bluuebunny/crossref_metadata_2025_split huggingface dataset:
False alarms: How early warning signals falsely predict abrupt sea ice loss
Authors: Wagner Till J. W. , Eisenman Ian 
Published: November 2015

AbstractUncovering universal early warning signals for critical transitions has become a coveted goal in diverse scientific disciplines, ranging from climate science to financial mathematics. There has been a flurry of recent research proposing such signals, with increasing autocorrelation and increasing variance being among the most widely discussed candidates. A number of studies have suggested that increasing autocorrelation alone may suffice to signal an impending transition, although some others have questioned this. Here we consider variance and autocorrelation in the context of sea ice loss in an idealized model of the global climate system. The model features no bifurcation, nor increased rate of retreat, as the ice disappears. Nonetheless, the autocorrelation of summer sea ice area is found to increase in a global warming scenario. The variance, by contrast, decreases. A simple physical mechanism is proposed to explain the occurrence of increasing autocorrelation but not variance when there is no approaching bifurcation. Additionally, a similar mechanism is shown to allow an increase in both indicators with no physically attainable bifurcation. This implies that relying on autocorrelation and variance as early warning signals can raise false alarms in the climate system, warning of “tipping points” that are not actually there.
A paleogeodetic record of variable interseismic rates and megathrust coupling at Simeulue Island, Sumatra
Authors: Tsang Louisa L. H. , Meltzner Aron J. , Hill Emma M. , Freymueller Jeffrey T. , Sieh Kerry 
Published: November 2015

AbstractAn ∼1100 year long paleogeodetic record of land‐height change along the Simeulue section of the Sumatran subduction zone reveals significant variations in vertical motion rates. From an ∼267 year long record, we develop models to explain rate variations in the decades before the 1861, 2004, and 2005 great earthquakes. The record shows that rates accelerated by a factor of 4 to 10 in the decades before the 1861 earthquake; one plausible explanation is a significant increase in the depth of interseismic coupling on the Sunda megathrust under Simeulue. Despite similarity of the 1861 and 2005 coseismic rupture patterns, the pattern of coupling during the decades before the two earthquakes may have been different. Most GPS observations of interseismic deformation at subduction zones span only a decade or two; our results highlight the need to treat GPS‐derived coupling maps as only a snapshot of fault conditions that are temporally variable.
Sudden changes in the amplitude‐frequency distribution of long‐period tremors at Aso volcano, southwest Japan
Authors: Sandanbata Osamu , Obara Kazushige , Maeda Takuto , Takagi Ryota , Satake Kenji 
Published: November 2015

AbstractWe observed the activity of long‐period tremors (LPTs) with a period of ~15 s at Aso volcano, Japan, during a 3 year period including the 2014 eruptions. The number of LPTs detected systematically increased 3 months before the Strombolian eruptions. LPT activity can be divided into five stages based on rapid changes in the maximum LPT amplitude. The amplitude‐frequency relation follows an exponential distribution during each stage before the Strombolian eruptions, with different characteristic amplitudes for each stage, indicating that the scale of the source property changed in stages. However, during a stage that persisted for 6 days after the onset of Strombolian activity, the amplitude‐frequency relation temporarily followed a power law distribution, indicating that the LPT source process no longer had a characteristic scale. In the last stage, the amplitude‐frequency relation returned to an exponential distribution. We therefore conclude that the physical source of volcanic LPTs changed during the eruption period.
Twenty‐five years of continuous borehole tilt and vertical displacement data at Mount Etna: Insights on long‐term volcanic dynamics
Authors: Bonaccorso A. , Bonforte A. , Gambino S. 
Published: November 2015

AbstractWe report a 25 year‐long data set (1990–2014) of combined continuous tilt and GPS vertical displacement series recorded at Etna volcano. To our knowledge, this is the first time that such a data set on an active volcano has been presented. We show the coherence of the two series, which help draw new insights on how the volcano, characterized by frequent flank eruptions, works in the long‐term (tens of years). This data set provides evidence that after the 1992–1993 flank eruption (the biggest in the last three centuries) and the following major recharging phase (1994–2001), all the ensuing eruptions fall within a single long‐term reequilibrium phase (2001–2014).
Oxidation of mercury by bromine in the subtropical Pacific free troposphere
Authors: Gratz L. E. , Ambrose J. L. , Jaffe D. A. , Shah V. , Jaeglé L. , Stutz J. , Festa J. , Spolaor M. , Tsai C. , Selin N. E. , Song S. , Zhou X. , Weinheimer A. J. , Knapp D. J. , Montzka D. D. , Flocke F. M. , Campos T. L. , Apel E. , Hornbrook R. , Blake N. J. , Hall S. , Tyndall G. S. , Reeves M. , Stechman D. , Stell M. 
Published: November 2015

AbstractMercury is a global toxin that can be introduced to ecosystems through atmospheric deposition. Mercury oxidation is thought to occur in the free troposphere by bromine radicals, but direct observational evidence for this process is currently unavailable. During the 2013 Nitrogen, Oxidants, Mercury and Aerosol Distributions, Sources and Sinks campaign, we measured enhanced oxidized mercury and bromine monoxide in a free tropospheric air mass over Texas. We use trace gas measurements, air mass back trajectories, and a chemical box model to confirm the origin and chemical history of the sampled air mass. We find the presence of elevated oxidized mercury to be consistent with oxidation of elemental mercury by bromine atoms in this subsiding upper tropospheric air mass within the subtropical Pacific High, where dry atmospheric conditions are conducive to oxidized mercury accumulation. Our results support the role of bromine as the dominant oxidant of mercury in the upper troposphere.
Dolomite abundance in Chinese loess deposits: A new proxy of monsoon precipitation intensity
Authors: Meng Xianqiang , Liu Lianwen , Balsam William , Li Shilei , He Tong , Chen Jun , Ji Junfeng 
Published: November 2015

AbstractDolomite of detrital origin in carbonate‐rich soil can help indicate the intensity of carbonate dissolution and leaching processes. Using Fourier transform infrared spectroscopy, we generated a high‐resolution record of dolomite and calcite contents from eight sections on the Chinese Loess Plateau spanning the last 130 kyr. Based on the relative abundance of calcite and dolomite, four dissolution phases of carbonate minerals related to summer monsoon (SM) variations are identified as follows: (1) coexistence of dolomite and calcite indicating a very weak SM with a mean annual precipitation (MAP) < 610 mm; (2) calcite without dolomite indicating a weak SM, 610 < MAP < 690 mm; (3) both dolomite and calcite are absent, but there is no downward leaching indicating a strong SM, 690 < MAP < 725 mm; and (4) both dolomite and calcite are absent, and downward leaching of the underlying loess layer suggesting a very strong SM with MAP > 725 mm.
Core solidification and dynamo evolution in a mantle‐stripped planetesimal
Authors: Scheinberg A. , Elkins‐Tanton L. T. , Schubert G. , Bercovici D. 
Published: November 2015

AbstractThe physical processes active during the crystallization of a low‐pressure, low‐gravity planetesimal core are poorly understood but have implications for asteroidal magnetic fields and large‐scale asteroidal structure. We consider a core with only a thin silicate shell, which could be analogous to some M‐type asteroids including Psyche, and use a parameterized thermal model to predict a solidification timeline and the resulting chemical profile upon complete solidification. We then explore the potential strength and longevity of a dynamo in the planetesimal's early history. We find that cumulate inner core solidification would be capable of sustaining a dynamo during solidification, but less power would be available for a dynamo in an inward dendritic solidification scenario. We also model and suggest limits on crystal settling and compaction of a possible cumulate inner core.
Accepting managed aquifer recharge of urban storm water reuse: The role of policy‐related factors
Authors: Mankad Aditi , Walton Andrea 
Published: November 2015

AbstractA between‐groups experimental design examined public acceptance for managed aquifer recharge of storm water for indirect potable and nonpotable reuse; acceptance was based on five policy‐related variables (fairness, effectiveness, trust, importance of safety assurances, and importance of communication activities). Results showed that public acceptance (N = 408) for managed aquifer recharge of storm water was higher for nonpotable applications, as was the importance of safety assurances. Analyses of variance also showed that perceptions of fairness and effectiveness were higher for a nonpotable scheme, but not trust. A three‐step hierarchical regression (Step 1: age, gender, education, and income; Step 2: type of use; Step 3: fairness, effectiveness, trust, safety assurance, and communication activities) demonstrated that type of storm water use and the policy‐related factors accounted for 73% of the variance in acceptance of storm water (R2 = 0.74, adjusted R2 = 0.74, F (10, 397) = 113.919, p < 0.001). Age, type of use, and three of the five policy‐related factors were also significant individual predictors of acceptance. The most important predictors were perceptions of trust in water authorities, perceptions of effectiveness, and perceptions of fairness. Interestingly, while safety assurance was important in attitudinal acceptance of managed aquifer recharge based on type of use, safety assurance was not found to be significant predictor of acceptance. This research suggests that policy‐makers should look to address matters of greater public importance and drive such as fairness, trust, and effectiveness of storm water programs and advocate these at the forefront of their policies, rather than solely on education campaigns.
Expedient Introduction of β‐Methoxyacrylate Unit onto 3‐Substituted Indoles and Application of the Resulting Indole‐Dienes in Organocascade toward Indolino‐Polycyclics
Authors: Guo Beibei , Ge Luo , Huang Guanxin , Zhao Long , Chen Jie , Cao Weiguo , Wu Xiaoyu 
Published: November 2015

AbstractAn efficient methodology for introducing a β‐alkoxy acrylate unit onto the indolic C‐2 position of 3‐substituted indoles has been realized by oxidative radical alkylation of indoles with a xanthate bearing dialkyl acetal functionality and subsequent elimination of alcohol by treatment with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU). The indole‐dienes thus prepared are quite stable and can be stored at room temperature for several months without obvious deterioration. Next, the indole‐dienes were successfully applied in an asymmetric cascade reaction with propargyl aldehyde catalyzed by MacMillan’s imidazolidinone and trichloroacetic acid (TCA), affording tetracyclic spiroindolines or tricyclic hydrocarbazoles in good to excellent yields with excellent ees. The practicality of this cascade was demonstrated by a gram scale preparation of a tetracyclic spiroindoline product with as low as 1 mol% catalyst loading and further elaboration of this spiroindoline compound into valuable intermediates for alkaloid synthesis.magnified image
Rhodium(III)‐Catalyzed Synthesis of Aryl Spirocycles by Aromatic CH Activation/Intramolecular Heck‐Type Reaction
Authors: Chabaud Laurent , Raynal Quentin , Barre Elvina , Guillou Catherine 
Published: November 2015

AbstractThe rhodium(III)‐catalyzed aromatic CH activation/intramolecular Heck‐type reaction has been studied to synthesize spirocyclic compounds, an important class of molecules in medicinal chemistry and natural product synthesis. This approach was efficient with a variety of substituted N‐methoxybenzamides tethered to different cyclic alkenes having a 5‐, 6‐ or 7‐membered ring. This practical method affords sterically hindered o‐substituted aryl spirocycles that are valuable compounds for further functionalization to access relevant building blocks.magnified image
Tuning the Synthetic Routes of Dimethylaminoethyl methacrylate‐Based Superabsorbent Copolymer Hydrogels Containing Sulfonate Groups: Elasticity, Dynamic, and Equilibrium Swelling Properties
Authors: Boyaci Talin , Orakdogen Nermin 
Published: November 2015

ABSTRACTSuperabsorbent copolymer hydrogels based on N,N‐dimethylaminoethyl methacrylate (DMAEMA) and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) were synthesized by free‐radical cross‐linking copolymerization using a bifunctional cross‐linking agent diethylene glycol dimethacrylate (DEGDMA). Poly(DMAEMA‐co‐AMPS) (P(DMAEMA‐co‐AMPS)) hydrogels were prepared at a fixed cross‐linker ratio, but at various ionic comonomer AMPS content between 0 and 50 mol%. The effect of ionic comonomer concentration on the equilibrium swelling, mechanical behavior, and swelling–deswelling kinetics was investigated to find materials with satisfactory swelling and elastic properties. The increase in the ionic comonomer AMPS content increased the equilibrium swelling of copolymer hydrogels. Using the Flory–Rehner theory, the equilibrium swelling behavior of P(DMAEMA‐co‐AMPS) hydrogels was successfully investigated and the effective charge density of the resulting copolymer hydrogels was calculated as an adjustable parameter. Scaling rules were derived for the ionic group content to explain the observed swelling behavior of P(DMAEMA‐co‐AMPS) hydrogels. The kinetics of copolymer hydrogel swelling as well as the mechanism of diffusion was investigated by dynamic swelling measurements at different pH values. The dominant physical mechanism controlling the water uptake of P(DMAEMA‐co‐AMPS) copolymer hydrogels was analyzed, and the diffusion coefficients were determined. The transport was found to be less Fickian for the copolymer hydrogels containing AMPS below 30 mol% at acidic pH values where the polymer networks were ionized.
Activation of specific neuronal networks leads to different seizure onset types
Authors: Shiri Zahra , Manseau Frédéric , Lévesque Maxime , Williams Sylvain , Avoli Massimo 
Published: November 2015

ObjectiveIctal events occurring in temporal lobe epilepsy patients and in experimental models mimicking this neurological disorder can be classified, based on their onset pattern, into low‐voltage, fast versus hypersynchronous onset seizures. It has been suggested that the low‐voltage, fast onset pattern is mainly contributed by interneuronal (γ‐aminobutyric acidergic) signaling, whereas the hypersynchronous onset involves the activation of principal (glutamatergic) cells.MethodsHere, we tested this hypothesis using the optogenetic control of parvalbumin‐positive or somatostatin‐positive interneurons and of calmodulin‐dependent, protein kinase–positive, principal cells in the mouse entorhinal cortex in the in vitro 4‐aminopyridine model of epileptiform synchronization.ResultsWe found that during 4‐aminopyridine application, both spontaneous seizure‐like events and those induced by optogenetic activation of interneurons displayed low‐voltage, fast onset patterns that were associated with a higher occurrence of ripples than of fast ripples. In contrast, seizures induced by the optogenetic activation of principal cells had a hypersynchronous onset pattern with fast ripple rates that were higher than those of ripples.InterpretationOur results firmly establish that under a similar experimental condition (ie, bath application of 4‐aminopyridine), the initiation of low‐voltage, fast and of hypersynchronous onset seizures in the entorhinal cortex depends on the preponderant involvement of interneuronal and principal cell networks, respectively. Ann Neurol 2016 ANN NEUROL 2016;79:354–365
Blocking Deprotonation with Retention of Aromaticity in a Plant ent‐Copalyl Diphosphate Synthase Leads to Product Rearrangement
Authors: Potter Kevin C. , Zi Jiachen , Hong Young J. , Schulte Samuel , Malchow Brandi , Tantillo Dean J. , Peters Reuben J. 
Published: November 2015

AbstractSubstitution of a histidine, comprising part of the catalytic base group in the ent‐copalyl diphosphate synthases found in all seed plants for gibberellin phytohormone metabolism, by a larger aromatic residue leads to rearrangements. Through a series of 1,2‐hydride and methyl shifts of the initially formed bicycle predominant formation of (−)‐kolavenyl diphosphate is observed. Further mutational analysis and quantum chemical calculations provide mechanistic insight into the basis for this profound effect on product outcome.
Cyclodextrin‐immobilized microspheres for uptake of the quorum‐sensing signaling molecule N‐acylhomoserine lactone
Authors: Okano Chigusa , Nasuno Eri , Iimura Ken-ichi , Kato Norihiro 
Published: November 2015

ABSTRACTβ‐Cyclodextrins (CDs) were immobilized on microspheres possessing poly(methacrylic acid) shell layers over polystyrene cores to effectively interact with N‐acylhomoserine lactone (AHL), the main signaling molecule for the bacterial cell‐to‐cell communication system known as quorum sensing (QS). Furthermore, these CD‐immobilized microspheres inhibited the expression of a QS‐dependent gene, pig cluster, in Serratia marcescens AS‐1. The AHL‐mediated production of prodigiosin was suppressed to approximately 30% when the culture was started in the presence of 9.1% (w/w) core/shell microspheres immobilized with β‐CD in a liquid broth, with shaking. This result suggested that the AHL concentration was maintained below the threshold of QS activation because transcription of the target genes would be activated via a stable AHL–receptor complex under high concentrations of AHL. The AHL reporter assay with Chromobacterium violaceum CV026 showed that the AHL concentration in the culture broth distinctly decreased after addition of the microspheres, confirming that uptake by the immobilized β‐CDs was responsible for the observed QS suppression. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43198.
Temperature‐Responsive Chiral (A)6B Supramolecular Cages Based on Conformational Preferences
Authors: Chen Shi‐Gui , Zhao Zhi‐Xiong , Jiang Xiao‐Nan , Wang Lu , Zhou Tian‐You , Lu Cheng‐Lu , Zhao Xin , Jiang Xi‐Kui , Ma Yuguo , Wang Ren‐Xiao , Li Zhan‐Ting 
Published: November 2015

AbstractTwo chiral (A)6B‐typed supramolecular cages were constructed from hydrogen‐bonded C6‐symmetric zinc porphyrin hexamers and chiral C3‐symmetric pyridyl hexadentates with a core of 1,3,5‐triphenylbenzene. Circular dichroism and molecular simulations revealed that the symmetry of the supramolecular cages switched from pseudo‐C3v to C3 with the rotational confinement of the biphenyl backbones at low temperatures, which generated conformationally chiral transfer and amplification. This unique phenomenon suggests a new strategy to develop smart materials with high sensitivity and excellent reversibility.
Advancements in the Synthesis and Applications of Cationic N‐Heterocycles through Transition Metal‐Catalyzed C−H Activation
Authors: Gandeepan Parthasarathy , Cheng Chien‐Hong 
Published: November 2015

AbstractCationic N‐heterocycles are an important class of organic compounds largely present in natural and bioactive molecules. They are widely used as fluorescent dyes for biological studies, as well as in spectroscopic and microscopic methods. These compounds are key intermediates in many natural and pharmaceutical syntheses. They are also a potential candidate for organic light‐emitting diodes (OLEDs). Because of these useful applications, the development of new methods for the synthesis of cationic N‐heterocycles has received a lot of attention. In particular, many C−H activation methodologies that realize high step‐ and atom‐economies toward these compounds have been developed. In this review, recent advancements in the synthesis and applications of cationic N‐heterocycles through C−H activation reactions are summarized. The new C−H activation reactions described in this review are preferred over their classical analogs.
Quality and safety control of tumor‐shrinking decoction (TSD): A Chinese herbal preparation for the treatment of uterine fibroids
Authors: Chen Xiao‐Xin , Lin Wai Ling , Yeung Wing Fai , Song Tian‐He , Lao Li‐Xing , Zhang Yan‐Bo , Meng Wei 
Published: November 2015

AbstractReproducible efficacy assessments of Chinese herbal medicines are largely based on well‐established quality control procedures. This study presents a comprehensive quality control procedure for tumor‐shrinking decoction (TSD), a 15‐herb preparation under study as a potential therapy for uterine fibroids. Morphological, microscopic, and physicochemical authentications were first carried out on individual herbal medicines composing TSD. Contaminant tests on TSD for the presence of heavy metals and pesticide residues were performed by atomic absorption spectrophotometry and gas chromatography–mass spectrometry analysis. Furthermore, batch‐to‐batch quality monitoring of the decoction was investigated via ultra‐performance liquid chromatography (UPLC) and high‐performance liquid chromatography (HPLC). An aqueous extract of the herbal medicines was prepared and formulated into TSD. The tested contaminants were within the maximum permitted levels of the Hong Kong government in proprietary Chinese medicines. UPLC and HPLC fingerprints for quality tracking on TSD were established. The decoction was quantitatively standardized by UPLC and HPLC, respectively, with five and three chemical compounds serving as references. Collectively, the procedure established in this study will not only serve as a fundamental basis for the investigation and development of TSD as a novel therapy for uterine fibroids, but also as a protocol for studying other polycomponent herbal preparations.