bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonic-vibration assisted arc-welding of aluminum alloys
Authors: Krajewski A. , Włosiński W. , Chmielewski T. , Kołodziejczak P. 
Published: March 2014

Abstract
The structure and hardness of the surface-welds and fusion-welds made on a 2017A aluminum alloy waveguide using the MIG and TIG methods with and without the participation of ultrasonic vibrations were examined. Cross-sections of the fusions and surface-welds thus obtained were observed in a microscope and the hardness distributions were determined. The aim of the study was to analyze the effects of the ultrasonic vibrations applied to the melted metal pool by a vibrating substrate which in our experiments was a waveguide. The interactions of the ultrasonic vibrations with the molten metal during its solidification and also with the heat-affected zone were examined at various phases of the vibration wave. The ultrasonic vibrations affected the structure of a weld. These changes are strongly depended on the wave phase.
Functional morphology of the brain of the African giant pouched rat (<i>Cricetomys gambianus</i> Waterhouse, 1840)
Authors: Ibe Chikera S. , Onyeanusi Barth I. , Hambolu Joseph O. 
Published: March 2014

A gross morphological study of the brain of the African giant pouched rat (Cricetomys gambianus Waterhouse, 1840) was undertaken in order to document its normal features and assess the structure-function paradigm. The study was conducted by direct observation of 29 adult African giant pouched rats’ brains. In the telencephalon, the cerebral cortex was devoid of prominent gyri and sulci, but the large olfactory bulb and tract relaying impulses to the olfactory cortex were very prominent. The large size of the olfactory bulb correlated with the established sharp olfactory acuity of the rodent. In the mesencephalic tectum, the caudal colliculi were bigger than the rostral colliculi, indicating a more acute sense of hearing than sight. In the metencephalon, the cerebellar vermis, the flocculus and the paraflocculus were highly coiled and, thus, well developed. The myelencephalon revealed a better organised ventral surface than dorsal surface; the cuneate fascicle, the intermediate sulcus and the lateral sulcus were not evident on the dorsal surface, but there were clearly visible pyramids and olivary prominence on the ventral surface. In conclusion, the highly coiled cerebellar vermis, flocculus and paraflocculus, as well as the conspicuous pyramids and olivary prominence are indicative of a good motor coordination and balance in the African giant pouched rat.
Multi-scale Calibration and Validation of MHYDAS-Erosion for A Small Mediterranean Vineyard Catchment: A Case Study
Authors: Gumiere Silvio Jose , Delattre Laurence , Le Bissonnais Yves , Cheviron Bruno , Ben Slimane Abir , Raclot Damien 
Published: March 2014

In this work we present a case study of the multi-scale calibration and validation of MHYDAS-Erosion applied to a Mediterranean vineyard. The calibration was performed using expert knowledge in linking physical parameters to land uses with the automatic parameter estimation software PEST. MHYDAS-Erosion was calibrated and validated using spatially distributed observations on total discharge and soil loss. Calibration has been performed within six rainfall events; both hydrological and erosion parameters were calibrated using RMSE, R2 and the modified version of the Nash-Sutcliffe model efficiency criteria. Calibration results indicate there was good agreement between simulated and observed total discharge and total soil loss at the seven observation points (modified Nash-Sutcliffe efficiency (mNSE) ranging between 0.89 and 0.95). Acceptable results were obtained in terms of parameter values, identification of their physical meaning and coherence. However, some limitations were also identified, and could be remedied in more detailed studies involving (i) spatially-distributed rainfall on the catchment, (ii) a description of groundwater exfiltration and (iii) spatially-distributed properties of the ditches over the catchment. Validation results were quite satisfactory for three of the four validation events. The results from this case study suggest that MHYDAS-Erosion may need a specific calibration when applied to another catchment, but once it is calibrated, it could be used for multi-scale soil loss forecasting.
Ionization due to electron and proton precipitation during the August 2011 storm
Authors: Huang Yanshi , Huang Cheryl Y. , Su Yi‐Jiun , Deng Yue , Fang Xiaohua 
Published: March 2014

AbstractThe parameterizations of monoenergetic particle impact ionization in Fang et al. (2010) (Fang2010) and Fang et al. (2013) (Fang2013) are applied to the complex energy spectra measured by DMSP F16 satellite to calculate the ionization rates from electron and ion precipitations for a Northern Hemisphere pass from 0030 UT to 0106 UT on 6 August 2011. Clear enhancement of electron flux is found in the polar cap. The mean electron energy in the polar cap is mostly above 100 eV, while the mean energy in the auroral zone is typically above 1 keV. At the same time, F16 captures a strong Poynting flux enhancement in the polar cap, which is comparable to those in the auroral zone. The particle impact ionization rates using Fang2010 and Fang2013 parameterizations show clear enhancement at F region altitudes mainly due to the low‐energy precipitating electrons, peaking probably in the cusp but also showing enhanced levels throughout most of the polar cap region. The general circulation models (GCMs), National Center for Atmospheric Research Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model, and Global Ionosphere‐Thermosphere Model, using their default empirical formulations of particle impact ionization, do not capture the observed features shown in the total particle ionization rate applying the Fang2010 and Fang2013 parameterizations to DMSP measurements. The difference between GCM simulations and Fang2010 and Fang2013 applied to DMSP data is due to the difference of both the inputs to the models and the parameterization of the ionization rates.
Gravity waves generated by convection during TWP‐ICE: I. Inertia‐gravity waves
Authors: Hankinson Mai C. N. , Reeder M. J. , Lane T. P. 
Published: March 2014

AbstractGravity waves are analyzed in radiosonde soundings taken during the Tropical Warm Pool‐International Cloud Experiment (TWP‐ICE) campaign. The properties of the inertia‐gravity waves are analyzed in Part I, whereas Part II focuses on high‐frequency gravity waves. Two groups of inertia‐gravity waves are detected: group L (Long vertical wavelength) in the middle stratosphere during the suppressed monsoon period and group S (Short vertical wavelength) in the lower stratosphere during the monsoon break period. Waves belonging to group L propagate to the southeast with a mean intrinsic period of 35 h and have vertical and horizontal wavelengths of about 5–6 km and 3000–6000 km, respectively. Ray‐tracing calculations indicate that these waves originate from a deep convective region near Indonesia. Waves belonging to group S propagate to the south‐southeast with an intrinsic period, vertical wavelength, and horizontal wavelength of about 45 h, 2 km, and 2000–4000 km, respectively. These waves appear to originate from convection in the vicinity of New Guinea.
Transition probability‐based stochastic geological modeling using airborne geophysical data and borehole data
Authors: He Xin , Koch Julian , Sonnenborg Torben O. , Jørgensen Flemming , Schamper Cyril , Christian Refsgaard Jens 
Published: March 2014

AbstractGeological heterogeneity is a very important factor to consider when developing geological models for hydrological purposes. Using statistically based stochastic geological simulations, the spatial heterogeneity in such models can be accounted for. However, various types of uncertainties are associated with both the geostatistical method and the observation data. In the present study, TProGS is used as the geostatistical modeling tool to simulate structural heterogeneity for glacial deposits in a head water catchment in Denmark. The focus is on how the observation data uncertainty can be incorporated in the stochastic simulation process. The study uses two types of observation data: borehole data and airborne geophysical data. It is commonly acknowledged that the density of the borehole data is usually too sparse to characterize the horizontal heterogeneity. The use of geophysical data gives an unprecedented opportunity to obtain high‐resolution information and thus to identify geostatistical properties more accurately especially in the horizontal direction. However, since such data are not a direct measurement of the lithology, larger uncertainty of point estimates can be expected as compared to the use of borehole data. We have proposed a histogram probability matching method in order to link the information on resistivity to hydrofacies, while considering the data uncertainty at the same time. Transition probabilities and Markov Chain models are established using the transformed geophysical data. It is shown that such transformation is in fact practical; however, the cutoff value for dividing the resistivity data into facies is difficult to determine. The simulated geological realizations indicate significant differences of spatial structure depending on the type of conditioning data selected. It is to our knowledge the first time that grid‐to‐grid airborne geophysical data including the data uncertainty are used in conditional geostatistical simulations in TProGS. Therefore, it provides valuable insights regarding the advantages and challenges of using such comprehensive data.
Accelerated lake expansion on the Tibetan Plateau in the 2000s: Induced by glacial melting or other processes?
Authors: Song Chunqiao , Huang Bo , Richards Keith , Ke Linghong , Hien Phan Vu 
Published: March 2014

AbstractAlpine lakes on the Tibetan Plateau are minimally disturbed by human activities and are sensitive indicators of climate variability. Accelerated lake expansion in the 2000s has been confirmed by both dramatic lake‐area increases (for 312 lakes larger than 10 km2) derived from optical images, and rapid water‐level rises (for 117 lakes with water‐level data) measured by satellite altimetry. However, the underlying climate causes remain unclear. This paper analyzes the relationship between the water‐level changes of lakes on the plateau and the potential driving factors, such as the glacier meltwater supply and a dependency on precipitation and runoff over the whole plateau and in each zone. The results show that the rates of change of non‐glacier‐fed lakes in the 2000s were as high as those of glacier‐fed lakes across the whole plateau and the lake‐level changes were closely associated with the lake supply coefficients (the basin/lake area ratio). The lake variations agreed well with the spatial pattern of precipitation changes. However, in different zones, especially at around 33°N north of the plateau, glacier‐fed lakes did exhibit faster lake level increases than no‐glacier‐fed lakes, indicating that the presence of a glacier meltwater supply augmented the precipitation‐driven lake expansions in these areas. Despite the absence of quantitative modeling due to limited data availability, this study provides qualitative support that the lake expansions on the Tibetan Plateau in the 2000s have been driven primarily by changes in precipitation and evapotranspiration and not solely by the effect of glacier wastage.
Interannual variability of evapotranspiration and vegetation productivity
Authors: Fatichi Simone , Ivanov Valeriy Y. 
Published: March 2014

AbstractInterannual variability of precipitation can influence components of the hydrological budget, affecting them directly and indirectly through adjustments in vegetation structure and function. We investigate the effects of fluctuations of annual precipitation on ecohydrological dynamics. Specifically, we use the advanced weather generator, AWE‐GEN, to simulate 200 years of hourly meteorological forcing obtained by imposing four types of precipitation annual process with identical long‐term mean. The generated time series force a mechanistic ecohydrological model, Tethys‐Chloris. Simulations with perturbed precipitation variability are performed for four locations characterized by different vegetation cover and climate. The results indicate that long‐term transpiration (T) and evapotranspiration (ET) fluxes as well as vegetation productivity expressed as Gross Primary Production (GPP) and Aboveground Net Primary Production (ANPP) are essentially unaffected by the imposed climate fluctuations. This finding supports the hypothesis of a relative insensitivity, except for water‐limited environments, of interannual evapotranspiration and vegetation productivity to annual climatic fluctuations, which are mostly reflected in the fluxes of deep leakage and runoff. The occurrence of short periods of favorable meteorological conditions randomly taking place within the year was found to be a better explanatory variable for interannual variability of ET and ANPP than average annual or growing season conditions. The results indicated that local, single‐site sensitivities are considerably smaller than those observed across climatic and vegetation spatial gradients and thus an important role of ecosystem reorganization in modifying ANPP and ET sensitivity in a changing climate is recognized.
A Convenient Photocatalytic Fluorination of Unactivated CH Bonds
Authors: Halperin Shira D. , Fan Hope , Chang Stanley , Martin Rainer E. , Britton Robert 
Published: March 2014

AbstractFluorination reactions are essential to modern medicinal chemistry, thus providing a means to block site‐selective metabolic degradation of drugs and access radiotracers for positron emission tomography imaging. Despite current sophistication in fluorination reagents and processes, the fluorination of unactivated CH bonds remains a significant challenge. Reported herein is a convenient and economic process for direct fluorination of unactivated CH bonds that exploits the hydrogen abstracting ability of a decatungstate photocatalyst in combination with the mild fluorine atom transfer reagent N‐fluorobenzenesulfonimide. This operationally straightforward reaction provides direct access to a wide range of fluorinated organic molecules, including structurally complex natural products, acyl fluorides, and fluorinated amino acid derivatives.
Modeling Heat Dissipation at the Nanoscale: An Embedding Approach for Chemical Reaction Dynamics on Metal Surfaces
Authors: Meyer Jörg , Reuter Karsten 
Published: March 2014

AbstractWe present an embedding technique for metallic systems that makes it possible to model energy dissipation into substrate phonons during surface chemical reactions from first principles. The separation of chemical and elastic contributions to the interaction potential provides a quantitative description of both electronic and phononic band structure. Application to the dissociation of O2 at Pd(100) predicts translationally “hot” oxygen adsorbates as a consequence of the released adsorption energy (ca. 2.6 eV). This finding questions the instant thermalization of reaction enthalpies generally assumed in models of heterogeneous catalysis.
Construction of Chiral Bridged Tricyclic Benzopyrans: Enantioselective Catalytic Diels–Alder Reaction and a One‐Pot Reduction/Acid‐Catalyzed Stereoselective Cyclization
Authors: Song Aiguo , Zhang Xishuai , Song Xixi , Chen Xiaobei , Yu Chenguang , Huang He , Li Hao , Wang Wei 
Published: March 2014

AbstractAn asymmetric two‐step approach to chiral bridged tricyclic benzopyrans, core structures featured in various natural products, is described. In the synthesis, an unprecedented enantioselective catalytic decarboxylative Diels–Alder reaction is developed using readily available coumarin‐3‐carboxylic acids and aldehydes as reactants under mild reaction conditions. Notably, the decarboxylation‐assisted release of the catalyst enables the process to proceed efficiently with high enantio‐ and diastereoselectivity. Furthermore, a one‐pot procedure for either a LiAlH4‐ or NaBH4‐mediated reduction with subsequent acid‐catalyzed intramolecular cyclization of the Diels–Alder adducts was identified for the efficient formation of the chiral bridged tricyclic benzopyrans.
Fibrin Accumulation Secondary to Loss of Plasmin‐Mediated Fibrinolysis Drives Inflammatory Osteoporosis in Mice
Authors: Cole Heather A. , Ohba Tetsuro , Nyman Jeffry S. , Hirotaka Haro , Cates Justin M. M. , Flick Matthew J. , Degen Jay L. , Schoenecker Jonathan G. 
Published: March 2014

ObjectiveOsteoporosis is a skeletal disorder characterized by low bone mass and increased bone fragility associated with aging, menopause, smoking, obesity, or diabetes. Persistent inflammation has been identified as an instigating factor in progressive bone loss. In addition to the role of fibrin in coagulation, inordinate fibrin deposition within a tissue matrix results in increased local inflammation. Given that fibrin accumulation is a hallmark of osteoporosis‐related comorbidities, we undertook this study to test the hypothesis that persistent fibrin deposition causes inflammatory osteoporosis.MethodsMultiple imaging modalities, bone integrity metrics, and histologic analyses were employed to evaluate skeletal derangements in relation to fibrin deposition, circulating fibrinogen levels, and systemic markers of inflammation in mice that were plasminogen deficient and in plasminogen‐deficient mice that were concomitantly either fibrinogen deficient or carrying a mutant form of fibrinogen lacking the αMβ2 binding motif.ResultsMice generated with a genetic deficit in the key fibrinolytic protease, plasmin, uniformly developed severe osteoporosis. Furthermore, the development of osteoporosis was fibrin(ogen) dependent, and the derangements in the bone remodeling unit were mechanistically tied to fibrin(ogen)‐mediated activation of osteoclasts via activation of the leukocyte integrin receptor αMβ2 on monocytes and secondary stimulation of osteoblasts by RANKL. Notably, the genetic elimination of fibrin(ogen) or the expression of a mutant form of fibrinogen retaining clotting function but lacking the αMβ2 binding motif prevented the degenerative skeletal phenotypes, resulting in normal local and systemic cytokine levels.ConclusionTaken together, these data reveal for the first time that fibrin promotes inflammation‐driven systemic osteoporosis, which suggests a novel association between hemostasis, inflammation, and bone biology.
Aging and Oxidative Stress Reduce the Response of Human Articular Chondrocytes to Insulin‐like Growth Factor 1 and Osteogenic Protein 1
Authors: Loeser Richard F. , Gandhi Uma , Long David L. , Yin Weihong , Chubinskaya Susan 
Published: March 2014

ObjectiveTo determine the effects of aging and oxidative stress on the response of human articular chondrocytes to insulin‐like growth factor 1 (IGF‐1) and osteogenic protein 1 (OP‐1).MethodsChondrocytes isolated from normal articular cartilage obtained from tissue donors were cultured in alginate beads or monolayer. Cells were stimulated with 50–100 ng/ml of IGF‐1, OP‐1, or both. Oxidative stress was induced using tert‐butyl hydroperoxide. Sulfate incorporation was used to measure proteoglycan synthesis, and immunoblotting of cell lysates was performed to analyze cell signaling. Confocal microscopy was performed to measure nuclear translocation of Smad4.ResultsChondrocytes isolated from the articular cartilage of tissue donors ranging in age from 24 years to 81 years demonstrated an age‐related decline in proteoglycan synthesis stimulated by IGF‐1 and IGF‐1 plus OP‐1. Induction of oxidative stress inhibited both IGF‐1– and OP‐1–stimulated proteoglycan synthesis. Signaling studies showed that oxidative stress inhibited IGF‐1–stimulated Akt phosphorylation while increasing phosphorylation of ERK, and that these effects were greater in cells from older donors. Oxidative stress also increased p38 phosphorylation, which resulted in phosphorylation of Smad1 at the Ser206 inhibitory site and reduced nuclear accumulation of Smad1. Oxidative stress also modestly reduced OP‐1–stimulated nuclear translocation of Smad4.ConclusionThese results demonstrate an age‐related reduction in the response of human chondrocytes to IGF‐1 and OP‐1, which are 2 important anabolic factors in cartilage, and suggest that oxidative stress may be a contributing factor by altering IGF‐1 and OP‐1 signaling.
Measurement of boundary layer ozone concentrations on‐board a Skywalker unmanned aerial vehicle
Authors: Illingworth Sam , Allen Grant , Percival Carl , Hollingsworth Peter , Gallagher Martin , Ricketts Hugo , Hayes Harry , Ładosz Paweł , Crawley David , Roberts Gareth 
Published: March 2014

AbstractThis study demonstrates novel measurements of in situ ozone (O3) concentrations and thermodynamics sampled on‐board an instrumented Skywalker Unmanned Aerial Vehicle (UAV). Small spatial and temporal gradients were observed over a localized region, which nearby ground‐based in situ measurements lack the ability to resolve. It was found that the UAV‐measured O3 concentrations provided a useful additional indicator of O3 variability at the sub‐urban scale. The ability to sample subtle variability over a localized area highlights the important and novel capabilities of UAVs to rapidly characterize local area micrometeorology and chemistry.
Long-term cost-effectiveness analysis of endovascular versus open repair for abdominal aortic aneurysm based on four randomized clinical trials
Authors: Epstein D , Sculpher M J , Powell J T , Thompson S G , Brown L C , Greenhalgh R M 
Published: March 2014

Abstract

Background
A number of published economic evaluations of elective endovascular aneurysm repair (EVAR) versus open repair for abdominal aortic aneurysm (AAA) have come to differing conclusions about whether EVAR is cost-effective. This paper reviews the current evidence base and presents up-to-date cost-effectiveness analyses in the light of results of four randomized clinical trials: EVAR-1, DREAM, OVER and ACE.

Methods
Markov models were used to estimate lifetime costs from a UK perspective and quality-adjusted life-years (QALYs) based on the results of each of the four trials. The outcomes included in the model were: procedure costs, surveillance costs, reintervention costs, health-related quality of life, aneurysm-related mortality and other-cause mortality. Alternative scenarios about complications, reinterventions and deaths beyond the trial were explored.

Results
Models based on the results of the EVAR-1, DREAM or ACE trials did not find EVAR to be cost-effective at thresholds used in the UK (up to £30 000 per QALY). EVAR seemed cost-effective according to models based on the OVER trial. These results seemed robust to alternative model scenarios about events beyond the trial intervals.

Conclusion
These analyses did not find that EVAR is cost-effective compared with open repair in the long term in trials conducted in European centres. EVAR did appear to be cost-effective based on the OVER trial, conducted in the USA. Caution must be exercised when transferring the results of economic evaluations from one country to another.