bluuebunny/crossref_metadata_2025 huggingface dataset:
Vanadium Dioxide: The Multistimuli Responsive Material and Its Applications
Authors: Ke Yujie , Wang Shancheng , Liu Guowei , Li Ming , White Timothy J. , Long Yi
Published: August 2018

The reversible, ultrafast, and multistimuli responsive phase transition of vanadium dioxide (VO2) makes it an intriguing “smart” material. Its crystallographic transition from the monoclinic to tetragonal phases can be triggered by diverse stimuli including optical, thermal, electrical, electrochemical, mechanical, or magnetic perturbations. Consequently, the development of high‐performance smart devices based on VO2 grows rapidly. This review systematically summarizes VO2‐based emerging technologies by classifying different stimuli (inputs) with their corresponding responses (outputs) including consideration of the mechanisms at play. The potential applications of such devices are vast and include switches, memories, photodetectors, actuators, smart windows, camouflages, passive radiators, resonators, sensors, field effect transistors, magnetic refrigeration, and oscillators. Finally, the challenges of integrating VO2 into smart devices are discussed and future developments in this area are considered.
The Influence of Carbon Nitride Nanosheets Doping on the Crystalline Formation of MIL‐88B(Fe) and the Photocatalytic Activities
Authors: Lei Zhen‐Dong , Xue Yuan‐Cheng , Chen Wen‐Qian , Li Lin , Qiu Wen‐Hui , Zhang Yong , Tang Liang
Published: August 2018

In this research, bulk graphitic carbon nitride (g‐C3N4) is exfoliated and transferred to the carbon nitride nanosheets (CNNSs), which are then coupled with MIL‐88B(Fe) to form the hybrid. From the results of the powder X‐ray diffraction, scanning electronic microscopy and thermogravimetric analysis, it is found that the doping of CNNSs on the surface of MIL‐88(Fe) could maintain the basic structure of MIL‐88B(Fe), and the smaller dimension of CNNSs might influence the crystallization process of metal‐organic frameworks (MOFs) compared to bulk g‐C3N4. Besides, the effects of the CNNSs incorporation on photocatalysis are also investigated. Through the photoluminescence spectra, electrochemical measurements, and photocatalytic experiments, the hybrid containing 6% CNNSs is certified to possess the highest catalytic activity to degrade methylene blue and reduce Cr(VI) under visible light. The improvement of the photocatalytic performance can be attributed to the matched energy level which favors the formation of the heterojunctions. Besides, it promotes the charge migration such that the contact between MOFs and CNNSs is more intimate, which can be inferred from the electronic microscopy images. Finally, a possible photocatalytic mechanism is put forward by the relative calculation and the employment of the scavengers to trap the active species.
Synthesis and Progress of New Oxygen‐Vacant Electrode Materials for High‐Energy Rechargeable Battery Applications
Authors: Wang Yuyin , Xiao Xiao , Li Qing , Pang Huan
Published: August 2018

During the last few years, a great amount of oxygen‐vacant materials have been synthetized and applied as electrodes for electrochemical storage. The presence of oxygen vacancies leads to an increase in the conductivity and the diffusion coefficient; consequently, the controllable synthesis of oxygen vacancy plays an important role in improving the electrochemical performance, including achieving high specific capacitance, high power density, high energy density, and good cycling stability of the electrode materials for batteries. This review mainly focuses on research progress in the preparation of oxygen‐vacant nanostructures and the application of materials with oxygen vacancies in various batteries (such as lithium‐ion, lithium–oxygen, and sodium‐ion batteries). Challenges related to and opportunities for oxygen‐vacant materials are also provided.
High‐Performance Biscrolled MXene/Carbon Nanotube Yarn Supercapacitors
Authors: Wang Zhiyu , Qin Si , Seyedin Shayan , Zhang Jizhen , Wang Jiangting , Levitt Ariana , Li Na , Haines Carter , Ovalle‐Robles Raquel , Lei Weiwei , Gogotsi Yury , Baughman Ray H. , Razal Joselito M.
Published: August 2018

Yarn‐shaped supercapacitors (YSCs) once integrated into fabrics provide promising energy storage solutions to the increasing demand of wearable and portable electronics. In such device format, however, it is a challenge to achieve outstanding electrochemical performance without compromising flexibility. Here, MXene‐based YSCs that exhibit both flexibility and superior energy storage performance by employing a biscrolling approach to create flexible yarns from highly delaminated and pseudocapacitive MXene sheets that are trapped within helical yarn corridors are reported. With specific capacitance and energy and power densities values exceeding those reported for any YSCs, this work illustrates that biscrolled MXene yarns can potentially provide the conformal energy solution for powering electronics beyond just the form factor of flexible YSCs.
Quantum Dot–Based FRET Immunoassay for HER2 Using Ultrasmall Affinity Proteins
Authors: Wu Yu‐Tang , Qiu Xue , Lindbo Sarah , Susumu Kimihiro , Medintz Igor L. , Hober Sophia , Hildebrandt Niko
Published: August 2018

Engineered scaffold affinity proteins are used in many biological applications with the aim of replacing natural antibodies. Although their very small sizes are beneficial for multivalent nanoparticle conjugation and efficient Förster resonance energy transfer (FRET), the application of engineered affinity proteins in such nanobiosensing formats has been largely neglected. Here, it is shown that very small (≈6.5 kDa) histidine‐tagged albumin‐binding domain‐derived affinity proteins (ADAPTs) can efficiently self‐assemble to zwitterionic ligand–coated quantum dots (QDs). These ADAPT–QD conjugates are significantly smaller than QD‐conjugates based on IgG, Fab', or single‐domain antibodies. Immediate applicability by the quantification of the human epidermal growth factor receptor 2 (HER2) in serum‐containing samples using time‐gated Tb‐to‐QD FRET detection on the clinical benchtop immunoassay analyzer KRYPTOR is demonstrated here. Limits of detection down to 40 × 10−12m (≈8 ng mL−1) are in a relevant clinical concentration range and outperform previously tested assays with antibodies, antibody fragments, and nanobodies.
High‐Throughput Optical Mapping of Replicating DNA
Authors: De Carli Francesco , Menezes Nikita , Berrabah Wahiba , Barbe Valérie , Genovesio Auguste , Hyrien Olivier
Published: August 2018

DNA replication is a crucial process for the universal ability of living organisms to reproduce. Genome‐wide methods to map DNA replication use large cell populations, which smoothes out variability between chromosomal copies. Single‐molecule methods may reveal this variability but remain refractory to automation, precluding genome‐wide analyses. Here, the Bionano Genomics Irys system, an optical DNA mapping device, is repurposed for high‐throughput optical mapping of replicating DNA (HOMARD). HOMARD combines direct fluorescent labeling of replication tracks and nicking endonuclease sites with DNA linearization in nanochannel arrays and dedicated image processing. The robustness of this approach is demonstrated by an ultrahigh coverage (23 311×) replication map of bacteriophage λ‐DNA in Xenopus egg extracts. This coverage, by far the highest ever reported for a single‐molecule replication study, confirms with unprecedented statistical significance the lack of sequence preference for replication initiation in this system. The tools developed here open the way to genome‐wide analysis of DNA replication at the single‐molecule level and may be readily adapted for similar studies of other epigenetic features.
Interpenetrated Bacteria‐Carbon Nanotubes Film for Microbial Fuel Cells
Authors: Kou Tianyi , Yang Yang , Yao Bin , Li Yat
Published: August 2018

Microbial fuel cells (MFCs) hold great potential for bioremediation and bioelectricity generation. To boost the power density of MFCs, tremendous efforts are devoted to improving the bioanode's design, mainly on increasing the bacteria‐accessible electrode surface area. However, even for porous electrodes, it is difficult to fully utilize the interior surface for bacteria colonization. While making the pores larger improves the mass transport of bacteria, it limits the total surface area per unit mass or volume, and thus, the loading number of bacteria. Here, a bacteria‐carbon nanotube (CNT) interpenetrated electrode structure is demonstrated that is capable of accommodating a large number of bacteria and offering a highly conductive network for charge transfer. The MFC device with the bacteria‐CNT composite film as the anode achieves a remarkable power density of 34 W m−3 (normalized to the volume of the anode chamber) and 12 102 W m−3 (normalized to the volume of the anode). In addition to high power density, the unique composite structure allows CNTs to have immediate and maximal access to the bacteria embedded in the electrode, and thus, skipping the step of biofilm formation and reaching the maximum current immediately.
Highly Efficient Non‐Fullerene Polymer Solar Cells Enabled by Wide Bandgap Copolymers With Conjugated Selenyl Side Chains
Authors: Li Zuojia , Xu Xiaopeng , Zhang Guangjun , Yu Ting , Li Ying , Peng Qiang
Published: August 2018

In this work, the authors design and synthesize two novel wide bandgap copolymers based on selenophene substituted benzo[1,2‐b:4,5‐b']dithiophene (BDTSe) as the donor unit and fluorinated benzotriazole as the acceptor unit for high performance non‐fullerene polymer solar cells (NF‐PSCs). A larger maximum molar extinction coefficient (ϵ) of 8.54 × 104 M−1 cm−1 is achieved when introducing sulfur atom onto the two‐dimensional (2D) BDTSe units, which should realize the better complementary absorption with ITIC as the acceptor, leading to a higher Jsc of 19.51 mA cm−2. Furthermore, a lower highest occupied molecular orbital (HOMO) energy level with almost no change in bandgap can be also achieved after inserting the sulfur atoms, thus resulting in an enhanced open‐circuit voltage (Voc) of 0.84 V without sacrificing the short‐current density (Jsc). In addition, the higher crystallinity and optimized morphology are found to be beneficial to more efficient exciton dissociation and charge transport, giving rise to a higher fill factor (FF) of 75.1% and an elevated power conversion efficiency (PCE) of 12.31%. The results indicate that the strategy of alkylthioselenyl side chains on the BDT unit for constructing the donor‐acceptor (D‐A) copolymer donor materials is an excellent approach for realizing highly efficient NF‐PSCs.
Influence of cyclic loading and frost on the behavior of bond of three‐wire strand
Authors: Jokūbaitis Aidas , Marčiukaitis Gediminas , Valivonis Juozas , Strauss Alfred
Published: August 2018

This paper presents the results of an experimental research investigating the influence of static and cyclic loading and frost impact on the bond between concrete and 6.2 mm three‐wire‐strand. From the pullout tests, it was determined that a cyclic load did not negatively influence the bond strength of three‐wire strand. On the contrary, the influence of cyclic loading after 200 freezing and thawing cycles resulted in a significant decrease of bond strength of three‐wire strand. Additionally, the new parameters for bond stress–slip relationship suggested in Model Code 2010 are proposed for the 6.2 mm three‐wire strand cast with concrete having compressive strength of 82.6 MPa with standard deviation of 6.65 MPa. The results of dynamic coefficient b for 6.2 mm three‐wire strand used in relationship between a slip of reinforcement and a number of loading cycles under unidirectional cyclic loading suggested in Model Code 2010 are analyzed.
Hybridization and Genetic Structure in Phenotypic Spotted Bass in Texas
Authors: Lutz‐Carrillo Dijar J. , Husemann Martin , Bean Preston T. , Williamson Jánaye C. , De Jesús Marcos J. , Ray Jesse W.
Published: August 2018

Hybridization is common in fishes and can result in a wide range of outcomes. The capture of a world record phenotypic Guadalupe BassMicropterus treculiiraised questions about potential hybridization with Spotted BassM. punctulatus. Subsequent, limited genetic sampling from the drainage (Colorado River) did not indicate hybridization in the world record sample or other phenotypic Guadalupe Bass, but phenotypic Spotted Bass produced unexpected genotypes. This called into question the assumed distribution of Spotted Bass in Texas. To address this disconnect, phenotypic Spotted Bass were acquired from drainages surrounding the Colorado River, ranging from central Texas to the Texas–Louisiana border, and the number of sequenced loci was expanded from one to seven. Results indicated that the westernmost extent of nonintrogressed Spotted Bass populations in Texas was the Trinity River. Phenotypic Spotted Bass west of this drainage were identified as Guadalupe Bass or hybrids. Admixed individuals identified in the San Antonio and Brazos River drainages (and previously in the Colorado River) may represent part of a hybrid zone. We also found that Spotted Bass from the Trinity River exhibited relatively large genetic divergence from Spotted Bass to the east and may represent the product of a vicariance event. Finally, we confirmed one mitochondrial and two nuclear taxa‐specific genetic markers for the efficient discrimination of these congeners and their hybrids. These markers should be useful for resource agencies attempting to enforce management regulations given the difficulty of identifying Spotted Bass by phenotype.
Fine’s Trilemma and the Reality of Tensed Facts
Authors: Loss Roberto ,   Philosophy Documentation Center
Published: August 2018

Fine (2005, 2006) has presented a ‘trilemma’ concerning the tense-realist idea that reality is constituted by tensed facts. According to Fine, there are only three ways out of the trilemma, consisting in what he takes to be the three main families of tense-realism: ‘presentism’, ‘(external) relativism’, and ‘fragmentalism’. Importantly, although Fine characterises tense-realism as the thesis that reality is constituted (at least in part) by tensed facts, he explicitly claims that tense realists are not committed to their fundamental existence. Recently, Correia and Rosenkranz (2011, 2012) have claimed that Fine’s tripartite map of tense realism is incomplete as it misses a fourth position they call ‘dynamic absolutism’. In this paper, I will argue that dynamic absolutists are committed to the irreducible existence of tensed facts and that, for this reason, they face a similar trilemma concerning the notion of fact-content. I will thus conclude that a generalised version of Fine’s trilemma, concerning both fact-constitution and fact-content, is indeed inescapable.
Re: In‐utero aspiration vs expectant management of anechoic fetal ovarian cysts: open randomized controlled trial. C. Diguisto , N. Winer , G. Benoist , H. Laurichesse‐Delmas , J. Potin , A. Binet , H. Lardy , B. Morel and F. Perrotin . Ultrasound Obstet Gynecol 2018; 52: 159–164.
Authors: D'Antonio F.
Published: August 2018

Linked Comment: Ultrasound Obstet Gynecol 2018; 52: 159–164
Association between pelvic floor muscle trauma and contraction in parous women from a general population
Authors: Nyhus M. Ø. , Salvesen K. Å. , Volløyhaug I.
Published: August 2018

Objective

To study possible associations between pelvic floor muscle contraction, levator ani muscle (LAM) trauma and/or pelvic organ prolapse (POP) ≥ Stage 2 in parous women recruited from a general population.

Methods

This was a secondary analysis of data from a cross‐sectional study of 608 parous women from a general population examined using the POP quantification system (POP‐Q) and three‐dimensional/four‐dimensional transperineal ultrasound for identification of LAM macrotrauma (avulsion) and microtrauma (distension of levator hiatal area > 75th percentile on Valsalva maneuver). Muscle contraction was assessed using the modified Oxford scale (MOS), perineometry and ultrasound measurement of proportional change of anteroposterior hiatal diameter and levator hiatal area at rest and on pelvic floor muscle contraction. The Mann–Whitney U‐test was used to study associations between pelvic floor muscle contraction, LAM trauma and POP.

Results

Women with macrotrauma (n = 113) had significantly weaker median pelvic floor muscle contraction, as measured using MOS and perineometry, than did women with an intact LAM (n = 493) (contraction strength was 1.5 (range, 0.0–5.0) vs 3.5 (range, 0.0–5.0) on MOS, and vaginal squeeze pressure was 15.0 (range, 0.0–78.0) cmH2O vs 28.0 (range, 0.0–129.0) cmH2O on perineometry; P < 0.001). This was also demonstrated by ultrasound measurement, with a proportional change in hiatal area of 19.9% (range, 4.1–48.0%) vs 34.0% (range, 0.0–64.0%) (P < 0.001) and proportional change in anteroposterior diameter of 16.2% (range, –5.7 to 42.6%) vs 26.0% (range, –3.4 to 49.4%) (P < 0.001). No statistically significant difference between women with (n = 65), and those without (n = 378), microtrauma was found after excluding women with macrotrauma. Women with POP had weaker muscle contraction than those without; in those with POP‐Q ≥ 2 (n = 275) compared with those with POP‐Q < 2 (n = 333), muscle contraction strength was 3.0 (range, 0.0–5.0) vs 3.5 (range, 0.0–5.0) on MOS, vaginal squeeze pressure was 21.0 (range, 0.0–98.0) cmH2O vs 28.0 (range, 3.0–129.0) cmH2O on perineometry, proportional change in hiatal area was 29.6% (range, 0.0–60.9%) vs 33.8% (range, 0.0–64.4%) and proportional change in anteroposterior diameter was 22.8% (range, –5.7 to 49.4%) vs 25.7% (range, –3.4 to 49.4%) (P < 0.001 for all).

Conclusions

LAM macrotrauma was associated with weaker pelvic floor muscle contraction measured using palpation, perineometry and ultrasound. Women with POP had weaker contraction than did women without POP. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.
Computation of the nonparametric maximum likelihood estimate of a univariate log‐concave density
Authors: Wang Yong
Published: August 2018

Algorithms for computing the nonparametric maximum likelihood estimate of a univariate log‐concave density are briefly described, and some relevant issues discussed. The fast few algorithms are further numerically compared in a small‐scale simulation study.

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Markov Chain Monte Carlo (MCMC)

Statistical and Graphical Methods of Data Analysis > Density Estimation

Statistical and Graphical Methods of Data Analysis > Nonparametric Methods

Algorithms and Computational Methods > Algorithms
To jump or not to jump: Mule deer and white‐tailed deer fence crossing decisions
Authors: Burkholder Emily N. , Jakes Andrew F. , Jones Paul F. , Hebblewhite Mark , Bishop Chad J.
Published: August 2018

Modified fencing structures have been recommended with the intention of enhancing ungulate movement. Ungulates such as mule deer (Odocoileus hemionus) and white‐tailed deer (O. virginianus) typically negotiate fences by jumping over them. We examined 2 fine‐scale fence crossing decisions to determine factors influencing 1) crossing success and 2) the mode of crossing by 2 sympatric deer species. From 2010 to 2016, we used remote cameras along fence lines in 2 study areas—Canadian Forces Base Suffield in southeastern Alberta, Canada, and The Nature Conservancy's Matador Ranch in north‐central Montana, USA—that captured images of deer–fence interactions before and after fence modifications were installed. We used logistic regression to model the probability of deer successfully crossing a fence and mode of crossing (jumping over vs. crawling under) based on fence characteristics and demographic factors. We documented 486 crossing attempts, of which 313 were successful (64.4%), indicating that pasture fences acted as a semipermeable barrier to deer. Of these 313 successful attempts, 152 crawled under the fence (48.6%) as opposed to jumping over it. We documented behavioral differences in mode of crossing between species when successfully crossing a fence. Results indicate that deer are selecting known crossing sites at broad scales as places to negotiate fences, and when assessing finer scale decisions at these sites, white‐tailed deer seemed to acclimate better than mule deer to our imposed changes (switched from crawling under to jumping over the fence). Though sample size was low in terms of use at modified fence sites, we recommend visually inconspicuous modifications (such as clips to increase the bottom wire height as opposed to goat‐bars) when implementing pasture fencing that was friendlier for deer. We also recommend modifications be implemented strategically; placement of modifications may be just as important to consider as the modification type. © 2018 The Wildlife Society.
Anhydrous Europium Phosphates: A Comprehensive Report on Syntheses, Crystal Structures, and Phase Relations
Authors: Grunwald Waldemar , Wittich Knut , Glaum Robert
Published: August 2018

In the ternary system Eu/P/O the anhydrous phosphates EuII3(PO4)2, EuII3EuIII(PO4)3, EuIII3O3(PO4), EuIIIPO4, EuIII(PO3)3, and EuIIIP5O14 exist at equilibrium conditions (ϑ ≈ 1000 °C). A superstructure model for EuII3EuIII(PO4)3 [Eulytite structure family, Fdd2, Z = 24, a = 14.298(1) Å, b = 42.123(3) Å, c = 10.3887(9) Å] is proposed. The results of single‐crystal X‐ray diffraction (SXRD) studies on EuII10–xEuIIIx(PO4)6O1+x/2 (x ≈ 1.5), EuIII3O3(PO4) and ht‐EuIII(PO3)3 are reported. The crystal structures of the thermodynamically metastable phases EuIII2P4O13 (isotypic to YIII2P4O13) and lt‐EuIII(PO3)3 (isotypic to GdIII(PO3)3) were refined from X‐ray powder diffraction data (XRPD). According to our investigation for the oxide phosphide “EuII4OP2” an europium deficiency has to be assumed according to EuII4–xEuIII2x/3OP2 (x ≈ 1.5).
Optimization of InP DHBT stacked-transistors for millimeter-wave power amplifiers
Authors: Squartecchia Michele , Johansen Tom K. , Dupuy Jean-Yves , Midili Virginio , Nodjiadjim Virginie , Riet Muriel , Konczykowska Agnieszka
Published: August 2018

In this paper, we report the analysis, design, and implementation of stacked transistors for power amplifiers realized on InP Double Heterojunction Bipolar Transistors (DHBTs) technology. A theoretical analysis based on the interstage matching between all the single transistors has been developed starting from the small-signal equivalent circuit. The analysis has been extended by including large-signal effects and layout-related limitations. An evaluation of the maximum number of transistors for positive incremental power and gain is also carried out. To validate the analysis, E-band three- and four-stacked InP DHBT matched power cells have been realized for the first time as monolithic microwave integrated circuits (MMICs). For the three-stacked transistor, a small-signal gain of 8.3 dB, a saturated output power of 15 dBm, and a peak power added efficiency (PAE) of 5.2% have been obtained at 81 GHz. At the same frequency, the four-stacked transistor achieves a small-signal gain of 11.5 dB, a saturated output power of 14.9 dBm and a peak PAE of 3.8%. A four-way combined three-stacked MMIC power amplifier has been implemented as well. It exhibits a linear gain of 8.1 dB, a saturated output power higher than 18 dBm, and a PAE higher than 3% at 84 GHz.
Heterogeneity of Doppler waveform description is decreased with the use of a dedicated classification
Authors: Omarjee Loukman , Stivalet Olivier , Hoffmann Clément , Scissons Robert , Bressollette Luc , Mahé Guillaume , Jaquinandi Vincent
Published: August 2018

Abstract. Background: The analysis of Doppler ultrasound waveforms (DW) provides a method for detecting and evaluating arterial stenosis in the lower limb arteries but no recommendation exists on how to describe the DWs. Aims of this study were to assess the heterogeneity of the description of DWs among vascular residents and the impact of the use of a 4-item classification. Methods: Thirty different DWs were presented to residents using Microsoft PowerPoint® slides. They were invited to describe the 30 DWs before and after the presentation of a 4-item classification (triphasic, biphasic, monophasic, and others). The heterogeneity was assessed by the number of different answers used by the residents. Nineteen residents with six to eighteen months of vascular medicine training and ultrasound experience were included. Results: The average of different answers was 9 ± 4 for the whole analysis of the 30 DWs without the use of a specific classification, whereas the average was 2 ± 1 using the 4-item classification (p < 0.005). There was a significant difference in correct answers, i. e. in combined continuous waveforms and pulsed waveforms between experienced residents and younger residents (p < 0.05). Conclusions: Using a 4-item classification for DWs reduced the heterogeneity of the DW description. There is an urgent need to standardize the DW description in order to improve the patients care with peripheral artery disease.
Tidal Flow Asymmetry Owing to Inertia and Waves on an Unstratified, Shallow Ebb Shoal
Authors: Wargula Anna , Raubenheimer Britt , Elgar Steve , Chen Jia‐Lin , Shi Fengyan , Traykovski Peter
Published: August 2018

Observations of water levels, waves, currents, and bathymetry collected for a month at an unstratified tidal inlet with a shallow (1 to 2 m deep) ebb shoal are used to evaluate the asymmetry in flows and dynamics owing to inertia and waves. Along‐channel currents ranged from −1.5 to 0.6 m/s (positive inland) inside the main (3 to 5 m deep) channel crossing the ebb shoal. Net discharge is negligible, and ebb dominance of the channel flows is owing to inflow and outflow asymmetries near the inlet mouth. Offshore wave heights ranged from 0.5 to 2.5 m. During moderate to large wave events (offshore significant wave heights >1.2 m), wave forcing enhanced onshore mass flux near the shoal edge and inside the inlet, leading to reduced ebb flow dominance. Momentum balances estimated with the water depths, currents, and waves simulated with a quasi 3‐D numerical model reproduce the momentum balances estimated from the observations reasonably well. Both observations and simulations suggest that ebb‐dominant bottom stresses are balanced by the ebb‐dominant pressure gradient and the tidally asymmetric inertia, which is a sink (source) of momentum on flood (ebb). Simulations with and without waves suggest that waves drive local and nonlocal changes in the water levels and flows. Specifically, breaking waves at the offshore edge of the ebb shoal induce setup and partially block the ebb jet (local effects), which leads to a more onshore‐directed mass flux, changes to the advection across the ebb shoal, and increased water levels inside the inlet mouth (nonlocal effects).
Annual and Semiannual Cycles of Diurnal Warming of Sea Surface Temperature in the South China Sea
Authors: Yan Yunwei , Wang Guihua , Chen Changlin , Ling Zheng
Published: August 2018

Based on the SeaFlux data set, an empirical parameterization, and a one‐dimensional ocean mixed‐layer model, the annual and semiannual cycles of diurnal warming of sea surface temperature (dSST) in the South China Sea (SCS) are examined. The amplitude of the annual cycle is greater than 0.1 °C, and the annual cycle reaches its maxima in April/May/June in most areas of the SCS, while the amplitude of the semiannual cycle of dSST increases from north to south with the month of its maxima changing from February to March along a northwest‐southeast axis. Relative to the amplitude of the annual cycle of dSST, the semiannual cycle is of much smaller amplitude north of 17°N, but of comparable or larger amplitude south of 17°N. The annual (semiannual) cycle of wind speed is the most important factor for the annual (semiannual) cycle of dSST. The annual (semiannual) cycle of wind speed drives the annual (semiannual) cycle of dSST primarily by influencing oceanic vertical turbulent mixing. Aside from these basin‐scale features, the dSST annual and semiannual cycles demonstrate robust mesoscale features in the lees of hills/islands as a result of sheltering from the monsoon.
Nighttime Mesospheric/Lower Thermospheric Tropical Ozone Response to the 27‐Day Solar Rotational Cycle: ENVISAT‐GOMOS Satellite Observations Versus HAMMONIA Idealized Chemistry‐Climate Model Simulations
Authors: Thiéblemont R. , Bekki S. , Marchand M. , Bossay S. , Schmidt H. , Meftah M. , Hauchecorne A.
Published: August 2018

Global Ozone Monitoring by Occultation of Stars (GOMOS) satellite data are analyzed to estimate the first observation‐based nighttime (22:00 median local time) ozone response to the 27‐day solar rotational cycle in the tropical mesosphere/lower thermosphere (50–110 km altitude). The ozone response to solar rotational variability is derived from linear correlation and regressions using Lyman‐α line (121.6 nm) as solar index that varies by about 10–15% over solar rotational cycles. In the lower mesosphere (50–70 km), the GOMOS ozone is found to be correlated with the solar fluctuations and exhibits a sensitivity of ~0.1 (expressed in percent change of ozone for 1% change in Lyman‐α). In the upper mesosphere/lower thermosphere (above 80 km), ozone variations become anticorrelated with solar rotational variations. In this region, the vertical profile of ozone sensitivity to the 27‐day solar cycle exhibits a maximum of 1.8 at 81 km, a minimum of 0.3 at 100 km, and a sharp increase above. Such high ozone sensitivities are observed for the first time. The observed ozone response is compared with chemistry‐climate simulations from the Hamburg model of the neutral and ionized atmosphere (HAMMONIA) that is forced with an idealized 27‐day solar spectral irradiance time series. Although observational and model results share some common features, substantial discrepancies are found. Namely, the altitude of transition from positive to negative solar ozone correlation signal in the model simulation is found about 10 km below the altitude of the observations and the amplitude of the ozone sensitivity is generally vastly underestimated by the model.
Assessment of the Shielding Effect of the Earth's Magnetic Field on Lunar OH/H2O
Authors: Cho E. , Yi Y. , Yu J. , Hong I. , Choi Y.
Published: August 2018

When the Moon passes through Earth's magnetosphere, it is believed that the amount of OH/H2O that would typically be created is reduced because the incident solar wind flux on the lunar surface decreases. To confirm this, we analyzed changes in OH/H2O absorption feature in the infrared region with or without the shielding effect of the magnetosphere using Moon Mineralogy Mapper (M3) data in low‐latitude regions. We report that the strength of absorption feature near 3 μm for the region from the equator up to the 10° latitude decreased when the Moon is inside Earth's magnetosphere relative to when it was outside of it. This indicates that the amount of OH/H2O on the shielded surface is less than on the unshielded surface. We confirmed that Earth's magnetosphere affects the OH/H2O distribution at low‐latitude regions, so the OH/H2O on the surface is originated by solar wind implantation. However, this study includes certain level of uncertainties in thermal corrections, and thus, sophisticated additional attempts are needed.
Relationships Among Nutrient and Sediment Fluxes, Hydrological Variability, Fire, and Land Cover in Coastal California Catchments
Authors: Aguilera Rosana , Melack John M.
Published: August 2018

Catchments along California's coast, and those with mediterranean climates elsewhere, experience large seasonal and interannual variations in rainfall, and occasional fires; land cover varies from natural vegetation to agricultural and urban development. Multiyear sampling of streams, with intensive collections during rainfall, and continuous measurements of stage, was used to determine the magnitude and variation of concentrations and fluxes of nutrients and suspended sediments during rainfall events and per year from catchments bordering the Santa Barbara Channel. Annual rainfall varied from 18 to 122 cm in water years 2002 through 2015. Hydrological variability, catchment topography, and land cover have strong statistical relationships to nutrient and suspended sediment fluxes. The link between nutrient fluxes and runoff during storms was strongest in sites with greater portions of impervious surfaces. The occurrence of fires followed by above average rainfall resulted in highest ammonium and suspended sediment fluxes. Nitrate fluxes during large storms in undeveloped catchments following wildfire were similar in magnitude to storm fluxes generated in catchments with intensive agriculture. Decreasing storm fluxes were observed with increasing cumulative discharge within a water year, which is consistent with the reduction of flux from each subsequent storm as the rainy season progressed.
Drivers of Dissolved Organic Matter in the Vent and Major Conduits of the World's Largest Freshwater Spring
Authors: Luzius Casey , Guillemette Francois , Podgorski David C. , Kellerman Anne M. , Spencer Robert G. M.
Published: August 2018

Wakulla Springs is the largest and deepest freshwater spring on Earth and has exhibited increased chromophoric dissolved organic matter (CDOM) inputs (i.e., browning) in recent decades. To examine the drivers of changing dissolved organic matter at the spring vent, we examined dissolved organic carbon concentrations and dissolved organic matter composition via optical parameters (i.e., absorbance and fluorescence) in the major conduits and a connecting spring over the course of 1 year. Sample sites separated clearly based on dissolved organic carbon concentration, CDOM absorbance, and optical parameters indicative of autochthonous (clear groundwater) versus allochthonous (terrestrial) dissolved organic matter. Seasonality was apparent in the allochthonous‐dominated sites with increasing terrestrial contribution particularly with large precipitation events post dry periods. Principle component analysis highlights the ability of optical parameters to show the dominance of sample sites draining from the southwest (i.e., Apalachicola National Forest) as responsible for the CDOM‐rich water at the vent, whereas water draining from the north was comparatively clear. Increasing CDOM‐rich waters at the vent suggests that either input from conduits draining from the southwest has increased, or the relative dilution with clear groundwater has decreased in the conduit system prior to discharge from the vent. Sea level rise impacts in the region have been suggested to result in more blackwaters delivered to the vent, and ongoing extraction of clear groundwater reduces the dilution capacity on CDOM‐rich waters. Thus, anthropogenic impacts in the region need to be addressed if the trend of increased CDOM inputs at Wakulla Springs is to be reversed.
Poynting Flux in the Dayside Polar Cap Boundary Regions From DMSP F15 Satellite Measurements
Authors: Lu Yang , Deng Yue , Sheng Cheng , Kilcommons Liam , Knipp Delores Jane
Published: August 2018

Poynting flux, which describes electromagnetic energy flux, is an important energy source for the high‐latitude upper atmosphere. After the launch of Defense Meteorological Satellite Program (DMSP) F15 spacecraft with a boom‐mounted magnetometer on board, there was a new opportunity to calculate Earth‐directed Poynting flux at satellite altitudes (~850 km) in the upper atmosphere. A persistent enhancement of thermospheric density in the dayside polar cap boundary regions has been reported in the CHAMP satellite observations. To understand the significance of different physical mechanisms including Poynting flux and particle precipitation, and the correlation between them, a statistical study of Poytning flux and particle energy flux in the dayside cusp and low‐latitude boundary layer (LLBL) regions has been conducted based on DMSP F15 measurements. DMSP satellite observations showed a dominate downward Poynting flux for most cases in the cusp region. Our analysis of DMSP F15 data for five years (2000–2004) reveals that approximately 53% of 660 cusp crossings at 800–850 km showed strong downward Poynting flux (S > 10 mW/m2), 32% of the crossings had noticeable downward Poynting flux (S > 3 mW/m2), and 7% of the crossings did not show clear Poynting flux (S < 1 mW/m2). Only 13 out of 660 cusp crossings (~2%) showed noticeable upward Poynting flux. In the LLBL region, 35% of 11,641 LLBL crossings showed significant downward Poynting flux, 34% of the crossings had noticeable downward Poynting flux, and only 13% of the crossings did not show clear Poynting flux. On average, Poynting flux in LLBL is smaller than that in the cusp. The results show a slightly negative correlation between Poynting flux and particle precipitation energy flux in the dayside polar cap boundary regions. Statistically, Poynting flux in the cusp is enhanced during interplanetary magnetic field By positive conditions.
Test of Ion Cyclotron Resonance Instability Using Proton Distributions Obtained From Van Allen Probe‐A Observations
Authors: Noh Sung‐Jun , Lee Dae‐Young , Choi Cheong‐Rim , Kim Hyomin , Skoug Ruth
Published: August 2018

Anisotropic velocity distributions of protons have long been considered as free energy sources for exciting electromagnetic ion cyclotron (EMIC) waves in the Earth's magnetosphere. Here we rigorously calculated the proton anisotropy parameter using proton data obtained from Van Allen Probe‐A observations. The calculations are performed for times during EMIC wave events (distinguishing the times immediately after and before EMIC wave onsets) and for times exhibiting no EMIC waves. We find that the anisotropy values are often larger immediately after EMIC wave onsets than the times just before EMIC wave onsets and the non‐EMIC wave times. The increase in anisotropy immediately after the EMIC wave onsets is rather small but discernible, such that the average increase is by ~15% relative to the anisotropy values during the non‐EMIC wave times and ~8% compared to those just before the EMIC wave onsets. Based on the calculated anisotropy values, we test the criterion for ion cyclotron instability suggested by Kennel and Petschek (1966, https://doi.org/10.1029/JZ071i001p00001) by applying it to the EMIC wave events. We find that despite the weak increase in anisotropy, the majority of the EMIC wave events satisfy the instability criterion. We suggest that the proton distributions often remain close to the marginal state to ion cyclotron instability, and consequently, the proton anisotropy values should often be observed near threshold values for ion cyclotron instability. Additionally, we demonstrate the usefulness and limitation of the instability criteria expressed in the form of an inverse relation between the anisotropy and plasma beta.
Energetic Particle Showers Over Mars from Comet C/2013 A1 Siding Spring
Authors: Sánchez – Cano Beatriz , Witasse Olivier , Lester Mark , Rahmati Ali , Ambrosi Richard , Lillis Robert , Leblanc François , Blelly Pierre‐Louis , Costa Marc , Cowley Stanley W. H. , Espley Jared R. , Milan Stephen E. , Plaut Jeffrey J. , Lee Christina , Larson Davin
Published: August 2018

This paper is a phenomenological description of multispacecraft observations of energetic particles caused by the close flyby of comet C/2013 A1 Siding Spring with Mars on 19 October 2014. This is the first time that cometary energetic particles have been observed at Mars. The Mars Atmosphere and Volatile EvolutioN (MAVEN)‐solar energetic particle (SEP) and the Mars Odyssey‐High Energy Neutron Detector (HEND) instruments recorded evidence of precipitating particles, which are likely O+ pickup ions, during the ~10 hr that Mars was within the region of the comet's coma. O+ pickup ions were also detected several hours after, although whether their origin is the comet or space weather is not conclusive. We discuss the possible origin of those particles and also the cause of an additional shower of energetic particles that HEND observed between 22 and 35 hr after the comet's closest approach, which may be related to dust impacts from the comet's dust tail. An O+ pickup ion energy flux simulation is performed with representative solar wind and cometary conditions, together with a simulation of their energy deposition profile in the atmosphere of Mars. Results indicate that the O+ pickup ion fluxes observed by SEP were deposited in the ionosphere around 105 to 120 km altitude, and they are compared with precomet flyby estimations of cometary pickup ions. The comet's flyby deposited a significant fluence of energetic particles into Mars' upper atmosphere, at a similar level to a large space weather event.
Effects of St. Patrick's Day Geomagnetic Storm of March 2015 and of June 2015 on Low‐Equatorial D Region Ionosphere
Authors: Maurya Ajeet K. , Venkatesham K. , Kumar Sushil , Singh Rajesh , Tiwari Prabhakar , Singh Abhay K.
Published: August 2018

D region effects of the 17–19 March 2015, a St Patrick's Day super geomagnetic storm (Dst = −223 nT), using a navigational transmitter very low frequency (VLF) signal (NWC, 19.8 kHz) recorded at a low‐latitude Indian station, Allahabad (geomag. lat., 16.45°N), have been analyzed and compared with similar strength of the 22–25 June 2015 storm (Dst = −204 nT). During the March storm, NWC signal amplitude decreased on 17 March (main phase of the storm) and recovered on 27 March, which is 1 day after the recovery of the storm, whereas for the June storm, VLF amplitude decreased for 2 days only during its recovery phase. The decrease in the amplitude was pronounced during evening terminator for both the storms. The modeling of VLF signal anomaly on 17 March and on 25 June using Long‐Wave Propagation Capability code shows an increase in the D region reference height (h′) by ~2.6 km and ~2.5 km, for March and June storms, respectively. The D region electron density (Ne) determined using storm time h′ and sharpness factor β shows a decrease in the Ne during the main phase followed by a slow recovery during the recovery phase of the March storm, whereas June 2015 storm showed a decrease in the Ne only on 25 and 26 June. Morlet Wavelet analysis of the amplitude for both the storms shows a presence of strong wave‐like signatures, suggesting propagation of atmospheric gravity waves/traveling ionosphere disturbances to the low latitude D region due to the Joule heating at high latitudes.
Energetic Radiation From Galactic Cosmic Ray Interactions With Saturn's Main Rings
Authors: Cooper John F. , Sturner Steven J.
Published: August 2018

Saturn's main rings have an energetic particle and gamma ray photon radiation environment produced by ring interactions of galactic cosmic ray (GCR) protons and heavier ions penetrating the planetary dipolar magnetic field. Accurate models of this radiation environment are important for interpretation of Pioneer 11 and Cassini in situ measurements near the rings and for constraints on radiolytic contributions to neutral gas production and ice chemistry. A GEANT (GEometry ANd Tracking) based simulation is used to model flux spectra of protons, electrons, positrons, charged pions, neutrons, and gamma ray photons emitted from GCR interactions with H2O ice spheres approximating the ring material. Dependent on location in the A to D rings within the planetary magnetic field of Saturn, only GCR protons above respective energies of 20 to 72 GeV can reach the rings without being deflected away by the magnetic field. Calculated differential and integral fluxes from our simulations have good agreement with in situ Pioneer‐11 measurements in selected energy channels. The charged particle and neutral radiation measurements are sensitive, respectively, to the sizes and areal mass densities of ring bodies. Computed gamma ray emission fluxes are 8% of our calculated limit for detection from the Earth by the Fermi Large Area Telescope. Addition of charged particle sensors and neutron‐photon imaging spectrometers to a future Saturn Ring Observer mission would provide valuable information on the ring mass structure. The present paper provides a foundation for modeling of Pioneer 11 and Cassini radiation measurements across the main rings and future measurements of radiation from the rings.
Long‐Term Estimation of Diurnal Vertical E × B Drift Velocities Using C/NOFS and Ground‐Based Magnetometer Observations
Authors: Habarulema John Bosco , Dubazane Makhosonke B. , Katamzi‐Joseph Zama T , Yizengaw Endawoke , Moldwin Mark B. , Uwamahoro Jean Claude
Published: August 2018

We report on the development of a new mathematical expression to estimate local daytime (0700–1700 LT) vertical E × B drift in low latitudes using a combination of ground‐based magnetometer measurements and Communications and Navigation Outage Forecasting System (C/NOFS) satellite observations. The expression was developed over Jicamarca (11.8°S, 77.2°W; 0.8°N geomagnetic) and validated with Jicamarca Unattended Long‐Term studies of the Ionosphere and Atmosphere (JULIA) mode and incoherent scatter radar (ISR) measurements during the period 2008–2014. The obtained correlation coefficient (R) values computed using observed and derived vertical E × B drift velocities are 0.79 and 0.84 for ISR and JULIA, respectively when data are available during 2008–2014. Storm‐time comparison between observed and derived vertical E × B drift velocities agreed well with R of 0.92 and 0.87 during 5–8 August 2011 and 8–11 March 2012 geomagnetic storm periods for ISR and JULIA observations, respectively. Overall, we found that the developed expression is applicable in estimating vertical E × B drift response during quiet and geomagnetic storm periods. Based on these findings, we suggest that it is possible to develop accurate daytime global vertical E × B drift model over the equatorial latitude regions using inexpensive magnetometer observations and available satellite data.
Recognition of Meteor Showers From the Heights of Ionization Trails
Authors: Lukianova Renata , Kozlovsky Alexander , Lester Mark
Published: August 2018

Meteoroids constantly enter the Earth's atmosphere, collide with atmospheric molecules, and heat and ablate in the sufficiently dense atmospheric layers at heights between 70 and 110 km. It is still a problem to recognize properties of the meteor streams among the sporadic background. The meteor radar observations at Sodankylä Geophysical Observatory (67°22′N, 26°38′E, Finland) during 2008–2017 show that meteoroids of some showers produce ionization trails at altitudes noticeably exceeding those of sporadic meteors. Using the median height of meteor trails and corresponding upper and lower quartiles as a metric, we unambiguously distinguish all northern hemisphere meteor showers with a zenithal hourly rate larger than 12, namely, the Quadrantids, Lyrids, Eta Aquariids, Arietids (or/and Daytime Zeta Perseids), Perseids, Orionids, Leonids, and Geminids. Additionally, signatures of a possible meteor stream during 26–30 January were detected, although identification of this stream is still under question. This new analysis indicates that the origin of the shower meteor trails at higher altitudes is likely due to higher speed and probably lighter or less dense meteoroids belonging to the showers.