bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coupling fluvial‐hydraulic models to predict gravel transport in spatially variable flows
Authors: Segura Catalina , Pitlick John 
Published: April 2015

AbstractThis study investigated spatial‐temporal variations of shear stress and bed load transport at three gravel bed river reaches of the Williams Fork River, Colorado. A two‐dimensional flow model was used to compute spatial distributions of shear stress (τ) for four discharge levels between one third of bankfull (Qbf) and Qbf. Results indicate that mean τ values are highly variable among sites. However, the properties of the mean‐normalized distributions of τ are similar across sites for all flows. The distributions of τ are then used with a transport function to compute bed load transport rates of individual grain size fractions. Probability distributions of the instantaneous unit‐width transport rates, qb, indicate that most of the bed load is transported through small portions of the bed with high τ. The mean‐normalized probability distributions of qb are different among sites for all flows except at Qbf, when the distributions overlap. We also find that the grain size distribution (GSD) of the bed load adjusts with discharge to resemble the grain size distribution of the subsurface at Qbf. We extend these results to 13 locations in the basin, using the mean‐normalized distributions of shear stress and measured subsurface grain sizes to compute bed load transport rates at Qbf. We found a remarkably similar shape of the qb distribution among sites highlighting the basin‐wide balance between flow forces and GSD at Qbf and the potential to predict sediment flux at the watershed scale.
Thermal and exhumation history of the Eocene Chumstick Basin, Washington State, USA
Authors: Enkelmann Eva , Ehlers Todd A. , Merli Gabriel , Methner Katharina 
Published: April 2015

AbstractThis study investigates the Cenozoic evolution of the Cascades Mountains, USA, by means of reconstructing the thermal history of the Chumstick Basin deposits that are located on the eastern flank of the orogen. We present new detrital apatite (U‐Th‐Sm)/He and detrital apatite fission‐track ages from the middle Eocene (~48–37 Ma) Chumstick Formation and modern river detritus. These data are integrated with the published thermochronometric ages of the adjoining Cascade Mountains basement. The new thermochronometer results are combined with existing vitrinite reflectance data for modeling of the basin's thermal history. Results suggest constant temperatures throughout the late Oligocene to early Miocene followed by rapid cooling since 17–10 Ma. Results indicate that the middle to late Miocene uplift of the Cascades resulted in reactivation of the fault zones bounding the Chumstick Basin. The structural reactivation and the weaker lithology of the basin strata in comparison to the harder and more resistant basement rocks of the Cascades resulted in significant basin exhumation. This interpretation is determined from younger apatite (U‐Th‐Sm)/He cooling ages observed in the reset detrital bedrock of the Chumstick Formation than in the adjoining basement rocks. These observations suggest a structural and lithological control on exhumation magnitudes in this region.
Abiotic and biotic controls of soil moisture spatiotemporal variability and the occurrence of hysteresis
Authors: Fatichi Simone , Katul Gabriel G. , Ivanov Valeriy Y. , Pappas Christoforos , Paschalis Athanasios , Consolo Ada , Kim Jongho , Burlando Paolo 
Published: April 2015

AbstractAn expression that separates biotic and abiotic controls on the temporal dynamics of the soil moisture spatial coefficient of variation Cv(θ) was explored via numerical simulations using a mechanistic ecohydrological model, Tethys‐Chloris. Continuous soil moisture spatiotemporal dynamics at an exemplary hillslope domain were computed for six case studies characterized by different climate and vegetation cover and for three configurations of soil properties. It was shown that abiotic controls largely exceed their biotic counterparts in wet climates. Biotic controls on Cv(θ) were found to be more pronounced in Mediterranean climates. The relation between Cv(θ) and spatial mean soil moisture
was found to be unique in wet locations, regardless of the soil properties. For the case of homogeneous soil texture, hysteretic cycles between Cv(θ) and
were observed in all Mediterranean climate locations considered here and to a lesser extent in a deciduous temperate forest. Heterogeneity in soil properties increased Cv(θ) to values commensurate with field observations and weakened signatures of hysteresis at all of the studied locations. This finding highlights the role of site‐specific heterogeneities in hiding or even eliminating the signature of climatic and biotic controls on Cv(θ), thereby offering a new perspective on causes of confounding results reported across field experiments.
CellDyM: A room temperature operating cryogenic cell for the dynamic monitoring of snow metamorphism by time‐lapse X‐ray microtomography
Authors: Calonne N. , Flin F. , Lesaffre B. , Dufour A. , Roulle J. , Puglièse P. , Philip A. , Lahoucine F. , Geindreau C. , Panel J.‐M. , du Roscoat S. Rolland , Charrier P. 
Published: April 2015

AbstractMonitoring the time evolution of snow microstructure in 3‐D is crucial for a better understanding of snow metamorphism. We, therefore, designed a cryogenic cell that precisely controls the experimental conditions of a sample while it is scanned by X‐ray tomography. Based on a thermoelectrical regulation and a vacuum insulation, the cell operates at room temperature. It is, thus, adaptable to diverse scanners, offering advantages in terms of imaging techniques, resolution, and speed. Three‐dimensional time‐lapse series were obtained under equitemperature and temperature gradient conditions at a 7.8 μm precision. The typical features of each metamorphism and the anisotropic faceting behavior between the basal and prismatic planes, known to occur close to −2°C, were observed in less than 30 h. These results are consistent with the temperature fields expected from heat conduction simulations through the cell. They confirm the cell's accuracy and the interest of relatively short periods to study snow metamorphism.
Ambient noise tomography across the southern Alaskan Cordillera
Authors: Ward Kevin M. 
Published: April 2015

AbstractI present the results of an extensive data mining effort integrating 197 permanent and temporary seismic stations into a Rayleigh wave ambient noise study across southern Alaska and westernmost Canada. Principal observations of my tomography model are largely consistent with mapped geology features and previous geophysical studies while providing previously unavailable, laterally continuous details of the southern Alaskan Cordillera lithosphere. At intermediate periods, a geophysically uniform crust is observed north of the Denali Fault and is consistent with a sharp transition in crustal thickness. Under the Wrangell volcanic belt, a prominent low‐phase‐velocity anomaly correlates well with the lateral extent of a relative low‐gravity anomaly and Neogene surface volcanics. At longer periods, a low‐phase‐velocity anomaly bounds the inferred eastern extent of the subducted Yakutat microplate beneath the Wrangell volcanic belt.
Crop models capture the impacts of climate variability on corn yield
Authors: Niyogi Dev , Liu Xing , Andresen Jeff , Song Yang , Jain Atul K. , Kellner Olivia , Takle Eugene S. , Doering Otto C. 
Published: April 2015

AbstractWe investigate the ability of three different crop models of varying complexity for capturing El Niño–Southern Oscillation‐based climate variability impacts on the U.S. Corn Belt (1981–2010). Results indicate that crop models, irrespective of their complexity, are able to capture the impacts of climate variability on yield. Multiple‐model ensemble analysis provides best results. There was no significant difference between using on‐site and gridded meteorological data sets to drive the models. These results highlight the ability of using simpler crop models and gridded regional data sets for crop‐climate assessments.
Vertical structure and physical processes of the Madden‐Julian oscillation: Synthesis and summary
Authors: Klingaman Nicholas P. , Jiang Xianan , Xavier Prince K. , Petch Jon , Waliser Duane , Woolnough Steven J. 
Published: April 2015

AbstractThe “Vertical structure and physical processes of the Madden‐Julian oscillation (MJO)” project comprises three experiments, designed to evaluate comprehensively the heating, moistening, and momentum associated with tropical convection in general circulation models (GCMs). We consider here only those GCMs that performed all experiments. Some models display relatively higher or lower MJO fidelity in both initialized hindcasts and climate simulations, while others show considerable variations in fidelity between experiments. Fidelity in hindcasts and climate simulations are not meaningfully correlated. The analysis of each experiment led to the development of process‐oriented diagnostics, some of which distinguished between GCMs with higher or lower fidelity in that experiment. We select the most discriminating diagnostics and apply them to data from all experiments, where possible, to determine if correlations with MJO fidelity hold across scales and GCM states. While normalized gross moist stability had a small but statistically significant correlation with MJO fidelity in climate simulations, we find no link with fidelity in medium‐range hindcasts. Similarly, there is no association between time step to time step rainfall variability, identified from short hindcasts and fidelity in medium‐range hindcasts or climate simulations. Two metrics that relate precipitation to free‐tropospheric moisture—the relative humidity for extreme daily precipitation and variations in the height and amplitude of moistening with rain rate—successfully distinguish between higher‐fidelity and lower fidelity GCMs in hindcasts and climate simulations. To improve the MJO, developers should focus on relationships between convection and both total moisture and its rate of change. We conclude by offering recommendations for further experiments.
The Potential for Handling Improvements by Global Chassis Control
Authors: Raste Thomas , Rieth Peter E. 
Published: April 2015

AbstractThe advances in global chassis control technology have been used to further improve the vehicle safety and handling qualities. The effects of active systems are well understood in the context of how they contribute to the overall vehicle performance. This chapter describes the effectiveness of active systems for handling improvements, a generic control architecture, and how actuator configurations can be selected and coordinated, as well as future trends for predictive handling control. Simulations based on a linear vehicle dynamics model are used throughout the chapter to illustrate the major statements and conclusions.
Spark Ignition Combustion
Authors: Spicher Ulrich 
Published: April 2015

AbstractThis chapter deals with the four‐stroke working process of a spark ignition engine for automotive application. The process of mixture formation is described for external port fuel injection as well as for internal direct injection of fuel. The two operating modes with direct injection, the combustion with homogeneous charge and with stratified charge, are explained. Conditions to be fulfilled for reliable ignition are specified. The combustion process is described by means of flame propagation and mass fraction burned. Influence of spark advance on thermal efficiency and engine torque is explained. Furthermore, some new features such as variable valve trains and boosting are specified. Finally, critical operation with combustion irregularities such as knocking combustion and the formation of undesired pollutants during theSIengine process are described and discussed.
Diesel Fuel Injection Systems
Authors: Nanjundaswamy Harsha , Laumen Hermann Josef 
Published: April 2015

AbstractDiesel engines work on the compression ignition principle, where the fuel is injected into compressed air inside the cylinder. Since the invention of the diesel engine, the diesel fuel injection systems have played a crucial role in defining engine operation. Over the decades, the advancements in fuel injection in conjunction with engine hardware components paved the way for diesel engines to exemplify high efficiency and clean combustion. With emphasis on precise fuel injection, better atomization of fuel to improve combustion, multiple injection, and precise control with electronics, the diesel fuel injection systems have come a long way evolving to meet every challenge that was posed. This chapter begins with a brief review of historic development of diesel fuel injection and discusses the state‐of‐the‐art common rail electronic diesel control system and its features.
Intelligent Transport Systems: Overview and Structure (History, Applications, and Architectures)
Authors: Miles John C. 
Published: April 2015

Abstract

This chapter traces the development of Intelligent Transport Systems (
ITS
) from its early beginnings through to the present day. It looks at the structure of
ITS
applications that has evolved and the important role that system architecture has played in providing a framework for these developments. The chapter considers the origins of
ITS
in Japan, Europe, and North America, leading to the emergence of
ITS
as part of mainstream transportation management. The essential characteristics of
ITS
are described with reference to
ITS
technologies and user services. Different
ITS
architecture viewpoints are described and the role of
ITS
standards is explained. This chapter concludes with some pointers for the future.
Abnormal cortical thickness connectivity persists in childhood absence epilepsy
Authors: Curwood Evan K. , Pedersen Mangor , Carney Patrick W. , Berg Anne T. , Abbott David F. , Jackson Graeme D. 
Published: April 2015

AbstractObjectiveChildhood absence epilepsy (CAE) is a childhood‐onset generalized epilepsy. Recent fMRI studies have suggested that frontal cortex activity occurs before thalamic involvement in epileptic discharges suggesting that frontal cortex may play an important role in childhood absence seizures. Neurocognitive deficits can persist after resolution of the epilepsy. We investigate whether structural connectivity changes are present in the brains of CAE patients in young adulthood.MethodsCortical thickness measurements were obtained for 30 subjects with CAE (mean age 21 ± 2 years) and 56 healthy controls (mean age 24 ± 4) and regressed for age, sex, and total intracranial volume (TIV). Structural connectivity was evaluated by measuring the correlation between average cortical thicknesses in 915 regions over the brain. Maps of connectivity strength were then obtained for both groups.ResultsWhen compared to controls, the CAE group shows overall increased “connectivity” with focal increased connection strength in anterior regions including; the anterior cingulate and the insula and superior temporal gyrus bilaterally; the right orbito‐frontal and supramarginal regions; and the left entorhinal cortex. Decreased connection strength in the CAE group was found in the left occipital lobe, with a similar trend in right occipital lobe.InterpretationBrains in young adults whose CAE was resolved had abnormal structural connectivity. Our findings suggest that frontal regions correlate most with cortical thickness throughout the brain in CAE patients, whereas occipital regions correlate most in well matched normal controls. We interpret this as evidence of a developmental difference in CAE that emphasizes these frontal lobe regions, perhaps driven by frontal lobe epileptiform activity.
The impact of endoscopic sinus surgery on total direct healthcare costs among patients with chronic rhinosinusitis
Authors: Purcell Patricia L. , Beck Sara , Davis Greg E. 
Published: April 2015

BackgroundThis study investigates how endoscopic sinus surgery (ESS) impacts total direct healthcare costs, medication usage, and frequency of imaging among patients with chronic rhinosinusitis (CRS).MethodsData were obtained from the MarketScan® Commercial Claims and Encounters databases (Truven Health Analytics); patients who underwent ESS for CRS in 2008 were identified. Healthcare costs, days of antibiotic and oral steroid usage, and number of computed tomography (CT) and magnetic resonance imaging (MRI) studies were collected for 12 months prior to and 36 months after surgery and compared in 1‐year intervals.ResultsA total of 8963 surgical patients were included. Median total direct costs fell from $4750 at preoperative baseline (95% confidence interval [CI], $4661 to $4838) to $4212 by year 3 after surgery (95% CI, $4078 to $4346). Disease‐specific costs related to conditions commonly associated with CRS—asthma, allergy, depression, and headache–all decreased in the years after surgery; the reduction was significant for all conditions but asthma. Mean days of antibiotic usage per year decreased from 28.2 days before surgery to 15.9 days by year 3 after surgery, p value <0.001. Days of oral corticosteroid usage remained stable at just over 7 days. Mean number of imaging studies fell from an average of 1.6 in the year before surgery to 0.2 by year 3 after surgery, p value <0.001.ConclusionAmong patients who underwent ESS for CRS, total direct healthcare costs, antibiotic usage, and number of imaging studies decreased after surgery, and remained below preoperative levels throughout all 3 years of follow‐up. Oral corticosteroid usage remained stable.
Front, back and sides: experimental replication and archaeological analysis of Hawaiian adzes and associated debitage
Authors: Clarkson Chris , Shipton Ceri , Weisler Marshall 
Published: April 2015

AbstractWe report our attempts to experimentally replicate 25 fine‐grained basalt Hawaiian quadrangular adzes using freehand percussion. We document the techniques, stages and distinctive debitage resulting from each stage of the reduction process. While the later experimental adzes in our series reproduced the Hawaiian quadrangular adze with accuracy, we were unable to achieve the level of finesse seen in some finished archaeological specimens. Our experiments, and the gap between our own results and the finest examples seen in some archaeological collections, indicates the very high levels of skill needed to make the most refined Hawaiian adzes, and supports the notion that some adze makers were undoubtedly specialists. Our experimental work complements another study of archaeological adzes that examines the technological strategies and the cumulative addition of morphological elements to adzes during manufacture. We hope this study will serve as a useful benchmark for objectively and systematically comparing quadrangular adze technology across Hawai‘i and throughout Polynesia, leading to a better understanding of regional and temporal variation in adze technology.
M/C2/c/K queuing model and optimization for a geriatric care center
Authors: Uzunoglu Kocer Umay , Ozkar Serife 
Published: April 2015

Queuing systems with finite buffers are reasonable models for many manufacturing, telecommunication, and healthcare systems. Although some approximations exist, the exact analysis of multi‐server and finite‐buffer queues with general service time distribution is unknown. However, the phase‐type assumption for service time is a frequently used approach. Because the Cox distribution, a kind of phase‐type distribution, provides a good representation of data with great variability, it has a vast area of application in modeling service times.The research focus is twofold. First, a theoretical structure of a multi‐server and finite‐buffer queuing system in which the service time is modeled by the two‐phase Cox distribution is studied. It is focused on finding an efficient solution to the stationary probabilities using the matrix‐geometric method. It is shown that the stationary probability vector can be obtained with the matrix‐geometric method by using level‐dependent rate matrices, and the mean queue length is computed. Second, an empirical analysis of the model is presented. The proposed methodology is applied in a case study concerning the geriatric patients. Some numerical calculations and optimizations are performed by using geriatric data. Copyright © 2015 John Wiley & Sons, Ltd.
Motivation and cognitive structures of store versus manufacturer brand consumers
Authors: Krystallis Athanasios 
Published: April 2015

AbstractThe present paper offers empirical evidence about the impact of the type and characteristics of the brand category (i.e. perceived purchasing risk and involvement) as drivers of store brand choice. The means‐end chains analysis methodology was applied on a sociodemographically homogeneous consumer sample, assigned through a 2 × 2 in‐between subjects design into four subgroups of regular (orange juice or toothpaste) store or manufacturer brand buyers, respectively. The introduction of a store brand fueled motivations and cognitive structures that were predominantly shaped by the specific brand type and its expected perceived benefits (i.e. good quality/price ratios); on the contrary, manufacturer brands allowed room for typical, category‐related motives and cognitive hierarchies to dominate. Moreover, in the case of store brand buyers across categories (orange juice versus toothpaste), different perceived risk and consumer involvement had a clear impact on the structure of overall cognitive map and on the sophistication of its most dominant cognitive area. In situations of high perceived risk and involvement, the cognitive structures of store brand buyers tend to resemble that of manufacturer brand buyers. Results add to the ongoing stream of research on store brand buyer behaviour by offering proof of the impact of consumer perceived risk and category involvement on the choice between manufacturer and store brands. Copyright © 2015 John Wiley & Sons, Ltd.
Enzymatic Transformations Involved in the Biosynthesis of Microbial Exo‐polysaccharides Based on the Assembly of Repeat Units
Authors: Schmid Jochen , Sieber Volker 
Published: April 2015

AbstractMicrobial exo‐polysaccharides can serve as valuable biopolymers in medicine, food and the feed industry as well as in various technical applications as substitutes of petro‐based polymers or with unusual performance. Due to their different natural functions, they have vastly diverse structures, which lead to a very different properties. This structural diversity is brought about by complex biosyntheses based on enzymes whose genes are mostly encoded in clusters within the genomes of the different microbial species. The organisation of the genes and the chemical structures of the corresponding polysaccharides are closely related. Here, we will mainly focus on the genetics and biosynthesis of some major bacterial hetero‐polysaccharides that are based on repeat unit assembly and will present specific examples of enzymatic transformation steps. Finally, a short outlook will be given on how in vivo modifications based on enzymatic transformations could be used to engineer these polymers.