ISO_q(3) and ISO_q(2,1)

We prove the embedding of ISO_q(3) \hook ISU^{ex}_{\sqrt{q}}(2) and ISO_q(2,1) \hook ISL^{ex}_q(2,R) as $^*$-algebras and give a Hilbert space representation of $ISU^{ex}_{\sqrt{q}}(2)$Comment: 10 pages, 12 figures, Late

Modeling effects of L-type ca(2+) current and na(+)-ca(2+) exchanger on ca(2+) trigger flux in rabbit myocytes with realistic T-tubule geometries.

The transverse tubular system of rabbit ventricular myocytes consists of cell membrane invaginations (t-tubules) that are essential for efficient cardiac excitation-contraction coupling. In this study, we investigate how t-tubule micro-anatomy, L-type Ca(2+) channel (LCC) clustering, and allosteric activation of Na(+)/Ca(2+) exchanger by L-type Ca(2+) current affects intracellular Ca(2+) dynamics. Our model includes a realistic 3D geometry of a single t-tubule and its surrounding half-sarcomeres for rabbit ventricular myocytes. The effects of spatially distributed membrane ion-transporters (LCC, Na(+)/Ca(2+) exchanger, sarcolemmal Ca(2+) pump, and sarcolemmal Ca(2+) leak), and stationary and mobile Ca(2+) buffers (troponin C, ATP, calmodulin, and Fluo-3) are also considered. We used a coupled reaction-diffusion system to describe the spatio-temporal concentration profiles of free and buffered intracellular Ca(2+). We obtained parameters from voltage-clamp protocols of L-type Ca(2+) current and line-scan recordings of Ca(2+) concentration profiles in rabbit cells, in which the sarcoplasmic reticulum is disabled. Our model results agree with experimental measurements of global Ca(2+) transient in myocytes loaded with 50 μM Fluo-3. We found that local Ca(2+) concentrations within the cytosol and sub-sarcolemma, as well as the local trigger fluxes of Ca(2+) crossing the cell membrane, are sensitive to details of t-tubule micro-structure and membrane Ca(2+) flux distribution. The model additionally predicts that local Ca(2+) trigger fluxes are at least threefold to eightfold higher than the whole-cell Ca(2+) trigger flux. We found also that the activation of allosteric Ca(2+)-binding sites on the Na(+)/Ca(2+) exchanger could provide a mechanism for regulating global and local Ca(2+) trigger fluxes in vivo. Our studies indicate that improved structural and functional models could improve our understanding of the contributions of L-type and Na(+)/Ca(2+) exchanger fluxes to intracellular Ca(2+) dynamics

Impact of multiscale dynamical processes and mixing on the chemical composition of the upper troposphere and lower stratosphere during the Intercontinental Chemical Transport Experiment–North America

We use high-frequency in situ observations made from the DC8 to examine fine-scale tracer structure and correlations observed in the upper troposphere and lower stratosphere during INTEX-NA. Two flights of the NASA DC-8 are compared and contrasted. Chemical data from the DC-8 flight on 18 July show evidence for interleaving and mixing of polluted and stratospheric air masses in the vicinity of the subtropical jet in the upper troposphere, while on 2 August the DC-8 flew through a polluted upper troposphere and a lowermost stratosphere that showed evidence of an intrusion of polluted air. We compare data from both flights with RAQMS 3-D global meteorological and chemical model fields to establish dynamical context and to diagnose processes regulating the degree of mixing on each day. We also use trajectory mapping of the model fields to show that filamentary structure due to upstream strain deformation contributes to tracer variability observed in the upper troposphere. An Eulerian measure of strain versus rotation in the large-scale flow is found useful in predicting filamentary structure in the vicinity of the jet. Higher-frequency (6–24 km) tracer variability is attributed to buoyancy wave oscillations in the vicinity of the jet, whose turbulent dissipation leads to efficient mixing across tracer gradients

Trace chemical measurements from the northern midlatitude lowermost stratosphere in early spring: Distributions, correlations, and fate

In situ measurements of a large number of trace chemicals from the midlatitude (37-57°N) lower stratosphere were performed with the NASA DC-8 aircraft during March 1994. Deepest penetrations into the stratosphere (550 ppb O3, 279 ppb N2O, and 350 K potential temperature) corresponded to a region that has been defined as the "lowermost stratosphere" (LS) by Holton et al [1995]. Analysis of data shows that the mixing ratios of long-lived tracer species (e. g. CH4, HNO3, NOy, CFCs) are linearly correlated with those of O3 and N2O. A ΔNOy/ΔO3 of 0.0054 ppb/ppb and ΔNOy/ΔN2O of -0.081 ppb/ppb is in good agreement with other reported measurements from the DC-8. These slopes are however, somewhat steeper than those reported from the ER-2 airborne studies. We find that the reactive nitrogen budget in the LS is largely balanced with HNO3 accounting for 80% of NOy, and PAN and NOx together accounting for 5%. A number of oxygenated species (e. g. acetone, H2O2) were present and may provide an important in situ source of HOx in the LS. SO2 mixing ratios were found to increase in the stratosphere at a rate that was comparable to the decline in OCS levels. No evidence of particle formation could be observed. Ethane, propane, and acetylene mixing ratios declined rapidly in the LS with Cl atoms likely playing a key role in this process. A number of reactive hydrocarbons/halocarbons (e. g. C6H6, CH3I) were present at low but measurable concentrations

Constraints on the age and dilution of Pacific Exploratory Mission-Tropics biomass burning plumes from the natural radionuclide tracer 210Pb

During the NASA Global Troposphere Experiment Pacific Exploratory Mission-Tropics (PEM-Tropics) airborne sampling campaign we found unexpectedly high concentrations of aerosol-associated 210Pb throughout the free troposphere over the South Pacific. Because of the remoteness of the study region, we expected specific activities to be generally less than 35 μBq m−3 but found an average in the free troposphere of 107 μBq m−3. This average was elevated by a large number of very active (up to 405 μBq m−3) samples that were associated with biomass burning plumes encountered on nearly every PEM-Tropics flight in the southern hemisphere. We use a simple aging and dilution model, which assumes that 222Rn and primary combustion products are pumped into the free troposphere in wet convective systems over fire regions (most likely in Africa), to explain the elevated 210Pb activities. This model reproduces the observed 210Pb activities very well, and predicts the ratios of four hydrocarbon species (emitted by combustion) to CO to better than 20% in most cases. Plume ages calculated by the model depend strongly on the assumed 222Rn activities in the initial plume, but using values plausible for continental boundary layer air yields ages that are consistent with travel times from Africa to the South Pacific calculated with a back trajectory model. The model also shows that despite being easily recognized through the large enhancements of biomass burning tracers, these plumes must have entrained large fractions of the surrounding ambient air during transport

India Summer Monsoon and Spatial Erosion Variability in the Arun Valley, Eastern Nepal

Abstract HKT-ISTP 2013 B

Improved quantification of Chinese carbon fluxes using CO2/CO correlations in Asian outflow

[1] We use observed CO2:CO correlations in Asian outflow from the TRACE-P aircraft campaign (February–April 2001), together with a three-dimensional global chemical transport model (GEOS-CHEM), to constrain specific components of the east Asian CO2 budget including, in particular, Chinese emissions. The CO2/CO emission ratio varies with the source of CO2 (different combustion types versus the terrestrial biosphere) and provides a characteristic signature of source regions and source type. Observed CO2/CO correlation slopes in east Asian boundary layer outflow display distinct regional signatures ranging from 10–20 mol/mol (outflow from northeast China) to 80 mol/mol (over Japan). Model simulations using best a priori estimates of regional CO2 and CO sources from Streets et al. [2003] (anthropogenic), the CASA model (biospheric), and Duncan et al. [2003] (biomass burning) overestimate CO2 concentrations and CO2/CO slopes in the boundary layer outflow. Constraints from the CO2/CO slopes indicate that this must arise from an overestimate of the modeled regional net biospheric CO2 flux. Our corrected best estimate of the net biospheric source of CO2 from China for March–April 2001 is 3200 Gg C/d, which represents a 45 % reduction of the net flux from the CASA model. Previous analyses of the TRACE-P data had found that anthropogenic Chinese C