3,122 research outputs found
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Extending CMIP5 projections of global mean temperature change and sea level rise due to the thermal expansion using a physically-based emulator
We present a physically-based emulator approach to extending 21st century CMIP5 model simulations of global mean surface temperature (GMST) and global thermal expansion (TE) to 2300. A two-layer energy balance model that has been tuned to emulate the CO2 response of individual CMIP5 models is combined with model-specific radiative forcings to generate an emulated ensemble to 2300 for RCP2.6, RCP4.5 and RCP8.5. Errors in the emulated time series are quantified using a subset of CMIP5 models with data available to 2300 and factored into the ensemble uncertainty. The resulting projections show good agreement with 21st century ensemble projections reported in IPCC AR5 and also compare favourably with individual CMIP5 model simulations post-2100. There is a tendency for the two-layer model simulations to overestimate both GMST rise and TE under RCP2.6, which is suggestive of a systematic error in the applied radiative forcings. Overall, the framework shows promise as a basis for extending process-based projections of global sea level rise beyond the 21st century time horizon that typifies CMIP5 simulations. The results also serve to illustrate the differing responses of GMST and Earth's energy imbalance (EEI) to reductions in greenhouse gas emissions. GMST responds relatively quickly to changes in emissions, leading to a negative trend post-2100 for RCP2.6, although temperature remains substantially elevated compared to present day at 2300. In contrast, EEI remains positive under all RCPs, and results in ongoing sea level rise from TE
Fluorescence of thermal control coatings on S0069 and A0114
Many of the thermal control surfaces exposed to the space environment during the 5.8 year LDEF mission experienced changes in fluorescence. All of the thermal control coatings flown on LDEF experiments S0069 and A0114 were characterized for fluorescence under ambient conditions. Some of the black coatings, having protective overcoats, appear bright yellow under ultraviolet exposure. Urethane based coatings exhibited emission spectra shifts toward longer wavelengths in the visible range. Zinc oxide pigment based coatings experienced a quenching of fluorescence, while zinc orthotitanate pigment based and other ceramic type coatings had no measurable fluorescence
Modeling and Simulation of Mucus Flow in Human Bronchial Epithelial Cell Cultures – Part I: Idealized Axisymmetric Swirling Flow
A multi-mode nonlinear constitutive model for mucus is constructed directly from micro- and macro-rheology experimental data on cell culture mucus, and a numerical algorithm is developed for the culture geometry and idealized cilia driving conditions. This study investigates the roles that mucus rheology, wall effects, and HBE culture geometry play in the development of flow profiles and the shape of the air-mucus interface. Simulations show that viscoelasticity captures normal stress generation in shear leading to a peak in the air-mucus interface at the middle of the culture and a depression at the walls. Linear and nonlinear viscoelastic regimes can be observed in cultures by varying the hurricane radius and mean rotational velocity. The advection-diffusion of a drug concentration dropped at the surface of the mucus flow is simulated as a function of Peclet number
On kHz oscillations and characteristic frequencies of accreting magnetospheres
When an accreting star is close to rotational equilibrium between the dipole
component of the stellar magnetic field and the accretion disk, the star's
rotation rate is roughly of the order of the Keplerean rotation rate at the
inner boundary of the disk, estimated as the conventional Alfven radius. A
range of frequencies higher than this equilibrium rotation frequency can
naturally arise if the accretion flow is channeled by higher multipoles of the
star's magnetic field. The higher multipole components of the magnetic field
will balance the material stresses of the accretion flow at radii closer to the
star. The Kepler frequencies associated with these generalized Alfven radii
increase with the order of the multipole. Other frequency bands, like the
epicyclic frequencies associated with the accretion flow, may in turn be higher
than the Kepler frequencies. We present expressions for the spectrum of higher
frequencies arising due to these effects. Kilohertz quasi-periodic oscillation
frequencies that are much higher than the rotation rate of the neutron star, as
observed from the recently discovered 11 Hz (P = 90 ms) X-ray pulsar IGR
J17480-2446 in the globular cluster Terzan 5, may be due to modulation of the
accretion rate by the excitation of these modes in the accretion flow. The very
high QPO frequencies observed from the soft gamma repeaters SGR 1806-20 (P =
5.2 s) and SGR 1900+14 (P = 7.5 s) may also correspond to these characteristic
frequencies if SGRs accrete from fallback disks around them.Comment: 8 pages, 1 figure. Accepted for publication in MNRA
Measuring Tumor Cycling Hypoxia and Angiogenesis Using a Side-firing Fiber Optic Probe
Hypoxia and angiogenesis can significantly influence the efficacy of cancer therapy and the behavior of surviving tumor cells. There is a growing demand for technologies to measure tumor hypoxia and angiogenesis temporally in vivo to enable advances in drug development and optimization. This paper reports the use of frequency-domain photon migration with a side-firing probe to quantify tumor oxygenation and hemoglobin concentrations in nude rats bearing human head/neck tumors administered with carbogen gas, cycling hypoxic gas or just room air. Significant increase (with carbogen gas breathing) or decrease (with hypoxic gas breathing) in tumor oxygenation was observed. The trend in tumor oxygenation during forced cycling hypoxia (CH) followed that of the blood oxygenation measured with a pulse oximeter. Natural CH was also observed in rats under room air. The studies demonstrated the potential of the technology for longitudinal monitoring of tumor CH during tumor growth or in response to therapy
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The Ultra-Potent and Selective TLR8 Agonist VTX-294 Activates Human Newborn and Adult Leukocytes
Background: Newborns display distinct immune responses that contribute to susceptibility to infection and reduced vaccine responses. Toll-like receptor (TLR) agonists may serve as vaccine adjuvants, when given individually or in combination, but responses of neonatal leukocytes to many TLR agonists are diminished. TLR8 agonists are more effective than other TLR agonists in activating human neonatal leukocytes in vitro, but little is known about whether different TLR8 agonists may distinctly activate neonatal leukocytes. We characterized the in vitro immuno-stimulatory activities of a novel benzazepine TLR8 agonist, VTX-294, in comparison to imidazoquinolines that activate TLR8 (R-848; (TLR7/8) CL075; (TLR8/7)), with respect to activation of human newborn and adult leukocytes. Effects of VTX-294 and R-848 in combination with monophosphoryl lipid A (MPLA; TLR4) were also assessed. Methods: TLR agonist specificity was assessed using TLR-transfected HEK293 cells expressing a NF-κB reporter gene. TLR agonist-induced cytokine production was measured in human newborn cord and adult peripheral blood using ELISA and multiplex assays. Newborn and adult monocytes were differentiated into monocyte-derived dendritic cells (MoDCs) and TLR agonist-induced activation assessed by cytokine production (ELISA) and co-stimulatory molecule expression (flow cytometry). Results: VTX-294 was ∼100x more active on TLR8- than TLR7-transfected HEK cells (EC50, ∼50 nM vs. ∼5700 nM). VTX-294-induced TNF and IL-1β production were comparable in newborn cord and adult peripheral blood, while VTX-294 was ∼ 1 log more potent in inducing TNF and IL-1β production than MPLA, R848 or CL075. Combination of VTX-294 and MPLA induced greater blood TNF and IL-1β responses than combination of R-848 and MPLA. VTX-294 also potently induced expression of cytokines and co-stimulatory molecules HLA-DR and CD86 in human newborn MoDCs. Conclusions: VTX-294 is a novel ultra-potent TLR8 agonist that activates newborn and adult leukocytes and is a candidate vaccine adjuvant in both early life and adulthood
Ambiguous figures and the content of experience
Representationalism is the position that the phenomenal character of an experience is either identical with, or supervenes on, the content of that experience. Many representationalists hold that the relevant content of experience is nonconceptual. I propose a counterexample to this form of representationalism that arises from the phenomenon of Gestalt switching, which occurs when viewing ambiguous figures. First, I argue that one does not need to appeal to the conceptual content of experience or to judgements to account for Gestalt switching. I then argue that experiences of certain ambiguous figures are problematic because they have different phenomenal characters but that no difference in the nonconceptual content of these experiences can be identified. I consider three solutions to this problem that have been proposed by both philosophers and psychologists and conclude that none can account for all the ambiguous figures that pose the problem. I conclude that the onus is on representationalists to specify the relevant difference in content or to abandon their position
Changes in chemical and optical properties of thin film metal mirrors on LDEF
Thin films of the metals Cu, Ni, Pt, Au, Sn, Mo, and W deposited on fused silica flats were exposed at ambient temperature on the leading and trailing faces of the LDEF. Reflectances of these films were measured from 250 to 2500 nm and compared with controls. The exposed films were subjected to the LDEF external environment including atomic oxygen, molecular contamination, and solar ultraviolet. Major changes in optical and infrared reflectance were seen for Cu, Mo, Ni, and W films on the leading face of LDEF and are attributed to partial conversion of metal to metal oxide. Smaller changes in optical properties are seen on all films and are probably caused by thin contaminant films deposited on top of the metal. The optical measurements are correlated with film thickness measurements, x-ray photoelectron spectroscopy, optical calculations, and, in the case of Cu, with x-ray diffraction measurements. In a few cases, comparisons with results from a similar UAH experiment on STS-8 have been drawn
Genome wide association analysis in a mouse advanced intercross line
We are grateful to Heather Lawson at Washington University in St. Louis for providing LG and SM genome sequences. We thank the Gilad Lab and Functional Genomics Facility at the University of Chicago for generating DNA- and RNA-seq data. We wish to acknowledge outstanding technical assistance from Apurva Chitre at UCSD and Mike Jarsulic at the Biological Sciences Division Center for Research Informatics at the University of Chicago. We thank Clarissa Parker, John Novembre, Graham McVicker, Joe Davis, Peter Carbonetto and Shyam Gopalakrishnan for advice, training, and mentorship. Our work was funded by NIDA (AAP: R01DA021336) and NIAMS (AL: R01AR056280). We received additional support from NIGMS (NMG: T32GM007197; MGD: T32GM07281), NIDA (NMG: F31DA03635803), NHGRI (MA: R01 HG002899), and the IMS Elphinstone Scholarship at the University of Aberdeen (AIHC). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.Peer reviewedPublisher PD
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