The flares of August 1972

Analysis is made of observations of the August, 1972 flares at Big Bear and Tel Aviv, involving monochromatic movies, magnetograms, and spectra. In each flare the observations fit a model of particle acceleration in the chromosphere with emission produced by impart and by heating by the energetic electrons and protons. The region showed twisted flux and high gradients from birth, and flares appear due to strong magnetic shears and gradients across the neutral line produced by sunspot motions. Post flare loops show a strong change from sheared, force-free fields parallel to potential-field-like loops, perpendicular to the neutral line above the surface

Homogeneous SPC/E water nucleation in large molecular dynamics simulations

We perform direct large molecular dynamics simulations of homogeneous SPC/E water nucleation, using up to $\sim 4\cdot 10^6$ molecules. Our large system sizes allow us to measure extremely low and accurate nucleation rates, down to $\sim 10^{19}\,\textrm{cm}^{-3}\textrm{s}^{-1}$, helping close the gap between experimentally measured rates $\sim 10^{17}\,\textrm{cm}^{-3}\textrm{s}^{-1}$. We are also able to precisely measure size distributions, sticking efficiencies, cluster temperatures, and cluster internal densities. We introduce a new functional form to implement the Yasuoka-Matsumoto nucleation rate measurement technique (threshold method). Comparison to nucleation models shows that classical nucleation theory over-estimates nucleation rates by a few orders of magnitude. The semi-phenomenological nucleation model does better, under-predicting rates by at worst, a factor of 24. Unlike what has been observed in Lennard-Jones simulations, post-critical clusters have temperatures consistent with the run average temperature. Also, we observe that post-critical clusters have densities very slightly higher, $\sim 5\%$, than bulk liquid. We re-calibrate a Hale-type $J$ vs. $S$ scaling relation using both experimental and simulation data, finding remarkable consistency in over $30$ orders of magnitude in the nucleation rate range, and $180\,$K in the temperature range.Comment: Accepted for publication in the Journal of Chemical Physic

Martian sample sites: Examples based on a global geologic perspective

Ten areas were selected that each include several rock units of varying lithology and age. These areas were chosen to optimize the geologic and chronologic data return from Mars. Geologic mapping and stratigraphic studies identify stratigraphic ages, rock types, and information on Martian geologic history that samples of a given site may yield. Volcanic rocks occur over much of the planet and in virtually all stratigraphic positions, and they are amenable to radioisotopic dating. Therefore, a reasonable and essential goal for a sample return mission is to return datable rocks from widely varying strata. Generally, about three or four major geologic units can be sampled at any of the given sites, most of which can probably be dated. The Mars Observer mission will aid greatly in interpreting lithology and defining contacts at the high resolution required to actually pinpoint good sample acquisition sites within these areas

Single-cycle THz pulses with amplitudes exceeding 1 MV/cm generated by optical rectification in LiNbO3

Using the tilted-pulse-intensity-front scheme, we generate single-cycle terahertz (THz) pulses by optical rectification of femtosecond laser pulses in LiNbO3. In the THz generation setup, the condition that the image of the grating coincides with the tilted-optical-pulse front is fulfilled to obtain optimal THz beam characteristics and pump-to-THz conversion efficiency. The designed focusing geometry enables tight focus of the collimated THz beam with a spot size close to the diffraction limit, and the maximum THz electric field of 1.2 MV/cm is obtained

Nonlinear magnetization dynamics of antiferromagnetic spin resonance induced by intense terahertz magnetic field

We report on the nonlinear magnetization dynamics of a HoFeO3 crystal induced by a strong terahertz magnetic field resonantly enhanced with a split ring resonator and measured with magneto-optical Kerr effect microscopy. The terahertz magnetic field induces a large change (~40%) in the spontaneous magnetization. The frequency of the antiferromagnetic resonance decreases in proportion to the square of the magnetization change. A modified Landau-Lifshitz-Gilbert equation with a phenomenological nonlinear damping term quantitatively reproduced the nonlinear dynamics

The First Beam from the J-PARC 50GeV-PS

On January 27, 2009, protons were accelerated by the 50GeV proton synchrotron (50GeV-PS) of the Japan Proton Accelerator Research Complex (J-PARC) up to its initial goal of 30GeV, and were successfully extracted for the first time to the Hadron Experimental Hall in the Particle and Nuclear Physics Facility of the J-PARC. The proton beam was transported to the secondary-particle production target, T1, in the Hadron Experimental Hall, which was 250 m away from the beam extraction point from the 50GeV-PS, and finally absorbed by the beam dump, which located 50 m downstream from T1

Flexible composite film for printed circuit board

A flexible printed circuit for a printed circuit board in which layers of reaction product composed of a combination of phenoxy resin - polyisocyanate - brominated epoxy resin, and in which the equivalent ratio of those functional groups is hydroxyl group: isocyanate group: epoxy group - 1 : 0.2 to 2 : 0.5 to 3 are laminated on at least one side of saturated polyester film is discussed