bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of In-Canopy Flux Footprints between Large-Eddy Simulation and the Lagrangian Simulation
Authors: Prabha T. V. , Leclerc M. Y. , Baldocchi D. 
Published: January 2008

Abstract
Flux footprints for neutral shear-driven canopy flows are evaluated using large-eddy simulation (LES) and a Lagrangian stochastic (LS) model. The Lagrangian stochastic model is driven by flow statistics derived from the large-eddy simulation. LES results suggest that both surface and elevated sources inside the canopy contribute equally to the cumulative flux from an upwind distance of 4 times the canopy height. LES flux footprints are more contracted than those obtained using the Lagrangian stochastic model. This is attributed to an enhanced vertical diffusion and reduced horizontal diffusion. The ejection and sweep contributions to momentum exchange in the Lagrangian stochastic model are weaker than those in the large-eddy simulation. Ejections of low-momentum air dominate at all levels in the canopy modeled by the LES. In contrast, high-momentum sweep events are dominant within the LES canopy and low-momentum ejection events are dominant above the canopy. Dispersion parameters for the first- and second-order statistics of concentration from both LES and LS for three line sources representing the canopy crown, midcanopy, and surface sources are also investigated. Lagrangian model results are sensitive to the choice of the time scale. A time scale based on the dissipation rate agrees well with the LS and LES plume heights of surface source. However, flux footprints from LS are closer to those from the LES, while an intermediate time scale (0.15z/σw) was used inside the canopy.
How Well Do Regional Climate Models Reproduce Radiation and Clouds in the Arctic? An Evaluation of ARCMIP Simulations
Authors: Tjernström Michael , Sedlar Joseph , Shupe Matthew D. 
Published: January 2008

Abstract
Downwelling radiation in six regional models from the Arctic Regional Climate Model Intercomparison (ARCMIP) project is systematically biased negative in comparison with observations from the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment, although the correlations with observations are relatively good. In this paper, links between model errors and the representation of clouds in these models are investigated. Although some modeled cloud properties, such as the cloud water paths, are reasonable in a climatological sense, the temporal correlation of model cloud properties with observations is poor. The vertical distribution of cloud water is distinctly different among the different models; some common features also appear. Most models underestimate the presence of high clouds, and, although the observed preference for low clouds in the Arctic is present in most of the models, the modeled low clouds are too thin and are displaced downward. Practically all models show a preference to locate the lowest cloud base at the lowest model grid point. In some models this happens also to be where the observations show the highest occurrence of the lowest cloud base; it is not possible to determine if this result is just a coincidence. Different factors contribute to model surface radiation errors. For longwave radiation in summer, a negative bias is present both for cloudy and clear conditions, and intermodel differences are smaller when clouds are present. There is a clear relationship between errors in cloud-base temperature and radiation errors. In winter, in contrast, clear-sky cases are modeled reasonably well, but cloudy cases show a very large intermodel scatter with a significant bias in all models. This bias likely results from a complete failure in all of the models to retain liquid water in cold winter clouds. All models overestimate the cloud attenuation of summer solar radiation for thin and intermediate clouds, and some models maintain this behavior also for thick clouds.
Some Space–Time Spectral Analyses of Tropical Convection and Planetary-Scale Waves
Authors: Hendon Harry H. , Wheeler Matthew C. 
Published: January 2008

Abstract
Three aspects of space–time spectral analysis are explored for diagnosis of the organization of tropical convection by the Madden–Julian oscillation (MJO) and other equatorial wave modes: 1) definition of the background spectrum upon which spectral peaks are assessed, 2) alternate variance preserving display of the spectra, and 3) the space–time coherence spectrum. Here the background spectrum at each zonal wavenumber is assumed to result from a red noise process. The associated decorrelation time for the red noise process for tropical convection is found to be half as long as for zonal wind, reflecting the different physical processes controlling each field. The significance of spectral peaks associated with equatorial wave modes for outgoing longwave radiation (OLR), which is a proxy for precipitating deep convection, and zonal winds that stand out above the red background spectrum is similar to that identified using a background spectrum resulting from ad hoc smoothing of the original spectrum. A variance-preserving display of the space–time power spectrum with a logarithmic frequency axis is useful for directly detecting Kelvin waves (periods 5–15 days for eastward zonal wavenumbers 1–5) and for highlighting their distinction from the MJO. The space–time coherence of OLR and zonal wind is predominantly associated with the MJO and other equatorial waves. The space–time coherence is independent of estimating the background spectrum and is quantifiable; thus, it is suggested as a useful metric for the MJO and other equatorial waves in observations and simulations. The space–time coherence is also used to quantify the association of Kelvin waves in the stratosphere with convective variability in the troposphere and for detection of barotropic Rossby–Haurwitz waves.
Characteristics of the Northern Australian Rainy Season
Authors: Smith I. N. , Wilson L. , Suppiah R. 
Published: January 2008

Abstract
A trend of increasing rainfall over much of north and northwest Australia over recent decades has contrasted with decreases over much of the rest of the continent. The increases have occurred during the summer months when the rainy season is dominated by the Australian monsoon but is also affected by other events such as tropical cyclones, Madden–Julian oscillations, and sporadic thunderstorms. The problem of diagnosing these trends is considered in terms of changes in the timing of the rainy season. While numerous definitions for rainy/monsoon season onset exist, most are designed to be useful in a predictive sense and can be limited in their application to diagnostic studies, particularly when they involve predetermined threshold amounts. Here the authors define indices, based on daily rainfall observations, that provide relatively simple, robust descriptions of each rainy season at any location. These are calculated using gridded daily rainfall data throughout the northern Australian tropics and also for selected stations. The results indicate that the trends in summer rainfall totals over the period from 1950 to 2005 appear to be mainly the result of similar trends in average intensity. Furthermore, the links between the September–October average Southern Oscillation index indicate that ENSO events affect season duration rather than average intensity. Because duration and average intensity are derived as independent features of each season, it is argued that the trends in rainfall totals are largely unrelated to trends in ENSO and most likely reflect the influence of other factors. Finally, diagnosing these features of the rainy season provides a basis for assessing the confidence one can attach to different climate model projections of changes to rainfall.
Soil Thermal and Ecological Impacts of Rain on Snow Events in the Circumpolar Arctic
Authors: Rennert Kevin J. , Roe Gerard , Putkonen Jaakko , Bitz Cecilia M. 
Published: January 2008

Abstract
Rain on snow (ROS) events are rare in most parts of the circumpolar Arctic, but have been shown to have great impact on soil surface temperatures and serve as triggers for avalanches in the midlatitudes, and they have been implicated in catastrophic die-offs of ungulates. The study of ROS is inherently challenging due to the difficulty of both measuring rain and snow in the Arctic and representing ROS events in numerical weather predictions and climate models. In this paper these challenges are addressed, and the occurrence of these events is characterized across the Arctic. Incidents of ROS in Canadian meteorological station data and in the 40-yr ECMWF Re-Analysis (ERA-40) are compared to evaluate the suitability of these datasets for characterizing ROS. The ERA-40 adequately represents the large-scale synoptic fields of ROS, but too often has a tendency toward drizzle. Using the ERA-40, a climatology of ROS events is created for thresholds that impact ungulate populations and permafrost. It is found that ROS events with the potential to harm ungulate mammals are widespread, but the large events required to impact permafrost are limited to the coastal margins of Beringia and the island of Svalbard. The synoptic conditions that led to ROS events on Banks Island in October of 2003, which killed an estimated 20 000 musk oxen, and on Svalbard, which led to significant permafrost warming in December of 1995, are examined. Compositing analyses are used to show the prevailing synoptic conditions that lead to ROS in four disparate parts of the Arctic. Analysis of ROS in the daily output of a fully coupled GCM under a future climate change scenario finds an increase in the frequency and areal extent of these events for many parts of the Arctic over the next 50 yr and that expanded regions of permafrost become vulnerable to ROS.
Observation Sensitivity Calculations Using the Adjoint of the Gridpoint Statistical Interpolation (GSI) Analysis System
Authors: Zhu Yanqiu , Gelaro Ronald 
Published: January 2008

Abstract
The adjoint of a data assimilation system provides an efficient way of estimating sensitivities of analysis or forecast measures with respect to observations. The NASA Global Modeling and Assimilation Office (GMAO) has developed an exact adjoint of the Gridpoint Statistical Interpolation (GSI) analysis scheme developed at the National Centers for Environmental Prediction (NCEP). The development approach is unique in that the adjoint is derived from a line-by-line tangent linear version of the GSI. Availability of the tangent linear scheme provides an explicit means of assessing not only the fidelity of the adjoint, but also the effects of nonlinear processes in the GSI itself. In this paper, the development of the tangent linear and adjoint versions of the GSI are discussed and observation sensitivity results for a near-operational version of the system are shown. Results indicate that the GSI adjoint provides accurate assessments of the sensitivities with respect to observations of wind, temperature, satellite radiances, and, to a lesser extent, moisture. Sensitivities with respect to ozone observations are quite linear for the ozone fields themselves, but highly nonlinear for other variables. The sensitivity information provided by the adjoint is used to estimate the contribution, or impact, of various observing systems on locally defined response functions based on the analyzed increments of temperature and zonal wind. It is shown, for example, that satellite radiances have the largest impact of all observing systems on the temperature increments over the eastern North Pacific, while conventional observations from rawinsondes and aircraft dominate the impact on the zonal wind increments over the continental United States. The observation impact calculations also provide an additional means of validating the observation sensitivities produced by the GSI adjoint.
The Incidence of Unplanned Returns to the Operating Room After Peripheral Arterial Bypass Surgery and Its Value as Indicator of Quality of Care
Authors: Ploeg Arianne J. , Lange Chris P. E. , Lardenoye Jan-Willem , Breslau Paul J. 
Published: January 2008

Background In recent years, a growing need has arisen to define possible indicators of quality of care. Methods To examine whether unplanned return to the operating room within 30 days after the initial procedure could serve as an indicator to assess quality of care in peripheral arterial bypass surgery, all bypass procedures performed between January 1996 and January 2004 were evaluated. Data were obtained from a prospectively kept hospital registration system. Results A total of 607 consecutive procedures were performed in 468 patients. The overall unexpected return to the operating room rate was 11.2%. Patients requiring peripheral arterial bypass surgery for critical ischemia with gangrene were significantly more at risk for an unplanned reoperation (20.2%) than patients with disabling claudication (2.1%) ( P < .0001). Patients requiring femorocrural bypass surgery (24.2%) were also more at risk than patients with a suprageniculate bypass procedure (5.2%) ( P < .0001). Conclusions Unplanned return to the operating room within 30 days after the initial operation can be a useful indicator of quality of care after peripheral arterial bypass surgery. However, a prospective, well-defined registration system to collect all data is essential. Furthermore, the severity of peripheral arterial disease and the type of procedure performed should be taken into account.
PRDM1 is involved in chemoresistance of T-cell lymphoma and down-regulated by the proteasome inhibitor
Authors: Zhao Wei-Li , Liu Yan-Yan , Zhang Qun-Ling , Wang Li , Leboeuf Christophe , Zhang Yi-Wen , Ma Jie , Garcia José-Francisco , Song Yong-Ping , Li Jun-Min , Shen Zhi-Xiang , Chen Zhu , Janin Anne , Chen Sai-Juan 
Published: January 2008

Abstract
The positive regulatory domain I (PRDM1) is a master regulator of terminal B-cell differentiation. However, PRDM1 is not B-cell specific. To determine its role in T-cell lymphoma, PRDM1 expression was investigated in 60 patients. PRDM1α and PRDM1β transcripts were detected in laser-microdissected T-lymphoma cells in 27 and 14 patients, respectively, mostly in cases with IRF4 expression. PRDM1β was associated with increased c-MYC expression. PRDM1β-positive patients displayed advanced Ann Arbor stage and high-risk International Prognostic Index and were linked to short survival times. In vitro, PRDM1β was related to resistance to chemotherapeutic agents and could be down-regulated by the proteasome inhibitor bortezomib. Kinetic studies showed that bortezomib down-regulation of PRDM1β preceded decreased IRF4 and c-MYC expression. An earlier retaining of cytoplasmic IκBα in bortezomib-treated cells was revealed, concomitant with blockade of NF-κB nuclear translocation. These results demonstrate the involvement of PRDM1β in T-cell lymphoma, with possible therapeutic interference by the proteasome inhibitor.
Platelet larceny: spurious hypoxaemia due to extreme thrombocytosis
Authors: Mehta A. , Lichtin A. E. , Vigg A. , Parambil J. G. 
Published: January 2008

Rapid oxygen consumption by markedly increased numbers of hypermetabolic leukocytes in leukaemic patients resulting in the apparent diagnosis of hypoxaemia on arterial blood gas analyses is termed leukocyte larceny.In the present report, a case of polycythaemia vera, extreme thrombocytosis, normal leukocyte counts and arterial hypoxaemia in the absence of clinical, radiological or physiological evidence of lung disease is described.This pseudohypoxaemia case was established by pulse oximetry, as well as by incubation of a blood specimen with potassium cyanide, and became less significant after the use of cytoreductive agents showed a proportionate increase in arterial oxygen tension as platelet counts decreased on serial arterial blood gas analyses.The present case report demonstrates spurious hypoxaemia due to extreme thrombocytosis and shows that, beside significant leukocytosis, even markedly elevated platelet counts can cause larceny of arterial blood oxygen.
Cannabis use and risk of lung cancer: a case–control study
Authors: Aldington S. , Harwood M. , Cox B. , Weatherall M. , Beckert L. , Hansell A. , Pritchard A. , Robinson G. , Beasley R. 
Published: January 2008

The aim of the present study was to determine the risk of lung cancer associated with cannabis smoking.A case–control study of lung cancer in adults ≤55 yrs of age was conducted in eight district health boards in New Zealand. Cases were identified from the New Zealand Cancer Registry and hospital databases. Controls were randomly selected from the electoral roll, with frequency matching to cases in 5-yr age groups and district health boards. Interviewer-administered questionnaires were used to assess possible risk factors, including cannabis use. The relative risk of lung cancer associated with cannabis smoking was estimated by logistic regression.In total, 79 cases of lung cancer and 324 controls were included in the study. The risk of lung cancer increased 8% (95% confidence interval (CI) 2–15) for each joint-yr of cannabis smoking, after adjustment for confounding variables including cigarette smoking, and 7% (95% CI 5–9) for each pack-yr of cigarette smoking, after adjustment for confounding variables including cannabis smoking. The highest tertile of cannabis use was associated with an increased risk of lung cancer (relative risk 5.7 (95% CI 1.5–21.6)), after adjustment for confounding variables including cigarette smoking.In conclusion, the results of the present study indicate that long-term cannabis use increases the risk of lung cancer in young adults.
Mucosal inflammation in idiopathic bronchiectasis: cellular and molecular mechanisms
Authors: Fuschillo S. , De Felice A. , Balzano G. 
Published: January 2008

Bronchiectasis is a chronic and debilitating lung disease, characterised by irreversible dilatation of the bronchi as consequence of airway injury and remodelling due to recurrent or chronic airway inflammation and infection. The underlying aetiologies include autoimmune diseases, severe infections, genetic abnormalities and acquired disorders.The pathogenesis of bronchiectasis is poorly understood. Three distinct pathogenetic elements, namely infection, inflammation and enzymatic actions, which interact with each other, have been implicated in the pathophysiology of bronchiectasis.Some recent observations indicate that airway inflammation in bronchiectasis comes from a deregulated cytokine network independent of bacterial airway colonisation.In the present review, current knowledge about cellular and molecular inflammatory events in the dynamic process of host–pathogen interaction that are thought to play a relevant role in the pathogenic mechanisms of airway wall destruction leading to bronchiectasis are discussed.
Endothelin receptor antagonists in pulmonary arterial hypertension
Authors: Dupuis J. , Hoeper M. M. 
Published: January 2008

The endothelin (ET) system, especially ET-1 and the ETAand ETBreceptors, has been implicated in the pathogenesis of pulmonary arterial hypertension (PAH). Together with prostanoids and phosphodiesterase 5 inhibitors, ET receptor antagonists have become mainstays in the current treatment of PAH.Three substances are currently available for the treatment of PAH. One of these substances, bosentan, blocks both ETAand ETBreceptors, whereas the two other compounds, sitaxsentan and ambrisentan, are more selective blockers of the ETAreceptor.There is ongoing debate as to whether selective or nonselective ET receptor blockade is advantageous in the setting of PAH, although there is no clear evidence that receptor selectivity is relevant with regard to the clinical effects of these drugs.For the time being, other features, such as safety profiles and the potential for pharmacokinetic interactions with other drugs used in the treatment of PAH, may be more important than selectivity or nonselectivity when selecting treatments for individual patients.
Nontypeable Haemophilus influenzae induces COX-2 and PGE2 expression in lung epithelial cells via activation of p38 MAPK and NF-kappa B
Authors: Xu Feng , Xu Zhihao , Zhang Rong , Wu Zuqun , Lim Jae-Hyang , Koga Tomoaki , Li Jian-Dong , Shen Huahao 
Published: January 2008

AbstractBackgroundNontypeableHaemophilus influenzae(NTHi) is an important respiratory pathogen implicated as an infectious trigger in chronic obstructive pulmonary disease, but its molecular interaction with human lung epithelial cells remains unclear. Herein, we tested that the hypothesis that NTHi induces the expression of cyclooxygenase (COX)-2 and prostaglandin E2 (PGE2) via activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappa B in pulmonary alveolar epithelial cells.MethodsHuman alveolar epithelial A549 cells were infected with different concentrations of NTHi. The phosphorylation of p38 MAPK was detected by Western blot analysis, the DNA binding activity of NF-kappa B was assessed by electrophoretic mobility shift assay (EMSA), and the expressions of COX-1 and 2 mRNA and PGE2 protein were measured by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assay (ELISA), respectively. The roles of Toll-like receptor (TLR) 2 and TLR4, well known NTHi recognizing receptor in lung epithelial cell and gram-negative bacteria receptor, respectively, on the NTHi-induced COX-2 expression were investigated in the HEK293 cells overexpressing TLR2 and TLR4in vitroand in the mouse model of NTHi-induced pneumonia by using TLR2 and TLR4 knock-out micein vivo. In addition, the role of p38 MAPK and NF-kappa B on the NTHi-induced COX-2 and PGE2 expression was investigated by using their specific chemical inhibitors.ResultsNTHi induced COX-2 mRNA expression in a dose-dependent manner, but not COX-1 mRNA expression in A549 cells. The enhanced expression of PGE2 by NTHi infection was significantly decreased by pre-treatment of COX-2 specific inhibitor, but not by COX-1 inhibitor. NTHi induced COX-2 expression was mediated by TLR2 in the epithelial cellin vitroand in the lungs of micein vivo. NTHi induced phosphorylation of p38 MAPK and up-regulated DNA binding activity of NF-kappa B. Moreover, the expressions of COX-2 and PGE2 were significantly inhibited by specific inhibitors of p38 MAPK and NF-kappa B. However, NTHi-induced DNA binding activity of NF-kappa B was not affected by the inhibition of p38 MAPK.ConclusionNTHi induces COX-2 and PGE2 expression in a p38 MAPK and NF-kappa B-dependent manner through TLR2 in lung epithelial cellsin vitroand lung tissuesin vivo. The full understanding of the role of endogenous anti-inflammatory PGE2 and its regulation will bring new insight to the resolution of inflammation in pulmonary bacterial infections.