bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma exchange for Alzheimer's disease Management by Albumin Replacement (AMBAR) trial: Study design and progress
Authors: Boada Mercè , López Oscar , Núñez Laura , Szczepiorkowski Zbigniew M. , Torres Mireia , Grifols Carlota , Páez Antonio
Published: February 2019

Introduction

Preliminary studies have shown that treatment with plasma exchange (PE) plus therapeutic albumin replacement in patients with Alzheimer's disease (AD) induced mobilization of plasma and cerebrospinal fluid amyloid β protein, associated with an improvement in memory and language functions, as well as the stabilization of brain perfusion, which persisted after treatment discontinuation.

Methods

Alzheimer's Management By Albumin Replacement (AMBAR) is a multicenter, randomized, blinded and placebo‐controlled, parallel‐group, phase IIb/III trial enrolling patients with mild to moderate AD. The study evaluates PE with different replacement volumes of therapeutic albumin (5% and 20% Albutein®, Grifols), with or without intravenous immunoglobulin (Flebogamma® 5% DIF, Grifols). Patients are randomized to one of three active treatment groups or one control (sham PE) group (1:1:1:1). The intervention regime includes a first 6‐week stage of intensive treatment, followed by a second 12‐month stage of maintenance treatment. The change from the baseline to the end of treatment periods in the ADAS‐Cog and ADCS‐ADL scores are the coprimary efficacy variables. Secondary efficacy variables include change from the baseline in scores on cognitive, functional, behavioral, and overall progression tests; changes in plasma and cerebrospinal fluid levels of amyloid β and tau protein; and assessment of structural and functional changes in brain areas of interest. Safety and tolerability are assessed.

Results

The study has enrolled 496 patients from 41 centers (19 in Spain and 22 in the USA); 347 of these patients were randomized and underwent close to 5000 PEs, of which approximately 25% were sham PEs.

Discussion

We present an innovative approach for treating AD. The study has been designed to demonstrate clinical efficacy, defined as slow decline of the patient's cognition and brain function. The sample size has adequate power to detect differences between any of the active treatment groups and the control group, as well as between the three active treatment groups combined and the control group.
Legislative Hardball
Authors: Green Matthew
Published: February 2019

Assertive bargaining occurs from time to time in the US Congress. It became an important feature of legislative negotiations within the House Republican Party when, following the 2014 elections, a group of organized conservatives called the House Freedom Caucus regularly issued threats against its own party's leadership. Such behavior by an ideologically extreme bloc of lawmakers is not accounted for by existing theories of legislative politics. This Element posits explanations for why such threat-making might occur and what might increase its likelihood of success, then tests those explanations using the Freedom Caucus as a case study.
Transport by deep convection in basin-scale geostrophic circulation: turbulence-resolving simulations
Authors: Vreugdenhil Catherine A. , Gayen Bishakhdatta , Griffiths Ross W.
Published: February 2019

Direct numerical simulations are used to investigate the nature of fully resolved small-scale convection and its role in large-scale circulation in a rotating$f$-plane rectangular basin with imposed surface temperature difference. The large-scale circulation has a horizontal geostrophic component and a deep vertical overturning. This paper focuses on convective circulation with no wind stress, and buoyancy forcing sufficiently strong to ensure turbulent convection within the thermal boundary layer (horizontal Rayleigh numbers$Ra\approx 10^{12}{-}10^{13}$). The dynamics are found to depend on the value of a convective Rossby number,$Ro_{\unicode[STIX]{x0394}T}$, which represents the strength of buoyancy forcing relative to Coriolis forces. Vertical convection shifts from a mean endwall plume under weak rotation ($Ro_{\unicode[STIX]{x0394}T}>10^{-1}$) to ‘open ocean’ chimney convection plus mean vertical plumes at the side boundaries under strong rotation ($Ro_{\unicode[STIX]{x0394}T}<10^{-1}$). The overall heat throughput, horizontal gyre transport and zonally integrated overturning transport are then consistent with scaling predictions for flow constrained by thermal wind balance in the thermal boundary layer coupled to vertical advection–diffusion balance in the boundary layer. For small Rossby numbers relevant to circulation in an ocean basin, vertical heat transport from the surface layer into the deep interior occurs mostly in ‘open ocean’ chimney convection while most vertical mass transport is against the side boundaries. Both heat throughput and the mean circulation (in geostrophic gyres, boundary currents and overturning) are reduced by geostrophic constraints.
On the brachistochrone of a fluid-filled cylinder
Authors: Gurram Srikanth Sarma , Raja Sharan , Mahapatra Pallab Sinha , Panchagnula Mahesh V.
Published: February 2019

We discuss a fluid dynamic variant of the classical Bernoulli’s brachistochrone problem. The classical brachistochrone for a non-dissipative particle is governed by maximization of the particle’s kinetic energy, resulting in a cycloid. We consider a variant where the particle is replaced by a cylinder (bottle) filled with a viscous fluid and attempt to identify the shape of the curve connecting two points along which the bottle would move in the shortest time. We derive the system of integro-differential equations governing system dynamics for a given shape of the curve. Using these equations, we pose the brachistochrone problem by invoking an optimal control formalism and show that (in general) the curve deviates from a cycloid. This is due to the fact that increasing the rate of change of the bottle’s kinetic energy is accompanied by increased viscous dissipation. We show that the bottle motion is governed by a balance between the desire to minimize travel time and the need to reach the end point in the face of increased dissipation. The trade-off between these two physical forces plays a vital role in determining the brachistochrone of a fluid-filled cylinder. We show that in the two limits of either vanishing or high viscosity, the brachistochrone for this problem reduces to a cycloid. An intermediate viscosity range is identified where the fluid brachistochrone is non-cycloidal. Finally, we show the relevance of these results to the dynamics of a rolling liquid marble.
The mechanism and boundary conditions of the relationship between customer incivility and service quality
Authors: Lin Cheng-Chen , Lai Fong-Yi
Published: February 2019

This study addresses the causal linkage between customer incivility and service quality through the lens of self-determination theory, according to which need satisfaction as a potential mechanism mediates this relationship. Additionally, it examines the moderating role of surface acting in the relationship between customer incivility and need satisfaction. Dyadic questionnaires were collected from restaurant employees and their customers in Taiwan. A total of 190 employees and 645 customers participated in this study. Results found that need satisfaction mediates the negative relationship between customer incivility and service quality. Surface acting moderates the relationship between customer incivility and need satisfaction as well as the mediation effect of customer incivility on service quality through need satisfaction. Specifically, the indirect effect of need satisfaction on the relation between customer incivility and service quality creativity was more significantly negative at a high level of surface acting than the effect at a low level.
A Neognathodus-based biozonation of the Desmoinesian Series (Pennsylvanian) in the Illinois Basin, USA
Authors: Zimmerman Alexander N. , Brown Lewis M. , Rexroad Carl B.
Published: February 2019

The Neognathodus Index (NI) is developed as a primary biostratigraphic indicator for the Desmoinesian Series of the Illinois Basin in Indiana, Illinois, and Kentucky. It is based on the gradual evolutionary morphotypic variations of P1 elements of named species of Neognathodus Dunn, 1970. The NI analyses and zonations presented herein are constructed from 472 productive conodont samples from 105 different localities. NIs for the Illinois Basin show morphologic drift in Indiana from the Perth Limestone Member of the Staunton Formation (NI = 2.03) to the Velpen Limestone and Mecca Quarry Shale members of the Linton Formation (NI = 5.04) followed by stability through the Alum Cave (NI = 4.83). Further morphologic drift then occurred through the Providence Limestone Member of the Dugger Formation (NI = 5.43) and continued through the West Franklin Limestone Member of the Shelburn Formation (NI = 6.32) until the extinction of Neognathodus at the end of Desmoinesian. The patterns of drift and stability translate to Neognathodus biozones and are supported by Kolmogorov-Smirnov tests of standardized Neognathodus morphotype distributions. Localized NI variations are due to morphologic shifts and differential evolution in response to localized environmental conditions. Examination of the NI differences in the states of Illinois, Kentucky, and Indiana reflect similar morphologic simplification of the P1 element from Perth to Velpen and Mecca Quarry in Indiana (NI = 2.03–5.04) and from Seville to Brereton in Illinois and Kentucky (NI = 2.80–5.00). Post-Brereton in Illinois and Kentucky (NI = 5.00–5.65) and post-Providence in Indiana (NI = 5.43–6.32) saw progressive P1 simplification, but it was much more pronounced in Indiana.
COMPACT WEIGHTED COMPOSITION OPERATORS ON -SPACES
Authors: LO CHING-ON , LOH ANTHONY WAI-KEUNG
Published: February 2019

Let
$u$
and
$\unicode[STIX]{x1D711}$
be two analytic functions on the unit disc
$D$
such that
$\unicode[STIX]{x1D711}(D)\subset D$
. A weighted composition operator
$uC_{\unicode[STIX]{x1D711}}$
induced by
$u$
and
$\unicode[STIX]{x1D711}$
is defined by
$uC_{\unicode[STIX]{x1D711}}f:=u\cdot f\circ \unicode[STIX]{x1D711}$
for every
$f$
in
$H^{p}$
, the Hardy space of
$D$
. We investigate compactness of
$uC_{\unicode[STIX]{x1D711}}$
on
$H^{p}$
in terms of function-theoretic properties of
$u$
and
$\unicode[STIX]{x1D711}$
.
American Recreation: Sportsmanship and the New Nationalism, 1900–1910
Authors: MCLAUGHLIN MALCOLM
Published: February 2019

This article is about the relationship between the culture of outdoors recreation and the development of progressive politics at the turn of the twentieth century in the United States. It considers the significance of popular outdoors magazines for American culture and politics before focussing in particular on the way in which Caspar Whitney, as editor ofOutingmagazine, constructed a notion of sportsmanship modelled upon the idealized figure of Theodore Roosevelt – an exemplar, by his reckoning, of the patrician class, and the template for his vision of a progressive citizenship. It was through the notion of sportsmanship that Whitney defined a set of values that would become synonymous with the strain of progressivism known as the New Nationalism, out of which the tradition of reform liberalism emerged in the twentieth century.
Effect of thermal treatment of whey contaminated with antibiotics on the growth of Kluyveromyces marxianus
Authors: Eluk Dafna , Ceruti Roberto , Nagel Orlando , Althaus Rafael
Published: February 2019

The objective of the studies reported in this research communication was to investigate the use of whey contaminated with antibiotics such as cephalosporins, quinolones and tetracyclines as a nutrient medium for the growth of Kluyveromyces marxianus with particular attention to the effect of thermal treatment used to overcome the inhibitory effects of antibiotic concentrations close to the Maximum Residue Limits. The heat treatments at 120 °C for 40 min, 120 °C for 83 min, and 120 °C for 91 min caused total inactivation of cephalosporins, tetracyclines and quinolone residues in whey respectively.
Enhancing dysphonia clinic consultations through a focus on patients’ expectations: streamlining and validation of a new tool (‘ACaPELa-R’ questionnaire)
Authors: Tikka T , Corson S , Kavanagh K , Lowit A , MacKenzie K
Published: February 2019

Objective

The Assessing and Caring for Patients’ Expectations in Laryngology (‘ACaPELa’) questionnaire was developed to guide laryngology clinic consultations. This study aimed to audit its use, revise it depending on outcomes and validate it.

Methods

The questionnaire was completed by all new patients attending a laryngology clinic over one year. The questionnaire was refined and validated in a new cohort of patients over a six-month period.

Results

Thirty-seven of 242 patients (15.3 per cent) incorrectly gave the same ranking to more than one question. Questions with similar content were collapsed to cover broader themes, and an outcome question was added, resulting in the five-item Assessing and Caring for Patients’ Expectations in Laryngology – Revised (‘ACaPELa-R’) questionnaire. Using this revised questionnaire, there was a significant reduction in the number of same-ranked questions (4.4vs15.3 per cent;p= 0.003) and high patient satisfaction post-consultation (95.7 per cent).

Conclusion

The Assessing and Caring for Patients' Expectations in Laryngology – Revised questionnaire makes patients’ rank ordering of questions easier. It can be used to inform how different topics should be approached during the consultation and utilised for clinician self-audit.
Contact discourse
Authors: Goebel Zane
Published: February 2019

Starting from the idea that all social life is characterized by contact between those who do not have the same trajectories of socialization, this article draws on insights from work on narrative, normativity, and social value to examine how contact is discursively policed. Building on scholarship on diversity talk and translingualism I propose the conceptcontact discourseto refer to the discursive work that constructs and evaluates those who inhabit contact zones. While both streams of scholarship cover the discursive policing of social life to greater and lesser extents, they cover very different participation and authorization frameworks.Contact discourseand the three associated terms—models of contact,contact commentary, andcontact talk—highlight the importance of participation and authorization frameworks for understanding the policing of social life in contact zones. My empirical focus is on discursive data from television, social media, interviews, and everyday talk. (Contact, discourse, diversity talk, normativization, translingualism, value)*
Forever young? An analysis of the factors influencing perceptions of ageing
Authors: Bordone Valeria , Arpino Bruno , Rosina Alessandro
Published: February 2019

Drawing on the revived literature on the subjective dimension of ageing, this paper investigates whether people aged 65+, usually defined as old, do actually feel old and which events they associate with feeling old. Logistic models are used on unique data from the 2013 survey called ‘I Do Not Want to Be Inactive’, conducted on individuals aged 65–74 in Italy (N = 828). It is found that a large proportion of respondents do not feel old at all. The analyses show that women are more likely than men to feel old and to think that society considers them old. While men feel old mainly when they retire, women associate this feeling with loneliness, loss of independence and death of loved ones. Higher-educated people are less likely to associate feeling old with loneliness and boredom than their lower-educated counterparts. The findings have important implications for the conceptualisation of ageing. Most people who are old according to the standard threshold of 65 do not consider reaching this age as a distinctive marker of old age in their lifecourse. This suggests that absolute thresholds for setting the start of old age are questionable. Feeling old seems to be mainly influenced by events, such as retirement and death of loved ones, hinting to the importance of the social construction of ageing in addition to its biological dimension. Researchers and policy makers are encouraged to give more attention to layperson views on ageing.
Developing Taiwan Studies Teaching Programmes in Europe and the US: The Experience of SOAS University of London and University of Texas at Austin
Authors: Fell Dafydd , Chang Sung-sheng Yvonne
Published: February 2019

Over the last two decades, there has been a rapid expansion in the number of Taiwan programmes at universities in America and Europe; however, few of these Taiwan programmes have attempted to develop teaching courses. Where Taiwan courses have been introduced, they have tended to be in isolation and not well integrated into existing academic programmes. Among the universities with Taiwan programmes, only two have attempted to create comprehensive teaching programmes through which students can graduate with a degree in Taiwan studies: SOAS University of London and the University of Texas at Austin. The purpose of this paper is to compare the experiences of these two institutions in developing such niche teaching programmes. It begins with a discussion of how these two programmes first emerged and then goes on to review their distinct development trajectories and key features. The paper offers an analysis of how these two programmes were able not only to survive but also to expand their offerings and thrive in an academic environment that should be hostile to such niche programmes. It concludes with a review of the remaining challenges facing these teaching programmes.
Ascertaining Business's Interests and Political Preferences
Authors: Broockman David E.
Published: February 2019

Medicare is one of the largest social programs in the world. Did organized industry favor Medicare's passage in 1965? If it did, this would represent powerful evidence in favor of the theory that social programs typically require cross-class alliances to pass, such as alliances between business and labor. However, in a previous article in this journal, I argued that answering questions about political actors’ preferences—such as whether organized industry favored Medicare's passage—can be surprisingly difficult due to the “problem of preferences”; that is, political actors might misrepresent their true policy preferences for many reasons. For example, when their ideal proposals are not politically feasible, political actors may wish to bolster support for a more politically viable alternative to a disliked proposal—even if they do not truly support this alternative to the status quo. To better understand political actors’ true policy preferences, I argued, scholars should trace how those actors’ expressed preferences change as a function of their strategic context—just as scholars seeking to understand the impact of any other variable trace the effects of changes in it.
Apathy Is Related to Cognitive Control and Striatum Volumes in Prodromal Huntington’s Disease
Authors: Misiura Maria B. , Ciarochi Jennifer , Vaidya Jatin , Bockholt Jeremy , Johnson Hans J. , Calhoun Vince D. , Paulsen Jane S. , Turner Jessica A. ,   the PREDICT-HD Investigators and Working Group
Published: February 2019

Objectives: Apathy is a debilitating symptom of Huntington’s disease (HD) and manifests before motor diagnosis, making it an excellent therapeutic target in the preclinical phase of Huntington’s disease (prHD). HD is a neurological genetic disorder characterized by cognitive and motor impairment, and psychiatric abnormalities. Apathy is not well characterized within the prHD. In previous literature, damage to the caudate and putamen has been correlated with increased apathy in other neurodegenerative and movement disorders. The objective of this study was to determine whether apathy severity in individuals with prHD is related to striatum volumes and cognitive control. We hypothesized that, within prHD individuals, striatum volumes and cognitive control scores would be related to apathy. Methods: We constructed linear mixed models to analyze striatum volumes and cognitive control, a composite measure that includes tasks assessing with apathy scores from 797 prHD participants. The outcome variable for each model was apathy, and the independent variables for the four separate models were caudate volume, putamen volume, cognitive control score, and motor symptom score. We also included depression as a covariate to ensure that our results were not solely related to mood. Results: Caudate and putamen volumes, as well as measures of cognitive control, were significantly related to apathy scores even after controlling for depression. Conclusions: The behavioral apathy expressed by these individuals was related to regions of the brain commonly associated with isolated apathy, and not a direct result of mood symptoms. (JINS, 2019, 25, 462–469)
Automatic enrollment and job market turnover
Authors: Hung Angela A. , Luoto Jill , Burke Jeremy , Utkus Stephen P. , Young Jean A.
Published: February 2019

Automatic enrollment has substantially increased employee participation in defined contribution plans. Yet little is known about how retirement plan design features influence retirement wealth accumulation in a setting of labor market turnover. We find that employees separating from jobs with automatic enrollment plans are significantly more likely to take a cash distribution (and potentially pay a tax penalty) than those separating from jobs with voluntary enrollment plans, offsetting some of the benefits from automatic enrollment. Yet given the sizeable improvements in plan participation from automatic enrollment, wealth accumulation for automatically enrolled participants, net of cash-outs and penalties, remain higher than it would have been under voluntary enrollment.
THE SUBJECT OF SOVEREIGNTY: LAW, POLITICS AND MORAL REASONING IN HUGO GROTIUS
Authors: BRETT ANNABEL
Published: February 2019

Hugo Grotius’s account of sovereign power inDe iure belli ac pacisoccupies a contested place in recent genealogies of modern sovereignty. This article takes a fresh approach by arguing that Grotius’s legal arguments do not do their work alone. They function within a broader horizon of what he calls “morals,” a field of reasoning that has debts to scholastic moral theology and Aristotelian moral science. Grotius's conception of sovereignty represents a modulation between law and “morals,” which allows him both to separate his scientific jurisprudence from the science of politics and nevertheless to reply to the political scientists on their own ground. The context of “morals,” however, is not narrowly political but inter-political, generating a potential tension between popular aspirations to sovereignty and the international order. Grotius’s “moral” handling of the issue offers an invitation to reflect on our current preoccupation with much the same concerns.
Descriptive Representation and the Political Engagement of Women
Authors: Wolak Jennifer
Published: February 2019

When women are represented on the campaign trail and in elected office, women in the electorate have been shown to report greater engagement in politics. However, most evidence of the effects of descriptive representation on women's empowerment is drawn from surveys from the 1980s and 1990s. I update these studies to consider how women candidates and officeholders affect the political knowledge, interest, and participation of other women in the electorate. Using responses from the Cooperative Congressional Election Study from 2006 to 2014, I find that both men and women are more politically knowledgeable when represented by women in Congress and in state government. Considering political engagement, I find little evidence that women are more politically interested or participatory when residing in places with more female officeholders or candidates. Women's political presence as candidates and officeholders does not uniquely encourage other women to engage in political life.
CROESUS’ GREAT NEMESIS
Authors: Dillery John D.
Published: February 2019

This article attempts to account for the fact thatnemesisoccurs only once in Herodotus. It connects the term to Phrygia and the importance of Nemesis there, esp. as seen in ‘confession-inscriptions’ (Beichtinschriften). It argues that the Atys-Adrastus story is meant as an interpretative guide to the rest of theHistorythrough its use of significant names, comparable to the use of significant names in the Old Testament.
A Simple Method for Extracting Water Depth From Multispectral Satellite Imagery in Regions of Variable Bottom Type
Authors: Geyman Emily C. , Maloof Adam C.
Published: February 2019

Satellite imagery offers an efficient and cost‐effective means of estimating water depth in shallow environments. However, traditional empirical algorithms for calculating water depth often are unable to account for varying bottom reflectance, and therefore yield biased estimates for certain benthic environments. We present a simple method that is grounded in the physics of radiative transfer in seawater, but made more robust through the calibration of individual color‐to‐depth relationships for separate spectral classes. Our cluster‐based regression (CBR) algorithm, applied to a portion of the Great Bahama Bank, drastically reduces the geographic structure in the residual and has a mean absolute error of 0.19 m with quantified uncertainties. Our CBR bathymetry is 3–5 times more accurate than existing models and outperforms machine learning protocols at extrapolating beyond the calibration data. Finally, we demonstrate how comparison of CBR with traditional models sensitive to bottom type reveals the characteristic length scales of biosedimentary facies belts.
Seasonal Evolution of Titan's Stratosphere During the Cassini Mission
Authors: Teanby N. A. , Sylvestre M. , Sharkey J. , Nixon C. A. , Vinatier S. , Irwin P. G. J.
Published: February 2019

Titan's stratosphere exhibits significant seasonal changes, including breakup and formation of polar vortices. Here we present the first analysis of midinfrared mapping observations from Cassini's Composite InfraRed Spectrometer to cover the entire mission (Ls=293–93°, 2004–2017)—midnorthern winter to northern summer solstice. The north polar winter vortex persisted well after equinox, starting breakup around Ls∼60° and fully dissipating by Ls∼90°. Absence of enriched polar air spreading to lower latitudes suggests large‐scale circulation changes and photochemistry control chemical evolution during vortex breakup. South polar vortex formation commenced soon after equinox and by Ls∼60° was more enriched in trace gases than the northern middle‐winter vortex and had temperatures ∼20 K colder. This suggests that early‐winter and middle‐winter vortices are dominated by different processes—radiative cooling and subsidence‐induced adiabatic heating respectively. By the end of the mission (Ls=93°) south polar conditions were approaching those observed in the north at Ls=293°, implying seasonal symmetry in Titan's vortices.
Morphology and Dynamics of Venus's Middle Clouds With Akatsuki/IR1
Authors: Peralta J. , Iwagami N. , Sánchez‐Lavega A. , Lee Y. J. , Hueso R. , Narita M. , Imamura T. , Miles P. , Wesley A. , Kardasis E. , Takagi S.
Published: February 2019

The Venusian atmosphere is covered by clouds with superrotating winds whose accelerating mechanism is still not well understood. The fastest winds, occurring at the cloud tops (∼70‐km height), have been studied for decades, thanks to their visual contrast in dayside ultraviolet images. The middle clouds (∼50–55 km) can be observed at near‐infrared wavelengths (800–950 nm), although with very low contrast. Here we present the first extensive analysis of their morphology and motions at lower latitudes along 2016 with 900‐nm images from the IR1 camera onboard Akatsuki. The middle clouds exhibit hemispherical asymmetries every 4–5 days, sharp discontinuities in elongated “hook‐like” stripes, and large contrasts (3–21%) probably associated with large changes in the optical thickness. Zonal winds obtained with IR1 images and with ground‐based observations reveal mean zonal winds peaking at the equator, while their combination with Venus Express unveils long‐term variations of 20 m/s along 10 years.
Evidence of Strong Contributions From Mixed‐Phase Clouds to Arctic Climate Change
Authors: Tan Ivy , Storelvmo Trude
Published: February 2019

Underestimation of the proportion of supercooled liquid in mixed‐phase clouds in climate models has called into question its impact on Arctic climate change. We show that correcting for this bias in the CESM model can either enhance or reduce Arctic amplification depending on the microphysical characteristics of the clouds as a corollary to the cloud phase feedback. Replacement of ice with liquid in the cloud phase feedback results in more downward longwave radiation, which is effectively trapped as heat at the surface in the Arctic due to its unique stable stratification conditions, and this ultimately leads to a more positive lapse rate feedback. The larger the ice particles are to begin with, the stronger Arctic amplification becomes due to the lower precipitation efficiency of liquid droplets compared to ice crystals. Our results emphasize the importance of realistic representations of microphysical processes in mixed‐phase clouds, particularly in the Arctic.
Rare Occurrence of Off‐Equatorial Edge Initiating and Equatorward Surging Plasma Depletions Observed in OI 630‐nm Imaging
Authors: Parihar Navin
Published: February 2019

Usual depletions in the Northern Hemisphere form a tree fork junction feature near the south (i.e., toward the equator) in all‐sky airglow images, and its branches surge toward the north (i.e., poleward). We report in this paper unusual airglow depletions in OI 630.0‐nm imaging over India that surged equatorward and formed an inverted tree fork junction feature on 3 January 2011. Airglow images showed faint signatures of medium‐scale traveling ionospheric disturbances in the beginning that were east‐west aligned and propagated toward equator. Within 06 to 18 min of its passing, turbulent structures were noted in the field of view, and two depleted patches appeared out of low airglow background over the off‐equatorial edge. The apex height of the associated geomagnetic flux tubes varied from ~ 1,400 to 1,600 km. Later, these dark regions intensified and surged equatorward while drifting slowly toward west. While remaining almost steady, one of them further intensified and continued to surge equatorward. The second dark patch got linked up with another isolated depletion to form an elongated depleted feature. Next, the southern end of this attached feature surged equatorward. When two depletions were well formed, an inverted tree fork junction was noticeable. During this time, the equatorward motion of the equatorial ionization anomaly structure is also seen. To the best of our knowledge, this is the first imaging observation of an inverted tree fork junction feature and brings out the unknown facets of ionospheric irregularities.
The Dominant Role of Energetic Ions in Solar Wind Interaction With the Moon
Authors: Omidi N. , Zhou X. Y. , Russell C. T. , Angelopoulos V.
Published: February 2019

We use the results of 3‐D electromagnetic hybrid (kinetic ions and fluid electrons) simulations and observations by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) /Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) spacecraft to investigate the nature of the solar wind interaction with the moon and the resulting wake and tail structure. In the absence of a global magnetic field and an atmosphere at the moon, this interaction is due to the absorption of the solar wind plasma on the dayside and the means by which the resulting cavity in the tail is refilled. To explore this process, we conducted simulations of specific case studies well‐monitored by the ARTEMIS spacecraft. Preliminary runs revealed that when the solar wind core plasma is driving the interaction, the results deviate significantly from observations. When the small population of solar wind energetic ions is incorporated in the model, the observations are reproduced much better. Simulations with different density or energy of energetic ions show considerable changes in the results indicating their dominance in establishing the electromagnetic properties of the tail. In contrast, the results show less sensitivity to the solar wind flow speed. Here we conclude that the structure of the interaction region consists of compressional and rarefaction wakes and a central tail region with areas of enhanced and possibly reduced magnetic field level. The compressional wake diverts the flow away from the tail, and its presence is found to be highly time dependent while the rarefaction wake diverts the flow toward the tail and is found to be a semipermanent feature of the lunar interaction region.
Measurement and Modeling of Air‐Broadened Methane Absorption in the MERLIN Spectral Region at Low Temperatures
Authors: Delahaye T. , Ghysels M. , Hodges J. T. , Sung K. , Armante R. , Tran H.
Published: February 2019

The ability to precisely model methane absorption in the R(6) manifold of the 2ν3 band at atmospheric pressure and temperature conditions is a key technical requirement of the German‐French, Methane Remote Sensing Lidar (MERLIN) space mission. To this end, 27 high‐resolution and high‐signal‐to‐noise‐ratio absorption spectra of air‐broadened 12CH4 were recorded using a variable‐temperature frequency‐stabilized cavity ring‐down spectroscopy apparatus. The measurement conditions corresponded to sample temperature, pressure, and methane molar fraction values spanning 220–290 K, 4–110 kPa, and 4–7 μmol/mol, respectively. The measured spectra were fit using the sum of isolated Hartmann‐Tran profiles with the addition of line mixing. For each line within the manifold, all spectroscopic parameters at room temperature were fixed to our previously obtained values (Delahaye et al., 2016, https://doi.org/10.1002/2015JD024524) and only the temperature dependences of the model parameters were adjusted. The results show that the fitted model agrees with the measured methane absorption to better than 0.3% for the entire R(6) manifold spectral region and to within 0.1% at the online position of the MERLIN for all considered pressure and temperature conditions. A first comparison with ground‐based atmospheric measurement was also made showing significant improvement with respect to existing spectroscopic modeling of methane absorption.
A Comparative Study of the Ray Theory Model With the Finite Difference Time Domain Model for Lightning Sferic Transmission in Earth‐Ionosphere Waveguide
Authors: Qin Zilong , Cummer Steven A. , Chen Mingli , Lyu Fanchao , Du Ya‐ping
Published: February 2019

The lightning sferic has been shown to be a valuable radio signal for detecting perturbations of the lower ionosphere caused by the lightning activity itself and by other terrestrial and space events (Shao et al., 2012, https://doi.org/10.1038/ngeo1668). Adding to many existing methods, we have recently proposed an improved ray theory (RT) model for investigating the lightning sferic transmission in the Earth‐ionosphere waveguide (Qin et al., 2017, https://doi.org/10.1002/2016JD025599). In the present study, a further modification to the RT model was made to increase its accuracy in modeling the lightning sferic in a broader frequency band and a larger distance range. The modification included two aspects: a new incident angle finding technique and a novel method for deriving the high‐order hop series. To quantitatively evaluate the effectiveness of the modification, a comparative study of this modified RT model with its previous version and the full‐wave finite difference time domain model was carried out. The results showed that this modified RT model did better than its previous version and was in close agreement with the full‐wave finite difference time domain method in modeling the lightning sferic in frequencies bands lower to 3, 5, and 7 kHz for distances up to 500, 800, and 1,000 km, respectively.
Changes in Evapotranspiration Over Global Semiarid Regions 1984–2013
Authors: Yang Zesu , Zhang Qiang , Hao Xiaocui , Yue Ping
Published: February 2019

Global mean evapotranspiration (ET) has been increasing in recent decades under climate warming. Yet the magnitude and spatial distribution of ET variation remain highly uncertain. ET changes in different regions are still poorly understood due to limitations in observation records, especially in semiarid regions with undeveloped economic systems and sparse observations. Based on the Priestley‐Taylor Jet Propulsion Laboratory model, ET was estimated over global typical semiarid regions for 1984–2013. All of these regions show a decreasing ET trend, which is opposite to the trend in global mean ET. In particular, North Africa has the fastest decreasing trend, 8.6 mm/year, while South Africa has the slowest decreasing trend, 0.7 mm/year. North America, South America, northern Africa, and Australia have declining trends in ET during both warm and cold seasons, while the Loess Plateau, East Asia, central Asia, and South Africa have declining trends in ET only during warm seasons. Accounting for basic factors controlling ET, three important results are identified: First, atmospheric demand is increasing over all semiarid regions due to climate warming; second, the effect of atmospheric composition and cloud weakening radiation is strengthening over all semiarid regions; and finally, annual precipitation is decreasing over all semiarid regions except for South Africa. Factorial experiments indicate that the remarkable declining trend in relative air humidity forces the decreasing trend in ET over all semiarid regions. These results imply a slowing water cycle in global semiarid regions.
The Geometry of Rimed Aggregate Snowflakes: A Modeling Study
Authors: Seifert Axel , Leinonen Jussi , Siewert Christoph , Kneifel Stefan
Published: February 2019

Computer simulations of the aggregation and riming of ice crystals are performed to investigate the geometry of rimed aggregate snowflakes. Due to the universality of the geometry of aggregates, the conversion to a graupel‐like particle is self‐similar and independent from specific properties of the aggregate, when formulated in properly normalized variables. Hence, the particle habit of the primary crystals, the size of the aggregate or the density of the rime mass, does not lead to a structural change in the transition to graupel. Therefore, this transition can be parameterized by a similarity approach using simulations of many individual rimed aggregates. These parameterizations can replace the classic fill‐in model used in many cloud models. The parameterizations are applied and tested in a one‐dimensional Lagrangian superparticle model to simulate the growth of aggregates in a liquid layer. We find that the similarity model for the geometry of rimed snowflakes leads to a more rapid growth by riming and, hence, an increased precipitation rate compared to the fill‐in model. The main reason for this is that the increase of the maximum dimension during the early stages of riming is properly taken into account by the similarity model, whereas it is neglected by the fill‐in model.
The Quest for Model Uncertainty Quantification: A Hybrid Ensemble and Variational Data Assimilation Framework
Authors: Abbaszadeh Peyman , Moradkhani Hamid , Daescu Dacian N.
Published: February 2019

This article presents a novel approach to couple a deterministic four‐dimensional variational (4DVAR) assimilation method with the particle filter (PF) ensemble data assimilation system, to produce a robust approach for dual‐state‐parameter estimation. In our proposed method, the Hybrid Ensemble and Variational Data Assimilation framework for Environmental systems (HEAVEN), we characterize the model structural uncertainty in addition to model parameter and input uncertainties. The sequential PF is formulated within the 4DVAR system to design a computationally efficient feedback mechanism throughout the assimilation period. In this framework, the 4DVAR optimization produces the maximum a posteriori estimate of state variables at the beginning of the assimilation window without the need to develop the adjoint of the forecast model. The 4DVAR solution is then perturbed by a newly defined prior error covariance matrix to generate an initial condition ensemble for the PF system to provide more accurate and reliable posterior distributions within the same assimilation window. The prior error covariance matrix is updated from one cycle to another over the main assimilation period to account for model structural uncertainty resulting in an improved estimation of posterior distribution. The premise of the presented approach is that it (1) accounts for all sources of uncertainties involved in hydrologic predictions, (2) uses a small ensemble size, and (3) precludes the particle degeneracy and sample impoverishment. The proposed method is applied on a nonlinear hydrologic model and the effectiveness, robustness, and reliability of the method is demonstrated for several river basins across the United States.
A Reduced Generalized Multiscale Basis Method for Parametrized Groundwater Flow Problems in Heterogeneous Porous Media
Authors: He Xinguang , Li Qiuqi , Jiang Lijian
Published: February 2019

In this paper, we develop a reduced generalized multiscale basis method for efficiently solving the parametrized groundwater flow problems in heterogeneous porous media. Recently proposed generalized multiscale finite element (GMsFE) method is one of the accurate and efficient methods to solve the multiscale problems on a coarse grid. However, the GMsFE basis functions usually depend on the random parameters in the parametrized model, which substantially impacts on the computation efficiency when the parametrized equation needs to be solved many times for many instances of parameters. To enhance computation efficiency, we construct reduced generalized multiscale basis functions independent of parameters from the high‐dimensional GMsFE space and generate a reduced‐order multiscale model by projecting the parameterized flow governing equation onto the low‐dimensional reduced GMsFE space. Then, in order to improve the online computation of reduced‐order model, we apply a matrix discrete empirical interpolation method to affinely decompose the nonaffine parametrized systems arising from the discretization of governing equation. Finally, a few numerical experiments are carried out for the parametrized transient flow problems in heterogeneous porous media to illustrate the efficiency and accuracy of the proposed model reduction method. The results show that the proposed reduced generalized multiscale basis method can significantly improve computation efficiency while maintaining comparative accuracy for the groundwater flow problems by selecting a suitable coarse mesh size and an optimal number of reduced GMsFE basis functions at each of coarse nodes.
Modeling Immiscible Two‐Phase Flow in Rough Fractures From Capillary to Viscous Fingering
Authors: Yang Zhibing , Méheust Yves , Neuweiler Insa , Hu Ran , Niemi Auli , Chen Yi‐Feng
Published: February 2019

We develop an efficient computational model for simulating fluid invasion patterns emerging in variable aperture fractures. This two‐dimensional model takes into account the effect of capillary force on the fluid‐fluid interfaces and viscous pressure drop in both fluid phases. The pressure distribution is solved at each time step based on mass balance and local cubic law, considering an imposed pressure jump condition at the fluid‐fluid interface. This pressure jump corresponds to the Laplace pressure which includes both terms related to the out‐of‐plane (aperture‐spanning) curvature and to the in‐plane curvature. Simulating a configuration that emulates viscous fingering in two‐dimensional random porous media confirms that the model accounts properly for the role of viscous forces. Furthermore, direct comparison with previously obtained experimental results shows that the model reproduces the observed drainage patterns in a rough fracture reasonably well. The evolutions of tip location, the inlet pressures, and the invading phase fractal dimensions are analyzed to characterize the transition from capillary fingering to viscous fingering regimes. A radial injection scenario of immiscible invasion is also studied with varying modified capillary number and viscosity ratio, showing displacement patterns ranging from capillary fingering to viscous fingering to stable displacement. Such simulations using two contact angles show that the invading phase becomes more compact when the wetting condition changes from strong to weak drainage, as already observed in 2‐D porous media. The model can be used to bridge the gap in spatial scales of two‐phase flow between pore‐scale modeling approaches and the continuum Darcy‐scale models.
Numerical Modeling of Hyperconcentrated Confluent Floods From the Middle Yellow and Lower Weihe Rivers
Authors: Wang Zenghui , Xia Junqiang , Zhou Meirong , Li Tao
Published: February 2019

Hyperconcentrated confluent floods in the Middle Yellow River and its tributaries are characterized by the phenomena of extremely high backwater stage, flood water intrusion, and local channel blockage in confluence areas. In order to study the propagation process of hyperconcentrated confluent floods, most existing channel network models need reinforcement in the computation of sediment transport and improvement in the treatment of interior boundary at channel junctions. A river network model for hyperconcentrated confluent floods is proposed based on the finite volume method scheme, in which the study domain is represented by ordinary 1‐D cells and junction cells. As a preprocess step, a bathymetry interpolation algorithm is developed to generate topography data and to extract the stage‐volume relationship for the junction cell. The storage change and sediment transport in the junction cell are calculated in each time step with no need to distinguish convergent or divergent flow pattern, and the solution in each reach can be executed simultaneously. The model was validated by simulating the hyperconcentrated confluent flood events in 1977 and 1966, with the maximum backwater stage and the occurrence time of flood water intrusion in the Lower Weihe River being well predicted. The response was investigated of the Middle Yellow River and Lower Weihe River to the arrangement of peak times of confluent floods, with the critical condition for flood water intrusion and the scenario that achieves the most effective scouring in the downstream channel being identified.
Decadal‐Scale Climate Forcing of Alpine Glacial Hydrological Systems
Authors: Lane S. N. , Nienow P. W.
Published: February 2019

Quantification of climate forcing of glacial hydrological systems at the decadal scale is rare because most measurement stations are too far downstream for glacier impacts to be clearly detected. Here we apply a measure of daily hydrograph entropy to a unique set of reliable, high‐altitude gauging stations, dating from the late 1960s. We find a progressive shift to a greater number of days with diurnal discharge variation as well as more pronounced diurnal discharge amplitude. These changes were associated with the onset of rapid warming in the 1980s as well as declining end of winter snow depths as inferred from climate data. In glaciated catchments, lower winter snow depths reduce the magnitude and duration of snowpack buffering and encourage the earlier onset of glacier ice exposure, with associated lower surface albedo and more rapid melt. Together, these processes explain the increase in the observed intensity of diurnal discharge fluctuations.