bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of sunlight on high‐latitude equivalent currents
Authors: Laundal K. M. , Gjerloev J. W. , Østgaard N. , Reistad J. P. , Haaland S. , Snekvik K. , Tenfjord P. , Ohtani S. , Milan S. E.
Published: February 2016

Ground magnetic field measurements can be mathematically related to an overhead ionospheric equivalent current. In this study we look in detail at how the global equivalent current, calculated using more than 30 years of SuperMAG magnetometer data, changes with sunlight conditions. The calculations are done using spherical harmonic analysis in quasi‐dipole coordinates, a technique which leads to improved accuracy compared to previous studies. Sorting the data according to the location of the sunlight terminator and orientation of the interplanetary magnetic field (IMF), we find that the equivalent current resembles ionospheric convection patterns on the sunlit side of the terminator but not on the dark side. On the dark side, with southward IMF, the current is strongly dominated by a dawn cell and the current across the polar cap has a strong dawnward component. The contrast between the sunlit and dark side increases with increasing values of the F10.7 index, showing that increasing solar EUV flux changes not only the magnitude but also the morphology of the equivalent current system. The results are consistent with a recent study showing that Birkeland currents indirectly determine the equivalent current in darkness and that Hall currents dominate in sunlight. This has implication for the interpretation of ground magnetic field measurements and suggests that the magnetic disturbances at conjugate points will be asymmetrical when the solar illumination is different.
Reconstructing the magnetosphere from data using radial basis functions
Authors: Andreeva Varvara A. , Tsyganenko Nikolai A.
Published: February 2016

A new method is proposed to derive from data magnetospheric magnetic field configurations without any a priori assumptions on the geometry of electric currents. The approach utilizes large sets of archived satellite data and uses an advanced technique to represent the field as a sum of toroidal and poloidal parts, whose generating potentials Ψ1 and Ψ2 are expanded into series of radial basis functions (RBFs) with their nodes regularly distributed over the 3‐D modeling domain. The method was tested by reconstructing the inner and high‐latitude field within geocentric distances up to 12RE on the basis of magnetometer data of Geotail, Polar, Cluster, Time History of Events and Macroscale Interactions during Substorms, and Van Allen space probes, taken during 1995–2015. Four characteristic states of the magnetosphere before and during a disturbance have been modeled: a quiet prestorm period, storm deepening phase with progressively decreasing SYM‐H index, the storm maximum around the negative peak of SYM‐H, and the recovery phase. Fitting the RBF model to data faithfully resolved contributions to the total magnetic field from all principal sources, including the westward and eastward ring current, the tail current, diamagnetic currents associated with the polar cusps, and the large‐scale effect of the field‐aligned currents. For two main phase conditions, the model field exhibited a strong dawn‐dusk asymmetry of the low‐latitude magnetic depression, extending to low altitudes and partly spreading sunward from the terminator plane in the dusk sector. The RBF model was found to resolve even finer details, such as the bifurcation of the innermost tail current. The method can be further developed into a powerful tool for data‐based studies of the magnetospheric currents.
Two hundred thirty years of relative sea level changes due to climate and megathrust tectonics recorded in coral microatolls of Martinique (French West Indies)
Authors: Weil‐Accardo Jennifer , Feuillet Nathalie , Jacques Eric , Deschamps Pierre , Beauducel François , Cabioch Guy , Tapponnier Paul , Saurel Jean‐Marie , Galetzka John
Published: February 2016

We sampled six coral microatolls that recorded the relative sea level changes over the last 230 years east of Martinique, on fringing reefs in protected bays. The microatolls are cup‐shaped, which is characteristic of corals that have been experiencing submergence. X‐ray analysis of coral slices and reconstructions of the highest level of survival (HLS) curves show that they have submerged at rates of a few millimeters per year. Their morphology reveals changes in submergence rate around 1829 ± 11, 1895, and 1950. Tide gauges available in the region indicate a regional sea level rise at a constant mean rate of 1.1 ± 0.8 mm/yr, which contrasts with our coral record, implying additional tectonic subsidence. Comparing our coral morphology with that of synthetic corals generated with Matlab by using the Key West tide gauge record (Florida), we show that their growth was controlled by tectonics and that a sudden relative sea level increase drowned them around 1950. Simple elastic models show that this sudden submergence probably occurred during the 21 May 1946 earthquake, which ruptured the plate interface in front of Martinique, in the mantle wedge, in an area of sustained seismic activity. The 1839M8+ earthquake probably occurred in the same area. Long‐term subsidence of microatolls indicates that this deep portion of the megathrust is probably locked down to 60 km depth during the interseismic period. Our oldest coral recorded a long‐lasting period (50 years) of stable relative sea level after the 1839 earthquake, indicating that transient interseismic strain rate variations may occur in the Lesser Antilles.
CMIP5 permafrost degradation projection:A comparison among different regions
Authors: Guo Donglin , Wang Huijun
Published: February 2016

The considerable impact of permafrost degradation on hydrology and water resources, ecosystems, human engineering facilities, and climate change requires us to carry out more in‐depth studies, at finer spatial scales, to investigate the issue. In this study, regional differences of the future permafrost changes are explored with respect to the regions (high altitude and high latitude, and in four countries) based on the surface frost index (SFI) model and multimodel and multiscenario data from the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Results show the following: (1) Compared with seven other sets of driving data, Climatic Research Unit air temperature combined with Climate Forecast System Reanalysis snow data (CRU_CFSR) yield a permafrost extent with the least absolute area bias and was thus used in the simulation. The SFI model, driven by CRU_CFSR data climatology plus multimodel mean anomalies, produces a present‐day (1986–2005) permafrost area of 15.45 × 106 km2 decade−1, which compares reasonably with observations of 15.24 × 106 km2 decade−1. (2) The high‐altitude (Tibetan Plateau) permafrost area shows a larger decreasing percentage trend than the high‐latitude permafrost area. This indicates that, in terms of speed, high‐altitude permafrost thaw is faster than high‐latitude permafrost, mainly due to the larger percentage sensitivity to rising air temperature of the high‐altitude permafrost compared to the high‐latitude permafrost, which is likely related to their thermal conditions. (3) Permafrost in China shows the fastest thaw, which is reflected by the percentage trend in permafrost area, followed by the United States, Russia, and Canada. These discrepancies are mainly linked to different percentage sensitivities of permafrost areas in these four countries to air temperature change. (4) In terms of the ensemble mean, permafrost areas in all regions are projected to decrease by the period 2080–2099. Under representative concentration pathway (RCP)4.5, permafrost retreats toward the Arctic, and the thaw in every region mainly occurs at the southern edge of the permafrost area. Under RCP8.5, almost no permafrost is expected to remain in China, the United States, and the Tibetan Plateau. Permafrost in Russia will remain mainly in the western part of the east Siberian Mountains, and permafrost in Canada will retreat to the north of 65°N. Possible uncertainties in this study are primarily attributed to the climate model's coarse horizontal resolution. The results of the present study will be useful for understanding future permafrost degradation from the regional perspective.
Transport of nitrogen oxides through the winter mesopause in HAMMONIA
Authors: Meraner Katharina , Schmidt Hauke
Published: February 2016

We analyze the importance of individual transport processes for the winter polar downward transport of nitrogen oxides (NOx) from the thermosphere to the mesosphere. The downward transport of NOx produced by energetic particle precipitation induces chemical alterations in the middle atmosphere and influences ozone chemistry. However, it remains unclear how much each transport process contributes to the downward transport. We use simulations of the atmospheric general circulation and chemistry model HAMMONIA (Hamburg Model of Neutral and Ionized Atmosphere) for the extended winter 2008/2009 with a passive tracer. The model enables us to separate the contributions of advection, eddy and molecular diffusion on the total transport by switching off processes. The results show that molecular diffusion and resolved vertical mixing due to advection effectively transport NOx to the mesosphere. While the impact of molecular diffusion on the transport rapidly decreases below 0.001 hPa, the impact of advection increases. Around the central date of the sudden stratospheric warming in January 2009, advection is strongly enhanced in the thermosphere and mesosphere and the downward transport through the mesopause region is almost entirely driven by advection. Eddy diffusion has limited impact on the transport in the upper mesosphere and negligible impact on the transport in the thermosphere. If eddy diffusion is enhanced as suggested by observations, it can potentially have a larger impact on transport through the mesopause than was previously assumed.
Overlap determination for temperature measurements from a pure rotational Raman lidar
Authors: Chen Hao , Chen Siying , Zhang Yinchao , Guo Pan , Chen He , Chen Binglong
Published: February 2016

We propose a new method to calibrate the effect of overlap for temperature measurements made with a pure rotational Raman lidar. This method is based on the construction of a factor in the signal intensity ratio, which has an approximately linear relationship with altitude within the troposphere and can be obtained from radiosonde temperature measurements. Using this relationship, the effect of overlap on the signal intensity ratio can be calibrated. The method has been verified by simulations and an experiment. Comparisons with results obtained from using the existing calibration method show that the overlap determined using the new method is more accurate.
Relativistic electrons from sparks in the laboratory
Authors: Østgaard N. , Carlson B. E. , Nisi R. S. , Gjesteland T. , Grøndahl Ø. , Skeltved A. , Lehtinen N. G. , Mezentsev A. , Marisaldi M. , Kochkin P.
Published: February 2016

Discharge experiments were carried out at the Eindhoven University of Technology in 2013. The experimental setup was designed to search for electrons produced in meter‐scale sparks using a 1 MV Marx generator. Negative voltage was applied to the high voltage (HV) electrode. Five thin (1 mm) plastic detectors (5 cm2 each) were distributed in various configurations close to the spark gap. Earlier studies have shown (for HV negative) that X‐rays are produced when a cloud of streamers is developed 30–60 cm from the negative electrode. This indicates that the electrons producing the X‐rays are also accelerated at this location, that could be in the strong electric field from counterstreamers of opposite polarity. Comparing our measurements with modeling results, we find that ∼300 keV electrons produced about 30–60 cm from the negative electrode are the most likely source of our measurements. A statistical analysis of expected detection of photon bursts by these fiber detectors indicates that only 20%–45% of the detected bursts could be from soft (∼10 keV) photons, which further supports that the majority of detected bursts are produced by relativistic electrons.
Constraints on the formation and properties of a Martian lobate debris apron: Insights from high‐resolution topography, SHARAD radar data, and a numerical ice flow model
Authors: Parsons Reid , Holt John
Published: February 2016

Lobate debris aprons (LDAs) are midlatitude deposits of debris‐covered ice formed during one or more periods of glaciation during the Amazonian period. However, little is known about the climate conditions that led to LDA formation. We explore a hypothesis in which a single, extended period of precipitation of ice on the steep slopes of Euripus Mons (45°S, 105°E—east of the Hellas Basin) produced a flowing ice deposit which was protected from subsequent ablation to produce the LDA found at this location. We test this hypothesis with a numerical ice flow model using an ice rheology based on low‐temperature ice deformation experiments. The model simulates ice accumulation and flow for the northern and southern lobes of the Euripus Mons LDA using basal topography constrained by data from the Shallow Radar (SHARAD) and a range of ice viscosities (determined by ice temperature and ice grain size). Simulations for the northern lobe of the Euripus LDA produce good fits to the surface topography. Assuming an LDA age of ∼60 Myr and an expected temperature range of 200 to 204 K (for various obliquities) gives an ice grain size of ≈2 mm. Simulations of the southern section produce poor fits to surface topography and result in much faster flow timescales unless multiple ice deposition events or higher ice viscosities are considered.
In situ characterization of forest litter using ground‐penetrating radar
Authors: André Frédéric , Jonard François , Jonard Mathieu , Lambot Sébastien
Published: February 2016

Decomposing litter accumulated on the soil surface in forests plays a major role in several ecosystem processes; its detailed characterization is therefore essential for thorough understanding of ecosystem functioning. In addition, litter is known to affect remote sensing radar data over forested areas and their proper processing requires accurate quantification of litter scattering properties. In the present study, ultrawideband (0.8–2.2 GHz) ground‐penetrating radar (GPR) data were collected in situ for a wide range of litter types to investigate the potential of the technique to reconstruct litter horizons in undisturbed natural conditions. Radar data were processed resorting to full‐wave inversion. Good agreement was generally found between estimated and measured litter layer thicknesses, with root‐mean‐square error values around 1 cm for recently fallen litter (OL layer) and around 2 cm for fragmented litter in partial decomposition (OF layer) and total litter (OL + OF). Nevertheless, significant correlations between estimated and measured thicknesses were found for total litter only. Inaccuracies in the reconstruction of the individual litter horizons were mainly attributed to weak dielectric contrasts amongst litter layers, with absolute differences in relative dielectric permittivity values often lower than 2 between humus horizons, and to uncertainties in the ground truth values. Radar signal inversions also provided reliable estimates of litter electromagnetic properties, with average relative dielectric permittivity values around 2.9 and 6.3 for OL and OF litters, respectively. These results are encouraging for the use of GPR for noninvasive characterization and mapping of forest litter. Perspectives for the application of the technique in biogeosciences are discussed.
Radio frequency ice dielectric permittivity measurements using CReSIS data
Authors: Stockham M. , Macy J. , Besson D.
Published: February 2016

We report on studies of the ice dielectric permittivity using 150–195 MHz radar depth sounding data accumulated by the Center for Remote Sensing of Ice Sheets group, based at the University of Kansas. In the context of astroparticle physics experiments aimed at understanding radio emissions from cosmic rays interacting in the Earth's polar regions, our goals for this study were twofold: (1) identify radio frequency wave speed polarization asymmetries in Antarctica and (for the first time) in Greenland and (2) directly extract the depth dependence of the radio frequency field attenuation length as well as map out the attenuation over a large area. We first examine asymmetries in the real part of the permittivity (index‐of‐refraction
) using Center for Remote Sensing of Ice Sheets bedrock radar reflection data taken from a single location, but with different signal polarizations. These data indicate birefringence for flow parallel‐, versus perpendicular‐to the local ice‐flow direction, with the former corresponding to smaller index‐of‐refraction (i.e., faster wave speed). Second, we have investigated the imaginary part of the permittivity (
) and extracted the depth dependence of the field attenuation length (
), as well as estimated the depth‐averaged radio frequency attenuation length from data taken near the Greenland Ice Core Project site near Summit, Greenland. We obtain
 m based on calculated values in the 1000–2000 m ice depth interval to which we have sensitivity and extrapolated to the full depth, where the errors shown reflect our uncertainty in our extrapolation. We also observe the expected decrease in attenuation length with increasing depth/temperature. A depth‐averaged attenuation length is also extracted directly from the relative strengths of the observed bedrock versus surface returns over large regions of both Greenland and Antarctica.
Characterization of interfade duration for satellite communication systems design and optimization in a temperate climate
Authors: Jorge Flávio , Riva Carlo , Rocha Armando
Published: February 2016

The characterization of the fade dynamics on Earth‐satellite links is an important subject when designing the so called fade mitigation techniques that contribute to the proper reliability of the satellite communication systems and the customers' quality of service (QoS). The interfade duration, defined as the period between two consecutive fade events, has been only poorly analyzed using limited data sets, but its complete characterization would enable the design and optimization of the satellite communication systems by estimating the system requirements to recover in time before the next propagation impairment. Depending on this analysis, several actions can be taken ensuring the service maintenance. In this paper we present for the first time a detailed and comprehensive analysis of the interfade events statistical properties based on 9 years of in‐excess attenuation measurements at Ka band (19.7 GHz) with very high availability that is required to build a reliable data set mainly for the longer interfade duration events. The number of years necessary to reach the statistical stability of interfade duration is also evaluated for the first time, providing a reference when accessing the relevance of the results published in the past. The study is carried out in Aveiro, Portugal, which is conditioned by temperate Mediterranean climate with Oceanic influences.
Residence times of stream‐groundwater exchanges due to transient stream stage fluctuations
Authors: McCallum James L. , Shanafield Margaret
Published: February 2016

The biogeochemical functioning of stream ecosystems is heavily dependent on water and water‐borne nutrient fluxes between the stream itself and the streambed and banks (i.e., the hyporheic zone). The travel time of water exchanges through the hyporheic zone has been investigated previously; however, these studies have primarily modeled exchanges under steady state conditions assuming spatial pressure variations. This assumes that the hydraulic gradients that drive the exchanges are maintained the whole time the stream water remains in the bed or banks, which is unrealistic. Therefore, in this study we use a transient approach to investigate residence time distributions (RTDs) of bank inflow and bank outflow during both regular, diurnal stream stage variations and storm flow events. We demonstrate that RTDs reflect the timing and magnitude bank inflows, rather than smooth RTDs. We also show that small percentages of water from a given bank inflow event may be present in bank outflows for long periods of time, due to dispersion and diffusion within the bank, and lower rates of bank outflow, relative to bank inflow. This is apparent in the synthetic model of a single storm flow event, where 10% remained in the bank after 50 days. Additionally, residence times for a given bank inflow event are longer when repeated events occur, because the bank outflows from one event are “interrupted” by an increase in stream stage during a successive event. For example, field data capturing events of variable timing and magnitude showed that 70 days after each of three storm flow events occurred, 40, 12 and 30% of the bank inflow event remained in the banks. These cases indicate that bank exchanges are temporally dynamic and the RTDs of return flows can have significant tailing, which will dictate rates of nutrient exchange within the near‐stream environment.
Crustal imaging across the North Anatolian Fault Zone from the autocorrelation of ambient seismic noise
Authors: Taylor George , Rost Sebastian , Houseman Gregory
Published: February 2016

Seismic images of active fault zones can be used to examine the structure of faults throughout the crust and upper mantle and give clues as to whether the associated deformation occurs within a narrow shear zone or is broadly distributed through the lower crust. Limitations on seismic resolution within the crust and difficulties imaging shallow structures such as the crust‐mantle boundary (Moho) place constraints on the interpretation of seismic images. In this study we retrieve body wave reflections from autocorrelations of ambient seismic noise. The instantaneous phase coherence autocorrelations allow unprecedented ambient noise images of the North Anatolian Fault Zone (NAFZ). Our reflection profiles show a Moho reflected P wave and additional structure within the crust and upper mantle. We image a distinct vertical offset of the Moho associated with the northern branch of the NAFZ indicating that deformation related to the fault remains narrow in the upper mantle.
Episodic ice velocity fluctuations triggered by a subglacial flood in West Antarctica
Authors: Siegfried Matthew R. , Fricker Helen A. , Carter Sasha P. , Tulaczyk Slawek
Published: February 2016

Height change anomalies in satellite altimeter data have been interpreted as the surface expressions of basal water moving into and out of subglacial lakes. These signals have been mapped throughout Antarctica on timescales of months to years, but only broad connections have been made between active lakes and ice dynamics. We present the first high‐frequency observations of ice velocity evolution due to a cascading subglacial lake drainage event, collected over 5 years (2010–2015) using Global Positioning System data on Whillans and Mercer ice streams, West Antarctica. We observed three episodic ice velocity changes over 2 years, where flow speed increased by up to 4%, as well as an 11 month disruption of the tidally modulated stick‐slip cycle that dominates regional ice motion. Our observations reveal that basal conditions of an Antarctic ice stream can rapidly evolve and drive a dynamic ice response on subannual timescales, which can bias observations used to infer long‐term ice sheet changes.
A new approach for assessing the future of aquifers supporting irrigated agriculture
Authors: Butler James J. , Whittemore Donald O. , Wilson Blake B. , Bohling Geoffrey C.
Published: February 2016

Aquifers supporting irrigated agriculture are under stress worldwide as a result of large pumping‐induced water deficits. To aid in the formulation of more sustainable management plans for such systems, we have developed a water balance approach for assessing the impact of proposed management actions and the prospects for aquifer sustainability. Application to the High Plains aquifer (HPA) in the state of Kansas in the United States reveals that practically achievable reductions in annual pumping (<22%) would have stabilized areally averaged water levels over much of the Kansas HPA from 1996 to 2013. This demonstrates that modest pumping reductions can have a significant impact and highlights the importance of reliable pumping data for determining the net inflow (capture) component of the water balance. The HPA is similar to many aquifers supporting critically needed agricultural production, so the presented approach should prove of value far beyond the area of this initial application.
Transport of ice into the stratosphere and the humidification of the stratosphere over the 21st century
Authors: Dessler A.E. , Ye H. , Wang T. , Schoeberl M.R. , Oman L.D. , Douglass A.R. , Butler A.H. , Rosenlof K.H. , Davis S.M. , Portmann R.W.
Published: February 2016

Climate models predict that tropical lower stratospheric humidity will increase as the climate warms. We examine this trend in two state‐of‐the‐art chemistry‐climate models. Under high greenhouse gas emissions scenarios, the stratospheric entry value of water vapor increases by ~1 ppmv over the 21st century in both models. We show with trajectory runs driven by model meteorological fields that the warming tropical tropopause layer (TTL) explains 50–80% of this increase. The remainder is a consequence of trends in evaporation of ice convectively lofted into the TTL and lower stratosphere. Our results further show that within the models we examined, ice lofting is primarily important on long time scales; on interannual time scales, TTL temperature variations explain most of the variations in lower stratospheric humidity. Assessing the ability of models to realistically represent ice lofting processes should be a high priority in the modeling community.
Earlier green‐up and spring warming amplification over Europe
Authors: Ma Shaoxiu , Pitman Andy J. , Lorenz Ruth , Kala Jatin , Srbinovsky Jhan
Published: February 2016

The onset of green‐up of plants has advanced in response to climate change. This advance has the potential to affect heat waves via biogeochemical and biophysical processes. Here a climate model was used to investigate only the biophysical feedbacks of earlier green‐up on climate as the biogeochemical feedbacks have been well addressed. Earlier green‐up by 5 to 30 days amplifies spring warming in Europe, especially heat waves, but makes few differences to heat waves in summer. This spring warming is most noticeable within 30 days of advanced green‐up and is associated with a decrease in low‐ and middle‐layer clouds and associated increases of downward short wave and net radiation. We find negligible differences in the Southern Hemisphere and low latitudes of the Northern Hemisphere. Our results provide an estimate of the level of skill necessary in phenology models to avoid introducing biases in climate simulations.
Dominant flood generating mechanisms across the United States
Authors: Berghuijs Wouter R. , Woods Ross A. , Hutton Christopher J. , Sivapalan M.
Published: February 2016

River flooding can have severe societal, economic, and environmental consequences. However, limited understanding of the regional differences in flood‐generating mechanisms results in poorly understood historical flood trends and uncertain predictions of future flood conditions. Through systematic data analyses of 420 catchments we expose the primary drivers of flooding across the contiguous United States. This is achieved by exploring which flood‐generating processes control the seasonality and magnitude of maximum annual flows. The regional patterns of seasonality and interannual variabilities of maximum annual flows are, in general, poorly explained by rainfall characteristics alone. For most catchments soil moisture dependent precipitation excess, snowmelt, and rain‐on‐snow events are found to be much better predictors of the flooding responses. The continental‐scale classification of dominant flood‐generating processes we generate here emphasizes the disparity in timing and variability between extreme rainfall and flooding and can assist predictions of flooding and flood risk within the continental U.S.
Observed and projected decrease in Northern Hemisphere extratropical cyclone activity in summer and its impacts on maximum temperature
Authors: Chang Edmund K. M. , Ma Chen‐Geng , Zheng Cheng , Yau Albert M. W.
Published: February 2016

Extratropical cyclones cause much of the high‐impact weather over the midlatitudes. With increasing greenhouse gases, enhanced high‐latitude warming will lead to weaker cyclone activity. Here we show that between 1979 and 2014, the number of strong cyclones in Northern Hemisphere in summer has decreased at a rate of 4% per decade, with even larger decrease found near northeastern North America. Climate models project a decrease in summer cyclone activity, but the observed decreasing rate is near the fastest projected. Decrease in summer cyclone activity will lead to decrease in cloud cover, giving rise to higher maximum temperature, potentially enhancing the increase in maximum temperature by 0.5 K or more over some regions. We also show that climate models may have biases in simulating the positive relationship between cyclone activity and cloud cover, potentially underestimating the impacts of cyclone decrease on accentuating the future increase in maximum temperature.
A new framework for monitoring flood inundation using readily available satellite data
Authors: Parinussa Robert M. , Lakshmi Venkat , Johnson Fiona M. , Sharma Ashish
Published: February 2016

Floods are deadly natural disasters that have large social and economic impact. Their impact can be reduced through near real‐time warning systems utilizing information from satellite remote sensing for flood tracking and forecasting. In this study we formulate that differences in day and night land surface temperature (ΔLST) are a skillful predictor for inundation and can serve parallel to soil moisture in warning systems. Satellite measurements of ΔLST and soil moisture revealed distinct spatial patterns for the extreme hydrological conditions that Australia has encountered since 2002. A significant flood revealed large negative ΔLST anomalies whereas droughts corresponded to positive anomalies. ΔLST and soil moisture showed distinct behavior prior to flooding as anomalies displayed gradual build up, suggesting signals could be valuable in flood warning systems. Strong agreement was found between ΔLST, antecedent precipitation index, and soil moisture anomalies over Australia and the Murray Darling Basin. This indicates their skills to represent wetness state, an important input additional to precipitation in flood warning systems.
Adichie, Chimamanda Ngozi
Authors: Iyer Nalini
Published: February 2016

Chimamanda Ngozi Adichie (b. 1977) is the author of three novels, a collection of short stories, a play, a collection of poems, and numerous uncollected short stories, essays, and poems. Her work has appeared in prestigious publications, including
The New Yorker
,
Zoetrope
,
Ms
., and
Calyx
. Born in Nigeria, Adichie moved to the United States for her education at the age of 19. She is recognized as a major twenty‐first‐century African voice and some critics see her as the literary descendant of Chinua Achebe.
Arabic Literature
Authors: Salama Mohammad
Published: February 2016

Despite vigorous multiplicity of naming and renaming the corpse of Arabic literature produced during and after the age of decolonization, basic questions like “What is post‐colonial Arabic literature?” or “What does the post‐colonial in Arabic literature stand for?” are seldom posed. It appears the question remains tangential for most literary scholarship, which tends to focus either on individual authors or, dialectically, on panoramic expositions of various themes, sub‐themes, or genres under a given rubric. As this entry shows, postcolonial Arabic literature follows a crooked line that at times tends to continue smoothly, while at others appears to swerve brusquely from, an earlier self‐assured national vision of the Arab world ‐ one that emerged in the first half of the twentieth century as anti‐colonial resistance literature. This position complicates doctrinal nomenclatural appropriations of modern Arabic literature and raises important questions about causality and continuity, especially as it pertains to an expanded and more complex context accentuating the spread of ideas and dialogue among multiple actors.
Roumain, Jacques
Authors: Kaussen Valerie
Published: February 2016

Jacques Roumain was a Haitian writer who continues to be best known for his 1944 novel
Gouverneurs de la rosée
(
Masters of the Dew
). Roumain also composed short fiction, poetry, works of ethnology, and several essays on the politics of race, colonialism, and social class. A classic of world literature,
Gouverneurs de la rosée
is also an example of the engaged international modernism of Caribbean intellectuals writing during the period of decolonization.
Utopia
Authors: Bahrawi Nazry
Published: February 2016

Utopia is a complex theoretical and material concept that runs the risk of oversimplification in today's world. This entry explores the idea of utopia from the postcolonial perspective. It outlines the ways in which utopianism can be seen as a ubiquitous impulse that exist in Western and non‐Western, civilizations, its revolutionary element as well as its link to the literary genres of travel writing, science fiction and the bildungsroman.
Chiral Brønsted Acid Catalyzed Kinetic Resolutions
Authors: Petersen Kimberly S.
Published: February 2016

The synthesis of enantioenriched small molecules is an ongoing goal of organic chemists. This Focus Review explores the use of kinetic resolutions catalyzed by chiral Brønsted acids. Methods include classic kinetic resolutions and dynamic kinetic resolutions. The small molecules obtained are potentially valuable intermediates in the synthesis of biologically important compounds.
Synthesis and Functionalization of 5,7‐Dinitroquinoline and Its N‐Oxide
Authors: Starosotnikov Alexey M. , Nikol'skiy Vladislav V. , Borodulya Anastasiya N. , Kachala Vadim V. , Bastrakov Maxim A. , Solkan Vitaly N. , Shevelev Svyatoslav A.
Published: February 2016

An efficient method was developed for the synthesis of 5,7‐dinitroquinoline and its N‐oxide. The reactions of these compounds with either thiols or sodium azide resulted in the regiospecific substitution of 5‐NO2 group and the formation of previously unknown quinoline derivatives. The 5‐azido derivatives underwent reactions with 1,3‐dicarbonyl compounds and, depending on the nature of reagent, afforded either 5‐(1,2,3‐triazol)‐1‐yl‐ or 5‐amino‐7‐nitroquinolines, which have been previously inaccessible by using other methods.
Thermally exfoliated graphene oxide reinforced fluorinated pentablock poly(l‐lactide‐co‐ε‐caprolactone) electrospun scaffolds: Insight into antimicrobial activity and biodegradation
Authors: Okan Burcu Saner , Marset Azucena , Seyyed Monfared Zanjani Jamal , Sut Pınar Akkus , Sen Ozlem , Çulha Mustafa , Menceloglu Yusuf
Published: February 2016

Three‐dimensional fluorinated pentablock poly(l‐lactide‐co‐ε‐caprolactone)‐based scaffolds were successfully produced by the incorporation of thermally exfoliated graphene oxide (TEGO) as an antimicrobial agent with an electrospinning technique. In a ring‐opening polymerization, the fluorinated groups in the middle of polymer backbone were attached with a perfluorinated reactive stabilizer having oxygen‐carrying ability. The fiber diameter and its morphologies were optimized through changes in TEGO amount, voltage, polymer concentration, and solvent type to obtain an ideal scaffold structure. Instead of the widely used graphene oxide synthesized by Hummer's method, TEGO sheets having a low amount of oxygen produced by thermal expansion were integrated into the fiber structure to investigate the effect of the oxygen functional groups of TEGO sheets on the degradation and antimicrobial activity of the scaffolds. There was no antimicrobial activity in TEGO‐reinforced scaffolds in the in vitro tests in contrast to the literature. This study confirmed that a low number of oxygen functional groups on the surface of TEGO restricted the antimicrobial activity of the fabricated composite scaffolds. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43490.
Macrocyclic 2,7‐Anthrylene Oligomers
Authors: Yamamoto Yuta , Wakamatsu Kan , Iwanaga Tetsuo , Sato Hiroyasu , Toyota Shinji
Published: February 2016

A macrocyclic compound consisting of six 2,7‐anthrylene units was successfully synthesized by Ni‐mediated coupling of the corresponding dibromo precursor as a novel π‐conjugated compound. This compound was sufficiently stable and soluble in organic solvents due to the presence of mesityl groups. X‐ray analysis showed that the molecule had a nonplanar and hexagonal wheel‐shaped framework of approximately S6 symmetry. The dynamic process between two S6 structures was observed by using the dynamic NMR technique, the barrier being 58 kJ mol−1. The spectroscopic properties of the hexamer were compared with those of analogous linear oligomers.
PEGylated protein separation using different hydrophobic interaction supports: Conventional and monolithic supports
Authors: Mayolo‐Deloisa Karla , González‐Valdez José , Rito‐Palomares Marco
Published: February 2016

Protein hydrophobicity can be modified after a PEGylation process. However, hydrophobic interaction chromatography (HIC) has been used to separate PEGylation reaction products less frequently than other techniques. In this context, chromatographic monoliths represent a good alternative to continue exploring the separation of PEGylated proteins with HIC. In this work, the separation of PEGylated proteins using C4 A monolith as well as Toyopearl Butyl 650C and Butyl Sepharose was analyzed. Three proteins were used as models: RNase A, β‐lactoglobulin, and lysozyme. All proteins were PEGylated in the N‐terminal amino groups with 20 kDa methoxy poly(ethylene glycol) propionaldehyde. The concentration of ammonium sulfate (1 M) used was the same for all stationary phases. The results obtained demonstrated that the C4 A monolith could better resolve all protein PEGylation reaction mixtures, since the peaks of mono‐ and di‐PEGylated proteins can be clearly distinguished in the chromatographic profiles. On the contrary, while using Butyl Sepharose media only the PEGylation reaction mixtures of RNase A could be partially separated at 35 and 45 CVs. PEGylated proteins of β‐lactoglobulin and lysozyme could not be resolved when Toyopearl Butyl 650C and Butyl Sepharose were used. It is then clear that monoliths are an excellent choice to explore the purification process of PEGylated proteins exploiting the advantages of HIC. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:702–707, 2016
A novel microtubule depolymerizing colchicine analogue triggers apoptosis and autophagy in HCT‐116 colon cancer cells
Authors: Kumar Ashok , Singh Baljinder , Sharma Parduman R. , Bharate Sandip B. , Saxena Ajit K. , Mondhe D. M.
Published: February 2016

Colchicine is a tubulin‐binding natural product isolated from Colchicum autumnale. Here we report the in vitro anticancer activity of C‐ring modified semi‐synthetic derivative of colchicine; N‐[(7S)‐1,2,3‐trimethoxy‐9‐oxo‐10‐(4‐phenyl‐piperidin‐1‐yl)‐5,6,7,9 tetrahydrobenzo[a]heptalen‐7‐yl]acetamide (4h) on colon cancer HCT‐116 cell line. The compound 4h was screened for anti‐proliferative activity against different human cancer cell lines and was found to exhibit higher cytotoxicity against colon cancer cell lines HCT‐116 and Colo‐205 with IC50 of 1 and 0.8 μM respectively. Cytotoxicity of the compound to the normal fR2 breast epithelial cells and normal HEK293 human embryonic kidney cells was evaluated in concentration and time‐dependent manner to estimate its selectivity for cancer cells which showed much better selectivity than that of colchicine. Compound 4h induced cell death in HCT‐116 cells by activating apoptosis and autophagy pathways. Autophagy inhibitor 3‐MA blocked the production of LC3‐II and reduced the cytotoxicity in response to 4h, but did not affect apoptosis, suggesting thereby that these two were independent events. Reactive oxygen species scavenger ascorbic acid pretreatment not only decreased the reactive oxygen species level but also reversed 4h induced cytotoxicity. Treatment with compound 4h depolymerized microtubules and the majority of cells arrested at the G2/M transition. Together, these data suggest that 4h has better selectivity and is a microtubule depolymerizer, which activates dual cell‐death machineries, and thus, it could be a potential novel therapeutic agent in cancer therapy. Copyright © 2016 John Wiley & Sons, Ltd.
Development of a Multifunctional Benzophenone Linker for Peptide Stapling and Photoaffinity Labelling
Authors: Wu Yuteng , Olsen Lasse B. , Lau Yu Heng , Jensen Claus Hatt , Rossmann Maxim , Baker Ysobel R. , Sore Hannah F. , Collins Súil , Spring David R.
Published: February 2016

Photoaffinity labelling is a useful method for studying how proteins interact with ligands and biomolecules, and can help identify and characterise new targets for the development of new therapeutics. We present the design and synthesis of a novel multifunctional benzophenone linker that serves as both a photo‐crosslinking motif and a peptide stapling reagent. Using double‐click stapling, we attached the benzophenone to the peptide via the staple linker, rather than by modifying the peptide sequence with a photo‐crosslinking amino acid. When applied to a p53‐derived peptide, the resulting photoreactive stapled peptide was able to preferentially crosslink with MDM2 in the presence of competing protein. This multifunctional linker also features an extra alkyne handle for downstream applications such as pull‐down assays, and can be used to investigate the target selectivity of stapled peptides.
Predictors of mortality after mitraclip therapy
Authors: Cilingiroglu Mehmet , Marmagkiolis Konstantinos
Published: February 2016

Key Points

Percutaneous mitral valve repair with Mitraclip remains to be the preferred therapy for those patients with congestive heart failure with severe mitral regurgitation who are deemed high‐surgical risk.

Failure of successful MR reduction, preprocedural NYHA functional class III‐IV, elevated ProBNP levels, presence of severe tricuspid regurgitation, pulmonary hypertension, right ventricular dysfunction and advanced age seems to be predictors of long term mortality.

Preprocedural patient characteristics needs to be carefully evaluated for optimal patient selection for Mitraclip therapy.
Simulator training: The bridge between “primum non nocere” and “learning by doing”
Authors: Seto Arnold H. , Kern Morton J.
Published: February 2016

Key Points

Simulator training provides practice for trainees without exposing patients to potentially higher‐risk operators early in their training.

This study suggests that simulator training shortens the learning curve for femoral access and reduces complications.

Commercial availability of inexpensive, realistic simulators would aid medical education and reduce the risk posed to patients.
The archaeology of uncommon interventions: Articulating the rationale for transcatheter closure of congenital coronary artery fistulas in asymptomatic children
Authors: McElhinney Doff B.
Published: February 2016

Key Points

Transcatheter closure of coronary artery fistulas can be executed successfully in infants and children with few serious procedural complications.

Indications for and long‐term outcomes of closure of coronary artery fistulas remain poorly defined.

Registries may offer the best opportunity for advancing our knowledge about uncommon interventions such as coil or device closure of coronary artery fistulas, but to do so, they must include sufficient data and evaluate factors potentially associated with salutary or adverse outcome.
Thrombin inhibition during PCI in heart failure patients
Authors: Bader Yusuf , Kimmelstiel Carey
Published: February 2016

Key Points

In this retrospective analysis, CHF patients undergoing PCI had a decrease in mortality, bleeding, and transfusion as well as decreased length of stay and hospital cost when bivalirudin was used when compared to heparin.

This study suggests bivalirudin may be the preferred anticoagulant for patients with CHF undergoing PCI.

Confirmation of these data might entail analysis of patient‐level, pooled data from randomized controlled trials comparing bivalirudin to heparin in PCI patients with pre‐existing CHF.
Risk‐guided use of the direct thrombin inhibitor bivalirudin
Authors: Hillegass William B.
Published: February 2016

Key Points

Mortality and bleeding risks after percutaneous coronary intervention (PCI) can be predicted with bedside models.

Bivalirudin reduces access and non‐access bleeding by almost half compared to heparin monotherapy and heparin with IIb/IIIa use.

In high (>10%) baseline one‐year mortality risk PCI patients, bivalirudin reduces mortality by 4% compared to heparin with IIb/IIIa therapy.

Increased acute stent thrombosis may be resolved with a 4‐hr post‐procedure bivalirudin infusion, eliminating bivalirudin's only major drawback except cost.
“More may mean less… ” the role for simulation‐based medical education in the cardiac catheterization laboratory
Authors: E. Westerdahl Daniel , D. Henry Timothy
Published: February 2016

Key Points

Implementation of simulation‐based medical education (SBME) can improve cardiovascular fellows’ angiography skills and knowledge

SBME focused on performing coronary angiography shortened procedure times and decreased the use of cine‐fluoroscopy

The ACGME mandate and SCAI's Simulation Committee recommendations suggest SBME will play an expanding and integral role in the field of cardiovascular medicine
Cu/Fe Catalyzed Intermolecular Oxidative Amination of Benzylic C−H Bonds
Authors: Liu Cong , Zhang Qi , Li Hongbo , Guo Shuangxi , Xiao Bin , Deng Wei , Liu Lei , He Wei
Published: February 2016

We report a Cu/Fe co‐catalyzed Ritter‐type C−H activation/amination reaction that allows efficient and selective intermolecular functionalization of benzylic C−H bonds. This new reaction is featured by simple reaction conditions, readily available reagents and general substrate scope, allowing facile synthesis of biologically interesting nitrogen containing heterocycles. The Cu and Fe salts were found to play distinct roles in this cooperative catalysis.
Pd/C‐Catalyzed Carbonylative Esterification of Aryl Halides with Alcohols by Using Oxiranes as CO Sources
Authors: Min Byul‐Hana , Kim Dong‐Su , Park Hyo‐Soon , Jun Chul‐Ho
Published: February 2016

A carbonylative esterification reaction between aryl bromides and alcohols, promoted by Pd/C and NaF in the presence of oxiranes, has been developed. In this process, oxiranes serve as sources of carbon monoxide by their conversion to aldehydes through a palladium‐promoted Meinwald rearrangement pathway. Intramolecular versions of this process serve as methods for the synthesis of lactones and phthalimides.
Chiral Nanozymes–Gold Nanoparticle‐Based Transphosphorylation Catalysts Capable of Enantiomeric Discrimination
Authors: Chen Jack L.‐Y. , Pezzato Cristian , Scrimin Paolo , Prins Leonard J.
Published: February 2016

Enantioselectivity in RNA cleavage by a synthetic metalloenzyme has been demonstrated for the first time. Thiols containing chiral ZnII‐binding head groups have been self‐assembled on the surface of gold nanoparticles. This results in the spontaneous formation of chiral bimetallic catalytic sites that display different activities (kcat) towards the enantiomers of an RNA model substrate. Substrate selectivity is observed when the nanozyme is applied to the cleavage of the dinucleotides UpU, GpG, ApA, and CpC, and remarkable differences in reactivity are observed for the cleavage of the enantiomerically pure dinucleotide UpU.