Fabrication of fuel pin assemblies, phase 3

Five full size and eight reduced length fuel pins were fabricated for irradiation testing to evaluate design concepts for a fast spectrum lithium cooled compact space power reactor. These assemblies consisted of uranium mononitride fuel pellets encased in a T-111 (Ta-8W-2Hf) clad with a tungsten barrier separating fuel and clad. Fabrication procedures were fully qualified by process development and assembly qualification tests. Detailed specifications and procedures were written for the fabrication and assembly of prototype fuel pins

Attention Deficit Disorder and Memory Capacity in Language-impaired and Inconspicuous Children

Ausgehend von der Hypothese einer geringeren Gedächtnisfähigkeit sprachauffälliger Kinder wurden 110 sprachauffällige und 123 sprachunauffällige Kinder im Grundschulalter (Altersdurchschnitt 10;0 Jahre) untersucht. Die Kinder absolvierten jeweils einzeln einen verbalen Gedächtnistest sowie einen Test zur Problemlösereflexivität. Ferner beurteilten die Lehrer ihre Schüler im Hinblick auf Aufmerksamkeitsstörungen und Aufmerksamkeitsverhalten. Im Ergebnis zeigen sich signifikante Unterschiede zwischen beiden Gruppen in bezug auf die Gedächtnisfähigkeit und die Anzahl der Fehler. Den sprachauffälligen Schülern gelingt es weniger gut, Wortlisten zu lernen und den Lerngewinn gegen eine Ablenkung aufrechtzuerhalten. Sie weisen eine signifikant geringere Behaltensstabilität auf. Die Gedächtnisfähigkeit ist ferner weitgehend unabhängig von der Problemlösereflexivität und dem im Lehrerurteil festgehaltenen Aufmerksamkeitsverhalten. Es wird geschlossen, daß sprachauffällige Kinder sowohl Schwierigkeiten bei der Informationsaufnahme als auch Einschränkungen der Gedächtniskapazität haben. Die unterschiedliche Gedächtnisfähigkeit von sprachauffälligen und sprachunauffälligen Kindern ist am ehesten durch die (meta)kognitiven Kompetenzen der Kinder erklärbar.(DIPF/Orig.)In order to investigate the hypothesis that language-impaired children also show deficits in memory, 110 language-impaired and 123 children showing no such impairments (average age 10;0 yrs.) were tested for verbal memory and selecting attention through a matching familiar figures test. As an additional measure, teachers assessed the children, using DSM criteria, for both general attentivenesse and attention deficit disorder. The results revealed significant differences between both groups concerning their ability to memorise word lists and difficulties resisting distractions. They also show a significantly diminished stability regarding the retention of memories. Furthermore, the ability to memorise has proved to be greatly independent of both selective attention and the rated attentiveness in class. It is therefore concluded that language-impaired children have difficulties in acquiring information as well as a limited capacity to memorise. These differences in ability to memorise between language-impaired children and children with no impairments are most likely attributable to the meta-cognitive competence of the child.(DIPF/Orig.

Phosphordünger aus Klärschlamm: Evaluierung von Pyrolysekohle und Alkalipyrolyse

Phosphorus (P) in sewage sludge holds the main proportion of P currently lost in waste streams, and options to recycle it for agriculture are needed. Pyrolysis is a promising local alternative to centralized sewage sludge incineration. Pathogens and organic pollutants are destroyed and a carbon-rich substrate known as biochar is formed. We evaluated pyrolysis of sewage sludge as well as sintering of pyrolysis char with alkali salts. The products were applied in a pot experiment with calcareous and acidic soils to determine P uptake by ryegrass (Lolium multiflorum) and changes in soil pH, available P and cation exchange capacity. Two products were also tested in a field experiment with maize (Zea mays) on a neutral soil. Cadmium and mercury were partly lost during pyrolysis. The pot experiment revealed interactions between soil pH and P use efficiency of the various products, including reference fertilizers permitted in organic farming. Pyrolysis changed plant P availability only slightly compared to the parent sewage sludge, but sintering with alkali salts increased plant P availability to levels comparable to triple superphosphate. Potential implications for organic agriculture are discussed

Stratigraphic distributions of genera and species of Neogene to Recent Caribbean reef corals

To document evolutionary patterns in late Cenozoic Caribbean reef corals, we compiled composite stratigraphic ranges of 49 genera and 175 species using Neogene occurrences in the Cibao Valley sequence of the northern Dominican Republic and faunal lists for 24 Miocene to Recent sites across the Caribbean region. This new compilation benefits in particular from increased sampling at late Miocene to early Pleistocene sites and from increased resolution and greater taxonomic consistency provided by the use of morphometric procedures in species recognition. Preliminary examination and quantitative analysis of origination and extinction patterns suggest that a major episode of turnover took place between 4 and 1 Ma during Plio-Pleistocene time. During the episode, extinctions were approximately simultaneous in species of all reef-building families, except the Mussidae. Most strongly affected were the Pocilloporidae (Stylophora and Pocillopora), Agariciidae (Pavona and Gardineroseris), and free-living members of the Faviidae and Meandrinidae. At the genus level, mono- and paucispecific as well as more speciose genera became regionally extinct. Many of the extinct genera live today in the Indo-Pacific region, and some are important components of modern eastern Pacific reefs. Global extinctions were concentrated in free-living genera. During the turnover episode, no new genera or higher taxa arose. Instead, new species originated within the surviving Caribbean genera at approximately the same time as the extinctions, including many dominant modern Caribbean reef-building corals (e.g., Acropora palmata and the Montastraea annularis complex). Excluding this episode, the taxonomic composition of the Caribbean reef-coral fauna remained relatively unchanged during the Neogene. Minor exceptions include: 1) high originations in the Agariciidae and free-living corals during late Miocene time; and 2) regional or global extinctions of several important Oligocene Caribbean reef builders during early to middle Miocene tim

Statistical Mechanics Analysis of LDPC Coding in MIMO Gaussian Channels

Using analytical methods of statistical mechanics, we analyse the typical behaviour of a multiple-input multiple-output (MIMO) Gaussian channel with binary inputs under LDPC network coding and joint decoding. The saddle point equations for the replica symmetric solution are found in particular realizations of this channel, including a small and large number of transmitters and receivers. In particular, we examine the cases of a single transmitter, a single receiver and the symmetric and asymmetric interference channels. Both dynamical and thermodynamical transitions from the ferromagnetic solution of perfect decoding to a non-ferromagnetic solution are identified for the cases considered, marking the practical and theoretical limits of the system under the current coding scheme. Numerical results are provided, showing the typical level of improvement/deterioration achieved with respect to the single transmitter/receiver result, for the various cases.Comment: 25 pages, 7 figure

Out-of-vacuum electron beam welding Technical program summary, Mar. 1966 - Apr. 1967

Metallographic studies, weld test data, and performance of out-of-vacuum electron beam welde