bluuebunny/crossref_metadata_2025 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).
Histochemical characteristics of the vitellogenic oocytes of the bluefin tuna, Thunnus thynnus L.
Authors: Sarasquete C , González-De-Canales ML , Piñuela C , Muñoz-Cueto JA , Rendón C , Mañanós EL , Rodríguez-Gómez FJ , Pascual E
Published: August 2017

Very little information is available with respect to dynamic aspects of oocyte development and to yolk composition of tuna species. Since histological approaches can offer considerable information about the ovarian development of fish, and because different cytochemical/immunohistochemical tests are suitable tools for proving the presence of different macromolecules in several organs/tissues/cells, they can be good biomarkers of the reproductive mechanism in fish. The present study investigates the presence and distribution of carbohydrates, proteins, glycoconjugates, lipids, calcium, iron and vitellogenin in the bluefin tuna, Thunnus thynnus oocytes during the synthesis of yolk (globules and granules) in the vitellogenic phase. During the initial vitellogenic phase, oocytes (diameter: 249 ± 21.87 mm) contain oil globules (or vacuoles) which consist exclusively of neutral lipids. During this phase very small yolk granules appear around the cytoplasm. Glycolipids, phospholipids, glycoproteins (Nacetyl- D-galactosamine –GalNAc– sugar residues), calcium, proteins rich in tyrosine, tryptophan, lysine, arginine, cysteine and cystine, as well as vitellogenin are the main constituents of the yolk granules and the follicular envelope of these real vitellogenic oocytes (diameter: 386 ± 79.04 mm). The intergranular cytoplasm of the vitellogenic oocytes also contain glycogen and glycoconjugates with Mannose –Man– and/or Glucose –Glc–; N-acetyl-D-galactosamine –GalNAc–; L-Fucose –Fuc– and Nacetyl- D-glucosamine –GlcNAc– and/or sialic acid –NANA– sugar residues. The zona radiata is mainly composed of proteins; in this cellular layer, scarce neutral glycoproteins and lipids (phospholipids/glycolipids) are also present.
Effect of irradiance on growth, photosynthesis, pigment content and nutrient consumption in dense cultures of Rhodomonas salina (Wislouch) (Cryptophyceae)
Authors: Bartual A , Lubián LM , Gálvez JA , Niell FX
Published: August 2017

The effects of different incident irradiances on growth, photosynthesis, pigment content and nutrient uptake were studied in dense cultures of the cryptophyte Rhodomonas salina (Wislouch) Hill y Wetherbee. Cells were grown for ten days at different incident irradiances: 11, 33, 75, 260 and 320 µmol photon m-2s-1. The average pigment content (phycoerythrin and chlorophyll a) was lower when cells were grown at high irradiances (260 and 320 µmol photon m-2s-1) compared with cells grown under low irradiances (11, 33 and 75 µmol photon m-2s-1).The maximum photosynthetic rate (Pmax) was maximal at 75 µmol photon m-2s-1 , decreasing considerably at the highest irradiance in which apparent photosynthetic efficiency per cell and per chlorophyll a unit (αcell and αchla) also decreased. Results showed that dense cultures of R. salina grew optimally in a range between 75 and 260 µmol photon m-2s-1 with optimal photosynthetic performance at 75 µmol photon m-2s-1. Nitrogen and phosphorus depletion occurred as a consequence of the exponential growth, except under the lowest and the highest irradiances (11 and 320 µmol photon m-2s-1, respectively). Associated to N-limitation, phycoerythrin (PE) and chlorophyll a decreased considerably. It is suggested that R.salina responds to nitrogen-depleted conditions by mobilizing nitrogen from PE, this behaviour being modelled by a relationship between external nitrogen availability and PE mobilization.
Population structure, effort and dye yielding of the snail Plicopurpura pansa (Gould, 1853) in the Mexican Pacific
Authors: Michel-Morfín JE , Chávez EA , González L
Published: August 2017

The purple snail (Plicopurpura pansa) is a conspicuous rocky-shore species in the tidal zone of the American tropical Pacific. It is considered a potential resource because of the dye it produces. In the 1980s the snail underwent exploitation in the Pacific coast of Mexico. Samples in 12 rocky shores of the Baja California Sur, Jalisco and Oaxaca states, and the Socorro Island were made, finding a sexual ratio near to 1:1, densities ranging from 0.47 to 1.24 snails m–2 and a relation between dye yield and specimens' length. By interviews with the Mixteco people in Oaxaca and milking of the snails over cotton skeins, dye yield was calculated as 2.5 liters of dye per week/fisherman or 2.2 skeins per week/fisherman.
Proteinaceous exotoxins of shrimp-pathogenic isolates of Vibrio penaeicida and Vibrio nigripulchritudo
Authors: Aguirre-Guzmán G , Labreuche Y , Ansquer D , Espiau B , Levy P , Ascencio F , Saulnier D
Published: August 2017

The pathogenicity of two V. penaeicida strains, AM101 and KH-1, with different geographic origin, and V. nigripulchritudo strain AM102, were investigated in juvenile blue shrimp species Litopenaeus stylirostris. Alive bacteria and protein fractions (PFs) obtained from cell-free supernatants (CFS) were used in experimental challenges. Strains AM102, AM101, and KH-1 produced respectively 60, 54 and 12% mortality at 96 h after infection using 104 cfu mL–1 of bacterial suspension. Exocellular toxin-like factors were evidenced in CFS from the New Caledonian strains (AM102 and AM101) but not in the Japanese strain (KH-1). At 48 h post injection of each CFS, mortality rates were respectively 96, 98 and 5% when these strains were cultivated at 20 ºC, whereas only 0, 16 and 5% mortality rates were observed when these strains were cultivated at 30ºC. Clear differences in pathogenicity between both V. penaeicida strains of distinct geographic origin (AM101 and KH-1) were thus emphasized. Protein fractions were obtained from CFS of all the strains tested in this study and cultivated at 20ºC, by ammonium sulfate precipitation. Whatever the used strain, significantly higher mortalities were produced with PFs obtained with 0–40% of ammonium sulfate saturation, in respect to those produced with PFs60 and PFs80. Shrimp injected with PFs40 from strains AM102, AM101 and KH-1, and at a 20-µg org–1 dose produced respectively 100, 90 and 60% mortality 46 h after the challenge. The strain AM101 showed a median lethal dose of approximately 5 µg protein org–1 (1–1.25 µg protein g–1 body weight) 59 h after injection. The PFs40 from New Caledonian strains were found sensitive to heating and proteinase K treatments, reinforcing thus the hypothesis of their proteinaceous nature. Surprisingly, PFs40 from each bacterial strain displayed similar protein bands by SDS-PAGE suggesting that the tested strains share a common exotoxic compound regardless their distinct geographic origin or species.
Antitumor potential of natural products from marine ascidians of the Gibraltar Strait: A survey
Authors: Zubía E , Ortega MJ , Salvá J
Published: August 2017

The chemical study of a selection of marine ascidians from the Gibraltar Strait has led to the characterization of a collection of natural products of diverse biosynthetic origin. The structures were elucidated by spectroscopic methods and, in certain instances, the absolute stereochemistry was determined using chiral auxiliaries following the Mosher method. In particular, the new compounds isolated from the ascidians Phallusia fumigata (Grübe, 1864), Botryllus leachi (Savigny, 1816), Stolonica socialis (Hartmayer, 1903), and Pseudodistoma obscurum (Pères, 1959) are presented and key aspects of the structural elucidation are discussed. In order to anticipate a possible antitumor application, the cytotoxicity of the new compounds was evaluated against cell lines P-388 (suspension culture of a lymphoid neoplasm from a DBA/2 mouse), A-549 (monolayer culture of a human lung carcinoma), HT-29 (monolayer culture of a human colon carcinoma), and MEL-28 (monolayer culture of a human melanoma).
Agar from two coexisting species of Gracilaria (Gracilariaceae) from the Mexican Caribbean
Authors: Espinoza-Avalos J , Hernández-Garibay E , Zertuche-González JA , Meave-del-Castillo ME
Published: August 2017

Gracilaria cornea and G. crassissima are similar species that coexist at Bajo Pepito in the Mexican Caribbean. Differences in agar properties from both species were determined for two reproductive categories: carposporic and undetermined, the latter mainly composed of tetrasporophytes. Agar yield (AY), agar gel strength (GS), 3,6-anhydrogalactose content (AG) and sulfate content (S) of native and alkali-treated agar were determined for both reproductive categories. Significant differences in native and alkali-treated agar between the reproductive categories were recorded for AY, GS and S from G. cornea and G. crassissima, as well as for AG of native agar from the latter species. Our results, and previous studies, demonstrate that neither reproductive stage was predominant over the other(s) in terms of having greater or lower values of agar properties. The potential economic use of agar differences from plants of different reproductive stage remains very limited. Lower AY and GS were found for G. cornea from the Caribbean side of the Yucatan peninsula (this study), in comparison to agar values reported for the Gulf of Mexico side of the peninsula. Warmer and nutrient-poorer waters on the Caribbean side could cause those differences. No pattern for GS or S was found when these two and other tropical species of Gracilariaceae were compared to temperate species. When plants of both reproductive categories were pooled together for each Gracilaria species, significant differences were found in all agar properties. Interspecific and intraspecific differences between and within species of Gracilariaceae have also been found for phenological events. We suggest that the coexistence of G. cornea and G. crassissima requires different phenological responses by each species to the environment at Bajo Pepito, which in turn could be reflected in differences in the agar properties we measured, both at the interspecific and intraspecific levels.
Mitochondrial diversity and genetic structure in allopatric populations of the Pacific red snapper Lutjanus peru
Authors: Rocha-Olivares A , Sandoval-Castillo JR
Published: August 2017

We analyzed the genetic diversity and structure of three allopatric populations of the Pacific red snapper Lutjanus peru (Nichols and Murphy, 1922) by means of restriction fragment length polymorphisms of the entire mitochondrial control region (1350 bp). We found high levels of haplotype (h = 0.966) and nucleotide (π = 3.23%) diversities among the 100 organisms analyzed from Baja California Sur, Sinaloa and Jalisco (Mexico). Most of the molecular variability was detected with only one of the five restriction enzymes used (MseI). Heterogeneity analysis of haplotype frequencies was not significant (χ2 = 125.1, P > 0.25); neither were Wright's fixation index (FST = 0.0062, P = 0.140) nor its molecular analogue (ΦST = 0.0194, P = 0.056). An analysis of molecular variance (AMOVA) confirmed the absence of differentiation between peninsular and continental populations, even though it produced a marginally significant ΦST (ΦST = 0.0116, P = 0.048). No phylogeographic pattern was detected in a Neighbor-Joining gene tree. We argue that high molecular diversity levels are consistent with a large population size and that the absence of an apparent genetic structure, in the extreme north of the species distribution, suggests the action of mechanisms favoring passive larval transport among allopatric populations; although active adult migration cannot be ruled out.
Composition, abundance and diversity of coral reef fishes at two sites in Mochima National Park, Venezuela
Authors: Ruiz LJ , Méndez-de-E E , Torres-de-J A , Prieto-A A , Marín B , Fariña A
Published: August 2017

The composition, abundance and diversity of fishes in two reef patches located in Mochima National Park (Venezuela) were analyzed from January 2001 to January 2002. Monthly captures were made in deep zones. A total of 829 individuals were found and 67 species were recorded, of which 25 were common to both localities. In Cautaro, 547 specimens, belonging to 51 species and 24 families, were caught. The most abundant families were Scaridae (39.31%), Chaetodontidae (17.18%), Pomacentridae (13.89%), and Haemulidae (11.71%). Diversity ranged from 0.68 to 3.21 bits/ind, evenness from 0.29 to 0.98, and species richness from 0.68 to 2.24. Five of the species were permanent residents, seven were recurrent visitors and thirty-nine were occasional visitors. The most abundant species were Sparisoma aurofrenatum (39.31%), Chaetodon capistratus (16.27%) and Abudefduf saxatilis (13.89%). In Manzanillo, 282 specimens, belonging to 41 species and 21 families, were caught. The most numerous families were Sparidae (23.76%), Haemulidae (16.31%), and Chaetodontidae (11.70%). Diversity ranged from 1.00 to 3.22 bits/ind, evenness from 0.5 to 1, and species richness from 0.95 to 2.50. Three of the species were permanent residents, eight were recurrent visitors and thirty were occasional visitors. The most abundant species were Diplodus argenteus (23.76%), C. capistratus (11.70%), and Haemulon flavolineatum (11.34%). The higher species diversity found in Cautaro than in Manzanillo could be due to the higher structural complexity of the former.
ESTUDO DAS POSSIBILIDADES DE RECICLAGEM DA GOMA DE MASCAR: ESTUDO DE CASO NO CENTRO UNIVERSITÁRIO METODISTA IZABELA HENDRIX (CEUNIH), BELO HORIZONTE, MG
Authors: Santos Souza Josimara Pereira , De Moraes Silmara Martins , Dode Adilza Condessa
Published: August 2017

A goma de mascar, popularmente conhecida como chiclete, é um resíduo que não tem a devida atenção, principalmente com relação à sua disposição final. Esse resíduo é depositado diariamente nas ruas e calçadas, causando danos ambientais e econômicos. O objetivo deste trabalho foi estudar uma forma de coleta e reciclagem adequada para a goma de mascar, procurando identificá-la como um resíduo e não como um rejeito, segundo a Política Nacional de Resíduos Sólidos, lei nº 12.305 de 2 de agosto de 2010 (BRASIL, 2010). Realizou-se um estudo de caso no Centro Universitário Metodista Izabela Hendrix, Campus Praça da Liberdade, em Belo Horizonte, MG, onde se instalaram, em alguns locais, coletores de goma de mascar e, com o material coletado, confeccionou-se uma estátua em formato de árvore demonstrando a viabilidade de uso de tal resíduo e estimulando a comunidade acadêmica a respeito do potencial de reciclagem e sobre gerenciamento dos resíduos em geral.
USO DE RESÍDUOS DE CERÂMICA VERMELHA PARA O MELHORAMENTO DE CAMADAS DE PAVIMENTOS DE BAIXO TRÁFEGO EM PALMAS-TO
Authors: Silva João Paulo Souza , Carvalho Silas Barbosa
Published: August 2017

A atividade humana tem sido um grande motivo de preocupação quando se trata do meio ambiente, principalmente pelos efeitos destrutivos gerados por ela. Nesse âmbito se enquadra a construção civil, a qual se revela como uma atividade humana geradora de resíduos, e é no intuito de minimizar o efeito ambiental da disposição de alguns desses resíduos que se desenvolve o presente trabalho. O material escolhido para a análise é o resíduo de cerâmica vermelha (RCV), proveniente do processo de fabricação de cerâmica vermelha e disposto, em sua maioria, de forma inadequada no meio ambiente. Assim, viu-se a possibilidade de adequar esse resíduo para a função estrutural, especificamente na camada de base de um pavimento. Para a análise e estudo, foram coletadas amostras de solo no município de Palmas-TO, o qual possui inúmeras vias de relevada importância ainda sem pavimentação. As análises das amostras consistiram na mistura de agregado de cerâmica vermelha ao solo coletado, as quais, por sua vez, foram devidamente caracterizadas por meio de ensaios normatizados. A partir da análise comparativa dos resultados das amostras ensaiadas entre si e também com relação ao solo original, observou-se o comportamento das amostras diante de esforços do tráfego. Por fim, conforme resultados obtidos e discutidos, a utilização de resíduos de cerâmica vermelha como agregado na camada de base de pavimento rodoviário no município de Palmas-TO é indicada, principalmente quando analisado o método ISC, obtendo um resultado conforme recomendação do DNIT (2006).
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

We 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

The 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

Single‐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

The 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

Previous 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

We 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

We 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

Kinetic‐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

Multibeam 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

We 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

The 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

The 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

The 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.
β‐Amyrin synthase from Conyza blinii expressed in Saccharomyces cerevisiae
Authors: Sun Rong , Liu Shan , Tang Zi‐Zhong , Zheng Tian‐Run , Wang Tao , Chen Hui , Li Cheng‐Lei , Wu Qi
Published: August 2017

Conyza blinii H.Lév. is a widely used medicinal herb in southwestern China. The main pharmacological components of C. blinii are a class of oleanane‐type pentacyclic triterpene glycosides known as conyzasaponins, which are thought to be synthesized from β‐amyrin. However, no genes involved in the conyzasaponin pathway have previously been identified. Here, we identify an oxidosqualene cyclase (OSC), a β‐amyrin synthase, which mediates cyclization of 2,3‐oxidosqualene to yield β‐amyrin. Ten OSC sequences were isolated from C. blinii transcript tags. Phylogenetic analysis was used to select the tag Cb18076 as the putative β‐amyrin synthase, named CbβAS. The open reading frame of CbβAS is 2286 bp and encodes 761 amino acids. Its mature protein contains the highly conserved motifs (QXXXGXW/DCTAE) of OSCs and (MWCYCR) of β‐amyrin synthases. Transcription of CbβAS was upregulated 4–24 h after treatment of the seedlings of the C. blinii cultivar with methyl jasmonate. Furthermore, expression of CbβAS in Saccharomyces cerevisiae successfully yielded β‐amyrin. The chemical structures and concentrations of β‐amyrin were confirmed by GC‐MS/MS. The target yeast ultimately produced 4.432 mg·L−1 β‐amyrin. Thus, CbβAS is an OSC involved in conyzasaponin biosynthesis.
Snail suppresses cellular senescence and promotes fibroblast‐led cancer cell invasion
Authors: Furuya Satoshi , Endo Kaori , Takahashi Akiko , Miyazawa Keiji , Saitoh Masao
Published: August 2017

Snail, a zinc finger transcription factor, induces an epithelial–mesenchymal transition (EMT) in various cancer and epithelial cells. We investigated the function of Snail (SNAI1) by downregulating its expression with short interfering RNA (siRNA). Suppression of Snail expression induced cellular senescence in several cancer cells and in normal fibroblast IMR90 cells. Cancer progression is facilitated by fibroblasts, so‐called fibroblast‐led cancer cell invasion. Snail‐silenced cancer cells exhibited reduced motility, which was further decreased by cocultivation with Snail‐silenced IMR90 cells. Our data suggest that cell motility and cellular senescence, which are regulated by Snail in cancer cells and fibroblasts, modulate fibroblast‐led cancer cell invasion. Therefore, we propose that local suppression of Snail in cancer and the cancer microenvironment represents a potent therapeutic strategy.
IMRT QA using machine learning: A multi‐institutional validation
Authors: Valdes Gilmer , Chan Maria F. , Lim Seng Boh , Scheuermann Ryan , Deasy Joseph O. , Solberg Timothy D.
Published: August 2017

Purpose

To validate a machine learning approach to Virtual intensity‐modulated radiation therapy (IMRT) quality assurance (QA) for accurately predicting gamma passing rates using different measurement approaches at different institutions.

Methods

A Virtual IMRT QA framework was previously developed using a machine learning algorithm based on 498 IMRT plans, in which QA measurements were performed using diode‐array detectors and a 3%local/3 mm with 10% threshold at Institution 1. An independent set of 139 IMRT measurements from a different institution, Institution 2, with QA data based on portal dosimetry using the same gamma index, was used to test the mathematical framework. Only pixels with ≥10% of the maximum calibrated units (CU) or dose were included in the comparison. Plans were characterized by 90 different complexity metrics. A weighted poison regression with Lasso regularization was trained to predict passing rates using the complexity metrics as input.

Results

The methodology predicted passing rates within 3% accuracy for all composite plans measured using diode‐array detectors at Institution 1, and within 3.5% for 120 of 139 plans using portal dosimetry measurements performed on a per‐beam basis at Institution 2. The remaining measurements (19) had large areas of low CU, where portal dosimetry has a larger disagreement with the calculated dose and as such, the failure was expected. These beams need further modeling in the treatment planning system to correct the under‐response in low‐dose regions. Important features selected by Lasso to predict gamma passing rates were as follows: complete irradiated area outline (CIAO), jaw position, fraction of MLC leafs with gaps smaller than 20 or 5 mm, fraction of area receiving less than 50% of the total CU, fraction of the area receiving dose from penumbra, weighted average irregularity factor, and duty cycle.

Conclusions

We have demonstrated that Virtual IMRT QA can predict passing rates using different measurement techniques and across multiple institutions. Prediction of QA passing rates can have profound implications on the current IMRT process.
Microfluidics Cell Loading‐Dock System: Ordered Cellular Array for Dynamic Lymphocyte‐Communication Study
Authors: Li Ying , Jang Joon Hee , Wang Crystal , He Bangshun , Zhang Kai , Zhang Pengchao , Vu Timothy , Qin Lidong
Published: August 2017

It remains a great challenge to establish a high‐throughput platform that can explore the interactions among multiple lymphocytes (>2 cells) and retrieve the interested cells for downstream analysis. This study demonstrates a microfluidics cell loading‐dock system (Cell‐Dock) to enclose multiple cells in 1D, 2D, and 3D chambers with high throughput and efficiency and single‐cell accuracy. The loading efficiencies of 95%, 85%, and 74% for one‐, three‐, and five‐cell systems are achieved, respectively. The Cell‐Dock system provides precise and dynamic cell packing models to facilitate lymphocyte‐interaction studies. The results demonstrate that individual natural killer (NK) cells may function independently rather than cooperate to lyse target cells in the defined microenvironment. Furthermore, the strong/weak NK cells are retrieved based on their on‐chip cytotoxicity and mRNA sequencing is conducted to find the possible mechanisms for “serial killing,” an important but unsolved issue. This study finds that the stronger NK cells overexpress multiple genes involved in cytotoxicity and adhesion molecules (including the well‐known ICAM1 and seldom reported B4GALT1) might play important roles in the regulation of NK cytolysis.
Effect of Creep and Aging on the Precipitation Kinetics of an Al–Cu Alloy after One Pass of ECAP
Authors: Härtel Markus , Frint Philipp , Abstoss Kevin G. , Wagner Martin F.‐X.
Published: August 2017

Recent work shows that severe plastic deformation processes such as ECAP or HPT considerably accelerate the precipitation kinetics of Al‐Cu alloys. In this study, the authors analyze how a combination of mechanical load, aging time (and increased plastic strain), and aging temperature affects the precipitation kinetics of an AA2017 alloy after ECAP. After solution annealing, the material is processed by one pass of ECAP (120°‐channel angle) at 140 °C. Compressive creep tests are performed on the initial condition and the ECAP‐deformed material. The resulting microstructures are studied in detail using electron microscopy. To investigate the influence of mechanical loading, interrupted compressive creep tests are performed and compared with aged samples (produced without any mechanical loading at the same temperature and after the same amount of time). By keeping time and load constant in another set of interrupted compressive creep tests, the influence of temperature is investigated. Our study shows that increasing mechanical loading further accelerates the precipitation kinetics. Temperature accelerates the precipitation kinetics as well, but results in coarser precipitates. The authors also find that different creep strains can lead to the formation of two different regions in the microstructure: regions with only a few coarsened θ‐phase precipitates, and regions with numerous, finely dispersed precipitates.