bluuebunny/crossref_metadata_2025 huggingface dataset:
LO36: The state of advocacy in postgraduate medical education: a literature review
Authors: Lavelle C. , Wen M. , McDonald M. , Sherbino J. , Hulme J.
Published: May 2018

Introduction: Health advocacy training is an important part of emergency medicine practice and education. There is little agreement, however, about how advocacy should be taught and evaluated in the postgraduate context, and there is no consolidated evidence-base to guide the design and implementation of post-graduate health advocacy curricula. This literature review aims to identify existing models used for teaching and evaluating advocacy training, and to integrate these findings with current best-practices in medical education to develop practical, generalizable recommendations for those involved in the design of postgraduate advocacy training programs. Methods: Ovid MEDLINE and PubMed searches combined both MeSH and non-MeSH variations on advocacy and internship and residency. Forward snowballing that incorporated grey literature searches from accreditation agencies, residency websites and reports were included. Articles were excluded if unrelated to advocacy and postgraduate medical education. Results: 507 articles were identified in the search. A total of 108 peer reviewed articles and 38 grey literature resources were included in the final analysis. Results show that many regulatory bodies and residency programs integrate advocacy training into their mission statements and curricula, but they are not prescriptive about training methods or assessment strategies. Barriers to advocacy training were identified, most notably confusion about the definition of the advocate role and a lower value placed on advocacy by trainees and educators. Common training methods included didactic modules, standardized patient encounters, and clinical exposure to vulnerable populations. Longitudinal exposure was less common but appeared the most promising, often linked to scholarly or policy objectives. Conclusion: This review indicates that postgraduate medical education advocacy curricula are largely designed in an ad-hoc fashion with little consistency across programs even within a given discipline. Longitudinal curriculum design appears to engage residents and allows for achievement of stated outcomes. Residency program directors from emergency medicine and other specialties may benefit from promising models in pediatrics, and a shared portal with access to advocacy curricula and the opportunity to exchange ideas related to curriculum design and implementation.
GLOBAL WELL-POSEDNESS OF THE PERIODIC CUBIC FOURTH ORDER NLS IN NEGATIVE SOBOLEV SPACES
Authors: OH TADAHIRO , WANG YUZHAO
Published: May 2018

We consider the Cauchy problem for the cubic fourth order nonlinear Schrödinger equation (4NLS) on the circle. In particular, we prove global well-posedness of the renormalized 4NLS in negative Sobolev spaces$H^{s}(\mathbb{T})$,$s>-\frac{1}{3}$, with enhanced uniqueness. The proof consists of two separate arguments. (i) We first prove global existence in$H^{s}(\mathbb{T})$,$s>-\frac{9}{20}$, via the short-time Fourier restriction norm method. By following the argument in Guo–Oh for the cubic NLS, this also leads to nonexistence of solutions for the (nonrenormalized) 4NLS in negative Sobolev spaces. (ii) We then prove enhanced uniqueness in$H^{s}(\mathbb{T})$,$s>-\frac{1}{3}$, by establishing an energy estimate for the difference of two solutions with the same initial condition. For this purpose, we perform an infinite iteration of normal form reductions on the$H^{s}$-energy functional, allowing us to introduce an infinite sequence of correction terms to the$H^{s}$-energy functional in the spirit of the$I$-method. In fact, the main novelty of this paper is this reduction of the$H^{s}$-energy functionals (for a single solution and for the difference of two solutions with the same initial condition) to sums of infinite series of multilinear terms of increasing degrees.
Perspective and Logical Pluralism in Hegel
Authors: Yeomans Christopher
Published: May 2018

In this paper, I consider the role of perspective in Hegel’s metaphysics, and in particular the role that multiple perspectives play within the ultimate structure in Hegel’s metaphysics, which Hegel calls ‘the idea [die Idee]’. My (somewhat anachronistic) way into this topic will be to inquire about Hegel’s stance on what Adrian Moore has called ‘absolute representations’. I argue for the claim that perspective is maintained, even in the absolute idea, which generates the task of understanding the nature of that perspective and its compatibility with absoluteness. I attempt to accomplish this task by asking what a logical perspective could be, and how it might be related to visual perspective. Then I inquire into the relation that perspectives have to each other, i.e., to the system of perspectives. I construe those relations in reciprocal and dynamic terms, so that absoluteness takes the form of a structured round of perspectives rather than a relation to reality ‘once and for all’.
The role of collective effects on settling velocity enhancement for inertial particles in turbulence
Authors: Huck P. D. , Bateson C. , Volk R. , Cartellier A. , Bourgoin M. , Aliseda A.
Published: May 2018

A particle-laden homogeneous isotropic turbulent flow is studied experimentally to understand the role of collective effects (e.g. particle–particle aerodynamic interactions caused by local particle accumulation) on the settling velocity of inertial particles (Stokes number: $0.3<St<0.6$). Conditional averaging of the particle vertical velocity on the local concentration identifies three settling regimes: modest enhancement by single particle–turbulence interactions in low concentration regions, rapid settling velocity increases in clusters at intermediate concentrations and saturation of the settling enhancement at large concentrations. The latter effect, associated with four-way coupling, displays qualitative agreement with simulations in the literature and is a new experimental observation. Fluctuations up to an order of magnitude larger than the background volume fraction are measured using Voronoï analysis. A model is developed following a classic volume-averaged multiphase flow methodology to provide an interpretation of the three settling regimes and quantitative predictions consistent with the measurements.
The influence of two-dimensional temperature modulation on nonlinear Marangoni waves in two-layer films
Authors: Nepomnyashchy Alexander A. , Simanovskii Ilya B.
Published: May 2018

The nonlinear dynamics of waves generated by the deformational oscillatory Marangoni instability in a two-layer film under the action of a two-dimensional temperature modulation on the solid substrate is considered. A system of long-wave equations governing the deformations of the upper surface and the interface between the liquids is presented. The long-wave approach is applied. The nonlinear simulations reveal the existence of different dynamic regimes, including stationary, time-periodic and quasi-periodic flows. The general diagrams of the flow regimes are constructed.
When is job control most useful for idea championing? Role conflict and psychological contract violation effects
Authors: De Clercq Dirk , Sun Wei , Belausteguigoitia Imanol
Published: May 2018

Drawing from conservation of resources theory, this article investigates the relationship between job control (a critical job resource) and idea championing, as well as how this relationship may be augmented by stressful work conditions that can lead to resource losses, such as conflicting work role demands and psychological contract violations. With quantitative data collected from employees of an organization that operates in the chemical sector, this study reveals that job control increases the propensity to champion innovative ideas. This effect is especially salient when employees experience high levels of role conflict and psychological contract violations. For organizations, the results demonstrate that giving employees more control over whether they invest in championing activities will be most beneficial when those employees also face resource-draining work conditions, in the form of either incompatible role expectations or unfilled employer obligations.
Mediated Massacre: Digital Nationalism and History Discourse on China's Web
Authors: Schneider Florian
Published: May 2018

On China's web, networked actors ranging from state agencies to private Internet users engage in highly active online discourse. Yet as diverse as this discourse may be, political content remains highly regulated, particularly on issues that affect the legitimacy of the ruling party. A prominent issue in this regard has been modern Chinese history, particularly the “national humiliation” that Japan inflicted on China's populace during events like the 1937 Nanjing Massacre. This article asks how the discourse on this particular event is structured on China's web, and what such practices of digital “remembering” can tell us about nationalism in the information age. Combining content analysis and digital tools, the article shows how the mass-media model that the Chinese authorities and various commercial actors apply to the web ultimately reproduces the very logic of “imagined communities” that makes reconciliation of historical disputes in East Asia so protracted.
New Wine in an Old Bottle: Female Politicians, Family Rule, and Democratization in Thailand
Authors: Nishizaki Yoshinori
Published: May 2018

Thailand has seen a growing number of women elected to Parliament in recent decades. Yet, little research has been done on who these women are and how they affect the quality of democracy. This article is an attempt to fill this lacuna. Drawing on previously untapped Thai-language primary sources, it argues that the majority of female members of Parliament elected since 1975 have contributed to entrenching family-based rule and stunting the growth of political pluralism. This argument is based on the finding that most female MPs are related, by blood or marriage, to former male MPs. These women from political families constitute one part of the long historical process through which Thailand has lapsed increasingly into a family-based patrimonial polity since the absolute monarchy was abolished in 1932. The importance of families remains undiminished over time; the advent of electoral politics has only accentuated it by bringing more women with powerful family connections into Parliament.
REGIONAL DIFFERENCES IN INTELLIGENCE IN EGYPT: A COUNTRY WHERE UPPER IS LOWER
Authors: Dutton Edward , Bakhiet Salaheldin Farah , Ziada Khaled Elsayed , Essa Yossry Ahmed Sayed , Ali Hamada Ali Abdelmuti , Alqafari Shehana Mohammed
Published: May 2018

Two administrations of the Coloured Progressive Matrices in Egypt were compared. The first was administered to a large, representative national sample between 2011 and 2013. The second was administered to primary school pupils in villages in Menoufia in northern Egypt in 2017. Adjusting for the Flynn Effect, the IQ of the rural northern Egyptians was shown to be statistically significantly higher than the national average. It is demonstrated that this is consistent with regional socioeconomic differences in Egypt, which strongly imply that northern Egypt has a higher average IQ than southern Egypt.
The politics of continuity and collusion in Zanzibar: political reconciliation and the establishment of the Government of National Unity
Authors: Roop Sterling , Tronvoll Kjetil , Minde Nicodemus
Published: May 2018

The popularity of unity governments to settle both internal political divisions and outright conflict has grown in the last 20 years. However, more often than not unity governments fail to mitigate the political dynamics baked into the political economies and suffer from being insufficiently anchored in local society. The Government of National Unity (GNU) in Zanzibar, formed in 2010 as the culmination of the ‘maridhiano’ political reconciliation process and following numerous attempts at reconciliation led to initial successes, is a case in point. Zanzibar's GNU turned out to be ‘position’ rather than ‘power’ sharing, constitutionalised through a hybrid format of the politics of continuity and collusion. As such the position sharing system broke down when voters in the 2015 election sought neither continuity nor collusion, but transformational change of governance. This was in turn blocked by veto actors in favour of continuity, resulting in the collapse and discontinuation of the GNU in Zanzibar.
Efficacy of treatment with belladonna in children with severe pallid breath-holding spells
Authors: Gonzalez Corcia M. Cecilia , Bottosso Adrien , Loeckx Isabelle , Mascart Françoise , Dembour Guy , François Geneviève
Published: May 2018

Introduction

Pallid breath-holding spells are common and dramatic forms of recurrent syncope in infancy. They are very stressful despite their harmless nature and sometimes require treatment.

Objective

The objective of this study was to evaluate the efficacy of belladonna in severe breath-holding spells.

Methods

This is a multicentric, retrospective series involving 84 children with severe pallid breath-holding spells. Inclusion criteria were >1 pallid breath-holding spell with loss of consciousness, paediatric cardiology evaluation, and follow-up >6 months. In total, 45 patients received belladonna and 39 patients did not receive treatment, according to physician preference.

Results

Mean age was 11 months, ranging from 4 to 18 months, with 54% of males. Mean spell duration was 30 seconds (interquartile range 15, 60), and the frequency was four episodes per month (interquartile range 0.5, 6.5). Comparison of baseline characteristics between groups showed similar demographics, with the single difference in the severity of the spells, being more severe in the treated group. When comparing the treated and non-treated groups at 3 months, only two (5%) patients had a complete remission in the first group, whereas 20 (44%) had remission in the belladonna group (p<0.01). When considering the characteristics of the spells before and after the initiation of treatment with belladonna, 75% of the patients presented a positive response, with 44% of the patients presenting with complete resolution of the spells (p<0.01). No major adverse reaction was reported, with only 5% minor adverse events.

Conclusions

Belladonna is highly effective to alleviate severe breath-holding spells in young children, without any major adverse effects.
On the object of archaeology
Authors: Nativ Assaf
Published: May 2018

The paper ponders the object of archaeology, called here ‘the archaeological’. It argues that the existence of such an object is a necessary premise of the field and that ultimately it is on this object that the validity of all claims and arguments must rest. The paper suggests that the archaeological be conceived as a cultural phenomenon that consists in being disengaged from the social, an understanding that positions archaeology as a counterpart to the social sciences and the humanities, rather than a member in the same milieu. The first part of the paper focuses on the position of the archaeological with reference to the concepts of ‘Nature’ and ‘Culture’, which eventually leads us to a confrontation between archaeological statics and the dynamics of the world. Efforts to justify and understand archaeological statics consequently lead to the recognition of a constitutive distinction between buried and non-buried conditions, upon which the differentiation of the archaeological from the social is established.
Archaeology is process
Authors: Harris Oliver
Published: May 2018

Assaf Nativ has written an interesting and, I think, important paper. It raises critical issues around the ontological status of ‘the archaeological’ and indeed about the purpose and aims of archaeology as a discipline. These are clearly topics that require consideration and critical analysis. His arguments are provocative, in the best sense, in that they will lead us to reflect on some of the basic foundations of what we believe archaeology to be. Such consideration is certainly necessary to disciplinary health. That said, and after some hefty reflection of my own, I have concluded that I disagree with much of the paper's argument. In the space afforded to me I aim to set out why.
For the objects, archaeology and the archaeological
Authors: Witmore Christopher
Published: May 2018

Archaeology turns round its objects as much as it turns them out. This is partially an artefact of its reflection, which is not always linear; it is sometimes cyclic. The cyclic is not a perfect circle. Our objects open themselves in new ways to archaeological engagement, but this new relevance surfaces through creative inspiration triangulated off previous orientations. In revolving around our objects, inevitably we return to a familiar place, even though it is where we have never been (González-Ruibal 2014). The linear orientation, by contrast, is progressive. It fashions its every step anew. Thus its movement is supersessive – it pushes forward by violently casting overboard what is considered to be of less value (often on misconstrued grounds) and assuming its position. Whereas the former oscillates with various degrees of awareness, the latter strikes out with inevitable levels of amnesia. To attain a genuinely novel position one must struggle against forgetting former orientations, for to eliminate is to run the risk of repetition – blind to whether or not one ever truly invents – and even redundancy – with multiple copies the impact of our work is diminished. Still, if true improvement constitutes progress, then archaeology, when properly executed, moves in spirals, and our objects move with us.
Wernicke encephalopathy without delirium that appeared as agitation in a patient with lung cancer
Authors: Onishi Hideki , Ishida Mayumi , Takahashi Takao , Taji Yoshitada , Ikebuchi Kenji , Furuya Daisuke , Uchida Nozomu , Akechi Tatsuo
Published: May 2018

Objective

Wernicke encephalopathy (WE) is a neuropsychiatric disorder caused by thiamine deficiency, and is sometimes overlooked because of the diversity of clinical symptoms.

Method

From a series of WE patients with cancer, we report a lung cancer patient who developed WE, the main symptom of which was agitation.

Result

A 50-year-old woman with lung cancer was referred to our psycho-oncology clinic because of agitation lasting for three days. No laboratory findings or drugs explaining her agitation were identified. Although the patient did not develop delirium, ophthalmoplegia, or ataxia, WE was suspected because she experienced a loss of appetite loss lasting 5 weeks. This diagnosis was supported by abnormal serum thiamine and disappearance of agitation one hour after intravenous thiamine administration.

Significance of results

This report emphasizes the clinical diversity of WE and indicates the limits of the ability to diagnose WE from typical clinical symptoms. The presence of a loss of appetite for more than two weeks may be the key to the accurate diagnosis of WE.
Conceptualizing and Measuring Women's Political Leadership: From Presence to Balance
Authors: Joshi Devin , Goehrung Ryan
Published: May 2018

Cross-national studies of women's political leadership (WPL) usually focus on female prime ministers and presidents or numbers of women in parliament. While illuminating, these studies fail to provide a comprehensive assessment of WPL in a particular place and time. Addressing this gap in the literature, we assert that WPL is inherently contingent upon the theoretical concepts of “structural power” and “male dominance,” encompassing multiple formal apex political decision-making institutions. In accordance with this perspective, we have constructed a novel women's political leadership index based on collective leadership across judicial (high court judges), executive (cabinet ministers), and legislative (parliamentary committee chairs) branches of governments to capture both the presence of women among political leaders and their balance across institutions. Applying our index to 21 diverse territories in Asia, we demonstrate the utility of our approach through a series of country case studies illustrating four prominent patterns of WPL: exclusion, illusion, imbalance, and balance. We conclude by discussing the potential benefits of globally expanding the scope of the index.
Bi-layered/tri-layered bio-media in direct contact with metal diagonal horn for hyperthermia
Authors: Singh Soni , Sahu Bhagirath , Singh S. P.
Published: May 2018

In this paper, theoretical/simulation study of specific absorption rate (SAR) and/or temperature distributions in a bi-layered bio-media (fat and muscle)/realistic tri-layered bio-media (skin, fat, and muscle layers) in direct contact with water-loaded metal diagonal horn (MDH) designed at 915 MHz are investigated. The effects of fat thickness on the input reflection coefficient, reflection coefficient at the interface between the MDH and the bi-layered bio-media, and the SAR distribution in the bi-layered bio-media are also studied through simulation and theoretically at 915 MHz. Further, the SAR parameters such as penetration depth and effective field size inside the bi-layered bio-media due to the MDH are evaluated theoretically and the theoretical results are compared with the corresponding simulation results. Finally, SAR and temperature distributions in tri-layered bio-media without and with embedded irregular/oval-shaped tumor are provided for demonstrating the hyperthermia performance of the MDH applicator.
A multi-band switchable antenna for Wi-Fi, 3G Advanced, WiMAX, and WLAN wireless applications
Authors: Ullah Sadiq , Ahmad Shaheen , Khan Burhan A. , Flint James A.
Published: May 2018

This paper presents a hexa-band frequency reconfigurable planar antenna, printed on a 1.6 mm thicker FR 4 substrate and backed by a truncated ground plane. The given antenna operates in four different frequency modes, depending on the state of the two lumped element switches. The proposed antenna works at six frequencies, 2.10, 2.40, 3.35, 3.50, 5.28, and 5.97 GHz. These frequency bands are dedicated to useful wireless applications, including 3G Advanced (2.10 GHz), Wireless Fidelity (Wi-Fi) (2.40 GHz), WiMAX (3.35 GHz), WiMAX (3.5 GHz), WLAN (5.28 GHz) and fixed-satellite and mobile satellite services (5.97 GHz). Satisfactory gain of 1.96, 2.20, 2.671, 2.81, 3.80, and 3.88 dBi, efficiency of 92.5, 94.5, 94.56, 95.0, 93.8, and 97.0% and bandwidth of 332, 485, 1020, 1080, 512, and 465 MHz has been obtained at 2.10, 2.40, 3.35, 3.50, 5.28, and 5.97 GHz, respectively. The modeling and simulations are conducted in CST MWS (2014). The simulated reflection coefficient and radiation pattern are validated in antenna measurement facility. In addition, the specific absorption rate of the antenna on a flat section of human body is also studied. The antenna is compact, low profile, and vastly suitable for multi-band wireless devices.
Looking at the Same Interaction and Seeing Something Different
Authors: Wall Helen J. , Taylor Paul J. , Campbell Claire , Heim Derek , Richardson Beth
Published: May 2018

Abstract. The role of information context, judgment perspective and cue type on the “accuracy” of first impressions of another’s Big5 personality was studied in three phases of data collection (n = 173). Accurate judgments were defined as the level of agreement between a target person’s aggregated personality score (i.e., average of self and informant ratings of personality) and a personality judgement about the target, indexed using item correlations. Results for Phase 1 found that completing a different task with the same partner improved accuracy for conscientiousness. Phase 2 investigated the relationship between a person’s role (judgment perspective) within an interaction (interactants, observers) and showed that Observers were better at judging the less interpersonal traits of conscientiousness and openness relative to Interactants. Finally, Phase 3 examined the types of cues that people used when rating another’s personality. Although Observers and Interactants had access to the same interaction, analyses revealed that they employed different types of cues when judging others. Findings are discussed in terms of Funder’s Realistic Accuracy Model (1995 , 1999 ) along with practical implications, limitations and suggestions for future research.
Uncovering the Iceland Hot Spot Track Beneath Greenland
Authors: Mordret Aurélien
Published: May 2018

During the past 120 Ma, the Greenland craton drifted over the Iceland hot spot; however, uncertainties in geodynamic modeling and a lack of geophysical evidence prevent an accurate reconstruction of the hot spot track. I image the Greenland lithosphere down to 200‐km depth with both group and phase velocity seismic noise tomography. The 3‐D shear wave velocity model obtained using 4–5 years of continuous seismic records from the Greenland Ice Sheet Monitoring Network is well resolved for most of the Greenland main island. The crustal part of the model clearly shows different tectonic units. The hot spot track is observed as a linear high‐velocity anomaly in the middle and lower crust associated with magmatic intrusions. In the upper mantle, a pronounced low‐velocity anomaly below the east coast might be due to the remnant effect of the Iceland hot spot when it was at its maximum intensity. Thermomechanical modeling suggests that this area has higher temperature and lower viscosity than the surrounding cratonic areas and experiences a higher than average surface heat flow. This new detailed picture of the Greenland lithosphere will drive more accurate geodynamic reconstructions of tectonic plate motions and help to better understand the North Atlantic tectonic history. Models of Greenland glacial isostatic adjustment will benefit from the 3‐D upper‐mantle viscosity model, which in turn will enable more precise estimations of the Greenland ice sheet mass balance.
Bubble‐Mediated Gas Transfer and Gas Transfer Suppression of DMS and CO2
Authors: Zavarsky A. , Goddijn‐Murphy L. , Steinhoff T. , Marandino C. A.
Published: May 2018

Direct dimethyl sulfide (DMS) flux measurements using eddy covariance have shown a suppression of gas transfer at medium to high wind speed. However, not all eddy covariance measurements show evidence of this suppression. Processes, such as wave‐wind interaction and surfactants, have been postulated to cause this suppression. We measured DMS and carbon dioxide eddy covariance fluxes during the Asian summer monsoon in the western tropical Indian Ocean (July and August 2014). Both fluxes and their respective gas transfer velocities show signs of a gas transfer suppression above 10 m/s. Using a wind‐wave interaction, we describe a flow separation process that could be responsible for a suppression of gas transfer. As a result we provide a Reynolds number‐based parameterization, which states the likelihood of a gas transfer suppression for this cruise and previously published gas transfer data. Additionally, we compute the difference in the gas transfer velocities of DMS and CO2 to estimate the bubble‐mediated gas transfer using a hybrid model with three whitecap parameterizations.
Link Between the Dynamics of Granular Flows and the Generated Seismic Signal: Insights From Laboratory Experiments
Authors: Farin Maxime , Mangeney Anne , de Rosny Julien , Toussaint Renaud , Trinh Phuong‐Thu
Published: May 2018

Granular column collapse experiments have been conducted on a flat rough surface tilted at various angles with synchronous measurements of the flow dynamics and the emitted seismic signal. Our results show that the ratio of radiated seismic energy to potential energy lost by the granular flows decreases slightly from 0.033% to 0.017% with increasing slope angle on a poly(methyl methacrylate) (acrylic) plate. This is about 90 times lower than for the impact of a single particle of the same diameter. The experimental granular flows generated signals with frequencies lower than 20 kHz, with a mean value around 5 kHz, which are shown to be similar to the frequencies emitted by a single‐particle impact. The rise phase and maxima of the amplitude and frequencies of the seismic signals generated by our experimental granular flows are mostly controlled by flow motion in the direction normal to the slope, while their decay phase depends on downslope particle speeds. The granular flow regime changes from dense to more agitated flows above a critical slope angle that is about half the friction angle of the granular material. This change is reflected in (1) the shape of the temporal variation of the seismic amplitude and frequencies, with a decay phase lasting much longer and (2) the shape of the cumulative radiated seismic energy, which changes above the same critical slope angle. Implications of these results for the interpretation of seismic emissions from experimental and natural granular flows are discussed.
Seismic Energy Analysis as Generated by Impact and Fragmentation of Single‐Block Experimental Rockfalls
Authors: Saló L. , Corominas J. , Lantada N. , Matas G. , Prades A. , Ruiz‐Carulla R.
Published: May 2018

The analysis of seismic signals obtained from near‐source triaxial accelerometer recordings of two sets of single‐block rockfall experiments is presented. The tests were carried out under controlled conditions in two quarries in northeastern Spain; in the first test (Foj limestone quarry, Barcelona), 30 blocks were released with masses ranging between 475 and 11,480 kg. The second test (Ponderosa andesite quarry, Tarragona) consisted of the release of 44 blocks with masses from 466 to 13,581 kg. An accelerometer and three high‐speed video cameras were deployed, so that the trajectories, velocities, and block fragmentation could be tracked precisely. These data were used to explore the relationship between seismic energy and rockfall kinetics (the latter obtained from video analysis). We determined absolute and relative values of seismic energy and used them to estimate rockfall volumes. Finally, the seismic signature of block fragmentation was assessed in both the frequency and time domains. The ratios of seismic energy after impact to kinetic energy before impact ranged between 10−7 and 10−4. These variables were weakly correlated. The use of seismic energy relative to impacting kinetic energy was preferred for the estimation of volumes. Block fragmentation impacts were dominated by higher acceleration spectrum centroid frequencies than those of nonfragmentation impacts: 56.62 ± 2.88 and 48.46 ± 4.39 Hz at Foj and 52.84 ± 12.73 and 38.14 ± 4.73 Hz at Ponderosa.
W‐Band Compact Slot Antenna Arrays With Polarization Flexibility
Authors: Numan Ahmed B. , Frigon Jean‐François , Laurin Jean‐Jacques
Published: May 2018

A novel W‐band arbitrary polarization compact radiating structure that can be used to design antenna arrays with wide angle beamforming and limited grating lobes is described in this article. The radiating element is a slot which can be oriented in any direction to achieve the desired polarization. This slot is placed on a rectangular cavity, which is operated in its fundamental mode to achieve compact size. The cavity is coupled with a substrate‐integrated waveguide feed line using a coupling slot. These radiating elements are series fed to form compact one‐dimensional arrays, which can be combined to design two‐dimensional arrays having field of view up to 120° and with limited grating lobes in the plane transverse to the one‐dimensional array axis. One‐ and two‐dimensional arrays for two orthogonal polarizations were fabricated and tested to validate the described structure.
A Near-Real-Time Tool to Characterize Global Landslide Hazards
Authors: Cook Terri
Published: May 2018

By fusing susceptibility information with precipitation data, a new model generates “nowcasts” to predict the potential for rainfall-triggered landslides in steep terrain between 50°N and 50°S.
Multihazard Scenarios for Analysis of Compound Extreme Events
Authors: Sadegh Mojtaba , Moftakhari Hamed , Gupta Hoshin V. , Ragno Elisa , Mazdiyasni Omid , Sanders Brett , Matthew Richard , AghaKouchak Amir
Published: May 2018

Compound extremes correspond to events with multiple concurrent or consecutive drivers (e.g., ocean and fluvial flooding, drought, and heat waves) leading to substantial impacts such as infrastructure failure. In many risk assessment and design applications, however, multihazard scenarios of extremes and compound events are ignored. In this paper, we review the existing multivariate design and hazard scenario concepts and introduce a novel copula‐based weighted average threshold scenario for an expected event with multiple drivers. The model can be used for obtaining multihazard design and risk assessment scenarios and their corresponding likelihoods. The proposed model offers uncertainty ranges of most likely compound hazards using Bayesian inference. We show that the uncertainty ranges of design quantiles might be large and may differ significantly from one copula model to the other. We also demonstrate that the choice of marginal and copula functions may profoundly impact the multihazard design values. A robust analysis should account for these uncertainties within and between multivariate models that translate into multihazard design quantiles.
Modeling Amateur Radio Soundings of the Ionospheric Response to the 2017 Great American Eclipse
Authors: Frissell N. A. , Katz J. D. , Gunning S. W. , Vega J. S. , Gerrard A. J. , Earle G. D. , Moses M. L. , West M. L. , Huba J. D. , Erickson P. J. , Miller E. S. , Gerzoff R. B. , Liles W. , Silver H. W.
Published: May 2018

On 21 August 2017, a total solar eclipse traversed the continental United States and caused large‐scale changes in ionospheric densities. These were detected as changes in medium‐ and high‐frequency radio propagation by the Solar Eclipse QSO Party citizen science experiment organized by the Ham Radio Science Citizen Investigation (hamsci.org). This is the first eclipse‐ionospheric study to make use of measurements from a citizen‐operated, global‐scale HF propagation network and develop tools for comparison to a physics‐based model ionosphere. Eclipse effects were observed ±0.3 hr on 1.8 MHz, ±0.75 hr on 3.5 and 7 MHz, and ±1 hr on 14 MHz and are consistent with eclipse‐induced ionospheric densities. Observations were simulated using the PHaRLAP raytracing toolkit in conjunction with the eclipsed SAMI3 ionospheric model. Model results suggest 1.8, 3.5, and 7 MHz refracted at h≥125 km altitude with elevation angles θ≥22°, while 14 MHz signals refracted at h < 125 km with elevation angles θ < 10°.
Intrathermocline Eddies Embedded Within an Anticyclonic Vortex Ring
Authors: Meunier Thomas , Tenreiro M. , Pallàs‐Sanz Enric , Ochoa Jose , Ruiz‐Angulo Angel , Portela Esther , Cusí Simò , Damien Pierre , Carton Xavier
Published: May 2018

High‐resolution hydrographic measurements reveal the presence of three intrathermocline eddies (ITEs) embedded within a loop current eddy. ITEs are lenticular bodies of nearly homogeneous water, which contrasts with the well‐stratified surrounding water. Their radii and thickness ranged between 19–32 km and 150–250 m. Negative relative vorticity within their cores (down to −0.85 times the Coriolis frequency), along with a large negative stratification anomaly, results in low Ertel potential vorticity and intense negative Ertel potential vorticity anomalies. Vortex stretching and relative vorticity have comparable contributions to potential vorticity anomaly, resulting in Burger numbers of order unity. The similarity of thermohaline properties within the ITE's cores and the surrounding loop current eddy water suggests that these ITEs likely form by intense mixing events followed by Rossby adjustment.
Opposite Aerosol Index‐Cloud Droplet Effective Radius Correlations Over Major Industrial Regions and Their Adjacent Oceans
Authors: Ma X. , Jia H. , Yu F. , Quaas J.
Published: May 2018

The Moderate Resolution Imaging Spectroradiometer (MODIS) C6 L3 and the European Centre for Medium‐Range Weather Forecasts (ECMWF) ERA‐Interim reanalysis data from 2003 to 2016 are employed to study aerosol‐cloud correlations over three industrial regions and their adjacent oceans, as well as explore the impact of meteorological conditions on the correlations. The analysis focusing on liquid and single‐layer clouds indicates an opposite aerosol‐cloud correlation between land and ocean; namely, cloud effective radius is positively correlated with aerosol index over industrial regions (positive slopes), but negatively correlated over their adjacent oceans (negative slopes), for a quasi‐constant liquid water path. The positive slopes are relatively large under low lower‐tropospheric stability (LTS; weakly stable condition), but much weaker or even become negative under high LTS (stable conditions) and high liquid water path. The occurrence frequency of cloud top height (CTH) and LTS suggests that positive correlations are more likely corresponding to relatively high CTH and low LTS, while negative to low CTH and high LTS.
Fluid Injection and Time‐Dependent Seismic Hazard in the Barnett Shale, Texas
Authors: Zhai Guang , Shirzaei Manoochehr
Published: May 2018

The Barnett Shale in Texas experienced an increase in seismicity since 2008, coinciding with high‐volume deep fluid injection. Despite the spatial proximity, the lack of a first‐order correlation between seismic records and the total volume of injected fluid requires more comprehensive geomechanical analysis, which accounts for local hydrogeology. Using time‐varying injections at 96 wells and employing a coupled linear poroelastic model, we simulate the spatiotemporal evolution of pore pressure and poroelastic stresses during 2007–2015. The overall contribution of poroelastic stresses to Coulomb failure stress change is ~10% of that of pore pressure; however, both can explain the spatiotemporal distribution of earthquakes. We use a seismicity rate model to calculate earthquake magnitude exceedance probability due to stress changes. The obtained time‐dependent seismic hazard is heterogeneous in space and time. Decreasing injection rates does not necessarily reduce probabilities immediately.
High‐Latitude Observations of a Localized Wind Wall and Its Coupling to the Lower Thermosphere
Authors: Shepherd Gordon G. , Shepherd Marianna G.
Published: May 2018

Reversals in the thermospheric zonal winds at altitudes of 140 to 250 km from eastward to westward have been found at southern geographic latitudes between 60° and 70°. These are confined to a narrow region between 100° and 200° in longitude with zonal velocities regularly of −400 m/s, sometimes reaching −600 m/s, so sharply defined that the authors describe it as a “wind wall.” The observations were made by the Wind Imaging Interferometer on National Aeronautics and Space Administration's Upper Atmosphere Research Satellite, and they occur as the field of view crosses the high polar cap wind field. The wind reversals at the wall boundaries create a convergence on the west side of the wall and a divergence on the east side that potentially generate vertical flows, consistent with observed perturbations in the O(1S) emission rate. They are present about one half of the time in local summer and autumn.
The Mars Topside Ionosphere Response to the X8.2 Solar Flare of 10 September 2017
Authors: Thiemann E. M. B. , Andersson L. , Lillis R. , Withers P. , Xu S. , Elrod M. , Jain S. , Pilinski M. D. , Pawlowski D. , Chamberlin P. C. , Eparvier F. G. , Benna M. , Fowler C. , Curry S. , Peterson W. K. , Deighan J.
Published: May 2018

On 10 September 2017, irradiance from a magnitude X8.2 solar flare impacted Mars while the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter was characterizing the Mars upper atmosphere. This solar flare was the largest to occur during the MAVEN mission to date, nearly tripling the ionizing irradiance impacting Mars in tens of minutes, and provides an opportunity to study the planet's response to extreme irradiance changes. This letter reports in situ observations of the Mars topside ionosphere's response to this flare above 155 km made 1.67 hr after the flare soft X‐ray peak. The observed plasma density increase is higher than expected based solely on increased ionization, and the electron temperature decreases below 225 km; both effects can be explained by an expanded neutral atmosphere, which efficiently dissipates any flare‐induced heating of the thermal electrons at altitudes where CO2 is the dominant species. Further, the ion density and composition change significantly at both fixed altitude and pressure level, which can be explained by a change in the O:CO2 density ratio, highlighting the importance this ratio has in determining ionospheric structure.
Ocean Carbon Cycle Feedbacks Under Negative Emissions
Authors: Schwinger Jörg , Tjiputra Jerry
Published: May 2018

Negative emissions will most likely be needed to achieve ambitious climate targets, such as limiting global warming to 1.5°. Here we analyze the ocean carbon‐concentration and carbon‐climate feedback in an Earth system model under an idealized strong CO2 peak and decline scenario. We find that the ocean carbon‐climate feedback is not reversible by means of negative emissions on decadal to centennial timescales. When preindustrial surface climate is restored, the oceans, due to the carbon‐climate feedback, still contain about 110 Pg less carbon compared to a simulation without climate change. This result is unsurprising but highlights an issue with a widely used carbon cycle feedback metric. We show that this metric can be greatly improved by using ocean potential temperature as a proxy for climate change. The nonlinearity (nonadditivity) of climate and CO2‐driven feedbacks continues to grow after the atmospheric CO2 peak.
Machine Learning Seismic Wave Discrimination: Application to Earthquake Early Warning
Authors: Li Zefeng , Meier Men‐Andrin , Hauksson Egill , Zhan Zhongwen , Andrews Jennifer
Published: May 2018

Performance of earthquake early warning systems suffers from false alerts caused by local impulsive noise from natural or anthropogenic sources. To mitigate this problem, we train a generative adversarial network (GAN) to learn the characteristics of first‐arrival earthquake P waves, using 300,000 waveforms recorded in southern California and Japan. We apply the GAN critic as an automatic feature extractor and train a Random Forest classifier with about 700,000 earthquake and noise waveforms. We show that the discriminator can recognize 99.2% of the earthquake P waves and 98.4% of the noise signals. This state‐of‐the‐art performance is expected to reduce significantly the number of false triggers from local impulsive noise. Our study demonstrates that GANs can discover a compact and effective representation of seismic waves, which has the potential for wide applications in seismology.
Test‐Particle Simulations of Linear and Nonlinear Interactions Between a 2‐D Whistler‐Mode Wave Packet and Radiation Belt Electrons
Authors: da Silva C. L. , Denton R. E. , Hudson M. K. , Millan R. M. , Liu K. , Bortnik J.
Published: May 2018

Using test‐particle simulations, we describe (in 2‐D) the interaction of an ensemble of electrons with a discrete whistler‐mode wave packet, which propagates with a moderate wave‐normal angle with respect to the background magnetic field. We evaluate both the average transport coefficients used in quasi‐linear diffusion transport and also the full nonlinear wave‐particle interactions. The magnitude of the calculated diffusion coefficients is found to increase proportionally to the wave amplitude squared, in agreement with quasi‐linear diffusion theory. Cyclotron resonance of counterstreaming electrons (n = 1 harmonic number) is more important for pitch angle scattering than Landau resonance. Landau resonance of costreaming electrons (n = 0) is comparable to cyclotron resonance for energy diffusion and advection. Strong acceleration of high pitch angle, costreaming electrons arises in nonlinear wave‐particle interactions with high‐amplitude waves. In our simulations with zero parallel electric field, the energy source for electron acceleration is the wave's perpendicular electric field, in both the cyclotron and Landau resonances. The Landau resonance can happen even with zero parallel electric field, if the wave packet propagates with a finite wave‐normal angle. This resonance between the particle's azimuthal velocity and the wave fields leads to trapping and substantial parallel acceleration.
Arctic Sea Ice Decline Significantly Contributed to the Unprecedented Liquid Freshwater Accumulation in the Beaufort Gyre of the Arctic Ocean
Authors: Wang Qiang , Wekerle Claudia , Danilov Sergey , Koldunov Nikolay , Sidorenko Dmitry , Sein Dmitry , Rabe Benjamin , Jung Thomas
Published: May 2018

The Beaufort Gyre (BG) is the largest liquid freshwater reservoir of the Arctic Ocean. The liquid freshwater content (FWC) significantly increased in the BG in the 2000s during an anticyclonic wind regime and remained at a high level despite a transition to a more cyclonic state in the early 2010s. It is not well understood to what extent the rapid sea ice decline during this period has modified the trend and variability of the BG liquid FWC in the past decade. Our numerical simulations show that about 50% of the liquid freshwater accumulated in the BG in the 2000s can be explained by the sea ice decline caused by the Arctic atmospheric warming. Among this part of the FWC increase, 60% can be attributed to surface freshening associated with the reduction of the net sea ice thermodynamic growth rate, and 40% to changes in ocean circulation, which makes freshwater more accessible to the BG for storage. Thus, the rapid increase of the BG FWC in the 2000s was due to the concurrence of the anticyclonic wind regime and the high freshwater availability. We also find that if the Arctic sea ice had not declined, the liquid FWC in the BG would have shown a stronger decreasing tendency at the beginning of the 2010s owing to the cyclonic wind regime. From our results we argue that changes in sea ice conditions should be adequately taken into account when it comes to understanding and predicting variations of BG liquid FWC in a changing climate.
Saturn's Planetary Period Oscillations During the Closest Approach of Cassini's Ring‐Grazing Orbits
Authors: Hunt G. J. , Provan G. , Cowley S. W. H. , Dougherty M. K. , Southwood D. J.
Published: May 2018

Saturn's planetary period oscillations (PPOs) are ubiquitous throughout its magnetosphere. We investigate the PPO's azimuthal magnetic field amplitude interior to the field‐aligned currents, during the closest approaches of Cassini's ring‐grazing orbits (October 2016 to April 2017), with periapses at ~2.5 RS. The amplitudes of the northern and southern PPO systems are shown to vary as a function of latitude. The amplitude ratio between the two PPO systems shows that the northern system is dominant by a factor of ~1.3 in the equatorial plane, and it is dominant to ~ −15° latitude in the southern hemisphere. The dayside amplitudes are approximately half of the 2008 nightside amplitudes, which agree with previous local time‐related amplitude observations. Overall, there is clear evidence that the PPOs are present on field lines that map to the outer edge of Saturn's rings, closer to Saturn than previously confirmed.