bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterned Optoelectronic Tweezers: A New Scheme for Selecting, Moving, and Storing Dielectric Particles and Cells
Authors: Zhang Shuailong , Shakiba Nika , Chen Yujie , Zhang Yanfeng , Tian Pengfei , Singh Jastaranpreet , Chamberlain M. Dean , Satkauskas Monika , Flood Andrew G. , Kherani Nazir P. , Yu Siyuan , Zandstra Peter W. , Wheeler Aaron R.
Published: October 2018

Optical micromanipulation has become popular for a wide range of applications. In this work, a new type of optical micromanipulation platform, patterned optoelectronic tweezers (p‐OET), is introduced. In p‐OET devices, the photoconductive layer (that is continuous in a conventional OET device) is patterned, forming regions in which the electrode layer is locally exposed. It is demonstrated that micropatterns in the photoconductive layer are useful for repelling unwanted particles/cells, and also for keeping selected particles/cells in place after turning off the light source, minimizing light‐induced heating. To clarify the physical mechanism behind these effects, systematic simulations are carried out, which indicate the existence of strong nonuniform electric fields at the boundary of micropatterns. The simulations are consistent with experimental observations, which are explored for a wide variety of geometries and conditions. It is proposed that the new technique may be useful for myriad applications in the rapidly growing area of optical micromanipulation.
Analysis of Puncture Resistant Steel for Tank Cars
Authors: Abotula Sandeep , Konda Bharath R. , Walsh William J. , Challa Venkata S. A. , Ros Tanya , Manohar Murali
Published: October 2018

A new puncture resistant steel is developed to improve the safety of tank cars transporting flammable liquids. The puncture behavior of the tank cars is simulated using a ductile damage model available in the finite element program, ABAQUS. The damage model assumes that, for a given stress‐state (triaxiality), failure initiates at the maximum load‐carrying capacity. The subsequent damage evolution is defined by its fracture energy. To investigate a range of triaxiality conditions, uniaxial tensile tests are performed on notched, round‐bar specimens for both current and new steel grades. Numerical simulations of each test are performed and validated with the test data. The relation between the equivalent plastic strain at failure initiation and the stress triaxiality (damage initiation) is obtained from the test data and the simulations, as is the fracture energy (damage evolution). Impact simulations are performed on the tank car and the results show that the new steel absorbs more impact energy, thereby delaying puncture.
Calculation method for flexural capacity of high strain‐hardening ultra‐high performance concrete T‐beams
Authors: Liu Chao , Zhang Yuxin , Yao Yuan , Huang Yuhao
Published: October 2018

In order to develop a calculation method for the ultimate flexural capacity of high strain‐hardening ultra‐high performance concrete (UHPC) T‐beams, four‐point loading tests on five specimens were carried out. The design parameters were the ratio and the strength of reinforcement. Based on the assumption of plane section, a linear regression analysis was carried out and the ultimate tensile strain of high strain‐hardening UHPC was obtained. The analysis results proved that the bond between reinforcement and UHPC is reliable and these two materials can maintain strain consistency before the reinforcement reaches its yield strain. A finite element model of the specimens was established using ANSYS and distributed reinforcement was added to simulate the behavior of UHPC after cracking. Considering the tensile contribution of the high strain‐hardening UHPC after cracking, the calculation method for flexural capacity of high strain‐hardening UHPC T‐beams was derived. The finite element simulation method and the theoretical formula calculation method proposed in this paper are in good agreement with the experimental values, and they can be applied for the theoretical analysis and the design of high strain‐hardening UHPC beams. The theoretical calculation method proposed in this paper is compared with calculation methods proposed by standards. The study shows that the proposed calculation method is accurate and generally applicable.
Black girls speak STEM: Counterstories of informal and formal learning experiences
Authors: King Natalie S. , Pringle Rose M.
Published: October 2018

This study presents the interpretations and perceptions of Black girls who participated in I AM STEM—a community‐based informal science, technology, engineering, and mathematics (STEM) program. Using narrative inquiry, participants generated detailed accounts of their informal and formal STEM learning experiences. Critical race methodology informed this research to portray the dynamic and complex experiences of girls of color, whose stories have historically been silenced and misrepresented. The data sources for this qualitative study included individual interviews, student reflection journals, samples of student work, and researcher memos, which were triangulated to produce six robust counterstories. Excerpts of the counterstories are presented in this article. The major findings of this research revealed that I AM STEM ignited an interest in STEM learning through field trips and direct engagement in scientific phenomena that allowed the girls to become agentic in continuing their engagement in STEM activities throughout the year. This call to awaken the voices of Black girls to speak casts light on their experiences and challenges as STEM learners—from their perspectives. The findings confirm that when credence and counterspaces are given to Black girls, they are poised to reveal their luster toward STEM learning. This study provided a space for Black girls to reflect on their STEM learning experiences, formulate new understandings, and make connections between the informal and formal learning environments within the context of their everyday lives, thus offering a more holistic approach to STEM learning that occurs across settings and over a lifetime.
Investigation of the science achievement models for low and high achieving schools and gender differences in Turkey
Authors: Acar Ömer
Published: October 2018

A science achievement model was separately investigated for students in low and high achieving schools (LAS and HAS) in Turkey. Then, gender differences based on variables that significantly contributed to each achievement model were investigated. The student‐level variables that were under investigation for multiple regression analyses include attitudes toward science, epistemological beliefs, metacognition, views on science teaching, and socioeconomic status (SES). The science achievement scores of students on a nationwide exam were used to measure science achievement. Both for LAS and HAS, two schools were selected. Results were reported for 241 and 320 students in LAS and HAS, respectively. According to the results, self‐concept in science, knowledge of cognition, SES, importance of science, gradual learning, and views on lab work significantly contributed to the science achievement model in LAS. On the other hand, self‐concept in science, SES, gradual learning, studying, and learning science in school significantly contributed to the science achievement model in HAS. Results also revealed that girls outperformed boys on knowledge of cognition and importance of science in LAS. Moreover, girls scored higher than boys on gradual learning and studying in HAS. According to these findings, implications for science education were discussed.
Outer loop filter for improvement of one‐cycle controller
Authors: Chararmart Kongphope , Aurasopon Apinan
Published: October 2018

The One‐Cycle Control (OCC) has the ability to operate in line disturbance rejection and provide a faster dynamic response. However, when used as a controller in dc−dc converters, it might contribute to steady‐state error. Furthermore, the non−ideal circuit components may cause a duty cycle error due to the error of converter output voltage. We proposed a new technique to address the error in OCC by using the technique of an outer loop filter based on OCC, called Outer Loop Filter for improvement of One‐Cycle Control (OLF−OCC). This technique maintains a constant output voltage, despite power source voltage perturbation and error from the control circuit, such as circuit integrator voltage slope or input voltage offset. Variation results show that the performance of the proposed technique is more effective and reliable than the traditional approach when compared to the experimental state. OLF–OCC performance is discussed in terms of variation of power source voltage or internal disturbance from the control, such as circuit integrator voltage slope or input voltage offset. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Semi-classical BMS3 blocks and flat holography
Authors: Hijano Eliot
Published: October 2018

Abstract

We present the construction of BMS3blocks in a two-dimensional field theory and compare the results with holographic computations involving probe particles propagating in flat space cosmologies. On the field theory side, we generalize the monodromy method used in the context of AdS/CFT to theories with BMS symmetry. On the bulk side, we consider geodesic Feynman diagrams, recently introduced in [1], evaluated in locally flat geometries generated by backreaction of heavy BMS primary operators. We comment on the implications of these results for the eigenstate thermalization hypothesis in flat holography.
Deep disagreement and hinge epistemology
Authors: Ranalli Chris
Published: October 2018

This paper explores the application of hinge epistemology to deep disagreement. Hinge epistemology holds that there is a class of commitments—hinge commitments—which play a fundamental role in the structure of belief and rational evaluation: they are the most basic general ‘presuppositions’ of our world views which make it possible for us to evaluate certain beliefs or doubts as rational. Deep disagreements seem to crucially involve disagreements over such fundamental commitments. In this paper, I consider pessimism about deep disagreement, the thesis that such disagreements are rationally irresolvable, and ask whether the Wittgensteinian account of deep disagreement—according to which such disagreements are disagreements over hinge commitments—provides adequate support for pessimism. I argue that the answer to this question depends on what hinge commitments are and what our epistemic relation to them is supposed to be. I argue for two core claims. First, that non-epistemic theories of hinge commitments provide adequate support for pessimism. Nevertheless, such theories have highly implausible consequences in the context of deep disagreement. Secondly, at least one epistemic theory of hinge commitments, the entitlement theory, permits optimism about such disagreements. As such, while hinge epistemology is mainly pessimistic about deep disagreement, it doesn’t have to be.
Damage to or Injury of the Distal Semitendinosus Tendon During Sporting Activities: A Systematic Review
Authors: Metcalf Kathryn B. , Knapik Derrick M. , Voos James E.
Published: October 2018

Background

Isolated distal semitendinosus tears and avulsions sustained during sporting activities are uncommon.

Question/Purposes

We sought to systematically review the literature to identify athletes sustaining distal semitendinosus tears and avulsions during sporting activities and to better understand injury mechanisms, management, and return-to-sport timing.

Methods

PubMed, Biosis Previews, SPORTDiscus, PEDro, and EMBASE databases were searched from January 1970 to January 2018 using the search terms distal hamstring, semitendinosus, sport, athlete, tear, rupture, and avulsion. Inclusion criteria were studies documenting (1) isolated, complete distal semitendinosus tears and avulsions during sporting activity, (2) injury management, and (3) athlete outcome. Exclusion criteria were studies reporting (1) partial tears, (2) injuries from non-sporting activities, or (3) athlete sustaining injury with concomitant injuries about the knee. Sporting activities, tear location, management strategy, time from injury to surgery, and return-to-sport timing were analyzed. Statistical analysis was used to evaluate return-to-sport timing based on treatment type and tear location.

Results

Four studies met the inclusion criteria, comprising a total of 23 cases of complete, isolated distal semitendinosus avulsions or tears. Injuries were sustained predominantly while running or sprinting and most commonly were avulsions off the tibia. Injuries were treated surgically in 70% of cases. Overall time to return to sport was 2.5 ± 1.4 months with athletes treated conservatively returning significantly more quickly (1.5 ± 0.8 months) than athletes undergoing surgery (3.0 ± 1.3 months). Return-to-sport time was significantly shorter in athletes with complete avulsions (2.2 ± 1.3 months) than in those sustaining tears at the musculotendinous junction (3.8 ± 0.8 months). No significant correlation between time to surgery and return-to-sport time was appreciated.

Conclusion

Isolated, complete distal semitendinosus tears and avulsions remain infrequently reported during sporting activities and, in this review, occurred predominantly during non-contact activity. Athletes treated conservatively were found to return to sport more quickly, although additional studies are needed to determine the clinical relevance of treatment option, tear location, and concurrent injuries.
Comparison of the Effect of Intermittent and Continuous Aerobic Physical Training on Sexual Function of Women With Polycystic Ovary Syndrome: Randomized Controlled Trial
Authors: Lopes Iris Palma , Ribeiro Victor Barbosa , Reis Rosana Maria , Silva Rafael Costa , Dutra de Souza Hugo Celso , Kogure Gislaine Satyko , Ferriani Rui Alberto , Silva Lara Lúcia Alves da
Published: October 2018

Background

Polycystic ovary syndrome (PCOS) is a common condition characterized by hyperandrogenism, anthropometric changes (increased weight and waist-to-hip ratio [WHR]), behavioral changes (sexual dysfunction, anxiety, and depression), and reduced quality of life. Physical exercise may reduce many of the adverse effects of PCOS. However, no studies have yet evaluated the effects of aerobic exercise on the sexual function of women with PCOS.

Aim

To compare the effects of continuous and intermittent aerobic physical training on the sexual function and mood of women with PCOS.

Methods

This is a secondary analysis of a controlled clinical trial in which women with PCOS (18–39 years of age) were randomly allocated to 1 of 3 groups for 16 weeks: continuous aerobic training (CAT, n = 23), intermittent aerobic training (IAT, n = 22), or no training (control group, n = 24). The Female Sexual Function Index (FSFI) was used to assess sexual function, and the Hospital Anxiety and Depression Scale (HADS) was used to assess anxiety and depression.

Main Outcome Measure

The main outcome measure used was the FSFI.

Outcomes

The primary outcomes were changes from baseline in total FSFI score and HAD scores at week 16 to prove the superiority of intermittent aerobic exercise compared with continuous aerobic exercise.

Results

After 16 weeks, the CAT group had a significant increase in the total FSFI score, improvements in the FSFI domains of satisfaction and pain, and a reduction in the WHR. The CAT and IAT groups also had significantly lower levels of testosterone after 16 weeks. The IAT group had a significant increase in the total FSFI score and improvements in the desire, excitation, lubrication, orgasm, and satisfaction FSFI domains. The CAT and IAT groups both had significant reductions in anxiety and depression scores after 16 weeks.

Clinical Implications

Aerobic physical training protocols could be indicated to promote mental and sexual health in women with PCOS.

Strength & Limitations

This is one of the first studies to examine the effects of different physical training protocols on the sexual function of women with PCOS. The limitations of this study are that we did not consider diet or the frequency of sexual relations of participants with their partners. These factors could have interfered with the outcomes.

Conclusion

The CAT and IAT protocols improved the sexual function and reduced the anxiety and depression of women with PCOS. Both protocols were similar to improve FSFI domain scores.
Risk and Self-Respect
Authors: Baderin Alice , Barnes Lucy
Published: October 2018

What is the nature of the experience of risk? Risk can impose distinctive burdens on individuals: making us anxious, impairing our relationships and limiting our ability to plan our lives. On the other hand, risky situations are sometimes exciting, liberating and even empowering. The article explores the idea that risk can result in benefits for the individuals who bear it. Specifically, we evaluate John Tomasi’s claim that the experience of economic risk is a precondition of individual self-respect. Philosophical claims about the social bases of self-respect such as Tomasi’s have not been subjected to sufficient empirical scrutiny. The article exemplifies an alternative approach, by integrating philosophical argument with the analysis of large-scale survey data. Whilst Tomasi’s claim has force in some contexts, evidence from the economic domain shows that risk tends to undermine rather than to support self-respect.
Rational Learners or Impervious Partisans? Economic News and Partisan Bias in Economic Perceptions
Authors: Matthews J. Scott , Pickup Mark
Published: October 2018

Decades of research have established the direct influence of partisanship on voter perception of a host of real-world conditions. Even so, numerous factors have been found to moderate this “partisan bias.” We examine one plausible moderator: the volume of perceptually relevant information that is available in the mass media. Both dissonance-theoretic and motivated-reasoning formulations of partisan bias in political perception suggest that the availability of perceptually relevant information may constrain perceptual bias. Yet this proposition has rarely been investigated systematically. This article investigates the moderation of partisan bias by informational conditions, focusing on the impact of economic news on economic perceptions during five Canadian general elections (1993–2006). Although the overall pattern is mixed, evidence suggests that bias reduction in response to information depends on the broader economic and political context.
Progress in Clinical Neurosciences: Evidence Based Care in the Neurosciences
Authors: Wiebe Samuel , Demaerschalk Bart
Published: October 2018

We examine the relevance of Evidence Based Care (EBC) to the field of clinical neurosciences, with particular emphasis on feasible methods of implementing EBC in clinical practice. By using pre-appraised EBC summaries, busy clinicians can move toward EBC without engaging in the laborious process of searching and critically appraising the literature. After reviewing the neurological content, accessibility and ease of use of current sources of EBC summaries, we find them substantially lacking in coverage of the neurosciences, and therefore of limited use to clinicians in this field. We emphasize a particular type of EBC summary, the critically appraised topic, and comment on its usefulness and limitations as a tool to assist clinical decision-making in the neurosciences. Finally, we propose that a collection of easily accessible, good quality, peer reviewed critically appraised topics, covering a breadth of relevant topics, is a reasonable way of moving toward EBC in the clinical neurosciences.
Blood Pressure Management in Acute Stroke: Comparison of Current Guidelines with Prescribing Patterns
Authors: Kanji Salmann , Corman Céline , Douen Andre G.
Published: October 2018

Objective:

Current recommendations for treating elevated blood pressure (BP) in the acute stroke are based largely on expert opinion and vary with regard to treatment thresholds and choice of antihypertensive agents. In this study we investigate the influence of these recommendations by comparing the management of hypertension in acute stroke at a tertiary care hospital with current guidelines.

Method:

Retrospective chart review of patients admitted with acute stroke at The Ottawa Hospital-General Campus over six consecutive months. The use of antihypertensive medications (type, dose, routes of administration, BP recordings) in the first seven days after admission was noted.

Results:

Transdermal nitroglycerin paste was the most commonly used antihypertensive agent. In contrast to the 15% reduction in BP over 24 hours recommended for lowering BP in hypertensive patients with ischemic stroke, nitroglycerin caused a >15% reduction of BPover the first 24 hours on 60% of the occasions used. Furthermore, despite concerns about sublingual nifedipine, this was the second most commonly prescribed agent. Surprisingly, the mean time to first BP measurement following initiation of antihypertensive therapy was 117 ± 43 minutes in ischemic stroke and 88 ± 89 minutes in hemorrhagic strokes.

Conclusions:

The current guidelines for management of acute poststroke hypertension appear to have little influence on prescribing patterns, leading to considerable variations in practice. Such variations, likely due to uncertainty caused by lack of evidence from randomised controlled trials, are intolerable as patients maybe submitted to nonstandardised, potentially harmful care such as inappropriate choice of antihypertensives and inadequate BP monitoring as observed in this study.
Ifosfamide Encephalopathy and Nonconvulsive Status Epilepticus
Authors: Primavera Alberto , Audenino Daniela , Cocito Leonardo
Published: October 2018

Background:

Ifosfamide (IFX), an alkylating agent and isomer of cyclophosphamide, is used as a single agent or a component of multi-agent chemotherapy in the treatment of ovarian, testicular, head and neck cancers, sarcomas and lymphomas. Encephalopathy is manifested by cerebellar ataxia, confusional state, complex visual hallucinations, extrapyramidal signs, seizures, and mutism.

Case reports:

We report two patients with non-Hodgkin’s lymphoma presenting with mutism and confusional state after IFX infusion. Nonconvulsive status epilepticus (NCSE) as the cause of confusion was diagnosed on the basis of EEG pattern and the apparent improvement following intravenous administration of diazepam.

Conclusions:

Electroencephalogram abnormalities during IFX treatment have been described but recordings are only available in six cases. In three of them, paroxysmal alterations warranted the diagnosis of NCSE; however, most cases of IFX encephalopathy might have associated NCSE.
HACH: A Polymer Designed to Optimize Protein Antigen Localization
Authors: Olesen J.B. , Heckman C.A. , Lukinius A. , Schwab D.W. , Upite D.V. , Fioravanti C.F.
Published: October 2018

Abstract: The purpose of this study was to determine whether a polymer could be formed from relatively innocuous monomeric ingredients and, if so, if it might serve as a suitable embedding medium for maximizing antigen retention. Such a polymer, HACH, was made up from a mixture of 2-hydroxyhexanedial and carbohydrazide. It polymerized spontaneously at room temperature within 24 hr. Preservation of protein antigenicity and subsequent immunocytochemical localization were demonstrated by three methods. To determine whether protein antigens were retained up to the polymerization stage, we studied hemoagglutination of red blood cells using antibodies directed against their protein antigens. In these trials, HACH-treated cells exhibited the same agglutination responses as control, untreated cells. Second, a guinea pig antibody was used to immunodecorate insulin in β cells of the islets of Langerhans. The number of gold particles, indicating sites where the antibody was bound, was several-fold greater in HACH- than in Lowicryl K4M-embedded pancreatic β cells. To assess the limit of detection of protein antigens in thin sections, an example of a protein present in mitochondria, lipoamide dehydrogenase, was also studied. An indirect procedure for immunodecoration, employing rabbit immunoglobulin G followed by gold-tagged secondary antibody, indicated that the enzyme was present at several sites within cross-sectioned mitochondria. The results suggest that the HACH polymer will be useful for the localization of antigens that are present in relatively few copies.
Atomistic Simulation of Ceramic/Metal Interfaces: {222}MgO/Cu
Authors: Benedek R. , Seidman D.N. , Yang L.H.
Published: October 2018

Abstract: Atomistic simulations were performed for the {222}MgO/Cu interface by local density functional theory (LDFT) methods, within the plane-wave-pseudopotential representation, and by (classical) molecular dynamics and statics. The electronic spectra obtained with LDFT calculations showed a localized interface state within the bulk MgO gap, approximately 1 eV above the MgO valence band edge. LDFT adhesive energy calculations, as a function of interface spacing and translations parallel to the interface, were employed to devise an interatomic potential suitable for large-scale atomistic simulation. The interface structure, which was obtained with molecular dynamics (and statics) calculations based on the resultant potential, exhibited a misfit dislocation network with trigonal symmetry, and no standoff dislocations.
The economic importance of judicial institutions, their performance and the proper way to measure them
Authors: MARCIANO ALAIN , MELCARNE ALESSANDRO , RAMELLO GIOVANNI B.
Published: October 2018

In the present paper we contribute to the previous literature on de facto enforcing mechanisms, by focusing on the role of judicial institutions and their performance and measurement. We propose both theoretical and empirical evidence supporting the necessity of a clear distinction between two measures of judicial performance, efficiency and efficacy, which have often been confused in previous literature. Not only might economic actors not be affected to the same extent by these two indicators, but we show that these measures do not even correlate significantly with each other. We also bring evidence against the alleged trade-off between the quality of justice and judicial performance in its quantitative dimension, showing that this relationship is much more complicated than is claimed by some legal scholars.
A New Global Storage‐Area‐Depth Data Set for Modeling Reservoirs in Land Surface and Earth System Models
Authors: Yigzaw Wondmagegn , Li Hong‐Yi , Demissie Yonas , Hejazi Mohamad I. , Leung L. Ruby , Voisin Nathalie , Payn Rob
Published: October 2018

Reservoir storage‐area‐depth relationships are the most important factors controlling thermal stratification in reservoirs and, more broadly, the water, energy, and biogeochemical dynamics in the reservoirs and subsequently their impacts on downstream rivers. However, most land surface or Earth system models do not account for the gradual changes of reservoir surface area and storage with the changing depth, inhibiting a consistent and accurate representation of mass, energy, and biogeochemical balances in reservoirs. Here we present a physically coherent parameterization of reservoir storage‐area‐depth data set at the global scale. For each reservoir, the storage‐area‐depth relationships were derived from an optimal geometric shape selected iteratively from five possible regular geometric shapes that minimize the error of total storage and surface area estimation. We applied this algorithm to over 6,800 reservoirs included in the Global Reservoir and Dam database. The relative error between the estimated and observed total storage is no more than 5% and 50% for 66% and 99% of all Global Reservoir and Dam reservoirs, respectively. More importantly, the storage‐depth profiles derived from the approximated reservoir geometry compared well with remote sensing based estimation at 40 major reservoirs from previous studies and ground‐truth measurements for 34 reservoirs in the United States and China. The new global reservoir storage‐area‐depth data set is critical for advancing future modeling and understanding of reservoir processes and subsequent effects on the terrestrial hydrological, ecological, and biogeochemical cycles at the regional and global scales.
Combining InSAR and Hydraulic Head Measurements to Estimate Aquifer Parameters and Storage Variations of Confined Aquifer System in Cangzhou, North China Plain
Authors: Jiang L. , Bai L. , Zhao Y. , Cao G. , Wang H. , Sun Q.
Published: October 2018

Groundwater storage (GWS) depletion and land subsidence caused by groundwater overexploitation threaten water supply and infrastructure security in the North China Plain. However, the aquifer system responses to groundwater changes are poorly understood in this region, although it is extremely important for groundwater management and land subsidence control. In this study, aquifer parameters and GWS variations of the confined aquifer system in central Cangzhou are quantified by using Interferometric Synthetic Aperture Radar (InSAR) and hydraulic head measurements. We apply the multitemporal InSAR method to detect land deformation time series with Envisat Advanced Synthetic Aperture Radar (ASAR) data from 2003 to 2010. Seasonal signals in land deformation and head data are isolated by multichannel singular spectrum analysis to derive the elastic skeletal storativity (Ske). The results reveal a spatially heterogeneous Ske pattern with values ranging from 1.7 × 10−4 to 4.4 × 10−3 that agree well with those derived from pumping tests. An abnormal Skezone is found in the land uplift zone, and a gradual increase of Ske is revealed in the eastern coastal plain, which are likely attributed to the hydrological properties in the aquifer systems. Additionally, we characterize spatiotemporal variations in the total GWS, recoverable GWS, and irreversible GWS. The annual depletion rates of recoverable GWS and irreversible GWS are −0.52 ± 1.27 × 107 and −7.68 ± 2.68 × 107 m3/year, accounting for 6.4% and 93.6% of annual total GWS depletion, respectively, suggesting that previous groundwater pumping practices are unsustainable in this region. Finally, we find a 1‐year lag of the IGWS depletion variations behind the head changes due to low vertical hydraulic conductivities in aquitards.
Novel Coalbed Methane (CBM) Origin Analysis and Source Apportionment Method Based on Carbon Isotope Ratio Using Infrared Dual‐Wavelength Laser Absorption Spectroscopy
Authors: Zhang Zhirong , Sun Pengshuai , Li Zhe , Xia Hua , Cui Xiaojuan , Pang Tao , Wu Bian , Guo Qiang , Shu Chimin , Dong Fengzhong
Published: October 2018

We report the application of an infrared dual‐wavelength laser absorption spectroscopy system, which combines tunable diode laser absorption spectroscopy and wavelength modulation integrated cavity output spectroscopy technologies based on two spectroscopic sources operating at 6,029 and 2,310 cm−1, to simultaneously measure the gas concentrations (CH4 and CO2) and carbon isotopic signatures (13C and 12C) in coalbed methane. The Allan variance is used to analyze the optimum mean time (t) and the standard deviation (SD), with t = 450 s, SD = 0.41‰ for 13CH4 monitoring and t = 70 s, SD = 0.17‰ for 13CO2 monitoring. Furthermore, 47 groups of coalbed methane samples collected from the Huaibei‐Qidong coal mine seam are analyzed based on the measured results for carbon isotopes and geophysical geochemistry. The δ13CH4 values of the Qidong coal mine fall between −44.57‰ and −61.57‰, and the δ13CO2 values fall between −21.65‰ and −17.06‰. The genetic types of methane may be divided into biogenic gas, thermogenic gas, and mixture gas. Carbon dioxide may be derived from coal pyrolysis, and it also has the characteristics of carbon‐isotope changes of organic genetic gas. The new approach for analyzing rapid genetic types, methane migration pathways, gas disaster source warning, and coal chemistry studies is expected to be further studied in the future.
MHD Modeling of the Plasma Interaction With Io's Asymmetric Atmosphere
Authors: Blöcker Aljona , Saur Joachim , Roth Lorenz , Strobel Darrell F.
Published: October 2018

Io's atmosphere, with an average equatorial column density of ≥1020 m−2, exhibits significant density variations with latitude and longitude. We apply a 3‐D magnetohydrodynamic model to investigate the effects of atmospheric asymmetries, both locally from volcanic plumes and globally, on the plasma and magnetic field environment of Io. The model takes into account collisions between ions and neutrals, plasma production and loss due to electron impact ionization and dissociative recombination, and the ionospheric Hall effect. Our simulation results show that volcanic plumes influence the plasma interaction locally, generating Alfvén winglets within Io's global Alfvén wing. Signals from individual plumes can however barely be probed by magnetic field measurements during spacecraft flybys at Io. In contrast, the surface number density, scale height, the longitudinal and latitudinal variations of the global atmosphere are crucial factors for modeling and understanding magnetic field and plasma perturbations. Comparing our model results with the magnetic field data from the I24 and I27 flybys of the Galileo spacecraft, we find that the measured perturbations can be primarily caused by the plasma interaction with the longitudinally asymmetric atmosphere. This implies that a significant magnetic induction signal from a partially molten magma ocean is not necessarily required to explain the Galileo magnetometer data.
Recurrent Magnetic Dipolarization at Saturn: Revealed by Cassini
Authors: Yao Z. H. , Radioti A. , Grodent D. , Ray L. C , Palmaerts B. , Sergis N. , Dialynas K. , Coates A. J. , Arridge C. S. , Roussos E. , Badman S. V. , Ye Sheng‐Yi , Gérard J.‐C. , Delamere P. A. , Guo R. L. , Pu Z. Y. , Waite J. H. , Krupp N. , Mitchell D. G. , Dougherty M. K.
Published: October 2018

Planetary magnetospheres receive plasma and energy from the Sun or moons of planets and consequently stretch magnetic field lines. The process may last for varied timescales at different planets. From time to time, energy is rapidly released in the magnetosphere and subsequently precipitated into the ionosphere and upper atmosphere. Usually, this energy dissipation is associated with magnetic dipolarization in the magnetosphere.This process is accompanied by plasma acceleration and field‐aligned current formation, and subsequently auroral emissions are often significantly enhanced. Using measurements from multiple instruments on board the Cassini spacecraft, we reveal that magnetic dipolarization events at Saturn could reoccur after one planetary rotation and name them as recurrent dipolarizations. Three events are presented, including one from the dayside magnetosphere, which has no known precedent with terrestrial magnetospheric observations. During these events, recurrent energizations of plasma (electrons or ions) were also detected, which clearly demonstrate that these processes shall not be simply attributed to modulation of planetary periodic oscillation, although we do not exclude the possibility that the planetary periodic oscillation may modulate other processes (e.g., magnetic reconnection) which energizes particles. We discuss the potential physical mechanisms for generating the recurrent dipolarization process in a comprehensive view, including aurora and energetic neutral atom emissions.
Magnetotail Configuration During a Steady Convection Event as Observed by Low‐Altitude and Magnetospheric Spacecraft
Authors: Sergeev V. A. , Tsyganenko N. A. , Angelopoulos V. , Runov A. V. , Singer H. J.
Published: October 2018

Motivated by ongoing discussion regarding the magnetic configuration in the near‐Earth and midtail regions and its role in populating the inner magnetosphere during long‐duration steady magnetospheric convection (SMC) events, we analyze a rich collection of observations during ~10 hr of strong, steady solar wind driving. Auroral boundaries and regions of stretched and dipolarized magnetic field in the plasma sheet were monitored using solar electron loss cone anisotropy observed by low‐altitude spacecraft. Following a southward turning of the interplanetary magnetic field and a subsequent 3‐ to 4‐hr period of large‐scale substorm‐related reconfigurations and plasma injections, the near‐Earth magnetic configuration evolved into a nonstandard type, which lasted until the end of this SMC event (5 hr). During that time a dipolarized region with complicated Bz landscape persisted in the midtail, while the configuration was very stretched in the near tail. This was manifested as a highly depressed magnetic Bz component at geostationary orbit and as persistent nonadiabatic electron scattering at the periphery of the outer radiation belt. In addition, in situ observations suggest that a thin current sheet extended longitudinally toward the dawn terminator. In the return convection region near the terminator, observations of this azimuthal current sheet were sporadically interrupted/modulated by earthward convecting plasma structures, either remnants of reconnection‐produced plasma bubbles or flapping waves. The hybrid magnetotail configuration (dipolar in the midtail and stretched in the near tail) observed during this long‐duration SMC event poses a challenge for empirical magnetospheric modeling.
Renewed Posteruptive Uplift Following the 2011–2012 Rhyolitic Eruption of Cordón Caulle (Southern Andes, Chile): Evidence for Transient Episodes of Magma Reservoir Recharge During 2012–2018
Authors: Delgado Francisco , Pritchard Matthew , Samsonov Sergey , Córdova Loreto
Published: October 2018

The VEI 4 rhyolitic eruption of Cordón Caulle volcano in 2011–2012 was immediately followed by ∼0.77 m of exponentially decaying uplift during 2012–2015. In this study, we present evidence of additional transient pulses of inflation with interferometric synthetic aperture radar (InSAR) time series during 2016–2018. We also assess whether the 2012–2015 uplift can be explained by viscoelastic relaxation or not. InSAR detected ∼12 cm of uplift during 2016–2017 and ∼5 cm during 2017–2018. The three inflation episodes have very similar spatial scales and can be modeled with the same inflating sill (z ∼ 6 km), but their time evolution is significantly different. Numerical models of a pressurized reservoir surrounded by a viscoelastic shell do not have a better fit than a magma injection model to the 2012–2015 InSAR time series, indicating that magma injection is the most likely mechanism to explain this uplift signal. The spatial similarities of the three pulses suggest that they are produced by episodic magma injection. These magma injection pulses provide the heat to remobilize the crystal mush beneath the volcano on timescales of a few months, but the end of the uplift is not predicted by existing models. None of these uplift pulses were related to abnormal seismicity, and we speculate that they are mostly aseismic because they caused stresses of lower magnitude than the coeruptive stresses. The meter scale displacement observed at Cordón Caulle between 2007 and 2018 suggests that the volcano undergoes episodic cycles of inflation like those observed in silicic calderas.
Causes of Interannual Variation of Summer Mean Alongshore Current Near the East Coast of Korea Derived From 16‐Year‐Long Observational Data
Authors: Park Jae‐Hyoung , Nam SungHyun
Published: October 2018

Interannual variation in the summer surface current near the east coast of Korea was analyzed using long‐term (~16 years) time series measurements. Significant interannual variations in the summer alongshore current, which have a magnitude comparable to that of the climatological summer mean (equatorward) current, were observed. Positive anomalies (more poleward) occurred during 2001, 2009, 2010, and 2014; negative anomalies (more equatorward) occurred during 2002, 2006, and 2012. A linear combination of equatorward propagating coastal‐trapped waves, forced primarily by remote winds off the Russian coast, and an upwelling/downwelling response to local wind forcing, though contribution of the latter is not as significant as that of the former, successfully reproduced (46%) the observed anomalies in the alongshore current (correlation coefficient of 0.68). The influence of cross‐shore movement of the poleward flowing offshore current explains 35% of the total variance in the interannual anomalies of the alongshore current (correlation coefficient of 0.59), yielding less equatorward or slight poleward current near the coast in 2001 and 2009 with onshore movement of the offshore current. The combined effects of wind and offshore current explain ~72% (correlation coefficient of 0.85) of the anomalies in the alongshore current observed during summer near the east coast of Korea, providing significant implications for interannual current dynamics near the midlatitude western boundary.
Impacts of Diabatic Heating on the Genesis and Development of an Inner Tibetan Plateau Vortex
Authors: Wu Di , Zhang Feimin , Wang Chenghai
Published: October 2018

A short‐lived (less than 2 days) inner Tibetan Plateau vortex (TPV) with heavy precipitation was simulated using the Weather Research and Forecasting model, and the sensitivity experiments with and without surface diabatic heating and atmospheric latent heating released by precipitation were conducted to investigate the roles of surface and atmospheric diabatic heating on the genesis and development of TPV. Results show that before the genesis of the TPV, there is an anomalous increase of surface heating flux; while a disturbance of potential vorticity (PV) at 500 hPa moves over this region, the PV is enhanced and induces the generation of TPV. The precipitation in turn reduces the surface heating flux. The release of condensation latent heating by precipitation during the development of TPV does not further contribute to its reinforcement. Instead, it is more likely a result of precipitation, tending to stabilize the atmosphere and conducive to the decay of TPV. The PV diagnoses further reveal that in the early phase, the strong diabatic heating in the lower levels associated with the increasing surface heating flux has a significantly positive contribution to the generation of the TPV. The precipitation results in the decrease of positive diabatic heating contribution at low levels. Inversely, the diabatic heating in the middle levels associated with the released latent heating of precipitation condensation tends to have the negative contribution to TPV, resulting in the decay of TPV. The study of this case can deepen our understanding on the mechanism of TPV and its precipitation.
Constraints on the Noachian Paleoclimate of the Martian Highlands From Landscape Evolution Modeling
Authors: Matsubara Yo , Howard Alan D. , Irwin Rossman P.
Published: October 2018

The progressive degradation and loss of impact craters throughout the Noachian Period on Mars indicate prolonged erosion, rather than only a brief spike around the Noachian/Hesperian transition. The purpose of this study is to determine which suite(s) of geomorphic processes and rates best reproduce the relict Noachian landscape. We modeled the evolution of two study areas in the Martian highlands, Noachis Terra and Terra Cimmeria, to constrain the long‐term erosional processes and rates that prevailed ~4.0–3.7 Ga, before the valley networks formed. Our model runs indicate a very low erosion rate and inefficient runoff production during the Middle and Late Noachian Epochs. The terrestrial equivalent of 2 and 1.5 Myr worth of erosional work under arid to semiarid conditions with inefficient runoff production was required in order to replicate the landscape at Noachis Terra and Terra Cimmeria, respectively, over ~300 Myr. Low areas in the landscape filled with sediments, while mass wasting and fluvial erosion were focused on crater rims and interior walls. The surface characteristics that best reproduce the observed landscape are a bedrock weathering rate around 0.0005–0.001 m/year with regolith that is 100 times more erodible than bedrock, suggesting that impact comminution and aqueous weathering produced abundant transportable material on Noachian Mars. The simulation results suggest that the Noachian paleoclimate was more arid than around the Noachian/Hesperian transition, but it supported occasional precipitation (snow or rain) that weathered surface materials and transported sediments.
A Positive Feedback Between Sediment Deposition and Tidal Prism May Affect the Morphodynamic Evolution of Tidal Deltas
Authors: Zhang Xiaohe , Fagherazzi Sergio , Leonardi Nicoletta , Li Jiufa
Published: October 2018

Tidal deltas are fragile systems whose morphology can be easily impacted by variations in water and sediment fluxes caused by natural and human processes. Here we explore the relation between tidal prism and sediment dynamics in tidal deltas using the recent evolution of the Yangtze River estuary, China, as an example. Using the numerical model Delft3D, we examine how changes in delta morphology can trigger variations in tidal signal, suspended and bed load transport, and how these could ultimately cause additional morphological changes. Our results show that a positive feedback between sediment deposition and tidal prism dominates the morphodynamic evolution of the delta. Accretion of the shoals in the delta front increases the dissipation of tides and decreases the tidal prism leading to weaker tidal flows. This reduction in tidal currents lowers the sediment flushing capacity of the system, promoting deposition on the shoals and tidal dissipation. This positive feedback potentially traps more sediment in the delta topset and possibly offsets the decrease in sediment load triggered by the construction of upstream dams, often present in tidal deltas.
Boulder Array Effects on Bedload Pulses and Depositional Patches
Authors: Papanicolaou A. N. (Thanos) , Tsakiris Achilleas G. , Wyssmann Micah A. , Kramer Casey M.
Published: October 2018

The influence of boulders in high gradient gravel‐bed rivers can be significant. Yet few studies have isolated their role in regulating bedload. It is hypothesized that boulder relative submergence and the corresponding eddies developing around boulders affect the frequency of bedload pulsations and the location of sediment deposits. Results show the occurrence of two distinct timescales in bedload exiting a boulder array, which were identified via time series analysis. These are the small‐scale periodicity, PS, and the large‐scale periodicity, PL. PS was identified in the range of 4–6 min and is believed to result from congested bedload movement due to reduced conveyance area within the array. PL was identified in the range of 8–46 min. It is suggested that PL corresponds to large bedload releases around boulders, which the authors consider to be caused by feedbacks between boulder eddies and bedload deposits. It is also found that boulder submergence and Froude number, Fr, influence the location of predominant deposition. At High Relative Submergence, deposition occurs in the boulder wake regions. At Low Relative Submergence, deposition instead occurs upstream of boulders in locations that depend on Fr. For Fr < 1, material deposits in the stoss of boulders due to the necklace structure of the horseshoe vortex. However, for Fr > 1, material deposits at the flanks of boulders due to the influence of local wave crests around boulders. The trapping efficiency of boulders reduces the dimensionless mean bedload transport rate by three orders of magnitude compared to conditions without boulders.