Ionization states of heavy elements observed in the 1974 May 14-15 anomalous solar particle event

The charge states of heavy ions accelerated in the (3)He-Fe rich solar particle event of 1974 May 14-15 are determined using data from the Interplanetary Monitoring Platform-8. In addition to Fe(+11,12) both 0(+5) and Fe(+16,17,18) are also present suggesting variations in coronal temperatures over a range from approximately 400,000 to 5,000,000 K. The presence of 0(+5) and Fe(+16-18) may be explained by a resonant plasma heating mechanism proposed to account for the enhancements of (3)He and Fe

Laser ignition and flame characteristics of pulsed methane jets in homogeneous isotropic turbulence without mean flow

The influence of turbulence on the minimum ignition energy (MIE) and ignited flame characteristics is investigated for pulsed methane diffusion jets ignited by laser-induced plasma. The methane jet is injected in a volume of homogeneous and isotropic air turbulence without mean flow, with the level of turbulence being controlled independently. The study is carried out for a range of fuel jet (Rejet) Reynolds number, namely 1000, 2000, and 3000, and a range of turbulent (Reλ) Reynolds number, namely 0–207. The results show that the position of the maximum intensity of flame emission was randomly scattered due to the fact that the ignited flame is deflected from the nozzle axis by the turbulent velocity fluctuations. The effect is more profound at higher Rejet. The value of the MIE, determined according to 50% ignitibility of mixture, increases by a factor of 2 for an increase of Reλ from 0 to 207 and by a factor of 5 for an increase of Rejet from 1000 to 3000. Two trends are observed on MIE with Reλ. For low Reλ, MIE is independent of Reλ. Past a critical value of Reλ, MIE increases as a linear function of Reλ. This transition occurs at critical values of Reλ,c = 158, 197 and 202 for Rejet= 1000, 2000 and 3000, respectively. The mean value of MIE for ignition before and after transition is a linear function of Rejet. The difference between the mean value of MIE before transition and after transition is around 5 mJ for all considered Rejet

Hiding Single Photons With Spread Spectrum Technology

We describe a proof-of-principal experiment demonstrating the use of spread spectrum technology at the single photon level. We show how single photons with a prescribed temporal shape, in the presence of interfering noise, may be hidden and recovered.Comment: 4 pages, 5 figures

A heparin-mimicking polymer conjugate stabilizes basic fibroblast growth factor.

Basic fibroblast growth factor (bFGF) is a protein that plays a crucial role in diverse cellular functions, from wound healing to bone regeneration. However, a major obstacle to the widespread application of bFGF is its inherent instability during storage and delivery. Here, we describe the stabilization of bFGF by covalent conjugation with a heparin-mimicking polymer, a copolymer consisting of styrene sulfonate units and methyl methacrylate units bearing poly(ethylene glycol) side chains. The bFGF conjugate of this polymer retained bioactivity after synthesis and was stable to a variety of environmentally and therapeutically relevant stressors--such as heat, mild and harsh acidic conditions, storage and proteolytic degradation--unlike native bFGF. Following the application of stress, the conjugate was also significantly more active than the control conjugate system in which the styrene sulfonate units were omitted from the polymer structure. This research has important implications for the clinical use of bFGF and for the stabilization of heparin-binding growth factors in general

Coarse-graining the dynamics of coupled oscillators

We present an equation-free computational approach to the study of the coarse-grained dynamics of {\it finite} assemblies of {\it non-identical} coupled oscillators at and near full synchronization. We use coarse-grained observables which account for the (rapidly developing) correlations between phase angles and oscillator natural frequencies. Exploiting short bursts of appropriately initialized detailed simulations, we circumvent the derivation of closures for the long-term dynamics of the assembly statistics.Comment: accepted for publication in Phys. Rev. Let

{BOAO Photometric Survey of Galactic Open Clusters. II. Physical Parameters of 12 Open Clusters

We have initiated a long-term project, the BOAO photometric survey of open clusters, to enlarge our understanding of galactic structure using UBVI CCD photometry of open clusters which have been little studied before. This is the second paper of the project in which we present the photometry of 12 open clusters. We have determined the cluster parameters by fitting the Padova isochrones to the color-magnitude diagrams of the clusters. All the clusters except for Be 0 and NGC 1348 are found to be intermediate-age to old (0.2 - 4.0 Gyrs) open clusters with a mean metallicity of [Fe/H] = 0.0.Comment: 11 page

Charged particle display

An optical shutter based on charged particles is presented. The output light intensity of the proposed device has an intrinsic dependence on the interparticle spacing between charged particles, which can be controlled by varying voltages applied to the control electrodes. The interparticle spacing between charged particles can be varied continuously and this opens up the possibility of particle based displays with continuous grayscale.Comment: typographic errors corrected in Eqs (37) and (39); published in Journal of Applied Physics; doi:10.1063/1.317648

An Optical and Infrared Photometric Study of the Young Open Cluster IC 1805 in the Giant H II Region W4

We present deep wide-field optical CCD photometry and mid-infrared Spitzer/IRAC and MIPS 24micron data for about 100,000 stars in the young open cluster IC 1805. The members of IC 1805 were selected from their location in the various color-color and color-magnitude diagrams, and the presence of Halpha emission, mid-infrared excess emission, and X-ray emission. The reddening law toward IC 1805 is nearly normal (R_V = 3.05+/-0.06). However, the distance modulus of the cluster is estimated to be 11.9+/-0.2 mag (d = 2.4+/-0.2 kpc) from the reddening-free color-magnitude diagrams, which is larger than the distance to the nearby massive star-forming region W3(OH) measured from the radio VLBA astrometry. We also determined the age of IC 1805 (tau_MSTO = 3.5 Myr). In addition, we critically compared the age and mass scale from two pre-main-sequence evolution models. The initial mass function with a Salpeter-type slope of Gamma = -1.3+/-0.2 was obtained and the total mass of IC 1805 was estimated to be about 2700+/-200 M_sun. Finally, we found our distance determination to be statistically consistent with the Tycho-Gaia Astrometric Solution Data Release 1, within the errors. The proper motion of the B-type stars shows an elongated distribution along the Galactic plane, which could be explained by some of the B-type stars being formed in small clouds dispersed by previous episodes of star formation or supernova explosions.Comment: 45 pages, 32 figures, 9 tables, accepted for publication in ApJ