bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractObjectives: 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

AbstractAutomatic 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

AbstractHugo 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

AbstractWhen 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.
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

AbstractTitan'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

AbstractThe 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

AbstractUnderestimation 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

AbstractUsual 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

AbstractWe 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

AbstractThe 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

AbstractThe 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

AbstractGlobal 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

AbstractComputer 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

AbstractThis 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

AbstractIn 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.