bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diversity, abundance, and host relationships of avian malaria and related haemosporidians in New Mexico pine forests
Authors: Marroquin-Flores Rosario A. , Williamson Jessie L. , Chavez Andrea N. , Bauernfeind Selina M. , Baumann Matthew J. , Gadek Chauncey R. , Johnson Andrew B. , McCullough Jenna M. , Witt Christopher C. , Barrow Lisa N. 
Published: August 2017

Avian malaria and related haemosporidian parasites (genera Haemoproteus, Plasmodium, and Leucocytozoon) affect bird demography, species range limits, and community structure, yet they remain unsurveyed in most bird communities and populations. We conducted a community-level survey of these vector-transmitted parasites in New Mexico, USA, to describe their diversity, abundance, and host associations. We focused on the breeding-bird community in the transition zone between piñon-juniper woodland and ponderosa pine forests (elevational range: 2,150–2,460 m). We screened 186 birds representing 49 species using both standard PCR and microscopy techniques to detect infections of all three avian haemosporidian genera. We detected infections in 68 out of 186 birds (36.6%), the highest proportion of which were infected with Haemoproteus (20.9%), followed by Leucocytozoon (13.4%), then Plasmodium (8.0%). We sequenced mtDNA for 77 infections representing 43 haplotypes (25 Haemoproteus, 12 Leucocytozoon, 6 Plasmodium). When compared to all previously known haplotypes in the MalAvi and GenBank databases, 63% (27) of the haplotypes we recovered were novel. We found evidence for host specificity at the avian clade and species level, but this specificity was variable among parasite genera, in that Haemoproteus and Leucocytozoon were each restricted to three avian groups (out of six), while Plasmodium occurred in all groups except non-passerines. We found striking variation in infection rate among host species, with nearly universal infection among vireos and no infection among nuthatches. Using rarefaction and extrapolation, we estimated the total avian haemosporidian diversity to be 70 haplotypes (95% CI [43–98]); thus, we may have already sampled ∼60% of the diversity of avian haemosporidians in New Mexico pine forests. It is possible that future studies will find higher diversity in microhabitats or host species that are under-sampled or unsampled in the present study. Fortunately, this study is fully extendable via voucher specimens, frozen tissues, blood smears, parasite images, and documentation provided in open-access databases (MalAvi, GenBank, and ARCTOS).
Seismoelectric responses to an explosive source in a fluid above a fluid‐saturated porous medium
Authors: Gao Yongxin , Wang Mengqiang , Hu Hengshan , Chen Xiaofei 
Published: August 2017

AbstractWe numerically compute seismoelectric wavefields generated at a fluid/porous medium interface by an explosive source in the fluid. Our numerical experiments show that electromagnetic (EM) signals accompanying the P, S, and interface waves can be observed at receivers located in the fluid regions near the interface. Such accompanying EM signals are produced by the inhomogeneous EM waves that are generated by the seismic waves at the interface and their amplitudes decrease with the distance from interface. Under the excitation of an explosive source whose strength is within the capability of industry air guns, electric and magnetic fields that accompany the Scholte wave are on the order of 1 μV/m and 0.01 nT, respectively. This means that the EM signals arising from the electrokinetic effect at an ocean bottom are detectable and suggest that it is possible to measure the EM signals during marine seismic explorations to study the properties of the seafloor material. EM signals that accompany the P, S, and interface waves are also observed in the porous medium region near the interface. Component analysis shows that they contain contributions from multiple modes of waves, among which the slow compressional wave contributes significantly to the vertical electric field, leading to a much stronger vertical electric field than the horizontal electric field during the passage of a seismic wave along the interface.
Permeability of porous media: Role of the critical pore size
Authors: Nishiyama Naoki , Yokoyama Tadashi 
Published: August 2017

AbstractThe knowledge of the permeability of porous media is crucial to understand fluid flow in various natural and artificial materials. Due to the complex nature of pore structure, the pore characteristic (porosity and pore radius) determining the permeability has long been under discussion. Here we determined the critical pore radius, which is the radius of the largest sphere that can freely pass through a porous medium, using the water expulsion method, an experimental technique measuring the pressure at which gas passes through a water‐saturated porous medium. We demonstrate that the critical pore radius correlates well with the permeability for a variety of porous granular media and volcanic products with an extensive range of porosities (0.71%–50%) and permeabilities (10−20–10−10 m2). We also obtained a porosity‐critical pore radius‐permeability relationship that provides a better prediction of the permeability compared with predictions obtained by previous correlations.
Why are mixed‐phase altocumulus clouds poorly predicted by large‐scale models? Part 2. Vertical resolution sensitivity and parameterization
Authors: Barrett Andrew I. , Hogan Robin J. , Forbes Richard M. 
Published: August 2017

AbstractSingle‐column model simulations of mixed‐phase altocumulus clouds were shown to have a strong vertical resolution sensitivity in Part 1 of this paper. Coarse‐resolution models were unable to simulate the long‐lived supercooled liquid layer at cloud top, typically only 200 m thick. In this paper, the sensitivity to vertical resolution is investigated using idealized simulations. Vertical gradients of ice water mixing ratio and temperature near cloud top are found to be inadequately represented at coarse resolution. The vertical discretization using grid box mean values, rather than the full vertical profile, leads to biased calculations of mixed‐phase microphysical process rates and affects the diagnosis of thin liquid water layers. As a result, the liquid water layer becomes quickly glaciated and altocumulus cloud lifetime is underestimated. Similar impacts are expected for mixed‐phase boundary layer clouds commonly observed at high latitudes. A novel parameterization is introduced that accounts for the vertical gradients of ice water mixing ratio and temperature in the microphysics calculations and the diagnosis of liquid near cloud top. It substantially improves the representation of altocumulus layers in coarse vertical resolution single‐column model simulations and reduces the bias identified in Part 1. The new parameterization removes the large underestimate in supercooled water content caused by the resolution sensitivity for temperatures warmer than −30°C. Given the radiative importance of mixed‐phase altocumulus clouds, their underestimation by numerical weather prediction models, and their potential to act as a negative climate feedback, there is a need to reevaluate the global climate sensitivity by implementing the findings in these two papers in a climate model.
The plasma environment inside geostationary orbit: A Van Allen Probes HOPE survey
Authors: Fernandes Philip A. , Larsen Brian A. , Thomsen Michelle F. , Skoug Ruth M. , Reeves Geoffrey D. , Denton Michael H. , Friedel Reinhard H. W. , Funsten Herbert O. , Goldstein Jerry , Henderson Michael G. , Jahn Jörg‐Micha , MacDonald Elizabeth A. , Olson David K. 
Published: August 2017

AbstractThe two full precessions in local time completed by the Van Allen Probes enable global specification of the near‐equatorial inner magnetosphere plasma environment. Observations by the Helium‐Oxygen‐Proton‐Electron (HOPE) mass spectrometers provide detailed insight into the global spatial distribution of electrons, H+, He+, and O+. Near‐equatorial omnidirectional fluxes and abundance ratios at energies 0.1–30 keV are presented for 2 ≤ L ≤ 6 as a function of L shell, magnetic local time (MLT), and geomagnetic activity. We present a new tool built on the UBK modeling technique for classifying plasma sheet particle access to the inner magnetosphere. This new tool generates access maps for particles of constant energy for more direct comparison with in situ measurements, rather than the traditional constant μ presentation typically associated with UBK. We present for the first time inner magnetosphere abundances of O+ flux relative to H+ flux as a function of Kp, L, MLT, and energy. At L = 6, the O+/H+ ratio increases with increasing Kp, consistent with previous results. However, at L < 5 the O+/H+ ratio generally decreases with increasing Kp. We identify a new “afternoon bulge” plasma population enriched in 10 keV O+ and superenriched in 10 keV He+ that is present during quiet/moderate geomagnetic activity (Kp < 5) at ~1100–2000 MLT and L shell 2–4. Drift path modeling results are consistent with the narrow energy and approximate MLT location of this enhancement, but the underlying physics describing its formation, structure, and depletion during higher geomagnetic activity are currently not understood.
Pulsating auroras produced by interactions of electrons and time domain structures
Authors: Mozer F. S. , Agapitov O. V. , Hull A. , Lejosne S. , Vasko I. Y. 
Published: August 2017

AbstractPrevious evidence has suggested that either lower band chorus waves or kinetic Alfven waves scatter equatorial kilovolt electrons that propagate to lower altitudes where they precipitate or undergo further low‐altitude scattering to make pulsating auroras. Recently, time domain structures (TDSs) were shown, both theoretically and experimentally, to efficiently scatter equatorial electrons. To assess the relative importance of these three mechanisms for production of pulsating auroras, 11 intervals of equatorial THEMIS data and a 4 h interval of Van Allen Probe measurements have been analyzed. During these events, lower band chorus waves produced only negligible modifications of the equatorial electron distributions. During the several TDS events, the equatorial 0.1–3 keV electrons became magnetic field‐aligned. Kinetic Alfven waves may also have had a small electron scattering effect. The conclusion of these studies is that time domain structures caused the most important equatorial scattering of ~1 keV electrons toward the loss cone to provide the main electron contribution to pulsating auroras. Chorus wave scattering may have provided part of the highest energy (>10 keV) electrons in such auroras.
Energetic particle loss through the magnetopause: A combined global MHD and test‐particle study
Authors: Sorathia K. A. , Merkin V. G. , Ukhorskiy A. Y. , Mauk B. H. , Sibeck D. G. 
Published: August 2017

AbstractWe study the spatiotemporal characteristics of energetic particle losses from the magnetosphere using test‐particle trajectories in electromagnetic fields from a global magnetosphere magnetohydrodynamic (MHD) simulation. We use a dynamically evolving distribution of high‐resolution electromagnetic fields from the Lyon‐Fedder‐Mobarry global MHD model and trace large ensembles of 100 keV hydrogen and oxygen ions as well as electrons from a near‐Earth plasma sheet location through their escape from the magnetosphere. In agreement with recent MMS observations, we demonstrate that both ions and electrons have access to and escape throughout the dayside magnetopause, including magnetically drift‐shadowed regions. Also, in agreement with MMS observations, the depth of penetration and persistence of particles in the magnetosheath has a clear mass dependence, heavier particles penetrating further and lingering longer. We demonstrate both magnetic local time and latitude dependence of particles losses as manifested by their crossings of the open‐closed boundary and relate them to the complex field topology. Finally, we establish a significant role of Kelvin‐Helmholtz instability in facilitating particle losses at the magnetopause flanks.
The parameterization of wave‐particle interactions in the Outer Radiation Belt
Authors: Watt Clare E. J. , Rae I. J. , Murphy K. R. , Anekallu C. , Bentley S. N. , Forsyth C. 
Published: August 2017

AbstractWe explore the use of mean value empirical wave models in diffusion models of the Outer Radiation Belt. We show that magnetospheric wave power is not normally distributed in time and that geomagnetic activity does not provide a deterministic proxy for the temporal variability of wave activity. Our findings indicate that current diffusion models significantly overestimate the action of wave‐particle interactions due to extremely low frequency and very low frequency waves in the magnetosphere. We suggest that other techniques such as stochastic parameterization will lead to a better characterization of subgrid diffusion physics in the Outer Radiation Belt.
A statistical study of kinetic‐size magnetic holes in turbulent magnetosheath: MMS observations
Authors: Huang S. Y. , Du J. W. , Sahraoui F. , Yuan Z. G. , He J. S. , Zhao J. S. , Le Contel O. , Breuillard H. , Wang D. D. , Yu X. D. , Deng X. H. , Fu H. S. , Zhou M. , Pollock C. J. , Torbert R. B. , Russell C. T. , Burch J. L. 
Published: August 2017

AbstractKinetic‐size magnetic holes (KSMHs) in the turbulent magnetosheath are statistically investigated using high time resolution data from the Magnetospheric Multiscale mission. The KSMHs with short duration (i.e., <0.5 s) have their cross section smaller than the ion gyroradius. Superposed epoch analysis of all events reveals that an increase in the electron density and total temperature significantly increases (resp. decrease) the electron perpendicular (resp. parallel) temperature and an electron vortex inside KSMHs. Electron fluxes at ~90° pitch angles with selective energies increase in the KSMHs are trapped inside KSMHs and form the electron vortex due to their collective motion. All these features are consistent with the electron vortex magnetic holes obtained in 2‐D and 3‐D particle‐in‐cell simulations, indicating that the observed KSMHs seem to be best explained as electron vortex magnetic holes. It is furthermore shown that KSMHs are likely to heat and accelerate the electrons.
Daytime zonal drifts in the ionospheric 150 km and E regions estimated using EAR observations
Authors: Pavan Chaitanya P. , Patra A. K. , Otsuka Y. , Yokoyama T. , Yamamoto M. , Stoneback R. A. , Heelis R. A. 
Published: August 2017

AbstractMultibeam observations of the 150 km echoes made using the Equatorial Atmosphere Radar (EAR), located at Kototabang, Indonesia, provide unique opportunity to study both vertical and zonal E × B plasma drifts in the equatorial ionosphere. In this paper, we focus on estimating daytime zonal drifts at the 150 km (140–160 km) and E (100–110 km) regions using multibeam observations of 150 km and E region echoes made using the EAR and study the daytime zonal drifts covering all seasons not studied before from Kototabang. Zonal drifts in the 150 km and E regions are found to be westward and mostly below −80 m s−1 and −60 m s−1, respectively. While the zonal drifts in the 150 km and E regions do not go hand in hand on a case‐by‐case basis, the seasonal mean drifts in the two height regions are found to be in good agreement with each other. Zonal drifts at the 150 km region show seasonal variations with three maxima peaking around May, September, and January. The zonal drifts at the 150 km region are found to be smaller than the F region drifts obtained from Coupled Ion Neutral Dynamics Investigation (CINDI) onboard Communication and Navigation Outage Forecasting System (C/NOFS) by about 25 m s−1 consistent with the height variations of F region zonal drifts observed by the Jicamarca radar. These results constitute the first comprehensive study of zonal drifts at the 150 km and E regions from Kototabang, Indonesia, and the results are discussed in the light of current understanding on the low‐latitude electrodynamics and coupling.
JTRF2014, the JPL Kalman filter and smoother realization of the International Terrestrial Reference System
Authors: Abbondanza Claudio , Chin Toshio M. , Gross Richard S. , Heflin Michael B. , Parker Jay W. , Soja Benedikt S. , van Dam Tonie , Wu Xiaoping 
Published: August 2017

AbstractWe present and discuss JTRF2014, the Terrestrial Reference Frame (TRF) the Jet Propulsion Laboratory constructed by combining space‐geodetic inputs from very long baseline interferometry (VLBI), satellite laser ranging (SLR), Global Navigation Satellite Systems (GNSS), and Doppler orbitography and radiopositioning integrated by satellite submitted for the realization of ITRF2014. Determined through a Kalman filter and Rauch‐Tung‐Striebel smoother assimilating position observations, Earth orientation parameters, and local ties, JTRF2014 is a subsecular, time series‐based TRF whose origin is at the quasi‐instantaneous center of mass (CM) as sensed by SLR and whose scale is determined by the quasi‐instantaneous VLBI and SLR scales. The dynamical evolution of the positions accounts for a secular motion term, annual, and semiannual periodic modes. Site‐dependent variances based on the analysis of loading displacements induced by mass redistributions of terrestrial fluids have been used to control the extent of random walk adopted in the combination. With differences in the amplitude of the annual signal within the range 0.5–0.8 mm, JTRF2014‐derived center of network‐to‐center of mass (CM‐CN) is in remarkable agreement with the geocenter motion obtained via spectral inversion of GNSS, Gravity Recovery and Climate Experiment (GRACE) observations and modeled ocean bottom pressure from Estimating the Circulation and Climate of the Ocean (ECCO). Comparisons of JTRF2014 to ITRF2014 suggest high‐level consistency with time derivatives of the Helmert transformation parameters connecting the two frames below 0.18 mm/yr and weighted root‐mean‐square differences of the polar motion (polar motion rate) in the order of 30 μas (17 μas/d).
The stratigraphy and history of Mars' northern lowlands through mineralogy of impact craters: A comprehensive survey
Authors: Pan Lu , Ehlmann Bethany L. , Carter John , Ernst Carolyn M. 
Published: August 2017

AbstractThe basin‐filling materials of the northern lowlands, which cover approximately one third of Mars' surface, record the long‐term evolution of Mars' geology and climate. The buried stratigraphy was inferred through analyses of impact crater mineralogy, detected using data acquired by the Compact Reconnaissance Imaging Spectrometer for Mars. Examining 1045 impact craters across the northern lowlands, we find widespread olivine and pyroxene and diverse hydrated/hydroxylated minerals, including Fe/Mg smectite, chlorite, prehnite, and hydrated silica. The distribution of mafic minerals is consistent with infilling volcanic materials across the entire lowlands (~1–4 × 107 km3), indicating a significant volume of volatile release by volcanic outgassing. Hydrated/hydroxylated minerals are detected more frequently in large craters, consistent with the scenario that the hydrated minerals are being excavated from deep basement rocks, beneath 1–2 km thick mafic lava flows or volcaniclastic materials. The prevalences of different types of hydrated minerals are similar to statistics from the southern highlands. No evidence of concentrated salt deposits has been found, which would indicate a long‐lived global ocean. We also find significant geographical variations of local mineralogy and stratigraphy in different basins (geological provinces), independent of dust cover. For example, many hydrated and mafic minerals are newly discovered within the polar Scandia region (>60°N), and Chryse Planitia has more mafic mineral detections than other basins, possibly due to a previously unrecognized volcanic source.
Borehole measurements indicate hard bed conditions, Kangerlussuaq sector, western Greenland Ice Sheet
Authors: Harper Joel T. , Humphrey Neil F. , Meierbachtol Toby W. , Graly Joseph A. , Fischer Urs H. 
Published: August 2017

AbstractThe hydrological processes and sliding dynamics of the Greenland Ice Sheet are closely linked to the structural framework of its bed. Establishing whether the ice mass rests on bedrock relatively clear of rock debris, a thick deformable till layer, or some intermediate combination, is therefore key to understanding the ice sheet response to changes in meltwater inputs. Here we report on direct observations of the ice‐bed interface along a flow line transect in the ablation zone of the western Greenland Ice Sheet. Our measurements are derived from a network of 32 boreholes that vary from ~100 m deep near the ice margin to 830 m deep, 46 km upflow from the terminus. We performed a suite of experiments and sampling techniques in the holes to investigate the bed conditions. In contrast to previous geophysical and drilling studies elsewhere in Greenland which have suggested that the ice rests on a thick layer of sediment, we find no evidence for a thick sediment cover on the bed of the Kangerlussuaq sector of the ice sheet. Our observations imply that this area has a relatively clean and hard bed and that this facilitates a basal hydraulic system governed by ice/bedrock interactions. The lack of sediment cover on the bed could be due to recent deglaciation and advance of this sector of the ice sheet and/or variable rates of erosion and preferential routing of sediment through bedrock troughs.
Modeled sensitivity of Lake Michigan productivity and zooplankton to changing nutrient concentrations and quagga mussels
Authors: Pilcher Darren J. , McKinley Galen A. , Kralj James , Bootsma Harvey A. , Reavie Euan D. 
Published: August 2017

AbstractThe recent decline in Lake Michigan productivity is often attributed to filter feeding by invasive quagga mussels, but some studies also implicate reductions in lakewide nutrient concentrations. We use a 3‐D coupled hydrodynamic‐biogeochemical model to evaluate the effect of changing nutrient concentrations and quagga mussel filtering on phytoplankton production and phytoplankton and zooplankton biomass. Sensitivity experiments are used to assess the net effect of each change separately and in unison. Quagga mussels are found to have the greatest impact during periods of isothermal mixing, while nutrients have the greatest impact during thermal stratification. Quagga mussels also act to enhance spatial heterogeneity, particularly between nearshore‐offshore regions. This effect produces a reversal in the gradient of nearshore‐offshore productivity: from relatively greater nearshore productivity in the prequagga lake to relatively lesser nearshore productivity after quaggas. The combined impact of both processes drives substantial reductions in phytoplankton and zooplankton biomass, as well as significant modifications to the seasonality of surface water pCO2, particularly in nearshore regions where mussel grazing continues year‐round. These results support growing concern that considerable losses of phytoplankton and zooplankton will yield concurrent losses at higher trophic levels. Comparisons to observed productivity suggest that both quagga mussel filtration and lower lakewide total phosphorus are necessary to accurately simulate recent changes in primary productivity in Lake Michigan.