoid and 2-methoxyestradiol in bleomycin-induced lung fibrosis in miceThis article is one of a selection of papers published in the Special Issue on Recent Advances in Asthma Research.
Authors: Langenbach Shenna Y. , Wheaton Ben J. , Fernandes Darren J. , Jones Catherine , Sutherland Tara E. , Wraith Bronwyn C. , Harris Trudi , Schuliga Michael J. , McLean Catriona , Stewart Alastair G. 
Published: September 2007

Bleomycin-induced lung fibrosis in mice reproduces some key features of pulmonary fibrosis in humans including alveolar inflammation, myofibroblast proliferation, and collagen deposition. Glucocorticoids have been used as first-line therapy for the treatment of lung fibrosis, although their clinical efficacy is equivocal. We examined the effect of the glucocorticoid, methylprednisolone (MP), and the estrogen metabolite, 2-methoxyestradiol (2MEO) on bleomycin-induced bronchoalveolar inflammation, fibrosis, and changes in lung function. The characterization of the time-course of the bleomycin-induced fibrosis indicated that lung dry mass and hydroxyproline content showed less variance than histopathological assessment of fibrosis. The bleomycin-induced increases in bronchoalveolar lavage (BAL) fluid cell number and protein levels were not significantly influenced by treatment with either MP (1 mg·(kg body mass)–1·day–1, i.p.) or 2MEO (50 mg·(kg body mass)–1·day–1, i.p.). Lung fibrosis, measured histopathologically or by hydroxyproline content, was not significantly influenced by either MP or 2MEO treatment, whereas the latter agent did reduce the increment in lung dry mass. The enlargement of alveolar airspaces and the decline in lung compliance were exacerbated by MP treatment. These data suggest that bleomycin-induced pulmonary fibrosis is resistant to inhibition by concurrent treatment with either glucocorticoids or 2MEO.
A Comparison of Three Canopy Interception Models for a Leafless Mixed Deciduous Forest Stand in the Eastern United States
Authors: Klingaman Nicholas P. , Levia Delphis F. , Frost Ethan E. 
Published: September 2007

Abstract
Canopy interception of incident precipitation is a critical component of the forest water balance during each of the four seasons. Models have been developed to predict precipitation interception from standard meteorological variables because of acknowledged difficulty in extrapolating direct measurements of interception loss from forest to forest. No known study has compared and validated canopy interception models for a leafless deciduous forest stand in the eastern United States. Interception measurements from an experimental plot in a leafless deciduous forest in northeastern Maryland (39°42′N, 75°50′W) for 11 rainstorms in winter and early spring 2004/05 were compared to predictions from three models. The Mulder model maintains a moist canopy between storms. The Gash model requires few input variables and is formulated for a sparse canopy. The WiMo model optimizes the canopy storage capacity for the maximum wind speed during each storm. All models showed marked underestimates and overestimates for individual storms when the measured ratio of interception to gross precipitation was far more or less, respectively, than the specified fraction of canopy cover. The models predicted the percentage of total gross precipitation (PG) intercepted to within the probable standard error (8.1%) of the measured value: the Mulder model overestimated the measured value by 0.1% of PG; the WiMo model underestimated by 0.6% of PG; and the Gash model underestimated by 1.1% of PG. The WiMo model’s advantage over the Gash model indicates that the canopy storage capacity increases logarithmically with the maximum wind speed. This study has demonstrated that dormant-season precipitation interception in a leafless deciduous forest may be satisfactorily predicted by existing canopy interception models.
Melting of Snow Cover in a Tropical Mountain Environment in Bolivia: Processes and Modeling
Authors: Lejeune Yves , Bouilloud Ludovic , Etchevers Pierre , Wagnon Patrick , Chevallier Pierre , Sicart Jean-Emmanuel , Martin Eric , Habets Florence 
Published: September 2007

Abstract
To determine the physical processes involved in the melting and disappearance of transient snow cover in nonglacierized tropical areas, the CROCUS snow model, interactions between Soil–Biosphere–Atmosphere (ISBA) land surface model, and coupled ISBA/CROCUS model have been applied to a full set of meteorological data recorded at 4795 m MSL on a moraine area in Bolivia (16°17′S, 68°32′W) between 14 May 2002 and 15 July 2003. The models have been adapted to tropical conditions, in particular the high level of incident solar radiation throughout the year. As long as a suitable function is included to represent the mosaic partitioning of the surface between snow cover and bare ground and local fresh snow grain type (as graupel) is adapted, the ISBA and ISBA/CROCUS models can accurately simulate snow behavior over nonglacierized natural surfaces in the Tropics. Incident solar radiation is responsible for efficient melting of the snow surface (favored by fresh snow albedo values usually not exceeding 0.8) and also for the energy stored in snow-free areas (albedo = 0.18) and transferred horizontally to adjacent snow patches. These horizontal energy transfers (by conduction within the upper soil layers and by turbulent advection) explain most of the snowmelt and prevent the snow cover from lasting more than a few days during the wet season in this high-altitude tropical environment.
Northern Lake Impacts on Local Seasonal Climate
Authors: Long Z. , Perrie W. , Gyakum J. , Caya D. , Laprise R. 
Published: September 2007

Abstract
It is well known that large lakes can perturb local weather and climate through mesoscale circulations, for example, lake effects on storms and lake breezes, and the impacts on fluxes of heat, moisture, and momentum. However, for both large and small lakes, the importance of atmosphere–lake interactions in northern Canada is largely unknown. Here, the Canadian Regional Climate Model (CRCM) is used to simulate seasonal time scales for the Mackenzie River basin and northwest region of Canada, coupled to simulations of Great Bear and Great Slave Lakes using the Princeton Ocean Model (POM) to examine the interactions between large northern lakes and the atmosphere. The authors consider the lake impacts on the local water and energy cycles and on regional seasonal climate. Verification of model results is achieved with atmospheric sounding and surface flux data collected during the Canadian Global Energy and Water Cycle Experiment (GEWEX) program. The coupled atmosphere–lake model is shown to be able to successfully simulate the variation of surface heat fluxes and surface water temperatures and to give a good representation of the vertical profiles of water temperatures, the warming and cooling processes, and the lake responses to the seasonal and interannual variation of surface heat fluxes. These northern lakes can significantly influence the local water and energy cycles.
Probabilistic Flood Forecasting with a Limited-Area Ensemble Prediction System: Selected Case Studies
Authors: Verbunt M. , Walser A. , Gurtz J. , Montani A. , Schär C. 
Published: September 2007

Abstract
A high-resolution atmospheric ensemble forecasting system is coupled to a hydrologic model to investigate probabilistic runoff forecasts for the alpine tributaries of the Rhine River basin (34 550 km2). Five-day ensemble forecasts consisting of 51 members, generated with the global ensemble prediction system (EPS) of the European Centre for Medium-Range Weather Forecasts (ECMWF), are downscaled with the limited-area model Lokal Modell (LM). The resulting limited-area ensemble prediction system (LEPS) uses a horizontal grid spacing of 10 km and provides one-hourly output for driving the distributed hydrologic model Precipitation–Runoff–Evapotranspiration–Hydrotope (PREVAH) hydrologic response unit (HRU) with a resolution of 500 × 500 m2 and a time step of 1 h. The hydrologic model component is calibrated for the river catchments considered, which are characterized by highly complex topography, for the period 1997–98 using surface observations, and validated for 1999–2002.
This study explores the feasibility of atmospheric ensemble predictions for runoff forecasting, in comparison with deterministic atmospheric forcing. Detailed analysis is presented for two case studies: the spring 1999 flood event affecting central Europe due to a combination of snowmelt and heavy precipitation, and the November 2002 flood in the Alpine Rhine catchment. For both cases, the deterministic simulations yield forecast failures, while the coupled atmospheric–hydrologic EPS provides appropriate probabilistic forecast guidance with early indications for extreme floods. It is further shown that probabilistic runoff forecasts using a subsample of EPS members, selected by a cluster analysis, properly represent the forecasts using all 51 EPS members, while forecasts from randomly chosen subsamples reveal a reduced spread compared to the representative members. Additional analyses show that the representation of horizontal advection of precipitation in the atmospheric model may be crucial for flood forecasts in alpine catchments.
Alpine Stream Temperature Response to Storm Events
Authors: Brown Lee E. , Hannah David M. 
Published: September 2007

Abstract
Despite continued interest in meteorological influences on the thermal variability of river systems, there are few detailed studies of stream temperature dynamics during storm events. This paper reports high-resolution (15 min) water column and streambed temperature data for storm events of contrasting magnitude, duration, and intensity for three streams (draining glacier, snow, and groundwater sources) across an alpine river system during summers 2002 and 2003. The results demonstrate clear spatial and temporal differences in water column and streambed thermal responses to precipitation events and streamflow peaks. Analysis of all storms across the three sites showed a decrease in water column temperature for 75% of events, with significant negative relationships between stream temperature and precipitation magnitude, precipitation intensity, and stream discharge peaks. Temperature decreases of 10.4°C were recorded, but temperature increases were less marked at up to 2.3°C. Temperature response to precipitation was dampened with increasing depth into the streambed at all sites. Spatial and temporal differences in thermal response to storm events were controlled by precipitation and stream discharge peak characteristics (above) plus antecedent basin conditions, which together determine the nature and rapidity of hydrological response. In this steep alpine basin, stream temperature variability appears to be enhanced by quick routing of precipitation to the river channel (i.e., direct precipitation/channel interception, rapid surface flow over impermeable bedrock/thin alpine soils, and subsurface flow through highly weathered scree slopes). This research highlights the need for integrated hydrometeorological research of precipitation event–hydrological response–stream temperature interactions to advance understanding of runoff generation processes driving event-scale thermal dynamics in alpine and other river systems.
The Impact of the Sierra Nevada on Low-Level Winds and Water Vapor Transport
Authors: Kim Jinwon , Kang Hyun-Suk 
Published: September 2007

Abstract
To understand the influence of the Sierra Nevada on the water cycle in California the authors have analyzed low-level winds and water vapor fluxes upstream of the mountain range in regional climate model simulations. In a low Froude number (Fr) regime, the upstream low-level wind disturbances are characterized by the rapid weakening of the crosswinds and the appearance of a stagnation point over the southwestern foothills. The weakening of the low-level inflow is accompanied by the development of along-ridge winds that take the form of a barrier jet over the western slope of the mountain range. Such upstream wind disturbances are either weak or nonexistent in a high-Fr case. A critical Fr (Frc) of 0.35 inferred in this study is within the range of those suggested in previous observational and numerical studies. The depth of the blocked layer estimated from the along-ridge wind profile upstream of the northern Sierra Nevada corresponds to Frc between 0.3 and 0.45 as well. Associated with these low-level wind disturbances are significant low-level southerly moisture fluxes over the western slope and foothills of the Sierra Nevada in the low-Fr case, which result in significant exports of moisture from the southern Sierra Nevada to the northern region. This along-ridge low-level water vapor transport by blocking-induced barrier jets in a low-Fr condition may result in a strong north–south precipitation gradient over the Sierra Nevada.
Estimates of the Global Water Budget and Its Annual Cycle Using Observational and Model Data
Authors: Trenberth Kevin E. , Smith Lesley , Qian Taotao , Dai Aiguo , Fasullo John 
Published: September 2007

Abstract
A brief review is given of research in the Climate Analysis Section at NCAR on the water cycle. Results are used to provide a new estimate of the global hydrological cycle for long-term annual means that includes estimates of the main reservoirs of water as well as the flows of water among them. For precipitation P over land a comparison among three datasets enables uncertainties to be estimated. In addition, results are presented for the mean annual cycle of the atmospheric hydrological cycle based on 1979–2000 data. These include monthly estimates of P, evapotranspiration E, atmospheric moisture convergence over land, and changes in atmospheric storage, for the major continental landmasses, zonal means over land, hemispheric land means, and global land means. The evapotranspiration is computed from the Community Land Model run with realistic atmospheric forcings, including precipitation that is constrained by observations for monthly means but with high-frequency information taken from atmospheric reanalyses. Results for E − P are contrasted with those from atmospheric moisture budgets based on 40-yr ECMWF Re-Analysis (ERA-40) data. The latter show physically unrealistic results, because evaporation often exceeds precipitation over land, especially in the Tropics and subtropics.
Assessing the Errors of Cloud Liquid Water and Precipitation Flux Retrievals in Marine Stratocumulus Based on Doppler Radar Parameters
Authors: Kogan Yefim L. , Kogan Zena N. , Mechem David B. 
Published: September 2007

Abstract
The errors of formulations of cloud retrievals based on radar reflectivity, mean Doppler velocity, and Doppler spectrum width are evaluated under the controlled framework of the Observing System Simulation Experiments (OSSEs). Cloud radar parameters are obtained from drop size distributions generated by the high-resolution Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) large-eddy simulation (LES) model with explicit microphysics. It is shown that in drizzling stratocumulus the accuracy of cloud liquid water (Ql) retrieval can be substantially increased when information on Doppler velocity or Doppler spectrum width is included in addition to radar reflectivity. In the moderate drizzle case (drizzle rate R of about 1 mm day−1) the mean and standard deviation of errors is of the order of 10% for Ql values larger than 0.2 g m−3; in stratocumulus with heavy drizzle (R &gt; 2 mm day−1) these values are approximately 20%–30%. Similarly, employing Doppler radar parameters significantly improves the accuracy of drizzle flux retrieval. The use of Doppler spectrum width σd instead of Doppler velocity yields about the same accuracy, thus demonstrating that both Doppler parameters have approximately the same potential for improving microphysical retrievals. It is noted that the error estimates herein represent the theoretical lower bound on retrieval errors, because the actual errors will inevitably increase, first and foremost, due to uncertainties in estimation contributions from air turbulence.
Effective Hydraulic Parameters in Horizontally and Vertically Heterogeneous Soils for Steady-State Land–Atmosphere Interaction
Authors: Mohanty Binayak P. , Zhu Jianting 
Published: September 2007

Abstract
In this study, the authors investigate effective soil hydraulic parameter averaging schemes for steady-state flow in heterogeneous shallow subsurfaces useful to land–atmosphere interaction modeling. “Effective” soil hydraulic parameters of the heterogeneous shallow subsurface are obtained by conceptualizing the soil as an equivalent homogeneous medium. It requires that the effective homogeneous soil discharges the same mean surface moisture flux (evaporation or infiltration) as the heterogeneous media. Using the simple Gardner unsaturated hydraulic conductivity function, the authors derive the effective value for the saturated hydraulic conductivity Ks or the shape factor α under various hydrologic scenarios and input hydraulic parameter statistics. Assuming one-dimensional vertical moisture movement in the shallow unsaturated soils, both scenarios of horizontal (across the surface landscape) and vertical (across the soil profile) heterogeneities are investigated. The effects of hydraulic parameter statistics, surface boundary conditions, domain scales, and fractal dimensions in case of nested soil hydraulic property structure are addressed. Results show that the effective parameters are dictated more by the α heterogeneity for the evaporation scenario and mainly by Ks variability for the infiltration scenario. Also, heterogeneity orientation (horizontal or vertical) of soil hydraulic parameters impacts the effective parameters. In general, an increase in both the fractal dimension and the domain scale enhances the heterogeneous effects of the parameter fields on the effective parameters. The impact of the domain scale on the effective hydraulic parameters is more significant as the fractal dimension increases.
Consistent Parameterization of Roughness Length and Displacement Height for Sparse and Dense Canopies in Land Models
Authors: Zeng Xubin , Wang Aihui 
Published: September 2007

Abstract
While progress has been made in the treatment of turbulence below, within, and above canopy in land models, not much attention has been paid to the convergence of canopy roughness length and displacement height to bare soil values as the above-ground biomass, or the sum of leaf and stem area indices, becomes zero. Preliminary formulations have been developed to ensure this convergence for the Community Land Model version 3 (CLM3) and are found to significantly improve the wintertime simulation of sensible heat flux (SH) compared with observational data over the Cabauw site in the Netherlands. The simulation of latent heat flux (LH) is also moderately improved. For global offline CLM3 simulations, the new formulations change SH by more than 5 W m−2 over many regions, while the change of LH is less than 1 W m−2 over most of the regions.