Thermal stability analysis of the fine structure of solar prominences

The linear thermal stability of a 2D periodic structure (alternatively hot and cold) in a uniform magnetic field is analyzed. The energy equation includes wave heating (assumed proportional to density), radiative cooling and both conduction parallel and orthogonal to magnetic lines. The equilibrium is perturbed at constant gas pressure. With parallel conduction only, it is found to be unstable when the length scale 1// is greater than 45 Mn. In that case, orthogonal conduction becomes important and stabilizes the structure when the length scale is smaller than 5 km. On the other hand, when the length scale is greater than 5 km, the thermal equilibrium is unstable, and the corresponding time scale is about 10,000 s: this result may be compared to observations showing that the lifetime of the fine structure of solar prominences is about one hour; consequently, our computations suggest that the size of the unresolved threads could be of the order of 10 km only

Investigation of dynamic stresses in detona- tion technical note no. 7

Axial and hoop stress calculation in blast loaded thin walled cylindrical pressure vessel

Applying quantitative semantics to higher-order quantum computing

Finding a denotational semantics for higher order quantum computation is a long-standing problem in the semantics of quantum programming languages. Most past approaches to this problem fell short in one way or another, either limiting the language to an unusably small finitary fragment, or giving up important features of quantum physics such as entanglement. In this paper, we propose a denotational semantics for a quantum lambda calculus with recursion and an infinite data type, using constructions from quantitative semantics of linear logic

Constraints on filament models deduced from dynamical analysis

The conclusions deduced from simultaneous observations with the Ultra-Violet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission satellite, and the Multichannel Subtractive Double Pass (MSPD) spectrographs at Meudon and Pic du Midi observatories are presented. The observations were obtained in 1980 and 1984. All instruments have almost the same field of view and provide intensity and velocity maps at two temperatures. The resolution is approx. 0.5 to 1.5" for H alpha line and 3" for C IV. The high resolution and simultaneity of the two types of observations allows a more accurate description of the flows in prominences as functions of temperature and position. The results put some contraints on the models and show that dynamical aspects must be taken into account

VHF discharges in storm cells producing microbursts

An experiment was carried out in which 3-D mapping of VHF sources was compared to a 3-D description of the reflectivity and dynamics of associated cloud cells observed by a radar network. Data from 61 microbursts were analyzed and it was found that, in 93 pct. of the cases, electrical activity precedes outflow development. The results confirm that the peak in intracloud activity precedes the maximum value of the outflow

Get Rid of Unanimity Rule: The Superiority of Majority Rules with Veto Power

We study unanimous decision making under incomplete information. We argue that all unanimous decision rules are not equivalent. We show that majority rules with veto power are (i) Pareto superior to commonly used unanimous rules, and (ii) ex-ante efficient in a broad class of situations

A weakly-intrusive multi-scale substitution method in explicit dynamics

For virtual testing of composite structures, the use of fine modeling seems preferable to simulate complex mechanisms like delamination. However, the associated computational costs are prohibitively high for large structures. Multi-scale coupling techniques aim at reducing such computational costs, limiting the fine model only where necessary. The dynamic adaptivity of the models represents a crucial feature to follow evolutive phenomena. Domain decomposition methods would have to be combined with re-meshing strategies, that are considered intrusive implementations within commercial software. Global-local approaches are considered less intrusive, because they allow one to use a global coarse model on the overall structure and a fine local patch eventually adapted to cover the interest zone. In our work, we developed a global-local coupling method for explicit dynamics, presented in [1] and [2] and implemented in Abaqus/Explicit via the co-simulation technique for the simulation of delamination under high velocity impact

Clinical significance identification in the of aero-allergen western Cape

Positive identification and documentation of the 'seasonal variation of aero-allergens and the immune responses to them has important implications for the timing of allergen avoidance measures and the selection of patients suitable for immunotherapy. The relative abundance of aero-allergens in the Cape Peninsula dUring 1984 - 1987 was measured by continuous volumetric air sampling, using a Burkard spore trap. Mould spore counts of > 3000 spores/m) were found throughout the year and were only exceeded by pollen grains in the months of September and October (range 4 800 - 7400 spores/m). Gramineae and Compositae spores were found perennially in significant numbers. Pollen from allergenic trees peaked at fixed times each year: oak in August; plane in September and pine between August and October. Grasses found on the Peninsula include sweet vernal, Bermuda grass, rye grass, commori reed, Johnson grass, brome grass, canary grass, annual meadow and kikuyu. In vivo skin tests in 209 children with known allergic disease were positive to Dermatophygoides pteronyssimus (73%), South African grasses (38%), tree pollens (22,4%), flower and weed pollens (19,6%), cat (27%), dog (12%) and feathers (18,6%). One-third of the 1 372 children screened at Red Cross War Memorial Children's Hospital Allergy Service had positive specific IgE responses to environmental allergens. Investigation of 62 children possibly allergic to grass using the radlo-allergosorbent test revealed positive results in 25 (41%). Of these, 92% were positive to Timothy grass, a grass not occurring in the Cape Peninsula. Knowledge of cross-reactivity profiles for local allergens minimises the number of tests required in allergy diagnosis

Changes in the electrophoretic pattern of sera of dogs suffering from various diseases

The sera of dogs suffering from three diseases commonly encountered in South Africa, viz. babesiosis, rickettsiosis and distemper, have been examined electrophoretically and compared with normal sera. Diagrams of the electrophoretic patterns are given with a description of changes found in them. These changes are discussed in the light of the present knowledge of the diseases as they affect the body organs. The potential value of electrophoresis in the differential diagnosis of these diseases is discussed, and it is concluded that the available information indicates a degree of specificity which could prove useful for this purpose.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format