bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Link Between External Forcings and Slope Instabilities in the Piton de la Fournaise Summit Crater, Reunion Island
Authors: Durand Virginie , Mangeney Anne , Haas Florian , Jia Xiaoping , Bonilla Fabian , Peltier Aline , Hibert Clément , Ferrazzini Valérie , Kowalski Philippe , Lauret Frédéric , Brunet Christophe , Satriano Claudio , Wegner Kerstin , Delorme Arthur , Villeneuve Nicolas
Published: September 2018

We have analyzed the impact of different forcings, such as rain and seismicity, on slope instabilites on an active volcano. For this, we compiled a catalog of the locations and volumes of rockfalls in the Piton de la Fournaise crater using seismic records. We validated it by comparing the locations and volumes to those deduced from photogrammetric data. We analyzed 10,477 rockfalls, spanning the period 2014 to 2016. This period corresponds to the renewal of volcanic activity after a 41‐month rest. Our analysis reveals that renewed eruptive activity has unsettled the crater edges. External forcings such as rain and seismicity are shown to potentially increase the number and the volume of rockfalls, with a stronger impact on the volume. Preeruptive seismicity seems to be the main triggering factor for the largest volumes, with a delay of one to several days. Rain alone does not seem to trigger especially large rockfalls. We infer that repetitive vibrations from the many seismic events, combined with the action of rain, induce crack (or slip) growth in highly fractured (or granular) materials, leading to the collapse of large volumes. Regarding their spatial distribution before an eruption, the largest rockfalls seem to migrate toward the location of magma extrusion.
Polar Region Variability in the Lower Thermosphere of Mars From Odyssey and Reconnaissance Orbiter Aerobraking Measurements
Authors: Forbes Jeffrey M. , Zhang Xiaoli
Published: September 2018

Accelerometer measurements of lower‐thermosphere densities during the aerobraking phases of Mars Odyssey (MO) and Mars Reconnaissance Orbiter (MRO) are analyzed to reveal new perspectives on the longitudinal, latitudinal, local time, and temporal variability of Mars atmosphere. The MO and MRO accelerometers sample the atmosphere similarly, making for interesting comparisons and insights. Periapsis measurements began near 70°N (MO) and 70°S (MRO) latitude, respectively, near winter solstices; slowly approached the poles at near‐constant 1730–2000 hr local times (LT); underwent nearly 8‐hr shifts in LT near the poles; and then descended in latitude to about 20°N and 20°S near 0330 hr LT. In contrast with most prior studies of Mars thermosphere, emphasis here is placed on the space‐based ks=1 (wave‐1) and ks=2 (wave‐2) components of the longitudinal density structures in the polar regions (≥70°). Expressed in terms of percent with respect to the zonal mean, ks=1 amplitudes are dominant with mission mean amplitudes of 22%(18.5%) for MO(MRO), and likely arise from the zonally symmetric diurnal tide (D0) and/or a stationary planetary wave with zonal wave number s = 1 (SPW1). Mission‐mean ks=2 amplitudes are 17.6%(13.6%) for MO(MRO) and are interpreted as arising from the zonally symmetric semidiurnal tide (S0) and the eastward propagating diurnal tide with s =− 1 (DE1). Phases of ks=1 and ks=2 are characterized by zonal migrations with periods between 15 and 45 sols; these features are interpreted in terms of modulations of D0, S0, and DE1 by slow waves in the lower atmosphere that have been reported in the literature.
Sea Surface Salinity Signature of the Tropical Atlantic Interannual Climatic Modes
Authors: Awo F. M. , Alory G. , Da‐Allada C. Y. , Delcroix T. , Jouanno J. , Kestenare E. , Baloïtcha E.
Published: September 2018

The characteristic sea surface salinity (SSS) patterns associated with the tropical Atlantic meridional and equatorial interannual modes are extracted from in situ observations, by a statistical analysis performed on the 1980–2012 period. These SSS signatures of the interannual climatic modes are reproduced in a regional numerical simulation. For each mode, oceanic and/or atmospheric processes driving the SSS signature are identified through a mixed‐layer salt budget in the validated model. During a positive meridional mode in spring, a northward shift of the Intertropical Convergence Zone and related precipitation maximum creates a south‐north dipole of positive‐negative SSS anomalies around the equator. Western boundary currents strengthen and advect relatively fresh equatorial waters, which creates negative SSS anomalies in the north and south west tropical Atlantic. Meridional and vertical advection create positive SSS anomalies off the Congo River. During a positive equatorial mode in summer, a southward shift of the Intertropical Convergence Zone‐related rainfall maximum creates a south‐north dipole of negative‐positive SSS anomalies between the equator and 10°N. Meridional advection also contributes to the positive SSS anomalies between 5°N and 10°N. Vertical advection and diffusion at the mixed‐layer base create positive SSS anomalies between 5°S and the equator. Horizontal advection creates large SSS anomalies in the North Brazil Current retroflection region, negative along the coast and positive further offshore. The SSS signatures of the meridional and equatorial modes described above are well captured by the Soil Moisture–Ocean Salinity satellite during the 2010 and 2012 events.
Impact of Seabed Resuspension on Oxygen and Nitrogen Dynamics in the Northern Gulf of Mexico: A Numerical Modeling Study
Authors: Moriarty Julia M. , Harris Courtney K. , Friedrichs Marjorie A. M. , Fennel Katja , Xu Kehui
Published: September 2018

Resuspension affects water quality in coastal environments by entraining seabed organic matter into the water column, which can increase remineralization, alter seabed fluxes, decrease water clarity, and affect oxygen and nutrient dynamics. Nearly all numerical models of water column biogeochemistry, however, simplify seabed and bottom boundary layer processes and neglect resuspension. Here we implemented HydroBioSed, a coupled hydrodynamic‐sediment transport‐biogeochemical model to examine the role of resuspension in regulating oxygen and nitrogen dynamics on timescales of a day to a month. The model was implemented for the northern Gulf of Mexico, where the extent of summertime hypoxia is sensitive to seabed and bottom boundary layer processes. Results indicated that particulate organic matter remineralization in the bottom water column increased by an order of magnitude during resuspension events. This increased sediment oxygen consumption and ammonium production, which were defined as the sum of seabed fluxes of oxygen and ammonium, plus oxygen consumption and ammonium production in the water column due to resuspended organic matter. The increases in remineralization impacted biogeochemical dynamics to a greater extent than resuspension‐induced seabed fluxes and oxidation of reduced chemical species. The effect of resuspension on bottom water biogeochemistry increased with particulate organic matter availability, which was modulated by sediment transport patterns. Overall, when averaged over the shelf and on timescales of a month in the numerical model, cycles of erosion and deposition accounted for about two thirds of sediment oxygen consumption and almost all of the sediment ammonium production.
A Color‐Index‐Based Empirical Algorithm for Determining Particulate Organic Carbon Concentration in the Ocean From Satellite Observations
Authors: Le Chengfeng , Zhou Xueying , Hu Chuanmin , Lee Zhongping , Li Lin , Stramski Dariusz
Published: September 2018

An empirical algorithm for estimating particulate organic carbon (POC) concentration in the surface ocean from satellite observations is formulated and validated using in situ POC data and remote‐sensing reflectance (Rrs) data obtained from match‐up satellite ocean color measurements. The algorithm builds upon the band‐difference algorithm concept, which was originally developed for estimating chlorophyll‐a concentration in clear waters. This algorithm utilizes three spectral bands centered approximately at 490, 550, and 670 nm to determine a color index (CIPOC), from which POC can be estimated from satellite measurements. For comparison, the blue‐green band‐ratio algorithm is also formulated using the same data set of in situ POC and satellite‐derived Rrs. Results show that the statistical parameters characterizing the differences between the satellite‐derived POC and matchup in situ POC are similar when the CIPOC and band ratio algorithms are applied to open ocean waters where the values of CIPOC are relatively low. In coastal waters where the values of CIPOC are generally higher, the statistical parameters of algorithm performance are better for the CIPOC algorithm. In addition, because the CIPOC algorithm is less sensitive to errors and noise in the satellite‐derived Rrs, the image quality obtained with this algorithm can be improved for both open‐ocean and coastal waters.
Net Modulation of Upper Ocean Thermal Structure by Typhoon Kalmaegi (2014)
Authors: Zhang Han , Wu Renhao , Chen Dake , Liu Xiaohui , He Hailun , Tang Youmin , Ke Daoxun , Shen Zheqi , Li Junde , Xie Juncheng , Tian Di , Ming Jie , Liu Fu , Zhang Dongna , Zhang Wenyan
Published: September 2018

In situ observation of a buoys/moorings array and a model simulation were used to study the modulation of upper ocean thermal structure by Typhoon Kalmaegi in September 2014. The inertial period signals were significant after forcing of Kalmaegi, but they did not account for the net heat change. Removing the inertial period signals showed that the net thermal response biased to the right of Kalmaegi's track. Vertical mixing caused surface cooling with an inverted‐cone structure and subsurface warming with a double‐wing structure. Net upwelling converted the left wing of the subsurface warming to cooling, while net downwelling warmed the upper ocean in front and on both sides of the net upwelling zone. Horizontal advection was not as important as vertical mixing and vertical advection in modulating the thermal structure but contributed to the net outward advection of thermal anomaly in the mixed layer during the forced stage and also in the net along‐track recovery of subsurface anomaly during the relaxation stage. In general, horizontal and vertical advection modulated thermal anomalies in the upper ocean across a broader horizontal range and into the deeper ocean compared with the effect of vertical mixing. Our results indicate the need to consider both mixing and advection (rather than only mixing) when studying the effects of tropical cyclones on local ocean heat uptake and global ocean heat transport.
The Competing Effects of Breaking Waves on Surfzone Heat Fluxes: Albedo Versus Wave Heating
Authors: Sinnett Gregory , Feddersen Falk
Published: September 2018

Depth‐limited wave breaking modifies the heat flux in the surfzone relative to the inner‐shelf (where waves are not breaking). Surfzone wave breaking generates heat through viscous dissipation (wave heating), but also increases surface foam coverage and albedo, thereby reducing solar heating, that is, cooling relative to the inner‐shelf. These two competing breaking wave effects are quantified with a yearlong experiment at the Scripps Institution of Oceanography Pier. Cross‐shore averaged surfzone albedo estimates were more than three times higher than inner‐shelf albedo, reducing the yearly averaged surfzone water‐entering shortwave radiation by 41 W/m2 relative to the inner‐shelf. Surfzone breaking wave dissipation added an additional yearly averaged 28 W/m2 relative to the inner‐shelf. The albedo‐induced solar heating reduction in spring, summer, and fall was usually greater than the wave heating. However, in winter, large waves and relatively weak shortwave solar radiation (due to both lower top of the atmosphere solar radiation and clouds) resulted in a nearly equal number of days of breaking wave‐induced heating or cooling. These two heat flux terms are coupled via wave breaking dissipation. Averaged over the surfzone, the albedo‐induced solar radiation reduction is linearly related to the downwelling solar radiation and is independent of wave height. Consequently, the albedo‐induced cooling to wave heating ratio is a function of breaking wave height to the −3/2 power, allowing evaluation of the relative importance of these terms in other geographic regions.
Preface to the Special Section: Dense Water Formations in the Northwestern Mediterranean: From the Physical Forcings to the Biogeochemical Consequences
Authors: Conan Pascal , Testor Pierre , Estournel Claude , D'Ortenzio Fabrizio , Pujo‐Pay Mireille , Durrieu de Madron Xavier
Published: September 2018

The northwestern Mediterranean Sea is one of the few sites of open‐sea deep convection and dense water formation. The area is characterized by intense air‐sea exchanges favored by the succession of strong northerly and northwesterly winds during autumn and winter that eventually induce deep convection episodes and the formation of the Western Mediterranean Deep Water. This region exhibits a significant spring phytoplankton bloom, which appears to be largely influenced in intensity and diversity by the winter mixing. To understand and resolve the interplay between the atmosphere and ocean, and the impact of ocean circulation and mixing on biogeochemistry, we carried out an unprecedented observational effort during a large experiment between July 2012 and July 2013. A multiplatform approach—combining aircraft, balloons, ships, moorings, floats, and gliders ‐ aimed both at characterizing the dynamics of the atmosphere and at quantifying the physical, biogeochemical, and biological properties of the water masses. Beyond a better understanding of the wind dynamics, the interannual variability of the deep convection, and the seasonal variability of the nutrient distribution and plankton structure in the pelagic ecosystem, the experiment provided a reference data set that was used as a benchmark for advancing the modeling of the surface fluxes, convective processes, dense water formation rates, and physical‐biogeochemical coupling processes. It also represented an opportunity for complementary investigations such as evaluating model parameterizations or studying the role of submesoscale eddies in dense water spreading and biogeochemistry.
The Characteristics and Mechanism of the Formation of Earth‐Air Pulsation in Extremely Arid Areas
Authors: Li Hongshou , Zhan Hongtao
Published: September 2018

The term earth‐air refers to the air inside the vadose zone. The observation of earth‐air was called hou‐qi, which was used to enact meter calendar in ancient China. Currently, however, as a detailed knowledge of hou‐qi has been lost for a long time, it has been denounced as a pseudoscience, as earth‐air is not scientifically and systematically monitored, and its characteristics and formation mechanism are unclear. We have attempted to scientifically monitor and measure earth‐air pressure and reveal its formation mechanism. Results from a specially devised set of air pressure measurements show that the pressure exhibits daily and yearly pulses at different depths. The main cause of the pulsation is soil temperature variation, which results in the soil‐combined water decomposing and air pressurization in warming, and water vapor recombining and air depressurization when cooling, leading to pulsation of the air pressure in the soil. Therefore, rather than a myth, hou‐qi has great significance in the geosciences and studies of the ancient Chinese civilization.
Airborne Observations of Reactive Inorganic Chlorine and Bromine Species in the Exhaust of Coal‐Fired Power Plants
Authors: Lee Ben H. , Lopez‐Hilfiker Felipe D. , Schroder Jason C. , Campuzano‐Jost Pedro , Jimenez Jose L. , McDuffie Erin E. , Fibiger Dorothy L. , Veres Patrick R. , Brown Steven S. , Campos Teresa L. , Weinheimer Andrew J. , Flocke Frank F. , Norris Gary , O'Mara Kate , Green Jaime R. , Fiddler Marc N. , Bililign Solomon , Shah Viral , Jaeglé Lyatt , Thornton Joel A.
Published: September 2018

We present airborne observations of gaseous reactive halogen species (HCl, Cl2, ClNO2, Br2, BrNO2, and BrCl), sulfur dioxide (SO2), and nonrefractory fine particulate chloride (pCl) and sulfate (pSO4) in power plant exhaust. Measurements were conducted during the Wintertime INvestigation of Transport, Emissions, and Reactivity campaign in February–March of 2015 aboard the NCAR‐NSF C‐130 aircraft. Fifty air mass encounters were identified in which SO2 levels were elevated ~5 ppb above ambient background levels and in proximity to operational power plants. Each encounter was attributed to one or more potential emission sources using a simple wind trajectory analysis. In case studies, we compare measured emission ratios to those reported in the 2011 National Emissions Inventory and present evidence of the conversion of HCl emitted from power plants to ClNO2. Taking into account possible chemical conversion downwind, there was general agreement between the observed and reported HCl:SO2 emission ratios. Reactive bromine species (Br2, BrNO2, and/or BrCl) were detected in the exhaust of some coal‐fired power plants, likely related to the absence of wet flue gas desulfurization emission control technology. Levels of bromine species enhanced in some encounters exceeded those expected assuming all of the native bromide in coal was released to the atmosphere, though there was no reported use of bromide salts (as a way to reduce mercury emissions) during Wintertime INvestigation of Transport, Emissions, and Reactivity observations. These measurements represent the first ever in‐flight observations of reactive gaseous chlorine and bromine containing compounds present in coal‐fired power plant exhaust.
Geologic History of the Northern Portion of the South Pole‐Aitken Basin on the Moon
Authors: Ivanov M. A. , Hiesinger H. , van der Bogert C. H. , Orgel C. , Pasckert J. H. , Head J. W.
Published: September 2018

We conducted a detailed photogeological analysis of the northern portion of the South Pole‐Aitken (SPA) basin (10–60°S, 125–175°W) and compiled a geological map (1:500,000 scale) of this region. Our new absolute model age for the Apollo basin, 3.98 + 0.04/−0.06 Ga, provides a lower age limit for the formation of the SPA basin. Some of the plains units in the study area were formed by distal ejecta from remote craters and basins. The characteristic concentrations of FeO and TiO2 of other plains are indicative of their volcanic origin. The oldest volcanic materials occur near the center of the SPA basin and have an Early Imbrian age of ~3.80 + 0.02/−0.02 Ga. Late Imbrian volcanic activity occurred in and around the Apollo basin. In total, the volcanic plains cover ~8% of the map area and cannot account for the extensive SPA iron signature. The sources of the signature are the oldest materials on the SPA floor (FeO ~11–14.5 wt%). In contrast, the ejecta composing the SPA rim are significantly poorer in FeO (<7.5 wt%). The signature could be related to the differentiation of the SPA impact melt. However, the spatial segregation of the ancient iron‐rich and iron‐poor materials suggests that the SPA iron signature predated the basin. Thus, the signature might be explained by a pre‐SPA lunar crust that was stratified with respect to the iron concentrations, so that the SPA impact excavated the upper, iron‐poorer portion of the crust to form the SPA rim and exposed the deeper, iron‐richer portion on the floor of the basin.
Polarimetry of Water Ice Particles Providing Insights on Grain Size and Degree of Sintering on Icy Planetary Surfaces
Authors: Poch O. , Cerubini R. , Pommerol A. , Jost B. , Thomas N.
Published: September 2018

The polarimetry of the light scattered by planetary surfaces is a powerful tool to provide constraints on their microstructure. To improve the interpretation of polarimetric data from icy surfaces, we have developed the POLarimeter for ICE Samples complementing the measurement facilities of the Ice Laboratory at the University of Bern. The new setup uses a high precision Stokes polarimeter to measure the degree of polarization in the visible light scattered by surfaces at moderate phase angles (from 1.5° to 30°). We present the photometric and polarimetric phase curves measured on various surfaces made of pure water ice particles having well‐controlled size and shape (spherical, crushed, and frost). The results show how the amplitude and the shape of the negative polarization branch change with the particles sizes and the degree of metamorphism of the ice. We found that fresh frost formed by water condensation on cold surfaces has a phase curve characterized by resonances (Mie oscillations) indicating that frost embryos are transparent micrometer‐sized particles with a narrow size distribution and spherical shape. Comparisons of these measurements with polarimetric observations of the icy satellites of the Solar System suggest that Europa is possibly covered by relatively coarser (~40–400 μm) and more sintered grains than Enceladus and Rhea, more likely covered by frost‐like particles of few micrometers in average. The great sensitivity of polarization to grain size and degree of sintering makes it an ideal tool to detect hints of ongoing processes on icy planetary surfaces, such as cryovolcanism.
An Ionosphere Specification Technique Based on Data Ingestion Algorithm and Empirical Orthogonal Function Analysis Method
Authors: Aa Ercha , Ridley Aaron , Huang Wengeng , Zou Shasha , Liu Siqing , Coster Anthea J. , Zhang Shunrong
Published: September 2018

A data ingestion method in reproducing ionospheric electron density and total electron content (TEC) was developed to incorporate TEC products from the Madrigal Database into the NeQuick 2 model. The method is based on retrieving an appropriate global distribution of effective ionization parameter (Az) to drive the NeQuick 2 model, which can be implemented through minimizing the difference between the measured and modeled TEC at each grid in the local time‐modified dip latitude coordinates. The performance of this Madrigal TEC‐driven‐NeQuick 2 result is validated through the comparison with various International Global Navigation Satellite Systems Services global ionospheric maps and ionosonde data. The validation results show that a general accuracy improvement of 30–50% can be achieved after data ingestion. In addition, the empirical orthogonal function (EOF) analysis technique is used to construct a parameterized time‐varying global Az model. The quick convergence of EOF decomposition makes it possible to use the first six EOF series to represent over 90% of the total variances. The intrinsic diurnal variation and spatial distribution in the original data set can be well reflected by the constructed EOF base functions. The associated EOF coefficients can be expressed as a set of linear functions of F10.7 and Ap indices, combined with a series of trigonometric functions with annual/seasonal variation components. The NeQuick TEC driven by EOF‐modeled Az shows 10–15% improvement in accuracy over the standard ionosphere correction algorithm in the Galileo navigation system. These preliminary results demonstrate the effectiveness of the combined data ingestion and EOF modeling technique in improving the specifications of ionospheric density variations.
Establishment of stable iPS-derived human neural stem cell lines suitable for cell therapies
Authors: Rosati Jessica , Ferrari Daniela , Altieri Filomena , Tardivo Silvia , Ricciolini Claudia , Fusilli Caterina , Zalfa Cristina , Profico Daniela C. , Pinos Francesca , Bernardini Laura , Torres Barbara , Manni Isabella , Piaggio Giulia , Binda Elena , Copetti Massimiliano , Lamorte Giuseppe , Mazza Tommaso , Carella Massimo , Gelati Maurizio , Valente Enza Maria , Simeone Antonio , Vescovi Angelo L.
Published: September 2018

Establishing specific cell lineages from human induced pluripotent stem cells (hiPSCs) is vital for cell therapy approaches in regenerative medicine, particularly for neurodegenerative disorders. While neural precursors have been induced from hiPSCs, the establishment of hiPSC-derived human neural stem cells (hiNSCs), with characteristics that match foetal hNSCs and abide by cGMP standards, thus allowing clinical applications, has not been described. We generated hiNSCs by a virus-free technique, whose properties recapitulate those of the clinical-grade hNSCs successfully used in an Amyotrophic Lateral Sclerosis (ALS) phase I clinical trial. Ex vivo, hiNSCs critically depend on exogenous mitogens for stable self-renewal and amplification and spontaneously differentiate into astrocytes, oligodendrocytes and neurons upon their removal. In the brain of immunodeficient mice, hiNSCs engraft and differentiate into neurons and glia, without tumour formation. These findings now warrant the establishment of clinical-grade, autologous and continuous hiNSC lines for clinical trials in neurological diseases such as Huntington’s, Parkinson’s and Alzheimer’s, among others.
Forward models demonstrate that repetition suppression is best modelled by local neural scaling
Authors: Alink Arjen , Abdulrahman Hunar , Henson Richard N.
Published: September 2018

Inferring neural mechanisms from functional magnetic resonance imaging (fMRI) is challenging because the fMRI signal integrates over millions of neurons. One approach is to compare computational models that map neural activity to fMRI responses, to see which best predicts fMRI data. We use this approach to compare four possible neural mechanisms of fMRI adaptation to repeated stimuli (scaling, sharpening, repulsive shifting and attractive shifting), acting across three domains (global, local and remote). Six features of fMRI repetition effects are identified, both univariate and multivariate, from two independent fMRI experiments. After searching over parameter values, only the local scaling model can simultaneously fit all data features from both experiments. Thus fMRI stimulus repetition effects are best captured by down-scaling neuronal tuning curves in proportion to the difference between the stimulus and neuronal preference. These results emphasise the importance of formal modelling for bridging neuronal and fMRI levels of investigation.
Tunable colloid trajectories in nematic liquid crystals near wavy walls
Authors: Luo Yimin , Beller Daniel A. , Boniello Giuseppe , Serra Francesca , Stebe Kathleen J.
Published: September 2018

The ability to dictate the motion of microscopic objects is an important challenge in fields ranging from materials science to biology. Field-directed assembly drives microparticles along paths defined by energy gradients. Nematic liquid crystals, consisting of rod-like molecules, provide new opportunities in this domain. Deviations of nematic liquid crystal molecules from uniform orientation cost elastic energy, and such deviations can be molded by bounding vessel shape. Here, by placing a wavy wall in a nematic liquid crystal, we impose alternating splay and bend distortions, and define a smoothly varying elastic energy field. A microparticle in this field displays a rich set of behaviors, as this system has multiple stable states, repulsive and attractive loci, and interaction strengths that can be tuned to allow reconfigurable states. Microparticles can transition between defect configurations, move along distinct paths, and select sites for preferred docking. Such tailored landscapes have promise in reconfigurable systems and in microrobotics applications.
Notch2 controls non-autonomous Wnt-signalling in chronic lymphocytic leukaemia
Authors: Mangolini Maurizio , Götte Frederik , Moore Andrew , Ammon Tim , Oelsner Madlen , Lutzny-Geier Gloria , Klein-Hitpass Ludger , Williamson James C. , Lehner Paul J. , Dürig Jan , Möllmann Michael , Rásó-Barnett Lívia , Hughes Katherine , Santoro Antonella , Méndez-Ferrer Simón , Oostendorp Robert A. J. , Zimber-Strobl Ursula , Peschel Christian , Hodson Daniel J. , Schmidt-Supprian Marc , Ringshausen Ingo
Published: September 2018

The Wnt signalling pathway, one of the core de-regulated pathways in chronic lymphocytic leukaemia (CLL), is activated in only a subset of patients through somatic mutations. Here we describe alternative, microenvironment-dependent mechanisms of Wnt activation in malignant B cells. We show that tumour cells specifically induce Notch2 activity in mesenchymal stromal cells (MSCs) required for the transcription of the complement factor C1q. MSC-derived C1q in turn inhibits Gsk3-β mediated degradation of β-catenin in CLL cells. Additionally, stromal Notch2 activity regulates N-cadherin expression in CLL cells, which interacts with and further stabilises β-catenin. Together, these stroma Notch2-dependent mechanisms induce strong activation of canonical Wnt signalling in CLL cells. Pharmacological inhibition of the Wnt pathway impairs microenvironment-mediated survival of tumour cells. Similarly, inhibition of Notch signalling diminishes survival of stroma-protected CLL cells in vitro and disease engraftment in vivo. Notch2 activation in the microenvironment is a pre-requisite for the activation of canonical Wnt signalling in tumour cells.
Influence of PEDOT:PSS crystallinity and composition on electrochemical transistor performance and long-term stability
Authors: Kim Seong-Min , Kim Chang-Hyun , Kim Youngseok , Kim Nara , Lee Won-June , Lee Eun-Hak , Kim Dokyun , Park Sungjun , Lee Kwanghee , Rivnay Jonathan , Yoon Myung-Han
Published: September 2018

Owing to the mixed electron/hole and ion transport in the aqueous environment, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-based organic electrochemical transistor has been regarded as one of the most promising device platforms for bioelectronics. Nonetheless, there exist very few in-depth studies on how intrinsic channel material properties affect their performance and long-term stability in aqueous environments. Herein, we investigated the correlation among film microstructural crystallinity/composition, device performance, and aqueous stability in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) films. The highly organized anisotropic ordering in crystallized conducting polymer films led to remarkable device characteristics such as large transconductance (∼20 mS), extraordinary volumetric capacitance (113 F·cm−3), and unprecedentedly high [μC*] value (∼490 F·cm−1V−1s−1). Simultaneously, minimized poly(styrenesulfonate) residues in the crystallized film substantially afforded marginal film swelling and robust operational stability even after >20-day water immersion, >2000-time repeated on-off switching, or high-temperature/pressure sterilization. We expect that the present study will contribute to the development of long-term stable implantable bioelectronics for neural recording/stimulation.
Repeated inversions within a pannier intron drive diversification of intraspecific colour patterns of ladybird beetles
Authors: Ando Toshiya , Matsuda Takeshi , Goto Kumiko , Hara Kimiko , Ito Akinori , Hirata Junya , Yatomi Joichiro , Kajitani Rei , Okuno Miki , Yamaguchi Katsushi , Kobayashi Masaaki , Takano Tomoyuki , Minakuchi Yohei , Seki Masahide , Suzuki Yutaka , Yano Kentaro , Itoh Takehiko , Shigenobu Shuji , Toyoda Atsushi , Niimi Teruyuki
Published: September 2018

How genetic information is modified to generate phenotypic variation within a species is one of the central questions in evolutionary biology. Here we focus on the striking intraspecific diversity of >200 aposematic elytral (forewing) colour patterns of the multicoloured Asian ladybird beetle, Harmonia axyridis, which is regulated by a tightly linked genetic locus h. Our loss-of-function analyses, genetic association studies, de novo genome assemblies, and gene expression data reveal that the GATA transcription factor gene pannier is the major regulatory gene located at the h locus, and suggest that repeated inversions and cis-regulatory modifications at pannier led to the expansion of colour pattern variation in H. axyridis. Moreover, we show that the colour-patterning function of pannier is conserved in the seven-spotted ladybird beetle, Coccinella septempunctata, suggesting that H. axyridis’ extraordinary intraspecific variation may have arisen from ancient modifications in conserved elytral colour-patterning mechanisms in ladybird beetles.
Gallium nitride nanowire as a linker of molybdenum sulfides and silicon for photoelectrocatalytic water splitting
Authors: Zhou Baowen , Kong Xianghua , Vanka Srinivas , Chu Sheng , Ghamari Pegah , Wang Yichen , Pant Nick , Shih Ishiang , Guo Hong , Mi Zetian
Published: September 2018

The combination of earth-abundant catalysts and semiconductors, for example, molybdenum sulfides and planar silicon, presents a promising avenue for the large-scale conversion of solar energy to hydrogen. The inferior interface between molybdenum sulfides and planar silicon, however, severely suppresses charge carrier extraction, thus limiting the performance. Here, we demonstrate that defect-free gallium nitride nanowire is ideally used as a linker of planar silicon and molybdenum sulfides to produce a high-quality shell-core heterostructure. Theoretical calculations revealed that the unique electronic interaction and the excellent geometric-matching structure between gallium nitride and molybdenum sulfides enabled an ideal electron-migration channel for high charge carrier extraction efficiency, leading to outstanding performance. A benchmarking current density of 40 ± 1 mA cm−2 at 0 V vs. reversible hydrogen electrode, the highest value ever reported for a planar silicon electrode without noble metals, and a large onset potential of +0.4 V were achieved under standard one-sun illumination.
Lung colonization by Aspergillus fumigatus is controlled by ZNF77
Authors: Gago Sara , Overton Nicola L. D. , Ben-Ghazzi Nagwa , Novak-Frazer Lilyann , Read Nick D. , Denning David W. , Bowyer Paul
Published: September 2018

Aspergillus fumigatus is a critical pathogen of humans. Exposure to A. fumigatus conidia occurs frequently but is normally cleared from the respiratory airways. In contrast, individuals with respiratory diseases are often highly colonized by fungi. Here, we use genome-edited epithelial cells to show that the genetic variant rs35699176 in ZNF77 causes loss of integrity of the bronchial epithelium and increases levels of extracellular matrix proteins. These changes promote A. fumigatus conidial adhesion, germination and growth. RNA-seq and LC/MS-MS analysis reveal rs35699176 upregulates vesicle trafficking leading to an increment of adhesion proteins. These changes make cells carrying rs35699176 more receptive to A. fumigatus in the early stages of infection. Moreover, patients with fungal asthma carrying rs35699176+/− have higher A. fumigatus loads in their respiratory airway. Our results indicate ZNF77 as a key controller of Aspergillus colonization and suggest its utility as a risk-marker for patient stratification.
Structures of insect Imp-L2 suggest an alternative strategy for regulating the bioavailability of insulin-like hormones
Authors: Roed Nikolaj Kulahin , Viola Cristina M. , Kristensen Ole , Schluckebier Gerd , Norrman Mathias , Sajid Waseem , Wade John D. , Andersen Asser Sloth , Kristensen Claus , Ganderton Timothy R. , Turkenburg Johan P. , De Meyts Pierre , Brzozowski Andrzej M.
Published: September 2018

The insulin/insulin-like growth factor signalling axis is an evolutionary ancient and highly conserved hormonal system involved in the regulation of metabolism, growth and lifespan in animals. Human insulin is stored in the pancreas, while insulin-like growth factor-1 (IGF-1) is maintained in blood in complexes with IGF-binding proteins (IGFBP1–6). Insect insulin-like polypeptide binding proteins (IBPs) have been considered as IGFBP-like structural and functional homologues. Here, we report structures of theDrosophilaIBP Imp-L2 in its free form and bound toDrosophilainsulin-like peptide 5 and human IGF-1. Imp-L2 contains two immunoglobulin-like fold domains and its architecture is unrelated to human IGFBPs, suggesting a distinct strategy for bioavailability regulation of insulin-like hormones. Similar hormone binding modes may exist in other insect vectors, as the IBP sequences are highly conserved. Therefore, these findings may open research routes towards a rational interference of transmission of diseases such as malaria, dengue and yellow fevers.
Discovering human diabetes-risk gene function with genetics and physiological assays
Authors: Peiris Heshan , Park Sangbin , Louis Shreya , Gu Xueying , Lam Jonathan Y. , Asplund Olof , Ippolito Gregory C. , Bottino Rita , Groop Leif , Tucker Haley , Kim Seung K.
Published: September 2018

Developing systems to identify the cell type-specific functions regulated by genes linked to type 2 diabetes (T2D) risk could transform our understanding of the genetic basis of this disease. However, in vivo systems for efficiently discovering T2D risk gene functions relevant to human cells are currently lacking. Here we describe powerful interdisciplinary approaches combining Drosophila genetics and physiology with human islet biology to address this fundamental gap in diabetes research. We identify Drosophila orthologs of T2D-risk genes that regulate insulin output. With human islets, we perform genetic studies and identify cognate human T2D-risk genes that regulate human beta cell function. Loss of BCL11A, a transcriptional regulator, in primary human islet cells leads to enhanced insulin secretion. Gene expression profiling reveals BCL11A-dependent regulation of multiple genes involved in insulin exocytosis. Thus, genetic and physiological systems described here advance the capacity to identify cell-specific T2D risk gene functions.
A cocoon silk chemistry strategy to ultrathin N-doped carbon nanosheet with metal single-site catalysts
Authors: Zhu Youqi , Sun Wenming , Luo Jun , Chen Wenxing , Cao Tai , Zheng Lirong , Dong Juncai , Zhang Jian , Zhang Maolin , Han Yunhu , Chen Chen , Peng Qing , Wang Dingsheng , Li Yadong
Published: September 2018

Development of single-site catalysts supported by ultrathin two-dimensional (2D) porous matrix with ultrahigh surface area is highly desired but also challenging. Here we report a cocoon silk chemistry strategy to synthesize isolated metal single-site catalysts embedded in ultrathin 2D porous N-doped carbon nanosheets (M-ISA/CNS, M = Fe, Co, Ni). X-ray absorption fine structure analysis and spherical aberration correction electron microscopy demonstrate an atomic dispersion of metal atoms on N-doped carbon matrix. In particular, the Co-ISA/CNS exhibit ultrahigh specific surface area (2105 m2 g−1) and high activity for C–H bond activation in the direct catalytic oxidation of benzene to phenol with hydrogen peroxide at room temperature, while the Co species in the form of phthalocyanine and metal nanoparticle show a negligible activity. Density functional theory calculations discover that the generated O = Co = O center intermediates on the single Co sites are responsible for the high activity of benzene oxidation to phenol.
A conformational sensor based on genetic code expansion reveals an autocatalytic component in EGFR activation
Authors: Baumdick Martin , Gelléri Márton , Uttamapinant Chayasith , Beránek Václav , Chin Jason W. , Bastiaens Philippe I. H.
Published: September 2018

Epidermal growth factor receptor (EGFR) activation by growth factors (GFs) relies on dimerization and allosteric activation of its intrinsic kinase activity, resulting in trans-phosphorylation of tyrosines on its C-terminal tail. While structural and biochemical studies identified this EGF-induced allosteric activation, imaging collective EGFR activation in cells and molecular dynamics simulations pointed at additional catalytic EGFR activation mechanisms. To gain more insight into EGFR activation mechanisms in living cells, we develop a Förster resonance energy transfer (FRET)-based conformational EGFR indicator (CONEGI) using genetic code expansion that reports on conformational transitions in the EGFR activation loop. Comparing conformational transitions, self-association and auto-phosphorylation of CONEGI and its Y845F mutant reveals that Y845 phosphorylation induces a catalytically active conformation in EGFR monomers. This conformational transition depends on EGFR kinase activity and auto-phosphorylation on its C-terminal tail, generating a looped causality that leads to autocatalytic amplification of EGFR phosphorylation at low EGF dose.
Alpha-enolase regulates the malignant phenotype of pulmonary artery smooth muscle cells via the AMPK-Akt pathway
Authors: Dai Jingbo , Zhou Qiyuan , Chen Jiwang , Rexius-Hall Megan L. , Rehman Jalees , Zhou Guofei
Published: September 2018

The molecular mechanisms underlying the metabolic shift toward increased glycolysis observed in pulmonary artery smooth muscle cells (PASMC) during the pathogenesis of pulmonary arterial hypertension (PAH) are not fully understood. Here we show that the glycolytic enzyme α-enolase (ENO1) regulates the metabolic reprogramming and malignant phenotype of PASMC. We show that ENO1 levels are elevated in patients with associated PAH and in animal models of hypoxic pulmonary hypertension (HPH). The silencing or inhibition of ENO1 decreases PASMC proliferation and de-differentiation, and induces PASMC apoptosis, whereas the overexpression of ENO1 promotes a synthetic, de- differentiated, and apoptotic-resistant phenotype via the AMPK-Akt pathway. The suppression of ENO1 prevents the hypoxia-induced metabolic shift from mitochondrial respiration to glycolysis in PASMC. Finally, we find that pharmacological inhibition of ENO1 reverses HPH in mice and rats, suggesting ENO1 as a regulator of pathogenic metabolic reprogramming in HPH.
Towards synthetic cells using peptide-based reaction compartments
Authors: Vogele Kilian , Frank Thomas , Gasser Lukas , Goetzfried Marisa A. , Hackl Mathias W. , Sieber Stephan A. , Simmel Friedrich C. , Pirzer Tobias
Published: September 2018

Membrane compartmentalization and growth are central aspects of living cells, and are thus encoded in every cell’s genome. For the creation of artificial cellular systems, genetic information and production of membrane building blocks will need to be coupled in a similar manner. However, natural biochemical reaction networks and membrane building blocks are notoriously difficult to implement in vitro. Here, we utilized amphiphilic elastin-like peptides (ELP) to create self-assembled vesicular structures of about 200 nm diameter. In order to genetically encode the growth of these vesicles, we encapsulate a cell-free transcription-translation system together with the DNA template inside the peptide vesicles. We show in vesiculo production of a functioning fluorescent RNA aptamer and a fluorescent protein. Furthermore, we implement in situ expression of the membrane peptide itself and finally demonstrate autonomous vesicle growth due to the incorporation of this ELP into the membrane.
An interstellar synthesis of phosphorus oxoacids
Authors: Turner Andrew M. , Bergantini Alexandre , Abplanalp Matthew J. , Zhu Cheng , Góbi Sándor , Sun Bing-Jian , Chao Kang-Heng , Chang Agnes H. H. , Meinert Cornelia , Kaiser Ralf I.
Published: September 2018

Phosphorus signifies an essential element in molecular biology, yet given the limited solubility of phosphates on early Earth, alternative sources like meteoritic phosphides have been proposed to incorporate phosphorus into biomolecules under prebiotic terrestrial conditions. Here, we report on a previously overlooked source of prebiotic phosphorus from interstellar phosphine (PH3) that produces key phosphorus oxoacids—phosphoric acid (H3PO4), phosphonic acid (H3PO3), and pyrophosphoric acid (H4P2O7)—in interstellar analog ices exposed to ionizing radiation at temperatures as low as 5 K. Since the processed material of molecular clouds eventually enters circumstellar disks and is partially incorporated into planetesimals like proto Earth, an understanding of the facile synthesis of oxoacids is essential to untangle the origin of water-soluble prebiotic phosphorus compounds and how they might have been incorporated into organisms not only on Earth, but potentially in our universe as well.
Publisher Correction: Heme enables proper positioning of Drosha and DGCR8 on primary microRNAs
Authors: Partin Alexander C. , Ngo Tri D. , Herrell Emily , Jeong Byung-Cheon , Hon Gary , Nam Yunsun
Published: September 2018

The original version of this Article contained an error in Fig. 1. In panel d, the model on the right of the panel was incorrectly labeled ‘+Heme’, and should have read ‘− Heme’. This has now been corrected in both the PDF and HTML versions of the Article.
Active particles bound by information flows
Authors: Khadka Utsab , Holubec Viktor , Yang Haw , Cichos Frank
Published: September 2018

Self-organization is the generation of order out of local interactions. It is deeply connected to many fields of science from physics, chemistry to biology, all based on physical interactions. The emergence of collective animal behavior is the result of self-organization processes as well, though they involve abstract interactions arising from sensory inputs, information processing, storage, and feedback. Resulting collective behaviors are found, for example, in crowds of people, flocks of birds, and swarms of bacteria. Here we introduce interactions between active microparticles which are based on the information about other particle positions. A real-time feedback of multiple active particle positions is the information source for the propulsion direction of these particles. The emerging structures require continuous information flows. They reveal frustrated geometries due to confinement to two dimensions and internal dynamical degrees of freedom that are reminiscent of physically bound systems, though they exist only as nonequilibrium structures.
Tuning topological phase and quantum anomalous Hall effect by interaction in quadratic band touching systems
Authors: Zeng Tian-Sheng , Zhu Wei , Sheng Donna
Published: September 2018

Interaction-driven topological phases significantly enrich the class of topological materials and thus are of great importance. Here, we study the phase diagram of interacting spinless fermions filling the two-dimensional checkerboard lattice with a quadratic band touching (QBT) point. By developing new diagnosis based on the state-of-the-art density-matrix renormalization group and exact diagonalization, we determine accurate quantum phase diagram for such a system at half-filling with three distinct phases. For weak nearest-neighboring interactions, we demonstrate the instability of the QBT towards an interaction-driven spontaneous quantum anomalous Hall (QAH) effect. For strong interactions, the system breaks the rotational symmetry realizing a nematic charge-density-wave (CDW) phase. Interestingly, for intermediate interactions we discover a symmetry-broken bond-ordered critical phase sandwiched in between the QAH and CDW phases, which splits the QBT into two Dirac points driven by interaction. Instead of the direct transition between QAH and CDW phases, our identification of an intermediate phase sheds new light on the theoretical understanding of the interaction-driven phases in QBT systems.