90,186 research outputs found
Carbon dioxide concentration indicator
Device will provide visual indication of concentration of carbon dioxide. It consists of small amounts of absorbent material contained in semipermeable membrane and device to detect color changes. Material will absorb quantity of carbon dioxide proportional to carbon dioxide concentration in atmosphere. Amount of absorption is indicated by color change
Home work in the elementary school: a study in two communities
Thesis (Ed.M.)--Boston Universit
Theoretical and Experimental Investigations of Antennas and Waves in Plasma Semiannual Status Report, Mar. 1 - Aug. 31, 1966
Experimental studies of antennas and acoustic waves in plasm
From adolescent to adult gambling: an analysis of longitudinal gambling patterns in South Australia [forthcoming]
Although there are many cross-sectional studies of adolescent gambling, very few longitudinal investigations have been undertaken. As a result, little is known about the individual stability of gambling behaviour and the extent to which behaviour measured during adolescence is related to adult behaviour. In this paper, we report the results of a 4-wave longitudinal investigation of gambling behaviour in a probability sample of 256 young people (50% male, 50% female) who were interviewed in 2005 at the age of 16-18 years and then followed through to the age of 20-21 years. The results indicated that young people showed little stability in their gambling. Relatively few reported gambling on the same individual activities consistently over time. Gambling participation rates increased rapidly as young people made the transition from adolescence to adulthood and then were generally more stable. Gambling at 15-16 years was generally not associated with gambling at age 20-21 years. These results highlight the importance of individual-level analyses when examining gambling patterns over time
Using Negotiation to Reduce Redundant Autonomous Mobile Program Movements
Distributed load managers exhibit thrashing where tasks are repeatedly moved between locations due to incomplete global load information. This paper shows that systems of Autonomous Mobile Programs (AMPs) exhibit the same behaviour, identifying two types of redundant movement and terming them greedy effects. AMPs are unusual in that, in place of some external load management system, each AMP periodically recalculates network and program parameters and may independently move to a better execution environment. Load management emerges from the behaviour of collections of AMPs. The paper explores the extent of greedy effects by simulation, and then proposes negotiating AMPs (NAMPs) to ameliorate the problem. We present the design of AMPs with a competitive negotiation scheme (cNAMPs), and compare their performance with AMPs by simulation
Transient Optical Characterisation of Donor-Acceptor Block Copolymers for Use in Solar Cells
This thesis presents a study of photo-active, semiconducting block copolymers for use in molecular solar cells. Current state-of-the-art organic devices utilise blends of two (or more) materials that are co-deposited from a common solution; the resulting structures formed are determined by material properties and deposition conditions, but often result in configurations that are detrimental to device performance. An answer to this problem comes in the form of the block copolymer; using these materials, devices can be formed from a single material active layer. In addition, the counterbalance of forces within films of block copolymer can lead to nano-scale self-assembly that allows for a strong degree of control over layer equilibrium morphology. Such control will be an important step forward in the evolution of molecular solar cells. The main body of this work is concerned with the study of the photo-physics of photo-conductive block copolymers, especially the generation of free charge. First, an investigation is made into the inherent structure-function relationship in block copolymers. A varying chain length is seen to drastically affect the photoluminescence quenching and yield of long-lived charges. Photovoltaic devices made using these materials show a peak efficiency of 0.11% and correlate with the spectroscopic results, subject to a trade off between charge generation and transport/collection. In a second investigation, the effects of post-fabrication annealing on block copolymer films are considered; studies on annealed samples lead to the conclusion that domain crystallinity is a significant factor in determining the yields of long-lived charge carriers. It is found that these yields are comparable with those of a standard blend (that achieve 75% photon to electron conversion efficiency). Annealing leads to increases in photovoltaic device performance over unannealed samples, although additional control over active layer morphology is necessary for these materials to attain their potential. Following this, a comparative study is made between a block copolymer and a similarly composed blend formed from well studied polyfluorene copolymers. Further advantages of block copolymers are highlighted, including the stability of morphologies generated under different deposition conditions. Finally, a novel tool set is introduced using a block copolymer sample to emphasise the experiments potential with regard to studying interfacial photophysical effects
NMSSM+
It is well known that the scale invariant NMSSM has lower fine-tuning than
the MSSM, but suffers from the domain wall problem. We propose a new improved
scale invariant version of the NMSSM, called the NMSSM+, which introduces extra
matter in order to reduce even more the fine-tuning of the NMSSM. The NMSSM+
also provides a resolution of the domain wall problem of the NMSSM due to a
discrete R-symmetry, which also stabilises the proton. The extra matter
descends from an E6 gauge group and fills out three complete 27-dimensional
representations at the TeV scale, as in the E6SSM. However the U(1)_N gauge
group of the E6SSM is broken at a high energy scale leading to reduced
fine-tuning. The extra matter of the NMSSM+ includes charge 1/3 colour triplet
D-fermions which may be naturally heavier than the weak scale because they
receive their mass from singlet field vacuum expectation values other than the
one responsible for the weak scale effective {\mu} parameter.Comment: 25 pages, minor changes, references adde
- …
