Video sync processor Patent

Video sync processor with phase locked syste

The correspondence between small-scale coronal structures and the evolving solar magnetic field

Solar coronal bright points, first identified in soft X-rays as X-ray Bright Points (XBPs), are compact, short lived and associated with small bipolar magnetic flux. Contradictory studies have suggested that XBPs are either a primary signature of the emerging flux spectrum of the quiet Sun, or that they are representative of the disappearance of pre-existing flux. Results are presented using coordinated data obtained during recent X-ray sounding rocket flights on 15 August and 11 December 1987 to determine the correspondence of XBPs with time-series, ground based observations of evolving bipolar magnetic structures, He-I dark points, and the network. The results are consistent with the view that coronal bright points are more likely to be associated with the annihilation of pre-existing flux than with emerging flux

Coronal loops and active region structure

We intercompared synoptic Hα, Ca K, magnetograph and Skylab soft X-ray and EUV data for the purpose of identifying the basic coronal magnetic structure of loops in a ‘typical’ active region and studying its evolution. We focussed on a complex of activity in July 1973, especially McMath 12417. Our principal results are: (1) Most of the brightest loops connected the bright f plage to either the sunspot penumbra or to p satellite spots; no non-flaring X-ray loops end in umbrae; (2) short, bright loops had one or both ends in regions of emergent flux, strong fields or high field gradients; (3) stable, strongly sheared loop arcades formed over filaments; (4) EFRs were always associated with compact X-ray arcades; and (5) loops connecting to other active regions had their bases in outlying plage of weak field strength in McM 417 where Hα fibrils marked the direction of the loops. We conclude that a typical loop brightens in response to magnetic field activity at its feet, which heats the plasma. This suggests that the loop acts as a trap for gas convected from its base

Coronal loops and active region structure

We intercompared synoptic Hα, Ca K, magnetograph and Skylab soft X-ray and EUV data for the purpose of identifying the basic coronal magnetic structure of loops in a ‘typical’ active region and studying its evolution. We focussed on a complex of activity in July 1973, especially McMath 12417. Our principal results are: (1) Most of the brightest loops connected the bright f plage to either the sunspot penumbra or to p satellite spots; no non-flaring X-ray loops end in umbrae; (2) short, bright loops had one or both ends in regions of emergent flux, strong fields or high field gradients; (3) stable, strongly sheared loop arcades formed over filaments; (4) EFRs were always associated with compact X-ray arcades; and (5) loops connecting to other active regions had their bases in outlying plage of weak field strength in McM 417 where Hα fibrils marked the direction of the loops. We conclude that a typical loop brightens in response to magnetic field activity at its feet, which heats the plasma. This suggests that the loop acts as a trap for gas convected from its base

Resistance, remission, and qualitative differences in HIV chemotherapy.

To understand the role of qualitative differences in multidrug chemotherapy for human immunodeficiency virus (HIV) infection in virus remission and drug resistance, we designed a mathematical system that models HIV multidrug chemotherapy including uninfected CD4+ T cells, infected CD4+ T cells, and virus populations. The model, which includes the latent and progressive stages of the disease and introduces chemotherapy, is a system of differential equations describing the interaction of two distinct classes of HIV (drug-sensitive [wild type] and drug-resistant [mutant]) with lymphocytes in the peripheral blood; the external lymphoid system contributes to the viral load. The simulations indicate that to preclude resistance, antiviral drugs must be strong enough and act fast enough to drive the viral population below a threshold level. The threshold depends upon the capacity of the virus to mutate to strains resistant to the drugs. Above the threshold, mutant strains rapidly replace wild-type strains. Below the threshold, resistant strains do not become established, and remission occurs. An important distinction between resistance and remission is the reduction of viral production in the external lymphoid system. Also the virus population rapidly rebounds when treatment is stopped even after extended periods of remission

Biomass and nutrient flux measurements on Holothuria atra populations on windward reef flats at Enewetak, Marshall Islands

Although it is reasonably well established that corals symbiotic with endozoic algae (the zooxanthellae) are capable of multitrophic (1) existence, we are still a long way away from evaluating the relative importance of the various trophic pathways (2). There is no question that zooplankton provide a source of materials and energy to corals, yet there is doubt whether zooplankton are plentiful enough to supply all the needs for these essentials (3). There appear to be alternate sources of supply. Sufficient energy is likely to be available to the symbiotic association by virtue of the photosynthetic capacity of the zooxanthellae (4); thus, energy wise, the effects of the limited quantities of available zooplankton may be obviated. But what of the balance of nutrient elements such as N and P?https://scholarworks.wm.edu/vimsbooks/1139/thumbnail.jp

Dynamics of a structured slug population model in the absence of seasonal variation

We develop a novel, nonlinear structured population model for the slug Deroceras reticulatum, a highly significant agricultural pest of great economic impact, in both organic and non-organic settings. In the absence of seasonal variations, we numerically explore the effect of life history traits that are dependent on an individual's size and measures of population biomass. We conduct a systematic exploration of parameter space and highlight the main mechanisms and implications of model design. A major conclusion of this work is that strong size dependent predation significantly adjusts the competitive balance, leading to non-monotonic steady state solutions and slowly decaying transients consisting of distinct generational cycles. Furthermore, we demonstrate how a simple ratio of adult to juvenile biomass can act as a useful diagnostic to distinguish between predated and non-predated environments, and may be useful in agricultural settings