Analytical and experimental studies of graphite-epoxy and boron-epoxy angle ply laminates in shear

The results of a comparison study between a test program on the inelastic response under inplane shear over a wide range of graphite-epoxy and boron-epoxy angle-ply laminates are reported. This investigation was aimed at evaluating the applicability and adequacy of these analyses to predict satisfactorily the responses of angle-ply laminates. It was observed that these analytical tools are inadequate for this purpose as they fail to predict with sufficient confidence the shape of response and in particular the strength values associated with a given laminate configuration. Consequently, they do not provide the sought-after information about failure mechanisms which trigger failure of a particular designed laminate

Surface sticking probabilities for sputtered atoms of Nb-93 and Rh-103

The capture coefficient probabilities for sputtered atoms of Nb-93 and Rh-103 incident on Al2O3 surfaces were measured using the backscattering of MeV heavy ions. In the circumstance where the collecting surface is thickly covered, the sticking probabilities integrated over the energy distribution of sputtered atoms are 0.97 plus or minus 0.01 for Nb-93 and 0.95 plus or minus 0.01 for Rh-103 respectively. In the limit of negligible areal coverage of the collector, the accuracy is less; in this case the sticking probabilities are 0.97 + 0.03 or -0.08 and 0.95 + 0.05 or -0.08

Iodine monoxide in the Antarctic snowpack

Recent ground-based and space borne observations suggest the presence of significant amounts of iodine monoxide in the boundary layer of Antarctica, which are expected to have an impact on the ozone budget and might contribute to the formation of new airborne particles. So far, the source of these iodine radicals has been unknown. This paper presents long-term measurements of iodine monoxide at the German Antarctic research station Neumayer, which indicate that high IO concentrations in the order of 50 ppb are present in the snow interstitial air. The measurements have been performed using multi-axis differential optical absorption spectroscopy (MAX-DOAS). Using a coupled atmosphere snowpack radiative transfer model, the comparison of the signals observed from scattered skylight and from light reflected by the snowpack yields several ppb of iodine monoxide in the upper layers of the sunlit snowpack throughout the year. Snow pit samples from Neumayer Station contain up to 700 ng/l of total iodine, representing a sufficient reservoir for these extraordinarily high IO concentrations

Símbolos, imágenes, rituales: el lenguaje simbólico del poder en la Europa del Antiguo Régimen

Una de las características más sobresalientes del Antiguo Régimen fue la gran trascendencia de los símbolos y rituales para la afirmación y la reproducción de las estructuras de poder, jerarquías y valores sociales. El siguiente artículo presentará una visión general de la investigación reciente sobre el tema de la comunicación simbólica. Concentrándose primero en los conceptos teóricos, se abordará después tres campos historiográficos ejemplares, a saber, la historia de la Corte, de la ciudad y de las relaciones internacionales, áreas en las que se ha empleado el enfoque de la comunicación simbólica con mucho éxito en los últimos años. En todos estos campos los actos simbólicos no eran un mero reflejo de las estructuras políticas y sociales, sino que constituían un código comunicativo mediante el cual los actores contemporáneos negociaban sus pretensiones de poder.-------One of the most striking characteristics of the Ancient Régime was the great importance of symbols and rituals for the affirmation and reproduction of power structures, hierarchies and social values. Concentrating on the theoretical concepts at stake, this article presents a general outline of recent investigation on symbolic communication through three different historiographical fields: the history of the court, the city, and international relations. I argue that within all of these historiographical fields, the approach of symbolic communication has recently been applied with good results. Foremost among the achievements was the postulization that symbolic acts were not only a mere reflection of political and social structure, but can be considered as a communicative code which allowed the contemporary actors to negotiate their pretensions of power

Keep the Flyin\u27 Eight Balls Rollin\u27: Military Leadership in the 3360th Quartermaster Truck Company

The 3360th Quartermaster Truck Company, originally Company D of the 2639th Quartermaster Truck Battalion, was created in 1942 by drawing troops and officers from anti-aircraft units stationed in North Africa, to meet an emergency need for highway transportation to support the Allied advance East across North Africa. The reassigned troops and officers received no training in their new duties, but were instead immediately dispatched to the front with vital supplies. The company continued operations through North Africa, and on into Sicily and Italy. While in Italy, Elmer H. Puchta, previously assigned to the company as a platoon commander, took command. Puchta instituted a number of changes designed to make maintenance and operations in the company more efficient. He was blessed with a great deal of independence in his command, which allowed him to make such changes with little to no interference from superiors. These changes helped the company operate smoothly in support of the invasion of Southern France, known first as Operation Anvil and later as Operation Dragoon. In contrast to those units broken up to serve as part of the Red Ball Express in Northern France, the 3360th Quartermaster Truck Company remained intact throughout the advance across France. This continuity fostered unit cohesion and enhanced morale. Post war analysis of Quartermaster Truck units indicates most did not perform well, but the 3360th was an exception, collecting accolades and racking up impressive records for maintenance and operations. The success of the 3360th can be linked to the general quality of the troops assigned, its longevity and continuity as a unit, and Puchta\u27 s leadership. The anti-aircraft troops were generally of a higher quality than most assigned to Quartermaster duties, by virtue of the Quartermaster Corps\u27 low place in the Army\u27s assignment process. The long service with minimal personnel disruption allowed the 3360th to develop a unit soul that fostered achievement, and allowed individual troops to become proficient at their individual duties. Puchta\u27 s leadership took advantage of these positive factors, and overcame the lack of formal training in Quartermaster duties. His willingness to innovate, deep concern for his troops, and measured discipline were crucial to the unit\u27s success. The operations and leadership of support units is not as widely studies as those of combat units. Such studies are of great value to both the historian and the professional warrior in understanding military leadership

Experimental studies of graphite-epoxy and boron-epoxy angle ply laminates in shear

The nonlinear/inelastic response under inplane shear of a large variety of graphite-epoxy and boron-epoxy angle-ply laminates was tested. Their strength allowables were obtained and the mechanisms which govern their mode of failure were determined. Two types of specimens for the program were chosen, tested, and evaluated: shear panels stabilized by an aluminum honeycomb core and shear tubes. A modified biaxially compression/tension loaded picture frame was designed and utilized in the test program with the shear panels. The results obtained with this test technique categorically prefer the shear panels, rather than the tubes, for adequate and satisfactory experimental definition of the objectives. Test results indicate the existence of a so-called core-effect which ought to be considered when reducing experimental data for weak in shear laminates

Analytical and experimental studies of graphite-epoxy and boron-epoxy angle ply laminates in compression

The applicability and adequacy of several computer techniques in predicting satisfactorily the nonlinear/inelastic response of angle ply laminates were evaluated. The analytical predictions were correlated with the results of a test program on the inelastic response under axial compression of a large variety of graphite-epoxy and boron-epoxy angle ply laminates. These comparison studies indicate that neither of the abovementioned analyses can satisfactorily predict either the mode of response or the ultimate stress value corresponding to a particular angle ply laminate configuration. Consequently, also the simple failure mechanisms assumed in the analytical models were not verified

Amylase release from streptolysin O-permeabilized pancreatic acinar cells. Effects of Ca2+, guanosine 5'-[gamma-thio]triphosphate, cyclic AMP, tetanus toxin and botulinum A toxin

The molecular requirements for amylase release and the intracellular effects of botulinum A toxin and tetanus toxin on amylase release were investigated using rat pancreatic acinar cells permeabilized with streptolysin O. Micromolar concentrations of free Ca2+ evoked amylase release from these cells. Maximal release was observed in the presence of 30 microM free Ca2+. Ca(2+)-stimulated, but not basal, amylase release was enhanced by guanosine 5'-[gamma-thio]triphosphate (GTP[S]) (3-4 fold) or cyclic AMP (1.5-2 fold). Neither the two-chain forms of botulinum A toxin and tetanus toxin, under reducing conditions, nor the light chains of tetanus toxin, inhibited amylase release triggered by Ca2+, or combinations of Ca2+ + GTP[S] or Ca2+ + cAMP. The lack of inhibition was not due to inactivation of botulinum A toxin or tetanus toxin by pancreatic acinar cell proteolytic enzymes, as toxins previously incubated with permeabilized pancreatic acinar cells inhibited Ca(2+)-stimulated [3H]noradrenaline release from streptolysin O-permeabilized adrenal chromaffin cells. These data imply that clostridial neurotoxins inhibit a Ca(2+)-dependent mechanism which promotes exocytosis in neural and endocrine cells, but not in exocrine cells