bluuebunny/crossref_metadata_2025_split huggingface dataset:
FASTEX IOP 18: A very deep tropopause fold. I: Synoptic description and modelling
Authors: Donnadille Jérǒme , Cammas Jean‐Pierre , Mascart Patrick , Lambert Dominique , Gall Robert 
Published: February 2007

AbstractThe life cycle of a very deep tropopause fold (820 hPa) is documented with aircraft and ship observations during the Intensive Observing Period 18 of the Fronts and Atlantic Storm‐Track EXperiment (FASTEX). The initial setting involves a coherent tropopause disturbance and an associated Arctic tropopause fold. The confluence episode that results from the phasing up of the tropopause disturbance and a southern ridge, ends in the formation of an intense jet streak, the dynamics of which are associated with the development of a polar tropopause fold. A diagnostic analysis suggests that the final dramatic stratospheric intrusion is the consequence of the vertical superposition of the Arctic and polar tropopause folds. The Mesoscale Non‐Hydrostatic (Meso‐NH) model is used to discuss this hypothesis. Mixing of the passive stratospheric tracer within the marine boundary layer is investigated with sensitivity tests which unplug, in turn, the model physical parametrizations. Finally, upper‐level forcings associated with the development of the tropopause fold are investigated in detail in a companion paper.
Stacked slantwise convective circulations
Authors: Browning K. A. , Chapman D. , Dixon R. S. 
Published: February 2007

AbstractIt is well known that classical (ana) cold fronts tend to be characterized by mesoscale circulations in which upright line convection feeds a layer of concentrated rearward slantwise ascent. Occasionally, however, as in the case‐study presented in this paper, two and sometimes more of these mesoscale circulations coexist within the same cold‐frontal zone. The two slantwise circulations described were observed to be stacked one above the other with a vertical wavelength of less than 2 km. Although it is often suspected that the circulations at ana‐cold fronts are enhanced by mesoscale processes such as conditional symmetric instability (CSI) or ΔM‐adjustment, it is notoriously difficult to discriminate between these circulations and the larger‐scale transverse circulation within which they are embedded. The occurrence in this study of multiple circulations with small vertical scale helps to distinguish them from the large‐scale circulation, and this has motivated the detailed examination of this case.Mesoscale circulations of the kind described are difficult to detect: numerical weather prediction (NWP) models, even high‐resolution models, do not usually represent them, and conventional observations do not show them clearly. This study takes advantage of observations from a high‐resolution microwave Doppler radar plus a high‐resolution analysis of ultra‐high‐frequency wind‐profiler radar data, analysed in the context of output from an operational mesoscale NWP model. The study defines the mesoscale structure of the event sufficiently carefully to provide a basis for future idealized modelling studies to investigate the possible roles of CSI and ΔM‐adjustment, both of which appear to play a part in the maintenance of the circulations.
Lightning initiation–conventional and runaway‐breakdown hypotheses
Authors: Solomon R. , Schroeder V. , Baker M. B. 
Published: February 2007

AbstractWe evaluate two candidate mechanisms for the onset of lightning in the relatively low electric fields measured inside thunderstorms. The first is conventional dielectric breakdown due to local enhancement of the electric field in the vicinity of hydrometeors. The second is runaway breakdown, due to extended acceleration of high‐energy electrons (from cosmic rays or terrestrial sources of ionizing radiation) by the in‐cloud electric field. We compare the electric fields required for lightning onset by each mechanism with those observed inside lightning‐producing clouds, and we examine the sensitivity of the computed results to input parameters and assumptions. The conclusion of our analysis is that the conventional breakdown mechanism alone cannot trigger lightning while the runaway breakdown mechanism appears a more likely candidate. We identify the parameters on which each mechanism depends and emphasize the impact of observational uncertainties on our conclusions.
Large wood debris recruitment on differing riparian landforms along a Gulf Coastal Plain (USA) stream: a comparison of large floods and average flows
Authors: Golladay Stephen W. , Battle Juliann M. , Palik Brian J. 
Published: February 2007

AbstractIn southeastern Coastal Plain streams, wood debris can be very abundant and is recruited from extensive forested floodplains. Despite importance of wood debris, there have been few opportunities to examine recruitment and redistribution of wood in an undisturbed setting, particularly in the southeastern Coastal Plain. Following extensive flooding in 1994, measurements of individual downed trees (species, dbh, orientation, distance from base‐flow channel and condition) were made across replicated riparian landforms in a Gulf Coastal Plain 5th‐order stream. Annually, the fate of these trees was determined and newly recruited trees were noted. More than 300 downed trees have been recorded. Recruitment varied across landforms with more constrained reaches having greatest mortality. Total tree mortality varied substantially across years. Generally, tree recruitment was greatest in years with substantial floods (1994 and 1998). For each riparian landform type, tree mortality was correlated with the maximum daily flow during the period preceding annual debris surveys. This relationship was particularly strong for sand ridges (r2 = 0.942) and low terraces (r2 = 0.915), but was significant for floodplains (r2 = 0.413). Greatest rates of debris recruitment per maximum daily flow were observed for sand ridges followed by low terraces. Flood characteristics also influenced debris recruitment. The 1994 flood was caused by a tropical storm and resulted in a rapid rise in streamflow. Much of the debris recruited during this flood was from toppled trees and was oriented parallel to the stream channel. In contrast, the 1998 flood was preceded by a wetter than average winter with more gradually rising flows and there was no relationship between riparian landform and debris characteristics. These results indicate that wood recruitment dynamics in Coastal Plain streams are complex. Wood recruitment rates are controlled by cyclical variations in climate interacting with riparian geomorphology. Infrequent high flows appear critical in the maintenance of the instream debris pool. Copyright © 2007 John Wiley & Sons, Ltd.
On learning thresholds of parities and unions of rectangles in random walk models
Authors: Roch Sébastien 
Published: February 2007

AbstractIn a recent breakthrough, [Bshouty et al., J Comput Syst Sci 71 (2005), 250–265] obtained the first passive‐learning algorithm for DNFs under the uniform distribution. They showed that DNFs are learnable in the Random Walk and Noise Sensitivity models. We extend their results in several directions. We first show that thresholds of parities, a natural class encompassing DNFs, cannot be learned efficiently in the Noise Sensitivity model using only statistical queries. In contrast, we show that a cyclic version of the Random Walk model allows to learn efficiently polynomially weighted thresholds of parities. We also extend the algorithm of Bshouty et al. to the case of Unions of Rectangles, a natural generalization of DNFs to {0,…,b − 1}n. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2007
Anatomy of a group model‐building intervention: building dynamic theory from case study research
Authors: Luna‐Reyes Luis Felipe , Martinez‐Moyano Ignacio J. , Pardo Theresa A. , Cresswell Anthony M. , Andersen David F. , Richardson George P. 
Published: February 2007

AbstractThe system dynamics group at the Rockefeller College of the University at Albany has been developing techniques to create system dynamic models with groups of managers during the last 25 years. Building upon their tradition in decision conferencing, the group has developed a particular style that involves a facilitation team in which people play different roles. Throughout these years of experience, the group has also developed several “scripts” to elicit knowledge from experts based on small‐groups research, and well‐established practices in the development of system dynamics models. This paper constitutes a detailed documentation of a relatively small‐scale modeling effort that took place in early 2001, offering a “soup to nuts” description of group model building at Albany. The paper describes in detail nine of the scripts that the group has developed, offering some reflections about their advantages and limitations. Copyright © 2006 John Wiley & Sons, Ltd.
Psychological well‐being and psychosocial work environment characteristics among emergency medical and nursing staff
Authors: Escribà‐Agüir Vicenta , Pérez‐Hoyos Santiago 
Published: February 2007

AbstractThe aim of this study was to determine if the effect of psychosocial work environment on psychological well‐being was different for doctors and nurses who work in emergency departments in Spain. A cross‐sectional survey was carried out among 945 emergency doctors and nurses staff from Spain. The outcome variable was the psychological well‐being measured by two dimensions of SF‐36 Health Survey (SF‐36) (mental health, vitality) and one dimension of Maslach's Burnout Inventory (emotional exhaustion). The explanatory variable was the psychosocial work environment evaluated according to Karasek and Johnson's demand‐control model that includes the dimensions of psychological demands, job control, supervisor social support and co‐workers' social support. The adjusted odds ratios and their 95 per cent confidence intervals were calculated by logistic regression. The prevalence of low vitality, bad mental health and high emotional exhaustion was higher among doctors than nurses. Exposure to high psychological demands increased the probability of low vitality, bad mental health and high emotional exhaustion among doctors and nurses. Low job control and low co‐workers' social support at work were associated with poor psychological well‐being only among doctors. Low job supervisors' social support increased the risk of bad mental health among doctors and of high emotional exhaustion among nurses. There is a different effect of psychosocial work environment on psychological well‐being between doctors and nurses. Copyright © 2007 John Wiley & Sons, Ltd.
Fabrication of CuO nanoparticle interlinked microsphere cages by solution method
Authors: Qi Jian Quan , Tian Hu Yong , Li Long Tu , Chan Helen Lai Wah 
Published: February 2007

Abstract
Here we report a very simple method to convert conventional CuO powders to nanoparticle interlinked microsphere cages by solution method. CuO is dissolved into aqueous ammonia, and the solution is diluted by alcohol and dip coating onto a glass substrate. Drying at 80 °C, the nanostructures with bunchy nanoparticles of Cu(OH)2can be formed. After the substrate immerges into the solution and we vaporize the solution, hollow microspheres can be formed onto the substrate. There are three phases in the as-prepared samples, monoclinic tenorite CuO, orthorhombic Cu(OH)2, and monoclinic carbonatodiamminecopper(II) (Cu(NH3)2CO3). After annealing at 150 °C, the products convert to CuO completely. At annealing temperature above 350 °C, the hollow microspheres became nanoparticle interlinked cages.
Formulation of ultralow interfacial tension systems using extended surfactants
Authors: Witthayapanyanon A. , Acosta E. J. , Harwell J. H. , Sabatini D. A. 
Published: February 2007

AbstractInspired by the concept of lipophilic and hydrophilic linkers, extended surfactants have been proposed as highly desirable candidates for the formulation of microemulsions with high solubilization capacity and ultralow interfacial tension (IFT), especially for triglyceride oils. The defining characteristic of an extended surfactant is the presence of one or more intermediate‐polarity groups between the hydrophilic head and the hydrophobic tail. Currently only limited information exists on extended surfactants; such knowledge is especially relevant for cleaning and separation applications where the cost of the surfactant and environmental regulations prohibit the use of concentrated surfactant solutions. In this work, we examine surfactant formulations for a wide range of oils using dilute solutions of the extended surfactant classes sodium alkyl polypropyleneoxide sulfate (R‐(PO)x−SO4Na), and sodium alkyl polypropyleneoxide‐polyethyleneoxide sulfate (R‐(PO)y‐(EO)z−SO4Na). The IFT of these systems was measured as a function of electrolyte and surfactant concentration for polar and nonpolar oils. The results show that these extended surfactant systems have low critical micelle concentrations (CMC) and critical microemulsion concentrations (CμC) compared with other surfactants. We also found that the unique structure of these extended surfactants allows them to achieve ultralow IFT with a wide range of oils, including highly hydrophobic oils (e.g., hexadecane), triolein, and vegetable oils, using only ppm levels of these extended surfactants. It was also found that the introduction of additional PO and EO groups in the extended surfactant yielded lower IFT and lower optimum salinity, both of which are desirable in most formulations. Based on the optimum formulation conditions, it was found that the triolein sample used in these experiments behaved as a very polar oil, and all other vegetable oils displayed very hydrophobic behavior. This unexpected triolein behavior is suspected to be due to uncharacterized impurities in the triolein sample, and will be further evaluated in future research.
Solubility in and affinity for the bile salt micelle of plant sterols are important determinants of their intestinal absorption in rats
Authors: Hamada Tadateru , Goto Hitomi , Yamahira Takashi , Sugawara Takashi , Imaizumi Katsumi , Ikeda Ikuo 
Published: February 2007

AbstractIntestinal absorption of various plant sterols was investigated in thoracic duct‐cannulated normal rats. Lymphatic recovery was the highest in campesterol, intermediate in brassicasterol and sitosterol, and the lowest in stigmasterol and sitostanol. Higher solubility in the bile salt micelle was observed in sitosterol, campesterol, and sitostanol than in brassicasterol and stigmasterol. The solubility of the latter two sterols was extremely low. When the affinity of plant sterols for the bile salt micelle was compared in an in vitro model system, which assessed sterol transfer from the micellar to the oil phase, the transfer rate was the highest in brassicasterol, intermediate in campesterol and stigmasterol, and lowest in sitosterol and sitostanol. Although no significant correlations between lymphatic recovery of plant sterols and their micellar solubility or transfer rate from the bile salt micelle were observed, highly positive correlation was obtained between the lymphatic recovery and the multiplication value of the micellar solubility and the transfer rate. These observations strongly suggest that both solubility in and affinity for the bile salt micelle of plant sterols are important determinants of their intestinal absorption in rats.
Diacylglycerol acyltransferases from Vernonia and Stokesia prefer substrates with vernolic acid
Authors: Yu Keshun , McCracken Charles T. , Li Runzhi , Hildebrand David F. 
Published: February 2007

AbstractGenetic engineering of common oil crops for industrially valuable epoxy FA production by expressing epoxygenase genes alone had limited success. Identifying other key genes responsible for the selective incorporation of epoxy FA into seed oil in natural high accumulators appears to be an important next step. We investigated the substrate preferences of acyl CoA: diacylglycerol acyltransferases (DGAT) of two natural high accumulators of vernolic acid, Vernonia galamensis and Stokesia laevis, as compared with a common oilseed crop soybean. Developing seed microsomes were fed with either [14C]oleoyl CoA or [14C]vernoloyl CoA in combinations with no exogenous DAG or with 1,2‐dioleoyl‐sn‐glycerol, 1‐palmitoyl‐2‐vernoloyl‐sn‐glycerol, 1,2‐divernoloyl‐sn‐glycerol, 1,2‐dioleoyl‐rac‐glycerol, or 1,2‐divernoloyl‐rac‐glycerol to determine their relative incorporation into TAG. The results showed that in using sn‐1,2‐DAG, the highest DGAT activity was from the substrate combination of vernoloyl CoA with 1,2‐divernoloyl‐sn‐glycerol, and the lowest was from vernoloyl CoA or oleoyl CoA with 1,2‐dioleoyl‐sn‐glycerol in both V. galamensis and S. laevis. Soybean DGAT was more active with oleoyl CoA than vernoloyl CoA, and more active with 1,2‐dioleoyl‐sn‐glycerol when oleoyl CoA was fed. DGAT assays without exogenous DAG, or with exogenous sn‐1,2‐DAG fed individually or simultaneously showed consistent results. In combinations with either oleoyl CoA or vernoloyl CoA, DGAT had much higher activity with rac‐1,2‐DAG than with their corresponding sn‐1,2‐DAG, and the substrate selectivity was diminished when rac‐1,2‐DAG were used instead of sn‐1,2‐DAG. These studies suggest that DGAT action might be an important step for selective incorporation of vernolic acid into TAG in V. galamensis and S. laevis.
HPLC method for quantification and characterization of cholesterol and its oxidation products in eggs
Authors: Mazalli Mônica R. , Sawaya Alexandra C. H. F. , Eberlin Marcos N. , Bragagnolo Neura 
Published: February 2007

AbstractA new method was developed for the simultaneous determination of cholesterol and its oxidation products in eggs, using HPLC with UV and refractive index (RI) detectors, and HPLC interfaced with atmospheric pressure chemical ionization coupled to MS (HPLC‐APCI‐MS). The best conditions for direct saponification of the sample and extraction of the nonsaponifiable material were defined using complete factorial designs with central points. The method showed accuracy and precision with a detection limit between 0.002 and 0.079 μg/g. The oxides cholest‐5‐ene‐3β, 20α‐diol identified by HPLC‐UV‐RI were not confirmed by HPLC‐APCI‐MS.
Feasibility of near real‐time image‐guided sinus surgery using intraoperative fluoroscopic computed axial tomography
Authors: Brown Seth M. , Sadoughi Babak , Cuellar Hernando , von Jako Ron , Fried Marvin P. 
Published: February 2007

ObjectiveOne of the main limitations of image‐guided surgery is that navigation relies on the use of a CT scan obtained before surgery and is unable to be updated during the procedure. A software addition has been developed to allow reconstruction of CT‐like images from a series of fluoroscopic scans and integrate these into an image‐guided system (GE Healthcare Surgical Navigation, Lawrence, MA). We report our initial experience with a series of patients undergoing intraoperative fluoroscopic navigation in sinus surgery.Study Design and SettingsAfter institutional review board clearance, we prospectively studied 14 consecutive patients undergoing image‐guided sinus surgery with the use of intraoperative fluoroscopy.ResultsAll patients had preoperative and postoperative fluoroscopic images reconstructed into CT‐like images. By the conclusion of the study, images were adequate in quality and accurate navigation was achieved.ConclusionReal‐time image‐guided sinus surgery using fluoroscopy is feasible. Future studies will need to focus on defining the procedures that could benefit, such as tumor resection, to enhance patient safety during these operations.
Efficacy of once‐daily esomeprazole treatment in patients with laryngopharyngeal reflux evaluated by 24‐hour pH monitoring
Authors: Reichel Oliver , Jeanette Keller , Rasp Gerd , Hagedorn Hjalmar , Berghaus Alexander 
Published: February 2007

ObjectiveLaryngopharyngeal reflux (LPR) is generally treated with twice‐daily proton‐pump inhibitor (PPI) therapy. In this study, the efficacy of esomeprazole 40 mg once‐daily together with lifestyle modifications was determined by repeated 24‐hour pH monitoring.Study Design and SettingA prospective study. Fortynine patients with suspected LPR underwent 24‐hour pH monitoring. Twenty‐seven of 49 patients with measurable abnormal proximal reflux reflected by a reflux area index (RAI) >6.3 were treated with esomeprazole 40 mg every day, and a second pH study was performed.ResultsIn 22 of 27 patients, everyday PPI treatment reduced the RAI. Four of 5 patients with no RAI reduction reported on symptomatic relief.ConclusionIn a considerable number of patients with suspected LPR, pH monitoring reveals no abnormal proximal reflux. Esomeprazole 40 mg every day together with lifestyle modifications could reach adequate acid suppression in a large number of patients. Symptom improvement is also reported by patients without measurable effects of therapy.
Total laryngectomy and T3‐T4 laryngeal cancer without other adverse histopathology
Authors: Ampil Federico L. , Nathan Cherie Ann O. , Lian Timothy S. , Caldito Gloria , Milligan Edward 
Published: February 2007

ObjectiveWe sought to determine the postoperative management, incidence of tumor recurrence in the neck, and outcome in laryngeal cancer patients whose risk for tumor relapse is not clear.Study Design and SettingThirty patients (27 of whom had transglottic tumors) met the study criteria (resected T3‐T4 laryngeal cancer, histologically negative cervical nodes, and no other adverse histopathology). A group of 12 patients who underwent surgery alone was compared with a second group of 18 patients with similar characteristics but who received postoperative radiotherapy.ResultsOverall survival at five years was 50% in the surgery alone group and 61% in the combined therapy group (P = 0.63). Among the 28 evaluable patients with a median follow‐up of 44 months, the relapse rate in the neck was 25% in the surgery alone group and was 0% in the postoperatively irradiated group (P = 0.07). Recurrences in the neck remained uncontrolled in two of the three patients at the time of death.Conclusion and SignificancePostoperative radiotherapy deserves consideration in selected cases of T3‐T4 laryngeal cancer without adverse histopathology.
Quantifying the source area of macroscopic charcoal with a particle dispersal model
Authors: Peters Matthew Edward , Higuera Philip Edward 
Published: February 2007

AbstractTo aid interpreting the source area of charcoal in lake-sediment records, we compare charcoal deposition from an experimental fire to predictions from a particle dispersal model. This provides both a theoretical framework for understanding how lake sediments reflect fire history and a foundation for simulating sediment-charcoal records. The dispersal model captures the two-dimensional patterns in the empirical data (predicted vs. observed r2 = 0.67, p < 0.001). We further develop the model to calculate the potential charcoal source area (PCSA) for several classes of fires. Results suggest that (1) variations in airborne charcoal deposition can be explained largely by the size of PCSAs relative to fire sizes and (2) macroscopic charcoal travels many kilometers, longer than suggested by dispersal data from experimental fires but consistent with dispersal data from uncontrolled fires.