5,592 research outputs found
Modeling radiation belt radial diffusion in ULF wave fields: 1. Quantifying ULF wave power at geosynchronous orbit in observations and in global MHD model
[1] To provide critical ULF wave field information for radial diffusion studies in the radiation belts, we quantify ULF wave power (f = 0.5–8.3 mHz) in GOES observations and magnetic field predictions from a global magnetospheric model. A statistical study of 9 years of GOES data reveals the wave local time distribution and power at geosynchronous orbit in field-aligned coordinates as functions of wave frequency, solar wind conditions (Vx, ΔPd and IMF Bz) and geomagnetic activity levels (Kp, Dst and AE). ULF wave power grows monotonically with increasing solar wind Vx, dynamic pressure variations ΔPd and geomagnetic indices in a highly correlated way. During intervals of northward and southward IMF Bz, wave activity concentrates on the dayside and nightside sectors, respectively, due to different wave generation mechanisms in primarily open and closed magnetospheric configurations. Since global magnetospheric models have recently been used to trace particles in radiation belt studies, it is important to quantify the wave predictions of these models at frequencies relevant to electron dynamics (mHz range). Using 27 days of real interplanetary conditions as model inputs, we examine the ULF wave predictions modeled by the Lyon-Fedder-Mobarry magnetohydrodynamic code. The LFM code does well at reproducing, in a statistical sense, the ULF waves observed by GOES. This suggests that the LFM code is capable of modeling variability in the magnetosphere on ULF time scales during typical conditions. The code provides a long-missing wave field model needed to quantify the interaction of radiation belt electrons with realistic, global ULF waves throughout the inner magnetosphere
Alpha- and Gammaproteobacterial Methanotrophs Codominate the Active Methane-Oxidizing Communities in an Acidic Boreal Peat Bog
The objective of this study was to characterize metabolically active, aerobic methanotrophs in an ombrotrophic peatland in the Marcell Experimental Forest, Minnesota, USA. Methanotrophs were investigated in the field and in laboratory incubations using DNA-stable isotope probing, expression studies on particulate methane monooxygenase (pmoA) genes, and amplicon sequencing of 16S rRNA genes. Potential rates of oxidation ranged from 14-17 μmol CH4 g dry wt soil-1 d-1. Within DNA-SIP incubations, the relative abundance of methanotrophs increased from 4% in situ to 25-36% after 8 -14 days. Phylogenetic analysis of the 13C-enriched DNA fractions revealed the active methanotrophs were dominated by the genera Methylocystis (Type II; Alphaproteobacteria), Methylomonas, and Methylovulum (Type I; Gammaproteobacteria). In field samples, a transcript-to-gene ratio of 1 to 2 was observed for pmoA in surface peat layers which attenuated rapidly with depth, indicating the highest methane consumption was associated with the 0-10 cm depth interval. Metagenomes and sequencing of cDNA pmoA amplicons from field samples confirmed the dominant active methanotrophs were Methylocystis and Methylomonas. Although Type II methanotrophs have long been shown to mediate methane consumption in peatlands, our results indicate members of the genera Methylomonas and Methylovulum (Type I) can significantly contribute to aerobic methane oxidation in these ecosystems
Combining stereotactic body radiation therapy with immunotherapy: Current data and future directions
Stereotactic body radiation therapy (SBRT) offers excellent local control of early-stage non-small cell lung cancer (NSCLC), but there currently is a need for tolerable systemic therapy to address regional and distant disease progression. One potential option is immunotherapy, which in metastatic NSCLC has shown promise for sustained disease control in a subset of patients. There is also growing evidence for a clinical synergy between radiation and immunotherapy, with several ongoing trials studying the abscopal effect. This review summarizes the current data in the fast-changing field of immuno-radiation therapy, highlighting updates from recent clinical trials
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Vulnerability of the frontal-temporal connections in temporal lobe epilepsy.
ObjectiveIn temporal lobe epilepsy (TLE), frontal-temporal connections are integral parts of the epileptogenic network. Although frontal-temporal gray matter abnormalities have been consistently demonstrated in TLE, white matter connections between these two lobes require further study in this disease setting. We therefore investigated the integrity of two major frontal-temporal white matter association tracts, uncinate fasciculus (UF) and arcuate fasciculus (AF), and their clinical correlates.MethodsUsing diffusion tensor imaging (DTI) tractography, integrity of the UF and AF was examined in 22 individuals (12 subjects with TLE and 10 age-matched healthy controls). DTI indices of these tracts were compared between the two subject groups and correlates examined with clinical variables that included age of seizure onset, duration of epilepsy, history of febrile seizure and antiepileptic medication exposure.ResultsIn subjects with TLE, the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of UF and AF ipsilateral to the side of seizure onset were abnormal when compared to healthy controls. Furthermore, lower UF FA correlated with earlier age of seizure onset.ConclusionTLE is associated with abnormal integrity of frontal-temporal white matter tracts, but only on the side of seizure onset. This suggests that frontal-temporal white matter tracts are vulnerable to recurrent seizures and/or the factors precipitating the epilepsy
Technological and Disruptive Innovations in a Nation\u27s Industrialization and Leadership Development
The turn of this new century has been witnessing the effort of various leading developed and developing countries in their attempt to materialize next round of industrialization by emphasizing on innovations. To potentially provide guidance to such national efforts, this paper explores the relationship between technological innovation and industrialization and the importance of disruptive innovation in the development of a nation\u27s international leadership. By employing the rigor of game theory, this work first looks at key conditions under which an established market invites competition and innovation. On top of such generally true results, it is consequently shown that technological innovation is a driving force behind industrialization and that disruptive innovation can assist a nation to become an international leader. Other than providing policy recommendations, this paper concludes with open problems for future research
Erythrocyte enrichment in hematopoietic progenitor cell cultures based on magnetic susceptibility of the hemoglobin
Using novel media formulations, it has been demonstrated that human placenta and umbilical cord blood-derived CD34+ cells can be expanded and differentiated into erythroid cells with high efficiency. However, obtaining mature and functional erythrocytes from the immature cell cultures with high purity and in an efficient manner remains a significant challenge. A distinguishing feature of a reticulocyte and maturing erythrocyte is the increasing concentration of hemoglobin and decreasing cell volume that results in increased cell magnetophoretic mobility (MM) when exposed to high magnetic fields and gradients, under anoxic conditions. Taking advantage of these initial observations, we studied a noninvasive (label-free) magnetic separation and analysis process to enrich and identify cultured functional erythrocytes. In addition to the magnetic cell separation and cell motion analysis in the magnetic field, the cell cultures were characterized for cell sedimentation rate, cell volume distributions using differential interference microscopy, immunophenotyping (glycophorin A), hemoglobin concentration and shear-induced deformability (elongation index, EI, by ektacytometry) to test for mature erythrocyte attributes. A commercial, packed column high-gradient magnetic separator (HGMS) was used for magnetic separation. The magnetically enriched fraction comprised 80% of the maturing cells (predominantly reticulocytes) that showed near 70% overlap of EI with the reference cord blood-derived RBC and over 50% overlap with the adult donor RBCs. The results demonstrate feasibility of label-free magnetic enrichment of erythrocyte fraction of CD34+ progenitor-derived cultures based on the presence of paramagnetic hemoglobin in the maturing erythrocytes. © 2012 Jin et al
The Sloan Bright Arcs Survey : Six Strongly Lensed Galaxies at z=0.4-1.4
We present new results of our program to systematically search for strongly
lensed galaxies in the Sloan Digital Sky Survey (SDSS) imaging data. In this
study six strong lens systems are presented which we have confirmed with
follow-up spectroscopy and imaging using the 3.5m telescope at the Apache Point
Observatory. Preliminary mass models indicate that the lenses are group-scale
systems with velocity dispersions ranging from 466-878 km s^{-1} at z=0.17-0.45
which are strongly lensing source galaxies at z=0.4-1.4. Galaxy groups are a
relatively new mass scale just beginning to be probed with strong lensing. Our
sample of lenses roughly doubles the confirmed number of group-scale lenses in
the SDSS and complements ongoing strong lens searches in other imaging surveys
such as the CFHTLS (Cabanac et al 2007). As our arcs were discovered in the
SDSS imaging data they are all bright (), making them ideally
suited for detailed follow-up studies.Comment: 13 pages, 3 figures, submitted to ApJL, the Sloan Bright Arcs page is
located here: http://home.fnal.gov/~kubo/brightarcs.htm
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