bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the contribution of thermal excitation to the total 630.0 nm emissions in the northern cusp ionosphere
Authors: Kwagala Norah Kaggwa , Oksavik Kjellmar , Lorentzen Dag A. , Johnsen Magnar G. 
Published: December 2016

AbstractDirect impact excitation by precipitating electrons is believed to be the main source of 630.0 nm emissions in the cusp ionosphere. However, this paper investigates a different source, 630.0 emissions caused by thermally excited atomic oxygen O(1D) when high electron temperature prevail in the cusp. On 22 January 2012 and 14 January 2013, the European Incoherent Scatter Scientific Association (EISCAT) radar on Svalbard measured electron temperature enhancements exceeding 3000 K near magnetic noon in the cusp ionosphere over Svalbard. The electron temperature enhancements corresponded to electron density enhancements exceeding 1011 m−3 accompanied by intense 630.0 nm emissions in a field of view common to both the EISCAT Svalbard radar and a meridian scanning photometer. This offered an excellent opportunity to investigate the role of thermally excited O(1D) 630.0 nm emissions in the cusp ionosphere. The thermal component was derived from the EISCAT Radar measurements and compared with optical data. For both events the calculated thermal component had a correlation coefficient greater than 0.8 to the total observed 630.0 nm intensity which contains both thermal and particle impact components. Despite fairly constant solar wind, the calculated thermal component intensity fluctuated possibly due to dayside transients in the aurora.
The plasmapause formation seen from meridian perspective by KAGUYA
Authors: Murakami Go , Yoshioka Kazuo , Yamazaki Atsushi , Nishimura Yukitoshi , Yoshikawa Ichiro , Fujimoto Masaki 
Published: December 2016

AbstractObservations by the extreme ultraviolet (EUV) imager on board the IMAGE spacecraft revealed that the formation of a sharp plasmapause occurs in the postmidnight sector soon (<1 h) after the convection enhancement. These results cannot be explained simply by the conventional theory of the plasmapause formation that the plasmapause coincides with the last closed equipotential of the convection electric field superposed on the Earth's corotation electric field. However, due to the limitation that the EUV imager provides information on only the azimuthal distribution of the plasmapause, the formation mechanism still remains an open issue. Now global images of the plasmasphere from meridian perspective become available, thanks to the telescope of extreme ultraviolet (TEX) instrument on board the KAGUYA spacecraft. Here we studied the plasmapause formation mechanism by analyzing the sequential TEX images of an erosion event during the geomagnetic disturbance (Kp = 5) on 1–2 May 2008. The temporal evolution of the plasmapause locations at postmidnight observed by TEX agreed with those predicted by the dynamic simulations based on the interchange mechanism. Furthermore, the He+ column density in the nightside plasmasphere decreased by ~30% only at the low latitudes (<20°) during the enhanced convection period. This suggests that the plasmapause formation occurs first near the equatorial region during a geomagnetic disturbance, and it agrees with the plasmapause formation mechanism based on the interchange instability. Although we cannot conclude exclusively for the interchange mechanism, this is the first study to present the plasmapause formation viewed from the meridian perspective.
Pulsations of the polar cusp aurora at Saturn
Authors: Palmaerts B. , Radioti A. , Roussos E. , Grodent D. , Gérard J.‐C. , Krupp N. , Mitchell D. G. 
Published: December 2016

AbstractThe magnetospheric cusp is a region connecting the interplanetary environment to the ionosphere and enabling solar wind particles to reach the ionosphere. We report the detection of several isolated high‐latitude auroral emissions with the Ultraviolet Imaging Spectrograph of the Cassini spacecraft. We suggest that these auroral spots, located in the dawn‐to‐noon sector and poleward of the main emission, are the ionospheric signatures of the magnetospheric cusp, in agreement with some previous observations with the Hubble Space Telescope. The high‐latitude cusp auroral signature has been associated with high‐latitude lobe reconnection in the presence of a southward interplanetary magnetic field. The occurrence rate of the polar cusp aurora suggests that lobe reconnection is frequent at Saturn. Several auroral imaging sequences reveal a quasiperiodic brightening of the polar cusp aurora with a period in the range of 60 to 70 min. Similar pulsations in the energetic electron fluxes and in the azimuthal component of the magnetic field are simultaneously observed by Cassini instruments, suggesting the presence of field‐aligned currents. Pulsed dayside magnetopause reconnection is a likely common triggering process for the cusp auroral brightenings at Saturn and the quasiperiodic pulsations in the high‐latitude energetic electron fluxes.
Evidence for a transient hydromechanical and frictional faulting response during the 2011 Mw 5.6 Prague, Oklahoma earthquake sequence
Authors: Norbeck J. H. , Horne R. N. 
Published: December 2016

AbstractMechanisms for the delayed triggering between the Mw 4.8 foreshock and Mw 5.6 main shock of the 2011 earthquake sequence near Prague, Oklahoma, USA, were investigated using a coupled fluid flow and fault mechanics numerical model. Because the stress orientations, stress magnitudes, fault geometry, and earthquake source mechanisms at the Prague site have been well characterized by previous studies, this particular earthquake sequence offered an opportunity to explore the range of physical processes and in situ fault properties that might be consistent with the 20 h delayed triggering effect observed at the site. Our numerical experiments suggest that an initial undrained response resulting from elastic stress transfer from the foreshock followed by transient fluid flow along the fault may have contributed to the earthquake nucleation process. The results of the numerical experiments were used to constrain fault compliance and fault transmissivity for the fault that hosted the Mw 5.6 event. Relatively compliant behavior in response to changes in normal stress, corresponding to Skempton pore pressure coefficients near 1, was consistent with the field observations. Fault transmissivity was estimated to range from 10−18 to 10−15 m3. This study has implications for understanding hydraulic properties, frictional properties, and faulting behavior of basement faults in Oklahoma that are large enough to host damaging earthquakes.
Bipolar lightning flashes observed at the Säntis Tower: Do we need to modify the traditional classification?
Authors: Azadifar Mohammad , Rachidi Farhad , Rubinstein Marcos , Rakov Vladimir A. , Paolone Mario , Pavanello Davide 
Published: December 2016

AbstractWe present and discuss current waveforms associated with 13 bipolar lightning flashes recorded at the Säntis Tower during the period from June 2010 to January 2015. During this period, a total of 427 flashes were recorded, of which 13 (3%) were classified as bipolar flashes. The majority of the recorded flashes (10 out of 13) exhibited a polarity reversal during the initial continuous current, therefore belonging to Category I according to the classification proposed by Rakov (2003). Of the three remaining flashes, two were characterized by different polarities of the initial stage current and the following return stroke or strokes (Category II), and one flash involved return strokes of opposite polarity within the same flash (Category III). In Category I bipolar flashes, the polarity reversal is usually assumed to be associated with in‐cloud processes. However, two of our 10 Category I flashes appeared to be each a sequence of two upward discharges of opposite polarity, initiated from the tower within tens of milliseconds of each other. This is the first time that such a sequence has been observed from the same tower. We suggest that the traditional classification of bipolar flashes should be modified to distinguish between two types of Category I flashes: those in which the polarity reversal during the initial stage is associated with in‐cloud processes (Category Ia) and those in which the polarity reversal is due to initiation of two opposite‐polarity leaders from the tower (Category Ib).
Atmospheric moisture budget and its regulation on the variability of summer precipitation over the Tibetan Plateau
Authors: Wang Ziqian , Duan Anmin , Yang Song , Ullah Kalim 
Published: December 2016

AbstractBased on station observations and reanalysis data sets, the atmospheric moisture budget and its critical role in regulating the variability of summer precipitation over the Tibetan Plateau (TP) are investigated. Results indicate that the yearly variability of summer precipitation over the southern TP (STP) is mainly controlled by remote moisture transport. Local surface evaporation presents an infinitesimal interannual fluctuation, but it cannot be ignored since it is a large component of total precipitation amount in every summer. Although the incoming moisture transport at the western boundary of STP is much weaker than that at the southern boundary, it primarily influences the temporal variation of STP summer precipitation. Further analysis shows that the summer North Atlantic Oscillation (NAO) also possesses a significant impact on the variation of STP summer precipitation. A strong NAO apparently weakens the moisture transport at the western boundary, inducing less precipitation over the STP. When the NAO is strong, wave‐activity flux obviously diverges eastward from the subtropical high over northwestern Europe. Then such flux converges toward the western TP, which weakens the baroclinic vertical structure of atmospheric circulation over the TP. The NAO also influences the meridional position of the Asian jet stream and modulates the specific humidity and moisture transport at the western boundary of STP. In addition, the dynamic processes of the atmosphere are more important than the thermodynamic processes in regulating the variability of TP summer precipitation.
A stationary phase solution for mountain waves with application to mesospheric mountain waves generated by Auckland Island
Authors: Broutman Dave , Eckermann Stephen D. , Knight Harold , Ma Jun 
Published: December 2016

AbstractA relatively general stationary phase solution is derived for mountain waves from localized topography. It applies to hydrostatic, nonhydrostatic, or anelastic dispersion relations, to arbitrary localized topography, and to arbitrary smooth vertically varying background temperature and vector wind profiles. A simple method is introduced to compute the ray Jacobian that quantifies the effects of horizontal geometrical spreading in the stationary phase solution. The stationary phase solution is applied to mesospheric mountain waves generated by Auckland Island during the Deep Propagating Gravity Wave Experiment. The results are compared to a Fourier solution. The emphasis is on interpretations involving horizontal geometrical spreading. The results show larger horizontal geometrical spreading for nonhydrostatic waves than for hydrostatic waves in the region directly above the island; the dominant effect of horizontal geometrical spreading in the lower ∼30 km of the atmosphere, compared to the effects of refraction and background density variation; and the enhanced geometrical spreading due to directional wind in the approach to a critical layer in the mesosphere.
Regional pollution and its formation mechanism over North China Plain: A case study with ceilometer observations and model simulations
Authors: Zhu Xiaowan , Tang Guiqian , Hu Bo , Wang Lili , Xin Jinyuan , Zhang Junke , Liu Zirui , Münkel Christoph , Wang Yuesi 
Published: December 2016

AbstractTo investigate regional haze formation, ceilometer observations at the Beijing (BJ), Shijiazhuang (SJZ), Tianjin (TJ), and Qinhuangdao (QHD) stations were conducted from 12 October to 10 November 2014, to obtain the boundary layer height (BLH) and the attenuated backscattering coefficients (ABC). Particles at the four stations were highly correlated, whereas precursors of particles exhibited weaker correlations. By analyzing the typical haze episode between 21 and 26 October 2014, we found that warm advection at a height of 850 hPa from the Loess Plateau caused a gradual decline in the regional BLH. Moreover, water vapor transported from the southern NCP caused the column water vapor amount to increase from 0.015 kg m−2 to 0.042 kg m−2 in the boundary layer in BJ. As southerly transport prevailed during the transition period, ABC profiles in the BJ, TJ, and QHD stations showed a bilayer pattern, and the second layer was between 500 and 1000 m. As a result, the ABC integrations of BJ and TJ increased by 74.2 and 139.7%, respectively. During the polluted period, due to the weakened transport effect, the ABC integrations of the four stations decreased by 7.9, 18.2, 16.2, and 28.2%, respectively. Contributions of the secondary inorganic species (sulfate, nitrate, and ammonium) at BJ increased from 37.3% to 56.9%, and the mean particle size increased from 107.8 nm to 140.8 nm. Emissions in southern NCP should be mitigated during the transition period, whereas the inorganic precursors are the most important air pollutants during the polluted period.
Iridium‐Catalyzed Asymmetric Hydrogenation of Tosylamido‐Substituted Pyrazines for Constructing Chiral Tetrahydropyrazines with an Amidine Skelton
Authors: Higashida Kosuke , Nagae Haruki , Mashima Kazushi 
Published: December 2016

AbstractDinuclear triply chloro‐bridged iridium(III) complexes bearing chiral diphosphine ligands catalyze the asymmetric hydrogenation of tosylamido‐substituted pyrazines to give the corresponding chiral tetrahydropyrazines with an amidine skeleton in high yield and with high enantioselectivity. Addition of N,N‐dimethylanilinium bromide enhanced the catalytic activity of the iridium complexes and also increased the enantioselectivity of the products by trapping the hydrogenated amine products with HBr from N,N‐dimethylanilinium bromide. The amidine skeleton of the products could be transformed to give chiral piperazinones and piperazines without loss of enantioselectivity.magnified image
Oberflächenfacettierung und Rekonstruktion von Ceroxid‐ Nanopartikeln
Authors: Yang Chengwu , Yu Xiaojuan , Heißler Stefan , Nefedov Alexei , Colussi Sara , Llorca Jordi , Trovarelli Alessandro , Wang Yuemin , Wöll Christof 
Published: December 2016

AbstractDie Anordnung der Atome an Metalloxid‐Oberflächen bestimmt deren physikalische und chemische Eigenschaften. Sie ist für viele Anwendungen von entscheidender Bedeutung, vor allem bei der heterogenen Katalyse und der Photokatalyse. Während für die Bestimmung von Oberflächenstrukturen von makroskopischen Einkristallen etablierte Methoden zur Verfügung stehen, stellen derartige Analysen für Nanopartikel (NP) eine große Herausforderung dar. In unserer wird CO als Sondenmolekül zur Bestimmung der Struktur von Oberflächen stabförmiger Ceroxid‐NP eingesetzt. Nach Kalibrierung der CO‐Streckschwingungsfrequenzen anhand von Ergebnissen für verschiedene Ceroxid‐Einkristalloberflächen kommen wir zu dem Schluss, dass die stabförmigen NP entgegen der Erwartung (111)‐facettierte Oberflächen aufweisen. Dieser Befund hat wichtige Folgen für das Verständnis der komplexen Oberflächenchemie dieser katalytisch besonders aktiven Ceroxid‐NP und liefert die Basis für ein rationales Design von Katalysatormaterialien im Nanomaßstab.
Synthesis of Discrete Oligomers by Sequential PET‐RAFT Single‐Unit Monomer Insertion
Authors: Xu Jiangtao , Fu Changkui , Shanmugam Sivaprakash , Hawker Craig J. , Moad Graeme , Boyer Cyrille 
Published: December 2016

AbstractUniform synthetic polymers with precisely defined molar mass and monomer sequence (primary structure) have many potential high‐value applications. However, a robust and versatile synthetic strategy for these materials remains one of the great challenges in polymer synthesis. Herein we describe proof‐of‐principle experiments for a modular strategy to produce discrete oligomers by a visible‐light‐mediated radical chain process. We utilize the high selectivity provided by photo‐induced electron/energy transfer (PET) activation to develop efficient single unit monomer insertion (SUMI) into reversible addition–fragmentation chain‐transfer (RAFT) agents. A variety of discrete oligomers (single unit species, dimers, and, for the first time, trimers) have been synthesized by sequential SUMI in very high yield under mild reaction conditions. The trimers were used as building blocks for the construction of uniform hexamers and graft copolymers with precisely defined branches.
Surface Faceting and Reconstruction of Ceria Nanoparticles
Authors: Yang Chengwu , Yu Xiaojuan , Heißler Stefan , Nefedov Alexei , Colussi Sara , Llorca Jordi , Trovarelli Alessandro , Wang Yuemin , Wöll Christof 
Published: December 2016

AbstractThe surface atomic arrangement of metal oxides determines their physical and chemical properties, and the ability to control and optimize structural parameters is of crucial importance for many applications, in particular in heterogeneous catalysis and photocatalysis. Whereas the structures of macroscopic single crystals can be determined with established methods, for nanoparticles (NPs), this is a challenging task. Herein, we describe the use of CO as a probe molecule to determine the structure of the surfaces exposed by rod‐shaped ceria NPs. After calibrating the CO stretching frequencies using results obtained for different ceria single‐crystal surfaces, we found that the rod‐shaped NPs actually restructure and expose {111} nanofacets. This finding has important consequences for understanding the controversial surface chemistry of these catalytically highly active ceria NPs and paves the way for the predictive, rational design of catalytic materials at the nanoscale.
Consensus of Delayed Multi‐agent Systems via Intermittent Impulsive Control
Authors: Yang Shasha , Liao Xiaofeng , Liu Yanbing , Chen Xin , Ge Dingling 
Published: December 2016

AbstractA novel intermittent impulsive scheme is presented to realize consensus of multi‐agent systems with time‐varying delay in this paper because intermittent impulsive control may break through the limitation of upper bound of impulsive intervals in general impulsive control in our consensus scheme. Instead of activating all the time, we introduce the intermittent impulsive control approach into the delayed multi‐agent systems where the impulsive controller is only functioned in the control windows. Based on the algebraic graph theory, the Lyapunov stability theory, and Halanay inequality matrix theory, some adequate conditions are proposed to guarantee the consensus of delayed multi‐agent systems via pinning intermittent impulsive control. Simulation results are provided ultimately to verify the validity of the proposed control mechanism.
Loop‐Shaping Feedback and Feedforward Control for Networked Systems With Saturation and Delay
Authors: Wigren Torbjörn 
Published: December 2016

AbstractThe paper proposes a new robust networked controller, for example suitable for packet data transfer control in wireless sensor networks with uncertain delays. The method adjusts a linear H2 loop‐shaping design towards consistency with a long delay and a saturation in the feedback loop, where the saturation results because of the one‐directional packet flow. Feedforward from a measurable disturbance is integrated in the design. By formally extending recently derived sensitivity function constraints to include feedforward, a subset of the
stability region is pre‐computed using the stability inequality of the Popov criterion. A robustly stable controller is then selected in the stability region. The new controller design method is applied to internet data flow control supporting 5G wireless connectivity. The results indicate a possible enhancement of the robustness against feedback delay uncertainty with a factor of 3‐4. Such robustness should be beneficial for example for packet data relying with variable routing over ad hoc wireless sensor networks.
Inhibition of glucuronidation and oxidative metabolism of buprenorphine using GRAS compounds or dietary constituents/supplements: in vitro proof of concept
Authors: Maharao Neha V. , Joshi Anand A. , Gerk Phillip M. 
Published: December 2016

AbstractThe present study investigated the potential of generally recognized as safe (GRAS) compounds or dietary substances to inhibit the presystemic metabolism of buprenorphine and to increase its oral bioavailability. Using IVIVE, buprenorphine extraction ratios in intestine and liver were predicted as 96% and 71%, respectively. In addition, the relative fraction of buprenorphine metabolized by oxidation and glucuronidation in these two organs was estimated using pooled human intestinal and liver microsomes. In both organs, oxidation appeared to be the major metabolic pathway with a 6 and 4 fold higher intrinsic clearance than glucuronidation in intestine and liver, respectively. The oral bioavailability of buprenorphine was predicted to be 1.16%. Inhibition of 75% and 50% of intestinal and hepatic presystemic metabolism would result in an Foral of 49%, which is comparable to the bioavailability of sublingual buprenorphine. In human liver microsomes, chrysin, curcumin, ginger extract, hesperitin, magnolol, quercetin and silybin inhibited ≥50% glucuronidation, whereas chrysin, curcumin, ginger extract, 6‐gingerol, pterostilbene, resveratrol and silybin exhibited ≥30% inhibition of oxidation. In human intestinal microsomes, curcumin, ginger extract, α‐mangostin, quercetin and silybin inhibited ≥50% glucuronidation while chrysin, ginger extract, α‐mangostin, pterostilbene and resveratrol exhibited ≥30% inhibition of oxidation. These results demonstrate the feasibility of our proposed approach of using GRAS or dietary compounds to inhibit the presystemic metabolism of buprenorphine and thus improve its oral bioavailability. An oral buprenorphine formulation containing these inhibitors or their combinations has promising potential to replace sublingual buprenorphine. Copyright © 2016 John Wiley & Sons, Ltd.
An HPLC‐UV method for determining plasma dimethylacetamide concentrations in patients receiving intravenous busulfan
Authors: Cendana Mildred , Lee Samiuela , Upadhyay Parth J. , Byrne Jennifer A. , Shaw Peter J. , Earl John , Nath Christa E. 
Published: December 2016

AbstractDimethylacetamide (DMA) is a solvent used in the preparation of intravenous busulfan, an alkylating agent used in blood or marrow transplantation. DMA may contribute to hepatic toxicity, so it is important to monitor its clearance. The aim of this study was to develop an HPLC‐UV assay for measurement of DMA in human plasma. After precipitation of plasma proteins with acetonitrile followed by dilution (1:4) with water, the extract was injected onto the HPLC and detected at 195 nm. Separation was performed using a Cogent‐HPS 5 μm C18 column (250 × 4.6 mm) preceded by a Brownlee 7 μm RP18, pre‐column (1.5 cm × 3.2 mm). The mobile phase was 25 mm sodium phosphate buffer (pH 3), containing 2.5% (v/v) acetonitrile and 0.0005% (v/v) sodium‐octyl‐sulfonate. Using a flow rate of 1 mL/min, the retention times of DMA and the internal standard (IS), 2‐chloroacetamide, were 9.5 and 3.5 min, respectively. Peak area ratio (DMA:IS) was a linear function of concentration from 1 to 1000 μg/mL. There was excellent intraday precision (<5% for 5–700 μg/mL DMA), accuracy (<3% deviation from the true concentration) and recovery (74–98%). The limits of detection and quantification were 1 and 5 μg/mL, respectively. In eight children who received intravenous busulfan, DMA concentrations ranged from 110 to 438 μg/mL.