A fluoroplanigraphy system for rapid presentation of single plane body sections

Fluoroplanigraphic system for rapid presentation of single plane body sections with reduced X ray exposure to patient

Dynamics of intracellular free calcium concentration in the presynaptic arbors of individual barnacle photoreceptors

At photoreceptor synapses, transmitter release is continuous and graded. At this type of synapse, the control of presynaptic [Ca2+]i and calcium's role in releasing transmitter might be different than at terminals invaded by all-or-none action potentials. To examine this possibility, we measured the spatial and temporal changes of [Ca2+]i in response to depolarization of individual photoreceptor terminals of the barnacle Balanus nubilus, which had been injected with the Ca2+ indicator Fura-2. Depolarizing pulses produced voltage-dependent Ca2+ entry that was confined to the tips of the arbor where the release sites are located. At increasing distances from the tips, the rate of [Ca2+]i increase was slower and the peak [Ca2+]i occurred later, suggesting that Ca2+ entered the tips and diffused back into the larger processes of the arbor. Consistent with this result, a stable gradient of [Ca2+]i was observed at maintained depolarizations, with the highest values at the tips of the arbor. Removal of external Na+ did not affect the time course of Ca2+ decline in the terminal, indicating that Na+/Ca2+ exchange was not the primary mechanism for restoring [Ca2+]i to basal levels. Computer simulations, assuming only Ca2+ entry at the arbor's tips and diffusion of Ca2+ away from the entry site, qualitatively reproduced these observations. The threshold for Ca2+ entry was near -60 mV, and entry was maintained during prolonged depolarizations, in agreement with previous experiments showing that Ca2+ channels in the terminal region do not inactivate. The time course of the measured [Ca2+]i change in the terminal paralleled voltage changes due to a Ca(2+)-activated K+ conductance, which senses [Ca2+]i just under the membrane. This parallelism is expected since the release sites are located on processes of small-enough diameter to permit radial equilibration of [Ca2+]i within the time course of physiological voltage changes. Therefore, the optical measurements reflect the mean level of [Ca2+]i under the membrane. Whether this mean concentration is also the value at the sites that trigger exocytosis will depend on how close the Ca2+ channels are to these sites

Usefulness of baseline lipids and C-reactive protein in women receiving menopausal hormone therapy as predictors of treatment-related coronary events.

Blood lipids and high-sensitivity C-reactive protein (hs-CRP) are altered by hormone therapy. The goal of the present study was to determine whether lipids and hs-CRP have predictive value for hormone therapy benefit or risk for coronary heart disease events in postmenopausal women without previous cardiovascular disease. A nested case-control study was performed in the Women\u27s Health Initiative hormone trials. Baseline lipids and hs-CRP were obtained from 271 incident patients with coronary heart disease (cases) and 707 controls. In a combined trial analysis, favorable lipid status at baseline tended to predict better coronary heart disease outcomes when using conjugated equine estrogen (CEE) with or without medroxyprogesterone acetate (MPA). Women with a low-density lipoprotein (LDL)/high-density lipoprotein (HDL) cholesterol ratioor =2.5 had increased risk of coronary heart disease (odds ratio 1.73, 95% confidence interval 1.18 to 2.53, p for interaction = 0.02). Low hs-CRP added marginally to the value of LDL/HDL rati

Tunable variation of optical properties of polymer capped gold nanoparticles

Optical properties of polymer capped gold nanoparticles of various sizes (diameter 3-6 nm) have been studied. We present a new scheme to extract size dependent variation of total dielectric function of gold nanoparticles from measured UV-Vis absorption data. The new scheme can also be used, in principle, for other related systems as well. We show how quantum effect, surface atomic co - ordination and polymer - nanoparticle interface morphology leads to a systematic variation in inter band part of the dielectric function of gold nanoparticles, obtained from the analysis using our new scheme. Careful analysis enables identification of the possible changes to the electronic band structure in such nanoparticles.Comment: 13 pages,7 figures, 1 tabl

Combination Service for Time-variable Gravity Fields: operational GRACE-FO combination and validation of Chinese GRACE time-series

The Combination Service for Time-variable Gravity Fields (COST-G) of the International Association of Geodesy (IAG) provides combined monthly gravity fields of its associated and partner Analysis Centers (ACs). In November 2020, the combination of monthly GRACE-FO gravity fields started its operational mode, providing consolidated L2 (spherical harmonics) and L3 (gridded and post-processed) products with a latency of currently 3 months. We present an overview and quality assessment of the available products. COST-G aims at the extension of its service to include further GRACE and GRACE-FO analysis centers. In January 2020 a collaboration with representatives of five Chinese ACs was initiated, who provided GRACE time-series according to the COST-G requirements. We present the results of a test combination with the Chinese AC models, including comparison and quality assessment of all contributing time-series and validation of the combined gravity fields

Combination Service for Time-variable Gravity Fields (COST-G): operations and new developments

Since its start of operations in July 2019, IAGâ?Ts Combination Service for Time-variable Gravity fields (COST-G) is providing a complete time-series of combined monthly GRACE gravity fields and a regularly updated time-series of monthly gravity fields derived from kinematic Swarm orbits. Starting from October 2020, the COST-G product line is complemented by a time-series of operationally combined and monthly updated GRACE-FO gravity fields. All these combinations are performed by variance component estimation on the solution level. We report on new developments, i.e., a planned extension of COST-G to include Chinese analysis centers of GRACE and GRACE-FO data, a re-consideration of the combination strategy to better focus on the range of spherical harmonic coefficients most relevant for the users, and the potential application of COST-G products for orbit determination of altimeter satellites