Transfer function determination of the primary loop of a conceptual nuclear Brayton space powerplant

Transfer functions for primary loop of conceptual nuclear Brayton space power plan

Investigations on the system boron-carbon silicon

The above elements form with each other binary compounds which are very interesting from the point of view of their structure and their chemistry and which are important for technology. The present investigation is concerned with the three-component system and the behavior of the binary compounds occurring in it. Investigations employing various techniques, such as X-ray, chemical analysis, microscopy and fusion experiments showed that no ternary phase exists within the boundary of the ternary system. There is no compound with a higher abrasion capacity than boron carbide. The probable phase field divisions at two isothermic intersections and the fusion isotherms are indicated

The Effects of Word Recognition and Comprehension Skills and Strategies Implemented with Explicit, Systematic, Balanced-Literacy Instruction

The purpose of this case study was to answer the question, “Does a tier three intervention plan using a balanced-literacy format and consistent implementation of phonological awareness, vocabulary, fluency, and comprehension activities improve literacy for English language learners (ELLs) with specific learning disability (SLD)?” The participant was a male, ELL-SLD fourth grade student who attended an urban parochial school. The duration of the intervention was one ninety minute session per week over a ten week period. The results showed moderate improvement in his ability to decode words and comprehend below level texts. The greatest gain was in his word attack and word comprehension, indicating the student\u27s ability to apply phonic and structural analysis skills, use analogies, and read vocabulary to comprehend words

Using subgoals as a Mechanism for altering perceptions of situational control, mastery, and task-related stress

The empirical literature suggests that subgoals may have an effect upon feelings of task-related stress which is more intense than the effect of distal goals on this variable. First, subgoals my alter an individual\u27s perception of the task in such a way that the task related goal is not seen as being so overwhelming. Second, there is an increased feedback mechanism associated with subgoals that may alter perceptions of situational mastery and control and in turn perceptions of situational stress. The effect of receiving more frequent feedback is dependent upon the valence of the feedback. Specifically, positive feedback leads to an increase in perceptions of situational control and mastery and therefore reduces feelings of situational stress. Negative feedback has the opposite effect. The relationship between subgoals and perceptions of mastery had been investigated; however, the suggested connections between subgoals, control, and stress had not. In order to investigate these possible effects, subjects were divided into six goal type by feedback type conditions. Each group was asked to participate in a timed arithmetic test for which they had been given four, five minute goals, one, 20 minute goal, or no goals. The goals were manipulated so that some groups received consistent negative feedback, some groups received consistent positive feedback, and some groups received no feedback. After the test, subjects were asked to fill out several self-report measures assessing perceptions of situational control, mastery, and feelings of task related stress. It was hypothesized that those subjects in the positive feedback condition would have scores on the mastery and control measures that were significantly higher, and scores on the stress measure that were significantly lower than the no-feedback condition subjects. The same differences were hypothesized between the scores on these measures for the no-feedback group and the negative feedback group. Further, it was hypothesized that those subjects in the positive feedback/subgoal groups would have scores on the mastery and control measures that were significantly higher, and scores on the stress measure that were significantly lower than the subjects in all other goal type/feedback type conditions. The results of this research confirm the hypotheses pertaining to the main effect of feedback on dependent variables. However, no significant differences were discovered due to the variable\u27s interaction

Experimental investigation of insolation-driven dust ejection from Mars’ CO2 ice caps

Mars’ polar caps are – depending on hemisphere and season - partially or totally covered with CO2 ice. Icy surfaces such as the polar caps of Mars behave differently from surfaces covered with rock and soil when they are irradiated by solar light. The latter absorb and reflect incoming solar radiation within a thin layer beneath the surface. In contrast, ices are partially transparent in the visible spectral range and opaque in the infrared. Due to this fact, the solar radiation can penetrate to a certain depth and raise the temperature of the ice or dust below the surface. This may play an important role in the energy balance of icy surfaces in the solar system, as already noted in previous investigations. We investigated the temperature profiles inside CO2 ice samples including a dust layer under Martian conditions. We have been able to trigger dust eruptions, but also demonstrated that these require a very narrow range of temperature and ambient pressure. We discuss possible implications for the understanding of phenomena such as arachneiform patterns or fan shaped deposits as observed in Mars’ southern polar region

The direct synthesis of crosslinked polymeric azomethines

Char yields of synthesized crosslinked polymeric azomethine

A copper-catalyzed arylation of tryptamines for the direct synthesis of aryl pyrroloindolines

An operationally simple, copper-catalyzed arylation of N-tosyltryptamines provides direct access to C3-aryl pyrroloindolines. A range of electron-donating and electron-withdrawing substituents is tolerated on both the indole backbone and the aryl electrophile. These reactions occur under ambient temperatures and with equimolar quantities of the coupling partners

A Mild and General Larock Indolization Protocol for the Preparation of Unnatural Tryptophans

A mild and general protocol for the Pd(0)-catalyzed heteroannulation of o-bromoanilines and alkynes is described. Application of a Pd(0)/P(^tBu)_3 catalyst system enables the efficient coupling of o-bromoanilines at 60 °C, mitigating deleterious side reactions and enabling access to a broad range of useful unnatural tryptophans. The utility of this new protocol is demonstrated in the highly convergent total synthesis of the bisindole natural product (−)-aspergilazine A

On a zero speed sensitive cellular automaton

Using an unusual, yet natural invariant measure we show that there exists a sensitive cellular automaton whose perturbations propagate at asymptotically null speed for almost all configurations. More specifically, we prove that Lyapunov Exponents measuring pointwise or average linear speeds of the faster perturbations are equal to zero. We show that this implies the nullity of the measurable entropy. The measure m we consider gives the m-expansiveness property to the automaton. It is constructed with respect to a factor dynamical system based on simple "counter dynamics". As a counterpart, we prove that in the case of positively expansive automata, the perturbations move at positive linear speed over all the configurations