High-energy Response Research Articles

The Sea-Breeze-Induced Coastal Calm Zone as Revealed by Satellite Data and Simulated by a Numerical Model

Abstract Meteorological satellite scanning radiometer data from a visual sensor during daylight hours are characteristically influenced by sunglint from the ocean surface as the sensor scans in the direction toward the sun (between the satellite subpoint and solar subpoint). When seas are calm in the region near the primary specular point (PSP), the sun's rays are either reflected directly into the spacecraft sensor yielding a high energy (bright) response, or away from the sensor yielding a low energy (dark) response. The particular effect depends on the proximity of the calm area to the PSP. This paper shows examples of bright and dark linear patterns adjacent to and tending to parallel coastlines. The patterns are interpreted to be sea-breeze-induced calm zones originating during periods of offshore flow when the pressure gradient causing the sea breeze is exactly counterbalanced by the larger-wale synoptic gradient. A two-dimensional planetary boundary layer (PBL) numerical model successfully simulate...

High energy spin-isospin modes in nulcei

The high energy response of nuclei to a spin-isospin excitation is investigated. We predict the existence of a strong contrast between the spin transverse and spin longitudinal responses. The second one undergoes a shadow effect in the Δ region and displays the occurence of the pionic branch.

Broad Band X-Ray Astronomical Spectroscopy

The Broad Band X-Ray Telescope (BBXRT) experiment has been designed for high sensitivity, moderate resolution spectrophotorietry of cosmic sources in the range 0.5 to 12 keV. Principal elements are two co-aligned imaging telescopes with cooled Si(Li) detectors at each focus. The mirror design uses an approximate geometry of tightly nested, conical, foil reflectors that allow a large filling factor (high throughput) at small grazing angles (high energy response). Each detector consists of a cluster of 5 elements defined with grooves on a single crystal. This arrangement affords some spatial resolution as well as a means of substantial background reduction. Shuttle borne measurements will typically be of 2000 s duration for sources with a flux of 10-12 ergs/cm2-s.

Application of Cavity Theories to High-Energy Response of LiF Dosimeters

The relative energy response of 0.4- and 1.16-mm thick LiF TLD-100 showed decreases of 5 and 9%, respectively, for 22-MV x rays and 6-, 9-, 12-, 15-, and 18-MeV electron energies when compared to responses for /sup 60/Co ..gamma.. rays in polystyrene and water media. The theories of Burlin, Burlin et al., Almond and McCray, and Holt et al. do not agree with these findings. Reasonable agreement is obtained with the Fregene expression and with Almond and McCray and Holt et al. only when the photon energy response at /sup 60/Co is calculated from the Fregene expression. The hitherto conflicting results are resolved where sufficient experimental and theoretical details are given in light of the present findings.

Random array grid collimators

X-ray collimators using grid patterns which are random offer several significant advantages over collimators using periodic grids. In particular, random array grid collimators (RAGC’s) eliminate the requirement that there be very closely spaced grids if a wide field of obscuration outside the central peak is desired. The RAGC should be less susceptible to systematic off-axis leaks, and the RAGC has a better high energy response than a periodic grid collimator. The random array technique can also be used to produce converging or diverging collimators. A general theory is presented which predicts the angular response of a RAGC. It is shown that pure random arrays have two problems: there are strong wings in the response function and the patterns are not self-supporting. Restrictions on the randomness of the pattern are suggested which eliminate these problems but at the price of putting an upper limit on the available throughput. However, even in the worst case, the upper limit for a two-dimensional collimator is as high as 23%. In other cases, throughputs the order of 40% are possible with two-dimensional collimators and of 50% with one-dimensional collimators. These techniques can provide 10 arc second two-dimensional collimators with a large collecting area. Suggestions are presented for easing the fabrication effort of the grids.

WA-B2 improved high-energy response of Ga1-xAlxAs-GaAs solar cells using fluorescent capping layers

WA-B2 improved high-energy response of Ga_1-xAl_xAs-GaAs solar cells using fluorescent capping layers

Hook opening in cucumber seedlings by narrow-band red and far-red light

Intermittent red (R, 660 nm, 3.9 Wm −2) and far-red (FR, 728 nm, 7.0 Wm −2) light treatments caused hook opening in etiolated cucumber ( Cucumis sativus L.) seedlings, by cell elongation at the concave side only, but had no significant effect on hypocotyl elongation. The relative positive effect of FR on the hook increased with age of the seedling. FR counteracted the hook opening effect of R only if given simultaneously with R in young seedlings, whereas FR by itself had no effect or a slightly negative one. Results are not readily explained in terms of high energy response (HER); alternative mechanisms are discussed.

Low Energy Effects of Light on Growth and Pigment Content in a Yellow-in-the-Dark Mutant of Chlamydomonas reinhardi

The y-2 mutant of Chlamydomonas reinhardi differs from the wild type in being unable to synthesize chlorophyll in the dark and in a requirement for catalytic amounts of light for organotrophic growth. Light-grown y-2 cells given acetate are capable of the equivalent of 9 to 10 divisions when placed in darkness. Cultures adapt gradually to dim white or monochromatic light and after 8 to 10 generations assume a steady state with respect to growth and pigment content.Two energetically distinct light reactions promote the growth of y-2 on acetate. A low energy requirement is satisfied at about 0.1 muw/cm(2) of white light which results in a growth rate of 0.5 log unit per day. A high energy response, which saturates at 2000 muw/cm(2) and a growth rate of 0.9 log unit per day, is probably attributable to net photosynthesis. An action spectrum for the low energy growth response contains a broad major peak in the blue between 462 and 502 nm and a minor peak in the far-red between 700 and 736 nm. All intermediate wavelengths have low but positive activity. The action spectrum was investigated with y-2 cultures that were grown for many generations under steady-state conditions in growth-limiting monochromatic light. Many wavelengths resulted in a selection pressure that strongly favored a strain of green-in-the dark cells that usually appeared after 5 to 8 generations of light-limited growth. Under the low light intensity of these experiments (0.15 +/- 0.05 muw/cm(2)) the green strain was much richer in chlorophyll than y-2 and divided more rapidly with the consequence that y-2 was generally replaced in the course of a few generations. Consideration of the results led to the conclusion that both chlorophyll and carotenoids act as photoreceptors in the low energy growth response of y-2.

Photocontrol of Mimosa pudica L. leaf movement

1. Mimosa pudica L. pinnae close in darkness when phytochrome is predominantly in the far-red-absorbing form (Pfr) and remain open when Pfr is low [6]. The leaflets remain open, however, in normal light periods irrespective of the form of phytochrome. Pinnae, after closing in darkness, regularly reopen in light. 2. An action spectrum for the opening response shows maxima for effectiveness near 710 and 480 nm. This action spectrum is similar to that for a high-energy response affecting morphogenesis in many plants. 3. Dropping of the petiole of M. pudica can be photostimulated by irradiation of the primary pulvinus after holding the plants in darkness [4]. 4. The photostimulation of the primary pulvinus is effective only at wavelengths less than 520 nm. Wave bands in the region of 400 to 470 nm are about equally effective. 5. These photoresponses of M. pudica are related to current discussion about the nature of the high-energy and phytochrome photomorphogenic reactions.