bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grounding line variability and subglacial lake drainage on Pine Island Glacier, Antarctica
Authors: Joughin Ian , Shean David E. , Smith Ben E. , Dutrieux P. 
Published: August 2016

AbstractWe produced a 6 year time series of differential tidal displacement for Pine Island Ice Shelf, Antarctica, using speckle‐tracking methods applied to fine‐resolution TerraSAR‐X data. These results reveal that the main grounding line has maintained a relatively steady position over the last 6 years, following the speedup that terminated in ~2009. In the middle of the shelf, there are grounded spots that migrate downstream over the 6 year record. Examination of high‐resolution digital elevation models reveals that these grounded spots form where deep keels (thickness anomalies) advect over an approximately flow‐parallel bathymetric high, maintaining intermittent contact with the bed. These data sets also reveal several subsidence and uplift events associated with subglacial lake drainages in the fast‐flowing region above the grounding line. Although these drainages approximately double the rate of subglacial water flow over periods of a few weeks, they have no discernible effect on horizontal flow speed.
Wind‐driven mixing at intermediate depths in an ice‐free Arctic Ocean
Authors: Lincoln Ben J. , Rippeth Tom P. , Lenn Yueng‐Djern , Timmermans Mary Louise , Williams William J. , Bacon Sheldon 
Published: August 2016

AbstractRecent seasonal Arctic Ocean sea ice retreat is a major indicator of polar climate change. The Arctic Ocean is generally quiescent with the interior basins characterized by low levels of turbulent mixing at intermediate depths. In contrast, under conditions of reduced sea ice cover, there is evidence of energetic internal waves that have been attributed to increased momentum transfer from the atmosphere to the ocean. New measurements made in the Canada Basin during the unusually ice‐free and stormy summer of 2012 show previously observed enhancement of internal wave energy associated with ice‐free conditions. However, there is no enhancement of mixing at intermediate depths away from significant topography. This implies that contrary to expectations of increased wind‐induced mixing under declining Arctic sea ice cover, the stratification in the central Canada Basin continues to suppress turbulent mixing at intermediate depths and to effectively isolate the large Atlantic and Pacific heat reservoirs from the sea surface.
A numerical study of nighttime ionospheric variations in the American sector during 28–29 October 2003
Authors: Chen Xuetao , Lei Jiuhou , Wang Wenbin , Burns Alan G. , Luan Xiaoli , Dou Xiankang 
Published: August 2016

AbstractVariations of nighttime F2 peak height (hmF2) over the American sector during the 28–29 October 2003 storm period were investigated using the National Center for Atmospheric Research Thermosphere‐Ionosphere Electrodynamics Global Circulation Model. The model was generally able to reproduce the ionospheric variations on 28–29 October 2003 observed by the ionosondes. A series of controlled model simulations were subsequently undertaken to examine the effects of electric fields and neutral winds on the ionosphere. The numerical experiments suggest that the dramatic nighttime increase of hmF2 on the storm day 29 October is mainly caused by traveling atmospheric disturbances (TADs) from the high latitudes of the Northern Hemisphere. However, the electric field plays an important role in causing the elevation of hmF2 in the equatorial region. The prompt penetration electric field (PPEF) associated with the southward component of the interplanetary magnetic field (Bz) is westward on the nightside, whereas when Bz reverses and becomes northward, the PPEF is westward in the premidnight and turns to eastward in the postmidnight. These PPEFs greatly affect the low‐latitude ionosphere during storm time. On 28 October, even though the Bz disturbance was weak with a short duration of southward Bz, the TADs from the Southern Hemisphere can propagate to the Northern Hemisphere and result in the corresponding oscillations in the nightside hmF2.
Constraints on residual topography and crustal properties in the western United States from virtual deep seismic sounding
Authors: Yu Chunquan , Chen Wang‐Ping , van der Hilst Robert D. 
Published: August 2016

AbstractWe use virtual deep seismic sounding (VDSS) and data from ~1000 broadband seismic stations to provide high‐resolution estimates of crustal structure in the western Cordillera of the United States (U.S.). The most robust result is the geographic distribution of residual topography (that is, the difference between observed elevation and that expected from crustal buoyancy alone) and, by implication, thermal or petrologic anomalies in the mantle. Overall, residual topography of the western U.S. Cordillera varies considerably; with contrasts of up to about 3 km across distances of 200 km or less. High residual topography, indicating large mantle effects, is evident along the periphery of the Colorado Plateau and the surroundings of the Great Basin. In contrast, the central Colorado Plateau and the Wyoming Basin show low residual topography, close to what is expected of a geologically stable lithosphere. Overall, in regions to the east of the Wasatch hinge line (the eastern limit of significant extension in the North American cratonic basement) patterns of high residual topography and anomalies of low seismic wave speeds in the upper mantle are similar, suggestive of a common, thermal origin. In contrast, such a similarity is absent in regions to the west of the hinge line, suggesting substantial effects of petrological heterogeneities in the mantle. Finally, joint analyses of VDSS and conventional receiver functions reveal a wide range of crustal P wave speeds, locally as high as 6.7 km/s, perhaps indicating magmatic modification of the crust.
Climate‐driven thresholds for chemical weathering in postglacial soils of New Zealand
Authors: Dixon Jean L. , Chadwick Oliver A. , Vitousek Peter M. 
Published: August 2016

AbstractChemical weathering in soils dissolves and alters minerals, mobilizes metals, liberates nutrients to terrestrial and aquatic ecosystems, and may modulate Earth's climate over geologic time scales. Climate‐weathering relationships are often considered fundamental controls on the evolution of Earth's surface and biogeochemical cycles. However, surprisingly little consensus has emerged on if and how climate controls chemical weathering, and models and data from published literature often give contrasting correlations and predictions for how weathering rates and climate variables such as temperature or moisture are related. Here we combine insights gained from the different approaches, methods, and theory of the soil science, biogeochemistry, and geomorphology communities to tackle the fundamental question of how rainfall influences soil chemical properties. We explore climate‐driven variations in weathering and soil development in young, postglacial soils of New Zealand, measuring soil elemental geochemistry along a large precipitation gradient (400–4700 mm/yr) across the Waitaki basin on Te Waipounamu, the South Island. Our data show a strong climate imprint on chemical weathering in these young soils. This climate control is evidenced by rapid nonlinear changes along the gradient in total and exchangeable cations in soils and in the increased movement and redistribution of metals with rainfall. The nonlinear behavior provides insight into why climate‐weathering relationships may be elusive in some landscapes. These weathering thresholds also have significant implications for how climate may influence landscape evolution and the release of rock‐derived nutrients to ecosystems, as landscapes that transition to wetter climates across this threshold may weather and deplete rapidly.
Impacts of three‐dimensional nonuniform flow on quantification of groundwater‐surface water interactions using heat as a tracer
Authors: Reeves Jonathan , Hatch Christine E. 
Published: August 2016

AbstractUse of heat‐as‐a‐tracer is a common method to quantify surface water‐groundwater interactions (SW‐GW). However, the method relies on assumptions likely violated in natural systems. Numerical studies have explored violation of fundamental assumptions such as heterogeneous streambed properties, two‐dimensional groundwater flow fields and uncertainty in thermal parameters for the 1‐D heat‐as‐a‐tracer method. Few studies to date have modeled complex, fully three‐dimensional groundwater flows to address the impacts of nonuniform, 3‐D flow vectors on use of heat‐as‐a‐tracer to quantify SW‐GW interactions. COMSOL Multiphysics was used to model scenarios in a fully three‐dimensional flow field in homogeneous, isotropic sand with a sinusoidal temperature upper boundary where vertical flows are deliberately disrupted by large and varied horizontal flows from two directions. Resulting temperature time series from multiple depths were used to estimate vertical Darcy flux and compared with modeled fluxes to assess the performance of the 1‐D thermal methods to quantify multidimensional groundwater flows. In addition, apparent effective thermal diffusivity was calculated from synthetic temperature time series and compared to model input diffusivity. Both increasingly nonuniform and nonvertical groundwater flow fields resulted in increasing errors for both the temperature‐derived flux and temperature‐derived effective thermal diffusivity. For losing (downward) flow geometries, errors in temperature‐derived effective thermal diffusivity were highly correlated with errors in temperature‐derived flux and were used to identify how and when underlying assumptions necessary to use heat‐as‐a‐tracer for quantifying groundwater flows were violated. Specifically, nonuniform flow fields (with flow lines that converge or diverge) produced the largest errors in simulated fluxes.
Academic Consequences of Multiple Victimization and the Role of School Security Measures
Authors: Gardella Joseph H. , Tanner‐Smith Emily E. , Fisher Benjamin W. 
Published: August 2016

AbstractAdolescents who experience multiple victimization (i.e., victimization on a regular basis) are at greater risk for having negative academic outcomes including lower achievement and poorer attendance than those who do not experience such victimization. Yet, the role of school contexts in this relationship remains unclear. Nevertheless, school‐based efforts to reduce victimization often focus on altering contexts without sufficient evidence of associations with improved student outcomes. School security measures constitute one such suite of contextual interventions aimed at reducing victimization. This study tested a moderated mediation model in which the relationship between multiple victimization and academic performance is mediated by absenteeism, and the relationship between multiple victimization and absenteeism is moderated by the presence of school security measures. Participants were 5930 (49.6% female and 79.51% White) 12‐ to 18‐year‐old adolescents from a national sample collected through the 2011 School Crime Supplement to the National Crime Victimization Survey. Results of path analysis models indicated that the relationship between multiple victimization and academic performance was partially mediated by absenteeism, and that both metal detectors and security guards moderated the relationship between multiple victimization and absenteeism. Additional analyses revealed the utility of considering subpopulations of victims characterized by specific facets of their contexts. Implications for practitioners and researchers are discussed.
ATXN2‐AS, a gene antisense to ATXN2, is associated with spinocerebellar ataxia type 2 and amyotrophic lateral sclerosis
Authors: Li Pan P. , Sun Xin , Xia Guangbin , Arbez Nicolas , Paul Sharan , Zhu Shanshan , Peng H. Benjamin , Ross Christopher A. , Koeppen Arnulf H. , Margolis Russell L. , Pulst Stefan M. , Ashizawa Tetsuo , Rudnicki Dobrila D. 
Published: August 2016

ObjectiveSpinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disease caused by a CAG repeat expansion in the gene ataxin‐2 (ATXN2). ATXN2 intermediate‐length CAG expansions were identified as a risk factor for amyotrophic lateral sclerosis (ALS). The ATXN2 CAG repeat is translated into polyglutamine, and SCA2 pathogenesis has been thought to derive from ATXN2 protein containing an expanded polyglutamine tract. However, recent evidence of bidirectional transcription at multiple CAG/CTG disease loci has led us to test whether additional mechanisms of pathogenesis may contribute to SCA2.MethodsIn this work, using human postmortem tissue, various cell models, and animal models, we provide the first evidence that an antisense transcript at the SCA2 locus contributes to SCA2 pathogenesis.ResultsWe demonstrate the expression of a transcript, containing the repeat as a CUG tract, derived from a gene (ATXN2‐AS) directly antisense to ATXN2. ATXN2‐AS transcripts with normal and expanded CUG repeats are expressed in human postmortem SCA2 brains, human SCA2 fibroblasts, induced SCA2 pluripotent stem cells, SCA2 neural stem cells, and lymphoblastoid lines containing an expanded ATXN2 allele associated with ALS. ATXN2‐AS transcripts with a CUG repeat expansion are toxic in an SCA2 cell model and form RNA foci in SCA2 cerebellar Purkinje cells. Finally, we detected missplicing of amyloid beta precursor protein and N‐methyl‐D‐aspartate receptor 1 in SCA2 brains, consistent with findings in other diseases characterized by RNA‐mediated pathogenesis.InterpretationThese results suggest that ATXN2‐AS has a role in SCA2 and possibly ALS pathogenesis, and may therefore provide a novel therapeutic target for these diseases. Ann Neurol 2016;80:600–615
Organische Reaktionen in Mikrotröpfchen: Analyse von Reaktionsbeschleunigungen durch Massenspektrometrie
Authors: Yan Xin , Bain Ryan M. , Cooks R. Graham 
Published: August 2016

AbstractDie bemerkenswerte Entdeckung, dass eine Reaktionsbeschleunigung in Lösungen mit begrenztem Volumen erfolgt, wirft ein augenscheinliches Rätsel auf. Durch Spray‐Ionisation gebildete Mikrotröpfchen können genutzt werden, um den Verlauf von Reaktionen in der Bulkphase zu verfolgen und außerdem Reaktionen zwischen den Reagentien in solch einer Reaktion zu beschleunigen. In diesem Kurzaufsatz werden Beschleunigungsphänomene in Tröpfchen und dünnen Filmen vorgestellt und moderne Methoden, die zur Untersuchung beschleunigter Reaktionen in Lösungen mit begrenztem Volumen und großer Oberfläche angewendet werden, zusammengefasst. Bedingungen, die entweder eine einfache Verfolgung oder eine Beschleunigung bestimmen, werden beim Auftreten von diskontinuierlicher und vollständiger Desolvatisierung als Endpunkt der Tropfenentwicklung abgestimmt. Die gegensätzlichen Merkmale von Reaktionen in Mikrotröpfchen und in Bulklösung werden in Verbindung mit möglichen Mechanismen, nach denen eine Reaktionsbeschleunigung in Mikrotröpfchen erfolgt, beschrieben. Derzeitige Anwendungen von Tröpfchen als Mikroreaktoren werden im Hinblick auf eine Reaktionsbeschleunigung in begrenzten Volumina und ein mögliches zukünftiges Scale‐up angeführt.
A Chemical Probe for the ATAD2 Bromodomain
Authors: Bamborough Paul , Chung Chun‐wa , Demont Emmanuel H. , Furze Rebecca C. , Bannister Andrew J. , Che Ka Hing , Diallo Hawa , Douault Clement , Grandi Paola , Kouzarides Tony , Michon Anne‐Marie , Mitchell Darren J. , Prinjha Rab K. , Rau Christina , Robson Samuel , Sheppard Robert J. , Upton Richard , Watson Robert J. 
Published: August 2016

AbstractATAD2 is a cancer‐associated protein whose bromodomain has been described as among the least druggable of that target class. Starting from a potent lead, permeability and selectivity were improved through a dual approach: 1) using CF2 as a sulfone bio‐isostere to exploit the unique properties of fluorine, and 2) using 1,3‐interactions to control the conformation of a piperidine ring. This resulted in the first reported low‐nanomolar, selective and cell permeable chemical probe for ATAD2.
A Microkinetic Model of Calcite Step Growth
Authors: Andersson M. P. , Dobberschütz S. , Sand K. K. , Tobler D. J. , De Yoreo J. J. , Stipp S. L. S. 
Published: August 2016

AbstractIn spite of decades of research, mineral growth models based on ion attachment and detachment rates fail to predict behavior beyond a narrow range of conditions. Here we present a microkinetic model that accurately reproduces calcite growth over a very wide range of published experimental data for solution composition, saturation index, pH and impurities. We demonstrate that polynuclear complexes play a central role in mineral growth at high supersaturation and that a classical complexation model is sufficient to reproduce measured rates. Dehydration of the attaching species, not the mineral surface, is rate limiting. Density functional theory supports our conclusions. The model provides new insights into the molecular mechanisms of mineral growth that control biomineralization, mineral scaling and industrial material synthesis.
Synthesis of Strophasterol A Guided by a Proposed Biosynthesis and Innate Reactivity
Authors: Heinze Robert C. , Lentz Dieter , Heretsch Philipp 
Published: August 2016

AbstractThe synthesis of strophasterol A, a moderator of endoplasmatic reticulum (ER) stress in Alzheimer's disease, and the first member of a structurally unprecedented class of secosterols, was achieved through the implementation of a key step of its proposed biosynthesis and two C−H oxidations. Analysis of the innate reactivity of the intermediates enabled the identification of a novel way to prepare an α‐chloro‐γ‐hydroxy‐δ‐keto enone, as well as its vinylogous α‐ketol rearrangement to a δ‐keto carboxylic acid.
A Parallel‐Displaced Directly Linked 21‐Carba‐23‐Thiaporphyrin Dimer Incorporating a Dihydrofulvalene Motif
Authors: Berlicka Anna , Białek Michał J. , Latos‐Grażyński Lechosław 
Published: August 2016

AbstractIn the search of porphyrin arrays with a unique geometry, the efficient synthesis of a directly linked 21‐carba‐23‐thiaporphyrin dimer with the distinctive dihydrofulvalene bridging motif has been developed. This compound acquires an uncommon parallel‐displaced arrangement of two carbaporphyrin planes. The dimer undergoes an acid‐triggered cleavage to create of the asymmetric carbathiaporphyrin–carbathiachlorin dyad or 2,3‐dihalo‐21‐carba‐23‐thiachlorin depending on choice of acid. A formation of a reactive carbocation intermediate is postulated to account for mechanism of cleavage.
Tunable molecular weights of poly(triphenylamine‐2,2′‐bithiophene) and their effects on photovoltaic performance as sensitizers for dye‐sensitized solar cells
Authors: Wang Haizhen , Ding Wenhui , Wang Gang , Pan Chunyue , Duan Meihong , Yu Guipeng 
Published: August 2016

ABSTRACTDespite the huge progress achieved over the past decade, the relationship between the molecular weights of dyes and the performance of dye‐sensitized solar cells (DSSCs) remains unclear. In this article, we report on the fine control of the number‐average molecular weight (Mn) of poly(triphenylamine‐2,2′‐bithiophene) (PPAT) dyes with cyanoacrylic acid moieties as acceptors. We found a correlation between the Mn and photovoltaic performance of these polymers when they were used for DSSC applications. In this study, three samples (PPAT‐01, PPAT‐02, and PPAT‐03) with different Mn values (Mns = 1700, 2800, and 3500 g/mol) were prepared through the control of the polymerization time and characterized by analytical gel permeation chromatography and NMR. Under the same experimental conditions, the overall cell efficiency of the oligomer dyes showed a nonmonotonic tendency with increasing molecular weight. The power‐conversion efficiencies were 2.81% for PPAT‐01, 4.72% for PPAT‐02, and 1.88% for PPAT‐03. UV absorption measurements proved that PPAT‐03 formed aggregation, whereas PPAT‐01 and PPAT‐02 were in the monolayer state adsorbed on TiO2. The larger aggregation decreased charge transfer; thus, poor photoelectric conversion performance was observed. Furthermore, a higher molecular weight reduced the amount of PPAT‐03 adsorbed on TiO2, and this had a crucial effect on the performance of the cells because of the reduced photocurrent. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44182.
Enhancing water swelling ability and mechanical properties of water‐swellable rubber by PAA/SBS nanofiber mats
Authors: Dehbari Nazila , Tavakoli Javad , Zhao Jinchao , Tang Youhong 
Published: August 2016

ABSTRACTInvestigation of the potential use of nanofibers to reinforce composites has gained significance in many applications. In this article, the nanofiber mats of poly(acrylic acid) (PAA) and styrene–butadiene–styrene (SBS) triblock copolymer with composites structure were interweaved by double needle electrospinning process. The multiple nanofiber mats were added to conventional water‐swellable rubber (WSR). Improved mechanical and physical properties of WSR were obtained. Enhancement of the swellability of WSR + PAA/SBS nanofiber mats was derived from the PAA constituent absorbing water from the surface into the bulk and introducing random internal water channels between discontinuous superabsorbent polymers. The role of SBS nanofibers in the composite of WSR + PAA/SBS nanofiber mats was more related to the mechanical properties, where the breaking force of the composite increased to twice that of the conventional WSR. Interestingly, after immersion of the WSR + PAA/SBS nanofiber mats in water for 1 week, there was only a slight decrease in their mechanical properties of less than 5% compared to the dry state. The mechanisms and effects of the nanofiber mats in enhancing the mechanical and water swelling properties of WSR are also discussed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44213.
Correlation study of damp heat and pressure cooker testing on backsheets
Authors: Ottersböck Bettina , Oreski Gernot , Pinter Gerald 
Published: August 2016

ABSTRACTFor photovoltaic (PV) modules, high‐quality backsheets are essential. To verify these qualities, hot and humid tests of up to 1000 h are standard in the PV industry. Damp heat (DH) tests are useful for evaluating material quality and infant failures, especially for materials that are sensitive to hydrolysis. However, shorter test periods are needed. Hence, the objective of this study was to investigate and correlate the aging behavior of hydrolysis‐sensitive polyester [poly(ethylene terephthalate) (PET)] based backsheets after exposure to DH and pressure cooker conditions. The material properties, such as thermal and mechanical parameters, correlated well between the pressure cooker at 120 °C and the DH test, with the qualification that differences in the failure mechanism were seen after 96 and 2000 h, respectively. Nevertheless, it should be acceptable to use pressure cooker tests (PCTs) for fast material testing. The PCT is proposed to significantly reduce the testing time for infant failures and material quality to around 4 days for PET‐based backsheets. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44230.