453 research outputs found
Advancing In Situ Modeling of ICMEs: New Techniques for New Observations
It is generally known that multi-spacecraft observations of interplanetary
coronal mass ejections (ICMEs) more clearly reveal their three-dimensional
structure than do observations made by a single spacecraft. The launch of the
STEREO twin observatories in October 2006 has greatly increased the number of
multipoint studies of ICMEs in the literature, but this field is still in its
infancy. To date, most studies continue to use on flux rope models that rely on
single track observations through a vast, multi-faceted structure, which
oversimplifies the problem and often hinders interpretation of the large-scale
geometry, especially for cases in which one spacecraft observes a flux rope,
while another does not. In order to tackle these complex problems, new modeling
techniques are required. We describe these new techniques and analyze two ICMEs
observed at the twin STEREO spacecraft on 22-23 May 2007, when the spacecraft
were separated by ~8 degrees. We find a combination of non-force-free flux rope
multi-spacecraft modeling, together with a new non-flux rope ICME plasma flow
deflection model, better constrains the large-scale structure of these ICMEs.
We also introduce a new spatial mapping technique that allows us to put
multispacecraft observations and the new ICME model results in context with the
convecting solar wind. What is distinctly different about this analysis is that
it reveals aspects of ICME geometry and dynamics in a far more visually
intuitive way than previously accomplished. In the case of the 22-23 May ICMEs,
the analysis facilitates a more physical understanding of ICME large-scale
structure, the location and geometry of flux rope sub-structures within these
ICMEs, and their dynamic interaction with the ambient solar wind
Barriers to the Intestinal Absorption of Four Insulin-Loaded Arginine-Rich Nanoparticles in Human and Rat
Peptide drugs and biologics provide opportunities for treatments of many diseases. However, due to their poor stability and permeability in the gastrointestinal tract, the oral bioavailability of peptide drugs is negligible. Nanoparticle formulations have been proposed to circumvent these hurdles, but systemic exposure of orally administered peptide drugs has remained elusive. In this study, we investigated the absorption mechanisms of four insulin-loaded arginine-rich nanoparticles displaying differing composition and surface characteristics, developed within the pan-European consortium TRANS-INT. The transport mechanisms and major barriers to nanoparticle permeability were investigated in freshly isolated human jejunal tissue. Cytokine release profiles and standard toxicity markers indicated that the nanoparticles were nontoxic. Three out of four nanoparticles displayed pronounced binding to the mucus layer and did not reach the epithelium. One nanoparticle composed of a mucus inert shell and cell-penetrating octarginine (ENCP), showed significant uptake by the intestinal epithelium corresponding to 28 ± 9% of the administered nanoparticle dose, as determined by super-resolution microscopy. Only a small fraction of nanoparticles taken up by epithelia went on to be transcytosed via a dynamin-dependent process. In situ studies in intact rat jejunal loops confirmed the results from human tissue regarding mucus binding, epithelial uptake, and negligible insulin bioavailability. In conclusion, while none of the four arginine-rich nanoparticles supported systemic insulin delivery, ENCP displayed a consistently high uptake along the intestinal villi. It is proposed that ENCP should be further investigated for local delivery of therapeutics to the intestinal mucosa.Swedish Research CouncilCompetitive Reference Groups, ConsellerĂa de EducaciĂłn e OrdenaciĂłn Universitaria, Xunta de GaliciaEuropean TRANS-INT ConsortiumEuropean Unionâs Seventh Framework Programme for research, technological development and demonstrationErasmus Mundus programme, âNanoFar: European Doctorate in Nanomedicine and Pharmaceutical InnovationâALF funds, Swedish Government, Swede
Porcine dentin matrix protein 1: gene structure, cDNA sequence, and expression in teeth
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73278/1/j.1600-0722.2006.00284.x.pd
A Helicity-Based Method to Infer the CME Magnetic Field Magnitude in Sun and Geospace: Generalization and Extension to Sun-Like and M-Dwarf Stars and Implications for Exoplanet Habitability
Patsourakos et al. (Astrophys. J. 817, 14, 2016) and Patsourakos and
Georgoulis (Astron. Astrophys. 595, A121, 2016) introduced a method to infer
the axial magnetic field in flux-rope coronal mass ejections (CMEs) in the
solar corona and farther away in the interplanetary medium. The method, based
on the conservation principle of magnetic helicity, uses the relative magnetic
helicity of the solar source region as input estimates, along with the radius
and length of the corresponding CME flux rope. The method was initially applied
to cylindrical force-free flux ropes, with encouraging results. We hereby
extend our framework along two distinct lines. First, we generalize our
formalism to several possible flux-rope configurations (linear and nonlinear
force-free, non-force-free, spheromak, and torus) to investigate the dependence
of the resulting CME axial magnetic field on input parameters and the employed
flux-rope configuration. Second, we generalize our framework to both Sun-like
and active M-dwarf stars hosting superflares. In a qualitative sense, we find
that Earth may not experience severe atmosphere-eroding magnetospheric
compression even for eruptive solar superflares with energies ~ 10^4 times
higher than those of the largest Geostationary Operational Environmental
Satellite (GOES) X-class flares currently observed. In addition, the two
recently discovered exoplanets with the highest Earth-similarity index, Kepler
438b and Proxima b, seem to lie in the prohibitive zone of atmospheric erosion
due to interplanetary CMEs (ICMEs), except when they possess planetary magnetic
fields that are much higher than that of Earth.Comment: http://adsabs.harvard.edu/abs/2017SoPh..292...89
Differential Association between HERG and KCNE1 or KCNE2
The small proteins encoded by KCNE1 and KCNE2 have both been proposed as accessory subunits for the HERG channel. Here we report our investigation into the cell biology of the KCNE-HERG interaction. In a co-expression system, KCNE1 was more readily co-precipitated with co-expressed HERG than was KCNE2. When forward protein trafficking was prevented (either by Brefeldin A or engineering an ER-retention/retrieval signal onto KCNE cDNA) the intracellular abundance of KCNE2 and its association with HERG markedly increased relative to KCNE1. HERG co-localized more completely with KCNE1 than with KCNE2 in all the membrane-processing compartments of the cell (ER, Golgi and plasma membrane). By surface labeling and confocal immunofluorescence, KCNE2 appeared more abundant at the cell surface compared to KCNE1, which exhibited greater co-localization with the ER-marker calnexin. Examination of the extracellular culture media showed that a significant amount of KCNE2 was extracellular (both soluble and membrane-vesicle-associated). Taken together, these results suggest that during biogenesis of channels HERG is more likely to assemble with KCNE1 than KCNE2 due to distinctly different trafficking rates and retention in the cell rather than differences in relative affinity. The final channel subunit constitution, in vivo, is likely to be determined by a combination of relative cell-to-cell expression rates and differential protein processing and trafficking
The Rac GTP Exchange Factor TIAM-1 Acts with CDC-42 and the Guidance Receptor UNC-40/DCC in Neuronal Protrusion and Axon Guidance
The mechanisms linking guidance receptors to cytoskeletal dynamics in the growth cone during axon extension remain mysterious. The Rho-family GTPases Rac and CDC-42 are key regulators of growth cone lamellipodia and filopodia formation, yet little is understood about how these molecules interact in growth cone outgrowth or how the activities of these molecules are regulated in distinct contexts. UNC-73/Trio is a well-characterized Rac GTP exchange factor in Caenorhabditis elegans axon pathfinding, yet UNC-73 does not control CED-10/Rac downstream of UNC-6/Netrin in attractive axon guidance. Here we show that C. elegans TIAM-1 is a Rac-specific GEF that links CDC-42 and Rac signaling in lamellipodia and filopodia formation downstream of UNC-40/DCC. We also show that TIAM-1 acts with UNC-40/DCC in axon guidance. Our results indicate that a CDC-42/TIAM-1/Rac GTPase signaling pathway drives lamellipodia and filopodia formation downstream of the UNC-40/DCC guidance receptor, a novel set of interactions between these molecules. Furthermore, we show that TIAM-1 acts with UNC-40/DCC in axon guidance, suggesting that TIAM-1 might regulate growth cone protrusion via Rac GTPases in response to UNC-40/DCC. Our results also suggest that Rac GTPase activity is controlled by different GEFs in distinct axon guidance contexts, explaining how Rac GTPases can specifically control multiple cellular functions
Long-Term Clinical Protection from Falciparum Malaria Is Strongly Associated with IgG3 Antibodies to Merozoite Surface Protein 3
Using data from malaria cases in Senegal, Pierre Druilhe and colleagues found that antibodies of the IgG3 isotype directed to merozoite surface protein 3 (MSP3) were strongly predictive of clinical outcome
Observation of associated near-side and away-side long-range correlations in âsNN=5.02ââTeV proton-lead collisions with the ATLAS detector
Two-particle correlations in relative azimuthal angle (ÎÏ) and pseudorapidity (Îη) are measured in âsNN=5.02ââTeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1ââÎŒb-1 of data as a function of transverse momentum (pT) and the transverse energy (ÎŁETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Îη|<5) ânear-sideâ (ÎÏâŒ0) correlation that grows rapidly with increasing ÎŁETPb. A long-range âaway-sideâ (ÎÏâŒÏ) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ÎŁETPb, is found to match the near-side correlation in magnitude, shape (in Îη and ÎÏ) and ÎŁETPb dependence. The resultant ÎÏ correlation is approximately symmetric about Ï/2, and is consistent with a dominant cosâĄ2ÎÏ modulation for all ÎŁETPb ranges and particle pT
Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV
The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of âs = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pTâ„20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60â€pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2â€{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
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