bluuebunny/crossref_metadata_2025 huggingface dataset:
Trophic pathways of phytoplankton size classes through the zooplankton food web over the spring transition period in the north‐west Mediterranean Sea
Authors: Hunt Brian P. V. , Carlotti François , Donoso Katty , Pagano Marc , D'Ortenzio Fabrizio , Taillandier Vincent , Conan Pascal
Published: July 2017

Knowledge of the relative contributions of phytoplankton size classes to zooplankton biomass is necessary to understand food‐web functioning and response to climate change. During the Deep Water formation Experiment (DEWEX), conducted in the north‐west Mediterranean Sea in winter (February) and spring (April) of 2013, we investigated phytoplankton‐zooplankton trophic links in contrasting oligotrophic and eutrophic conditions. Size fractionated particulate matter (pico‐POM, nano‐POM, and micro‐POM) and zooplankton (64 to >4000 μm) composition and carbon and nitrogen stable isotope ratios were measured inside and outside the nutrient‐rich deep convection zone in the central Liguro‐Provencal basin. In winter, phytoplankton biomass was low (0.28 mg m−3) and evenly spread among picophytoplankton, nanophytoplankton, and microphytoplankton. Using an isotope mixing model, we estimated average contributions to zooplankton biomass by pico‐POM, nano‐POM, and micro‐POM of 28, 59, and 15%, respectively. In spring, the nutrient poor region outside the convection zone had low phytoplankton biomass (0.58 mg m−3) and was dominated by pico/nanophytoplankton. Estimated average contributions to zooplankton biomass by pico‐POM, nano‐POM, and micro‐POM were 64, 28 and 10%, respectively, although the model did not differentiate well between pico‐POM and nano‐POM in this region. In the deep convection zone, spring phytoplankton biomass was high (1.34 mg m−3) and dominated by micro/nano phytoplankton. Estimated average contributions to zooplankton biomass by pico‐POM, nano‐POM, and micro‐POM were 42, 42, and 20%, respectively, indicating that a large part of the microphytoplankton biomass may have remained ungrazed.
Homogeneity testing for spatially correlated data in multivariate regional frequency analysis
Authors: Šimková Tereza
Published: July 2017

Identification of homogeneous regions is a key task in regional frequency analysis (RFA) to obtain adequate quantile estimates for an event of interest. Recently, the frequently used univariate Hosking‐Wallis L‐moment homogeneity test was extended to the multivariate case. Multivariate L‐moments are used as a tool to define the test statistic and copula models to describe the statistical behavior of the analyzed dependent variables. To avoid drawbacks in fitting a parametric joint distribution to the data and a rejection threshold which is based on simulations, its nonparametric alternatives were also proposed. Although the simulation studies performed demonstrated the usefulness of both the parametric and nonparametric tests, the powers obtained were valid only for regions without intersite dependence. Examples from practice nevertheless demonstrate that intersite correlation may be expected for some kinds of data. To overcome the problem of cross correlation between stations, the parametric testing procedure is generalized using D‐vine copulas to model intersite dependence when generating synthetic homogeneous regions during the testing procedure. Monte Carlo simulations were performed and illustrate how intersite dependence negatively impacts the multivariate L‐moment homogeneity tests by significantly reducing their powers. The results of simulations also demonstrate the superiority of the proposed modification over both the original parametric and nonparametric procedures inasmuch as it improves the heterogeneity detection and avoids miscategorization of a region. The modified test is also applied in a case study for meteorological data in the Czech Republic.
Adaptation to flood risk: Results of international paired flood event studies
Authors: Kreibich Heidi , Di Baldassarre Giuliano , Vorogushyn Sergiy , Aerts Jeroen C. J. H. , Apel Heiko , Aronica Giuseppe T. , Arnbjerg‐Nielsen Karsten , Bouwer Laurens M. , Bubeck Philip , Caloiero Tommaso , Chinh Do T. , Cortès Maria , Gain Animesh K. , Giampá Vincenzo , Kuhlicke Christian , Kundzewicz Zbigniew W. , Llasat Maria Carmen , Mård Johanna , Matczak Piotr , Mazzoleni Maurizio , Molinari Daniela , Dung Nguyen V. , Petrucci Olga , Schröter Kai , Slager Kymo , Thieken Annegret H. , Ward Philip J. , Merz Bruno
Published: July 2017

As flood impacts are increasing in large parts of the world, understanding the primary drivers of changes in risk is essential for effective adaptation. To gain more knowledge on the basis of empirical case studies, we analyze eight paired floods, that is, consecutive flood events that occurred in the same region, with the second flood causing significantly lower damage. These success stories of risk reduction were selected across different socioeconomic and hydro‐climatic contexts. The potential of societies to adapt is uncovered by describing triggered societal changes, as well as formal measures and spontaneous processes that reduced flood risk. This novel approach has the potential to build the basis for an international data collection and analysis effort to better understand and attribute changes in risk due to hydrological extremes in the framework of the IAHSs Panta Rhei initiative. Across all case studies, we find that lower damage caused by the second event was mainly due to significant reductions in vulnerability, for example, via raised risk awareness, preparedness, and improvements of organizational emergency management. Thus, vulnerability reduction plays an essential role for successful adaptation. Our work shows that there is a high potential to adapt, but there remains the challenge to stimulate measures that reduce vulnerability and risk in periods in which extreme events do not occur.
Using 3‐D‐printed analogues to investigate the fall speeds and orientations of complex ice particles
Authors: Westbrook C. D. , Sephton E. K.
Published: July 2017

The terminal velocity vt and preferred orientations of ice particles have been investigated using 3‐D‐printed analogues sedimenting in glycerine solutions at Reynolds numbers typical of natural ice particles falling in air. Twenty‐two different particle geometries were investigated: these included both simple shapes, such as hexagonal plates, and more complex particles, such as bullet rosettes, plate polycrystals, and aggregates. Two widely used prescriptions for ice particle fall speed were tested against the new experimental data, to determine the accuracy of their predictions. We show that for open particles, such as bullet rosettes and aggregates, one of these prescriptions systematically overestimates vt, by as much as 80%.
Emerging European winter precipitation pattern linked to atmospheric circulation changes over the North Atlantic region in recent decades
Authors: Ummenhofer Caroline C. , Seo Hyodae , Kwon Young‐Oh , Parfitt Rhys , Brands Swen , Joyce Terrence M.
Published: July 2017

Dominant European winter precipitation patterns over the past century, along with their associated extratropical North Atlantic circulation changes, are evaluated using cluster analysis. Contrary to the four regimes traditionally identified based on daily wintertime atmospheric circulation patterns, five distinct seasonal precipitation regimes are detected here. Recurrent precipitation patterns in each regime are linked to changes in atmospheric blocking, storm track, and sea surface temperatures across the North Atlantic region. Multidecadal variability in the frequency of the precipitation patterns reveals more (fewer) winters with wet conditions in northern (southern) Europe in recent decades and an emerging distinct pattern of enhanced wintertime precipitation over the northern British Isles. This pattern has become unusually common since the 1980s and is associated with changes in moisture transport and more frequent atmospheric river events. The observed precipitation changes post‐1950 coincide with changes in storm track activity over the central/eastern North Atlantic toward the northern British Isles.
Remarkable separability of circulation response to Arctic sea ice loss and greenhouse gas forcing
Authors: McCusker K. E. , Kushner P. J. , Fyfe J. C. , Sigmond M. , Kharin V. V. , Bitz C. M.
Published: July 2017

Arctic sea ice loss may influence midlatitude climate by changing large‐scale circulation. The extent to which climate change can be understood as greenhouse gas‐induced changes that are modulated by this loss depends on how additive the responses to the separate influences are. A novel sea ice nudging methodology in a fully coupled climate model reveals that the separate effects of doubled atmospheric carbon dioxide (CO2) concentrations and associated Arctic sea ice loss are remarkably additive and insensitive to the mean climate state. This separability is evident in several fields throughout most of the year, from hemispheric to synoptic scales. The extent to which the regional response to sea ice loss sometimes agrees with and sometimes cancels the response to CO2 is quantified. The separability of the responses might provide a means to better interpret the diverse array of modeling and observational studies of Arctic change and influence.
Submarine landslide and tsunami hazards offshore southern Alaska: Seismic strengthening versus rapid sedimentation
Authors: Sawyer Derek E. , Reece Robert S. , Gulick Sean P. S. , Lenz Brandi L.
Published: July 2017

The southern Alaskan offshore margin is prone to submarine landslides and tsunami hazards due to seismically active plate boundaries and extreme sedimentation rates from glacially enhanced mountain erosion. We examine the submarine landslide potential with new shear strength measurements acquired by Integrated Ocean Drilling Program Expedition 341 on the continental slope and Surveyor Fan. These data reveal lower than expected sediment strength. Contrary to other active margins where seismic strengthening enhances slope stability, the high‐sedimentation margin offshore southern Alaska behaves like a passive margin from a shear strength perspective. We interpret that seismic strengthening occurs but is offset by high sedimentation rates and overpressure. This conclusion is supported by shear strength outside of the fan that follow an active margin trend. More broadly, seismically active margins with wet‐based glaciers are susceptible to submarine landslide hazards because of the combination of high sedimentation rates and earthquake shaking.
Triggering of volcanic eruptions by large earthquakes
Authors: Nishimura Takeshi
Published: July 2017

When a large earthquake occurs near an active volcano, there is often concern that volcanic eruptions may be triggered by the earthquake. In this study, recently accumulated, reliable data were analyzed to quantitatively evaluate the probability of the occurrence of new eruptions of volcanoes located near the epicenters of large earthquakes. For volcanoes located within 200 km of large earthquakes of magnitude 7.5 or greater, the eruption occurrence probability increases by approximately 50% for 5 years after the earthquake origin time. However, no significant increase in the occurrence probability of new eruptions was observed at distant volcanoes or for smaller earthquakes. The present results strongly suggest that new eruptions are likely triggered by static stress changes and/or strong ground motions caused by nearby large earthquakes. This is not similar to the previously presented evidence that volcanic earthquakes at distant volcanoes are remotely triggered by surface waves generated by large earthquakes.
Impact of M‐solar flare‐induced solar proton event on mesospheric Na layer over Utah (41.8°N,112°W)
Authors: Bag Tikemani
Published: July 2017

The influence of solar proton event, induced by M‐solar flare, on the mesospheric sodium layer is studied over a midlatitude location Utah(41.8°N, 112°W) during 19 July 2012. The variation in sodium concentration (cm−3) is examined with temperature and atomic oxygen concentration obtained from NRLMSISE‐00 empirical model. In the vicinity of peak sodium concentration, the temperature shows a strong negative correlation with sodium concentration, atomic oxygen concentration shows a positive correlation with sodium concentration. An enhancement in sodium concentration is observed during the solar proton event with highest concentration at the time of maximum proton flux. The altitude of peak sodium concentration shows a downward movement with lowest altitude corresponding to the time of maximum proton flux. However, the altitude of peak sodium concentration is found in the altitude region of 85–90 km throughout the solar proton event.
Generation of rising‐tone chorus in a two‐dimensional mirror field by using the general curvilinear PIC code
Authors: Ke Yangguang , Gao Xinliang , Lu Quanming , Wang Xueyi , Wang Shui
Published: July 2017

Recently, the generation of rising‐tone chorus has been implemented with one‐dimensional (1‐D) particle‐in‐cell (PIC) simulations in an inhomogeneous background magnetic field, where both the propagation of waves and motion of electrons are simply forced to be parallel to the background magnetic field. In this paper, we have developed a two‐dimensional (2‐D) general curvilinear PIC simulation code and successfully reproduced rising‐tone chorus waves excited from an anisotropic electron distribution in a 2‐D mirror field. Our simulation results show that whistler waves are mainly generated around the magnetic equator and continuously gain growth during their propagation toward higher‐latitude regions. The rising‐tone chorus waves are observed off the magnetic equator, which propagate quasi‐parallel to the background magnetic field with the wave normal angle smaller than 25°. Due to the propagating effect, the wave normal angle of chorus waves is increasing during their propagation toward higher‐latitude regions along an enough curved field line. The chirping rate of chorus waves is found to be larger along a field line with a smaller curvature.
Self‐consistent formation of a 0.5 cyclotron frequency gap in magnetospheric whistler mode waves
Authors: Ratcliffe H. , Watt C. E. J.
Published: July 2017

Decades of in situ observations of whistler mode waves in Earth's magnetosphere reveal that there is frequently a gap in the spectral power at around half the local electron gyrofrequency. Recent theoretical and kinetic simulation studies have suggested that the gap arises due to the presence of temperature anisotropy in both a “warm” and a “hot” electron population, leading to two separate (and independent) regions of wave growth in frequency space. We present two‐dimensional kinetic plasma simulations using the powerful EPOCH (Extendable PIC Open Collaboration) particle‐in‐cell code that offer an alternative explanation. After an initial linear‐growth period, our simulations show self‐consistent formation of a gap feature. In most cases this arises where linear theory predicts the maximum growth rate and is associated with subtle local structuring of the hot electron distributions. This feature persists in multiple simulations with varying hot electron parameters. We discuss these results in the context of in situ observations of both waves and electron distribution functions and argue that the rapid reorganization of electron distributions in a small, but key, region of phase space during the growth of whistler mode waves naturally results in the spectral gap often observed at half the electron gyrofrequency.
Stress‐dependent permeability and wave dispersion in tight cracked rocks: Experimental validation of simple effective medium models
Authors: Sarout Joel , Cazes Emilie , Delle Piane Claudio , Arena Alessio , Esteban Lionel
Published: July 2017

We experimentally assess the impact of microstructure, pore fluid, and frequency on wave velocity, wave dispersion, and permeability in thermally cracked Carrara marble under effective pressure up to 50 MPa. The cracked rock is isotropic, and we observe that (1) P and S wave velocities at 500 kHz and the low‐strain (<10−5) mechanical moduli at 0.01 Hz are pressure‐dependent, (2) permeability decreases asymptotically toward a small value with increasing pressure, (3) wave dispersion between 0.01 Hz and 500 MHz in the water‐saturated rock reaches a maximum of ~26% for S waves and ~9% for P waves at 1 MPa, and (4) wave dispersion virtually vanishes above ~30 MPa. Assuming no interactions between the cracks, effective medium theory is used to model the rock's elastic response and its permeability. P and S wave velocity data are jointly inverted to recover the crack density and effective aspect ratio. The permeability data are inverted to recover the cracks' effective radius. These parameters lead to a good agreement between predicted and measured wave velocities, dispersion and permeability up to 50 MPa, and up to a crack density of ~0.5. The evolution of the crack parameters suggests that three deformation regimes exist: (1) contact between cracks' surface asperities up to ~10 MPa, (2) progressive crack closure between ~10 and 30 MPa, and (3) crack closure effectively complete above ~30 MPa. The derived crack parameters differ significantly from those obtained by analysis of 2‐D electron microscope images of thin sections or 3‐D X‐ray microtomographic images of millimeter‐size specimens.
Annual nitrate drawdown observed by SOCCOM profiling floats and the relationship to annual net community production
Authors: Johnson Kenneth S. , Plant Joshua N. , Dunne John P. , Talley Lynne D. , Sarmiento Jorge L.
Published: July 2017

Annual nitrate cycles have been measured throughout the pelagic waters of the Southern Ocean, including regions with seasonal ice cover and southern hemisphere subtropical zones. Vertically resolved nitrate measurements were made using in situ ultraviolet spectrophotometer (ISUS) and submersible ultraviolet nitrate analyzer (SUNA) optical nitrate sensors deployed on profiling floats. Thirty‐one floats returned 40 complete annual cycles. The mean nitrate profile from the month with the highest winter nitrate minus the mean profile from the month with the lowest nitrate yields the annual nitrate drawdown. This quantity was integrated to 200 m depth and converted to carbon using the Redfield ratio to estimate annual net community production (ANCP) throughout the Southern Ocean south of 30°S. A well‐defined, zonal mean distribution is found with highest values (3–4 mol C m−2 yr−1) from 40 to 50°S. Lowest values are found in the subtropics and in the seasonal ice zone. The area weighted mean was 2.9 mol C m−2 yr−1 for all regions south of 40°S. Cumulative ANCP south of 50°S is 1.3 Pg C yr−1. This represents about 13% of global ANCP in about 14% of the global ocean area.
Heartbeat of the Southern Oscillation explains ENSO climatic resonances
Authors: Bruun John T. , Allen J. Icarus , Smyth Timothy J.
Published: July 2017

The El Niño‐Southern Oscillation (ENSO) nonlinear oscillator phenomenon has a far reaching influence on the climate and human activities. The up to 10 year quasi‐period cycle of the El Niño and subsequent La Niña is known to be dominated in the tropics by nonlinear physical interaction of wind with the equatorial waveguide in the Pacific. Long‐term cyclic phenomena do not feature in the current theory of the ENSO process. We update the theory by assessing low (>10 years) and high (<10 years) frequency coupling using evidence across tropical, extratropical, and Pacific basin scales. We analyze observations and model simulations with a highly accurate method called Dominant Frequency State Analysis (DFSA) to provide evidence of stable ENSO features. The observational data sets of the Southern Oscillation Index (SOI), North Pacific Index Anomaly, and ENSO Sea Surface Temperature Anomaly, as well as a theoretical model all confirm the existence of long‐term and short‐term climatic cycles of the ENSO process with resonance frequencies of {2.5, 3.8, 5, 12–14, 61–75, 180} years. This fundamental result shows long‐term and short‐term signal coupling with mode locking across the dominant ENSO dynamics. These dominant oscillation frequency dynamics, defined as ENSO frequency states, contain a stable attractor with three frequencies in resonance allowing us to coin the term Heartbeat of the Southern Oscillation due to its characteristic shape. We predict future ENSO states based on a stable hysteresis scenario of short‐term and long‐term ENSO oscillations over the next century.
Validation of the MIPAS CO2 volume mixing ratio in the mesosphere and lower thermosphere and comparison with WACCM simulations
Authors: López‐Puertas Manuel , Funke B. , Jurado‐Navarro Á. A. , García‐Comas M. , Gardini A. , Boone C. D. , Rezac L. , Garcia R. R.
Published: July 2017

We present the validation of Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) CO2 daytime concentration in the mesosphere and lower thermosphere by comparing with Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) data. MIPAS shows a very good agreement with ACE below 100 km with differences of ∼5%. Above 100 km, MIPAS CO2 is generally lower than ACE with differences growing from ∼5% at 100 km to 20–40% near 110–120 km. Part of this disagreement can be explained by the lack of a nonlocal thermodynamic equilibrium correction in ACE. MIPAS also agrees very well (∼5%) with SABER below 100 km. At 90–105 km, MIPAS is generally smaller than SABER by 10–30% in the polar summers. At 100–120 km, MIPAS and SABER CO2 agree within ∼10% during equinox but, for solstice, MIPAS is larger by 10–25%, except near the polar summer. Whole Atmosphere Community Climate Model (WACCM) CO2 shows the major MIPAS features. At 75–100 km, the agreement is very good (∼5%), with maximum differences of ∼10%. At 95–115 km MIPAS CO2 is larger than WACCM by 20–30% in the winter hemisphere but smaller (20–40%) in the summer. Above 95–100 km WACCM generally overestimates MIPAS CO2 by about 20–80% except in the polar summer where underestimates it by 20–40%. MIPAS CO2 favors a large eddy diffusion below 100 km and suggests that the meridional circulation of the lower thermosphere is stronger than in WACCM. The three instruments and WACCM show a clear increase of CO2 with time, more markedly at 90–100 km.
Azodicarbonamid [MAK Value Documentation in German language, 2017]
Authors: Lessmann H. , Kreis P. , Hartwig A. ,   MAK Commission
Published: July 2017

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has evaluated azodicarbonamide [123‐77‐3] to derive a maximum concentration at the workplace (MAK value), considering all toxicological endpoints. Available publications and unpublished study reports are described in detail. The critical effect is the occurrence of reactions in the airways in exposed workers. In the view of the Commission, the present inhalation studies in animals are not appropriate for the derivation of a MAK value as human airways are probably more sensitive than rodent airways. The workplace investigations show no clear correlation of exposure and frequency of respiratory symptoms. Nevertheless, from the NOAEC of 36 µg/m3for lung function measurements in a small group of injection‐molding workers in the plastics industry, a MAK value of 20 µg/m3 I is established. Due to the incomplete information on the relevant exposure scenario and the uncertainty regarding first occurrence of workplace related symptoms, this value should be considered as preliminary. As local effects are critical, azodicarbonamide is assigned to Peak Limitation Category I and the default excursion factor of 1 is designated. Since developmental toxicity studies are not available, Pregnancy Risk Group D is assigned. There are no carcinogenicity studies and azodicarbonamide is not regarded as germ cell mutagen. Skin contact is not expected to contribute significantly to systemic toxicity. The metabolism of azodicarbonamide and its reactivity do not point to stable protein binding in vivo and therefore, skin or respiratory sensitization is unlikely. Clear‐cut clinical findings or positive results from animal studies on skin sensitization are not available, but the negative results in experimental animals are difficult to evaluate due to the low solubility of the compound. Although azodicarbonamide affects the respiratory tract in several case reports with positive bronchial provocation tests, sensitization by a known mechanism is not adequately verified. Additionally, it appears questionable whether a mono‐causal relationship of respiratory symptoms and azodicarbonamide exposure can really be assumed. In conclusion, a sensitizing effect of azodicarbonamide is not sufficiently proven.
Calcium oxide [MAK Value Documentation, 2014]
Authors: Hartwig A. ,   MAK Commission
Published: July 2017

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has derived a maximum concentration at the work place (MAK value) for calcium oxide [
1305‐78‐8
], considering all toxicity endpoints. The critical effect of calcium oxide is irritation of eyes and upper airways. From studies in volunteers with calcium oxide, a MAK value of 1 mg/m
3
for the inhalable fraction is derived. Since local effects are critical, calcium oxide is assigned to Peak Limitation Category I and as there were no irritation effects after 20 minutes exposure to 2 mg/m
3
, an excursion factor of 2 is set. Studies with calcium oxide show that damage to the embryo or foetus is unlikely when the MAK value is observed and the substance is assigned to Pregnancy Risk Group C. Calcium oxide is neither genotoxic nor carcinogenic. Skin contact is not expected to contribute significantly to systemic toxicity or to lead to sensitization.
Dimethyl sulfoxide (DMSO) [MAK Value Documentation, 2011]
Authors: Hartwig A. ,   MAK Commission
Published: July 2017

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the designation with “H” (for substances for which skin contact is expected to contribute significantly to the systemic toxicity) for DMSO [67‐68‐5]. Based on a diffusion cell study with excised human skin, 35.2 g DMSO (about 500 mg/kg body weight) would be dermally absorbed each hour through an area of 2000 cm
2
of skin. This amount corresponds to about half of the LOAEL (lowest observed adverse effect level) established in volunteers. Therefore, skin contact is expected to contribute significantly to the systemic toxicity of DMSO, and DMSO is still designated with an “H”.
Dimethyl sulfoxide (DMSO) [MAK Value Documentation, 2016]
Authors: Hartwig A. ,   MAK Commission
Published: July 2017

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the work place (MAK value) of dimethyl sulfoxide [67‐68‐5] of 50 ml/m3, considering the endpoints local and systemic toxicity as well as developmental toxicity. In a 13‐week inhalation study the olfactory and respiratory epithelia and the pharynx of rats are the target tissues, and a reduction of body weight gain, possibly secondary to the irritation, is seen. The NOAEC for these effects is 964 mg/m3(297 ml/m3, vapour). Since 2014 the Commission uses an empirical approach to set MAK‐values for substances with critical effects on the upper respiratory tract or the eyes. According to this approach, a MAK value of 50 ml/m3can be calculated from this study, taking into account that a lower NOAEC has to be expected with chronic exposure. Therefore, the previous MAK value is confirmed. As local effects are critical, the assignment to Peak Limitation Category I and the excursion factor of 2 are confirmed. In a screening study with rats according to OECD test guideline 421, the borderline increase in incidences of pups with dilated renal pelvis seen in a developmental toxicity study, are not confirmed. However, in rabbits, dimethyl sulfoxide causes kidney malformations with a NOAEL of 300 mg/kg body weight. Therefore, damage to the embryo or foetus cannot be excluded even when the MAK value is observed and dimethyl sulfoxide is assigned to Pregnancy Risk Group B.
Structure‐function relationships in the visual system in multiple sclerosis: an MEG and OCT study
Authors: Tewarie Prejaas , Balk Lisanne J. , Hillebrand Arjan , Steenwijk Martijn D. , Uitdehaag Bernard M. J. , Stam Cornelis J. , Petzold Axel
Published: July 2017

Background

We conducted a multi‐modal optical coherence tomography (OCT) and magnetoencephalography (MEG) study to test whether there is a relationship between retinal layer integrity and electrophysiological activity and connectivity (FC) in the visual network influenced by optic neuritis (ON) in patients with multiple sclerosis (MS).

Methods

One hundred and two MS patients were included in this MEG/OCT study. Retinal OCT data were collected from the optic discs, macular region, and segmented. Neuronal activity and FC in the visual cortex was estimated from source‐reconstructed resting‐state MEG data by computing relative power and the phase lag index (PLI). Generalized estimating equations (GEE) were used to account for intereye within‐patient dependencies.

Results

There was a significant relationship for both relative power and FC in the visual cortex with retinal layer thicknesses. The findings were influenced by the presence of MSON, particularly for connectivity in the alpha bands and the outer macular layers. In the absence of MSON, this relationship was dominated by the lower frequency bands (theta, delta) and inner and outer retinal layers.

Conclusion

These results suggest that visual cortex FC more than activity alters in the presence of MSON, which may guide the understanding of FC plasticity effects following MSON.
Impact of diabetes in the Friedreich ataxia clinical outcome measures study
Authors: McCormick Ashley , Farmer Jennifer , Perlman Susan , Delatycki Martin , Wilmot George , Matthews Katherine , Yoon Grace , Hoyle Chad , Subramony Sub H. , Zesiewicz Theresa , Lynch David R. , McCormack Shana E.
Published: July 2017

Objective

Friedreich ataxia (FA) is a progressive neuromuscular disorder caused byGAAtriplet repeat expansions or point mutations in theFXNgene.FAis associated with increased risk of diabetes mellitus (DM). This study assessed the age‐specific prevalence ofFA‐associatedDMand its impact on neurologic outcomes.

Research Design and Methods

Participants were 811 individuals withFAfrom 12 international sites in a prospective natural history study (FAClinical Outcome Measures Study,FACOMS). Physical function was assessed, using validated instruments. Multivariable regression analyses examined the independent association ofDMwith outcomes.

Results

Mean age of participants was 30.1 years (SD15.3, range: 7–82), 50% were female, and 94% were non‐Hispanic white. 9% (42/459) of adults and 3% (10/352) of children hadDM. Individuals withFA‐associatedDMwere older (P< 0.001), had longerGAArepeat length on the least affectedFXNallele (P= 0.037), and more severeFA(P= 0.0001). Of individuals withDM, 65% (34/52) were taking insulin. Even after accounting statistically for both age andGAArepeat length,DMwas independently associated with greaterFAsymptom burden (P= 0.010), reduced capacity to perform activities of daily living (P= 0.021), and a decrease of 0.33SDs on a composite performance measure (95%CI: −0.56–0.11,P= 0.004); the relative impact ofDMwas most apparent in younger individuals.

Conclusions

DM‐associatedFAhas an independent adverse impact on well‐being in affected individuals, particularly at younger ages. In future, evidence‐based approaches for identification and management ofFA‐relatedDMmay improve both health and function.
Observer‐based adaptive control for stochastic nonstrict‐feedback systems with unknown backlash‐like hysteresis
Authors: Bai Lu , Zhou Qi , Wang Lijie , Yu Zhandong , Li Hongyi
Published: July 2017

This paper studies an observer‐based adaptive fuzzy control problem for stochastic nonlinear systems in nonstrict‐feedback form. The unknown backlash‐like hysteresis is considered in the systems. In the design process, the unknown nonlinearities and unavailable state variables are tackled by introducing the fuzzy logic systems and constructing a fuzzy observer, respectively. By using adaptive backstepping technique with dynamic surface control technique, an adaptive fuzzy control algorithm is developed. For the closed‐loop system, the proposed controller can guarantee all the signals are 4‐moment semiglobally uniformly ultimately bounded. Finally, simulation results further show the effectiveness of the presented control scheme.
Distributed adaptive iterative learning control for nonlinear multiagent systems with state constraints
Authors: Shen D. , Xu J.‐X.
Published: July 2017

This paper addresses the consensus problem of nonlinear multiagent system with state constraints. A novel γ‐type barrier Lyapunov function is adopted to handle with the bounded constraints. The iterative learning control strategy is introduced to estimate the unknown parameter and basic control signal. Five control schemes are designed, in turn, to address the consensus problem comprehensively from both theoretical and practical viewpoints. These schemes include the original adaptive scheme, projection‐based scheme, smooth function‐based scheme and its alternative, and dead‐zone–like scheme. The consensus convergence and constraints guarantee are strictly proved for each control scheme by using the barrier composite energy function approach. Illustrative simulations verify the theoretical analysis.
Compressive Response and Energy Absorption Characteristics of In Situ Grown CNT‐Reinforced Al Composite Foams
Authors: Yang Xudong , Yang Kunming , Wang Jiwei , Shi Chunsheng , He Chunnian , Li Jiajun , Zhao Naiqin
Published: July 2017

Carbon nanotube (CNT) reinforced Al composite foams with different CNT contents are fabricated through an improved powder metallurgy approach by combining in‐situ chemical vapor deposition (CVD), short time ball‐milling, and space‐holder method. The CNTs are uniformly dispersed on the surface of Al particles by in‐situ CVD process, followed by a short time ball‐milling process enabling an excellent interfacial bonding between CNTs and the Al matrix. The pore size and microstructures of the composite foams can be well tailored by the carbamide particle templates. The yield strength and energy absorption capacity of composite foams reach 18.1 MPa and 15.8 MJ m−3 with 3.0 wt% CNT addition, which are ≈1.3 and ≈3.6 times higher than those of pure Al foam, respectively. The energy absorption efficiency of the CNT/Al composite foams achieves a maximum of ≈0.86, when the CNT content is up to 3.0 wt%. Additionally, compressive and energy absorption properties of the CNT/Al composite foams increase with the increment of relative density. The failure mode of the Al foam changes from plastic mode to brittle mode combined with ductile mode, as a result of CNT addition.
Highly Transparent, Stretchable, and Self‐Healing Ionic‐Skin Triboelectric Nanogenerators for Energy Harvesting and Touch Applications
Authors: Parida Kaushik , Kumar Vipin , Jiangxin Wang , Bhavanasi Venkateswarlu , Bendi Ramaraju , Lee Pooi See
Published: July 2017

Recently developed triboelectric nanogenerators (TENGs) act as a promising power source for self‐powered electronic devices. However, the majority of TENGs are fabricated using metallic electrodes and cannot achieve high stretchability and transparency, simultaneously. Here, slime‐based ionic conductors are used as transparent current‐collecting layers of TENG, thus significantly enhancing their energy generation, stretchability, transparency, and instilling self‐healing characteristics. This is the first demonstration of using an ionic conductor as the current collector in a mechanical energy harvester. The resulting ionic‐skin TENG (IS‐TENG) has a transparency of 92% transmittance, and its energy‐harvesting performance is 12 times higher than that of the silver‐based electronic current collectors. In addition, they are capable of enduring a uniaxial strain up to 700%, giving the highest performance compared to all other transparent and stretchable mechanical‐energy harvesters. Additionally, this is the first demonstration of an autonomously self‐healing TENG that can recover its performance even after 300 times of complete bifurcation. The IS‐TENG represents the first prototype of a highly deformable and transparent power source that is able to autonomously self‐heal quickly and repeatedly at room temperature, and thus can be used as a power supply for digital watches, touch sensors, artificial intelligence, and biointegrated electronics.
Graphene Conformal‐Coated Ceramics in Arbitrary Shape Targeting Smart Widgets
Authors: Tan Lifang , Han Jiangli , Zuo Junlai , Huang Ke , Chen Jilei , Wang Chenxiao , Lu Wenjing , Fu Lei
Published: July 2017

The 2D atomic structure and fascinating properties of graphene provide new opportunities for the surface‐functionalization of the traditional structural materials to meet the demands for intelligent and informational applications. Conformal coating of graphene in any arbitrary‐shape, even 3D irregular shapes, is critical to the surface‐functionalized structural materials in their actual form for practical applications. Herein, as demonstrated by ceramics, this study successfully obtains graphene conformal‐coated ceramics via rationally designed a compatible strategy with the fabrication of traditional ceramics. The graphene films show intimate adherence on the arbitrary‐shaped ceramics and exhibit uniform distribution even on the concave and convex surfaces. With a practical scalability, the present work stimulates various applications of heating devices, electroluminescent devices, and touchpads in real‐life scenarios.
Regiodivergent Conjugate Addition Controlled by Rhodium(I) and Palladium(II) Catalysts: A Combined Computational and Experimental Study
Authors: Jung Hoimin , Lee Ansoo , Kim Jin , Kim Hyunwoo , Baik Mu‐Hyun
Published: July 2017

A new divergent catalytic method for the 1,4‐ and 1,6‐selective conjugate additions of arylboronic acids to α,β,γ,δ‐unsaturated imino esters mediated by two different transition metal systems was developed. The rhodium complex carrying briphos, a new bicyclic, bridgehead phosphoramidite ligand, showed excellent regioselectivity towards 1,4‐addition with product ratios of >50:1, whereas the palladium catalyst Pd(OPiv)2 reversed the regiochemistry to afford the 1,6‐product with mild levels of selectivity of ≈1:7. Both theoretical and experimental studies were utilized to understand the catalytic systems and to elucidate the molecular level mechanism leading to the selective reactions. Since Rh(I) and Pd(II) are both d8‐complexes, their electronic structures and binding behaviours can be compared. Our calculations suggest that the outcome of the catalysis in the Rh(I) system is under kinetic control, where the migratory insertion of the alkene is the step that determines the regiochemistry. When the Pd(II) catalyst is used, the regiochemistry is under thermodynamic control where the relative stability of the η3‐π‐allyl‐ over the η3‐aza‐π‐allyl‐intermediate dictates the selectivity at the 1,6‐migratory insertion step.

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MetILs3: A Strategy for High Density Energy Storage Using Redox‐Active Ionic Liquids
Authors: Small Leo J. , Pratt Harry D. , Staiger Chad L. , Anderson Travis M.
Published: July 2017

A systematic approach is presented for increasing the concentration of redox‐active species in electrolytes for nonaqueous redox flow batteries (RFBs). Starting with an ionic liquid consisting of a metal coordination cation (MetIL), ferrocene‐containing ligands and iodide anions are substituted incrementally into the structure. While chemical structures can be drawn for molecules with 10 m redox‐active electrons (RAE), practical limitations such as melting point and phase stability constrain the structures to 4.2 m RAE, a 2.3× improvement over the original MetIL. Dubbed “MetILs3,” these ionic liquids possess redox activity in the cation core, ligands, and anions. Throughout all compositions, infrared spectroscopy shows the ethanolamine‐based ligands primarily coordinate to the Fe2+ core via hydroxyl groups. Calorimetry conveys a profound change in thermophysical properties, not only in melting temperature but also in suppression of a cold crystallization only observed in the original MetIL. Square wave voltammetry reveals redox processes characteristic of each molecular location. Testing a laboratory‐scale RFB demonstrates Coulombic efficiencies >95% and increased voltage efficiencies due to more facile redox kinetics, effectively increasing capacity 4×. Application of this strategy to other chemistries, optimizing melting point and conductivity, can yield >10 m RAE, making nonaqueous RFB a viable technology for grid scale storage.
Cause‐specific mortality and cancer morbidity in 390 male workers exposed to high purity talc, a six‐decade follow‐up
Authors: Wergeland Ebba , Gjertsen Finn , Vos Linda , Grimsrud Tom K.
Published: July 2017

Background

This study updates information on mortality and cancer morbidity in a cohort of Norwegian talc workers.

Methods

Follow‐up was extended with 24 years, covering 1953‐2011. Comparisons were made with the general population and between subgroups within the cohort.

Results

Standardized mortality ratio for non‐malignant respiratory disease (NMRD) was 0.38 (95%CI: 0.18, 0.69) and for diseases of the circulatory system (CVD) 0.98 (95%CI: 0.82, 1.16). A non‐significantly increased NMRD risk was observed at high dust exposures. There were no deaths from pneumoconiosis.

Conclusions

With the clear limitations of a small cohort, our results do hint at an effect of talc dust on mortality from NMRD other than pneumoconiosis, covered by a strong and persisting healthy worker effect. Also, an effect on CVD mortality, masked by a healthy worker selection into the cohort cannot be ruled out. Excess mortality from pneumoconiosis seen in other studies, may reflect exposure to quartz and, possibly, bias due to comparability problems.
Out‐of‐Equilibrium Fluctuation‐Dissipation Relations Verified by the Electrical and Thermoelectrical AC‐Conductances in a Quantum Dot
Authors: Crépieux Adeline
Published: July 2017

The electrical and heat currents flowing through a quantum dot are calculated in the presence of a time‐modulated gate voltage with the help of the out‐of‐equilibrium Green function technique. From the first harmonics of the currents, we extract the electrical and thermoelectrical trans‐admittances and ac‐conductances. Next, by a careful comparison of the ac‐conductances with the finite‐frequency electrical and mixed electrical‐heat noises, we establish the fluctuation‐dissipation relations linking these quantities, which are thus generalized out‐of‐equilibrium for a quantum system. It is shown that the electrical ac‐conductance associated to the displacement current is directly linked to the electrical noise summed over reservoirs, whereas the relation between the thermoelectrical ac‐conductance and the mixed noise contains an additional term proportional to the energy step that the electrons must overcome when traveling through the junction. A numerical study reveals however that a fluctuation‐dissipation relation involving a single reservoir applies for both electrical and thermoelectrical ac‐conductances when the frequency dominates over the other characteristic energies.
Pikomolare Spuren von AmIII verursachen drastische Unterschiede in der Koordinationschemie von TbIII: ein Sprung über die “Gadoliniumecke”
Authors: Welch Jan M. , Müller Danny , Knoll Christian , Wilkovitsch Martin , Giester Gerald , Ofner Johannes , Lendl Bernhard , Weinberger Peter , Steinhauser Georg
Published: July 2017

Die Kristallisation von Terbium‐5,5′‐azobis[1H‐tetrazol‐1‐id] (ZT) in Gegenwart von Americium in Spurenmengen (ca. 50 Bq, ca. 1.6 pmol) resultiert in 1) der Anreicherung des Americium‐Tracers im kristallinen Feststoff und 2) einem Produkt mit anderer Kristallstruktur als jener, welche in Abwesenheit von Americium gebildet wird. Americium‐dotiertes [Tb(Am)(H2O)7ZT]2 ZT⋅10 H2O ist isostrukturell zu den ZT‐Verbindungen der leichten Lanthanoide (Ce–Gd) und nicht zu den ZT‐Verbindungen der schweren Lanthanoide (Tb–Lu; z. B. [Tb(H2O)8]2ZT3⋅6 H2O). Trotz eines 108‐fachen Tb‐Überschusses scheinen Spuren von Am die Tb‐Verbindung in eine Struktur zu zwingen, die normalerweise von den leichteren Lanthanoiden bevorzugt wird. Das Americium‐dotierte Material wurde mittels Einkristall‐Strukturbestimmung, Schwingungsspektroskopie, Neutronenaktivierungsanalyse und Rasterelektronenmikroskopie untersucht. Darüber hinaus wurde das Einschlussverhalten von ZT in Bezug auf Americium quantifiziert und ein Modell für den Kristallisationsvorgang vorgeschlagen.
Picomolar Traces of Americium(III) Introduce Drastic Changes in the Structural Chemistry of Terbium(III): A Break in the “Gadolinium Break”
Authors: Welch Jan M. , Müller Danny , Knoll Christian , Wilkovitsch Martin , Giester Gerald , Ofner Johannes , Lendl Bernhard , Weinberger Peter , Steinhauser Georg
Published: July 2017

The crystallization of terbium 5,5′‐azobis[1H‐tetrazol‐1‐ide] (ZT) in the presence of trace amounts (ca. 50 Bq, ca. 1.6 pmol) of americium results in 1) the accumulation of the americium tracer in the crystalline solid and 2) a material that adopts a different crystal structure to that formed in the absence of americium. Americium‐doped [Tb(Am)(H2O)7ZT]2 ZT⋅10 H2O is isostructural to light lanthanide (Ce–Gd) 5,5′‐azobis[1H‐tetrazol‐1‐ide] compounds, rather than to the heavy lanthanide (Tb–Lu) 5,5′‐azobis[1H‐tetrazol‐1‐ide] (e.g., [Tb(H2O)8]2ZT3⋅6 H2O) derivatives. Traces of Am seem to force the Tb compound into a structure normally preferred by the lighter lanthanides, despite a 108‐fold Tb excess. The americium‐doped material was studied by single‐crystal X‐ray diffraction, vibrational spectroscopy, radiochemical neutron activation analysis, and scanning electron microcopy. In addition, the inclusion properties of terbium 5,5′‐azobis[1H‐tetrazol‐1‐ide] towards americium were quantified, and a model for the crystallization process is proposed.
Thermal, mechanical, and dielectric properties of aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) layered composites
Authors: Yan Shicheng , Xue Yahong , Yang Yulin , Qi Xiaowen , Song Laizhou , Sun Yingbing
Published: July 2017

In this study, a novel aluminum phosphate (AlPO4) heat‐resistant layer reinforced with aluminum silicate fiber (ASF) was successfully compounded on a poly(ether sulfone) (PES) matrix via the preparation process of high‐temperature heat treatment and vacuum hot‐pressing sintering technique. The influence of the ASF content on the morphology, thermal, mechanical, and dielectric properties of the as‐fabricated aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) (ASF/AlPO4–PES) layered composite was investigated. The results reveal that the incorporation of aluminum silicate fiber/aluminum phosphate (ASF/AlPO4) heat‐resistant layer can significantly improve the thermal stability and mechanical performances of the PES matrix composites. Compared with the pristine PES, the ASF/AlPO4–PES layered composite containing 8.0 wt % ASF exhibited better high‐temperature resistance properties (300 °C) and a lower thermal conductivity (0.16 W m−1 K−1). Furthermore, the dielectric constant and dielectric loss tangent of this PES matrix composite decreased to 2.16 and 0.007, respectively. Meanwhile, the frequency stability of the dielectric properties for the ASF/AlPO4–PES layered composites was remarkably enhanced with increasing ASF addition at frequencies ranging from 102 Hz to 5 MHz. This was attributed to the existence of microscopic pores within the ASF/AlPO4 layer and the strong interfacial bonding between the ASF/AlPO4 layer and the PES matrix. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45542.