Light Induced AC Loss in Amorphous Silicon

Light-induced AC losses have been observed in sputtered a-Si, a-Si:H and a-Ge. The aim of this work was to investigate the effect of light on the ac loss in sputtered a-Si and glow discharge a-Si:H and compare the results with previous research. The glow discharge a-Si:H showed an optical response which was intensity dependent. At intensity greater than ~1muWcm-2 the response was rapid and reached a saturation value within minutes. At lower illuminating intensities an integrating response was observed in which saturation values may not be reached for many hours. The intensity dependence of the optically induced loss is similar to that observed in sputtered a-Si, although the illuminating intensities used to create a similar magnitude of response are around 2 orders of magnitude loss in sputtered material. A power law relation is found in which Deltaepsilon alpha IA where A = 0.2 in glow discharge samples and A - 0.25 in sputtered a-Si. The induced loss in sputtered a-Si has been attributed to optically excited carriers becoming trapped in defect states within the band gap where they respond to the ac measuring field. Evidence is found from the frequency and temperature dependences of the dark and optically induced losses to show that band-tail states are responsible for trapping carriers and hence for the induced ac loss, in glow discharge a-Si:H. The mechanism postulated to account for the light induced ac loss involves the excitation of carriers by the applied light. Carriers thermalise rapidly through the extended states and subsequently become trapped in the band-tails. They can now recombine by tunnelling through the band-tails until they recombine with an excess hole via defect states. The dark decay towards equilibrium is accounted for by considering trapped carriers recombining, by tunnelling, leading to a greater spacing between the remaining carriers. This then leads to a reduced response which decays slowly with time. The temperature dependence of these decays was also investigated and it was found that the decays were faster as the temperature was increased from 4.2K to 60K. A model involving the physical principle described above was used to obtain parameters to quantify the rate of decay

The Energy Transfer Process in Planetary Flybys

We illustrate the energy transfer during planetary flybys as a function of time using a number of flight mission examples. The energy transfer process is rather more complicated than a monotonic increase (or decrease) of energy with time. It exhibits temporary maxima and minima with time which then partially moderate before the asymptotic condition is obtained. The energy transfer to angular momentum is exhibited by an approximate Jacobi constant for the system. We demonstrate this with flybys that have shown unexplained behaviors: i) the possible onset of the "Pioneer anomaly" with the gravity assist of Pioneer 11 by Saturn to hyperbolic orbit (as well as the Pioneer 10 hyperbolic gravity assist by Jupiter) and ii) the Earth flyby anomalies of small increases in energy {\it in the geocentric system} (Galileo-I, NEAR, and Rosetta, in additioon discussing the Cassini and Messenger flybys). Perhaps some small, as yet unrecognized effect in the energy-transfer process can shed light on these anomalies.Comment: 29 pages, 43 images combined into 13 figures. Additions to answer comments of refere

One lithium level >1.0 mmol/L causes an acute decline in eGFR: findings from a retrospective analysis of a monitoring database

Objectives Lithium is a mainstay of bipolar disorder treatment, however, there are still differences in opinion on the effects of lithium use on renal function. The aim of this analysis was to determine if there is an association between short-term exposure to various elevated lithium levels and estimated-glomerular filtration rate (eGFR) at ≤3 months, 6 months (±3 months) and 1 year (±3 months) follow-up. Setting Norfolk-wide (UK) lithium register and database. Participants 699 patients from the Norfolk database. Primary outcome measures eGFR change from baseline at ≤3 months, 6 months (±3 months) and 1 year (±3 months) after exposure to a lithium level within these ranges: 0.81–1.0 mmol/L (group 2), 1.01–1.2 mmol/L (group 3) and 1.21–2.0 mmol/L (group 4). The reference group was patients whose lithium levels never exceeded 0.8 mmol/L. Results Compared to the reference group, groups 3 and 4 showed a significant decrease in eGFR in the first 3 months after exposure (p=0.047 and p=0.040). At 6 months (±3 months) postexposure group 4 still showed a decline in eGFR, however, this result was not significant (p=0.298). Conclusions These results show for the first time that a single incident of a lithium level >1.0 mmol/L is associated with a significant decrease in eGFR in the following 3 months when compared to patients whose lithium levels never exceeded 0.8 mmol/L. It is still not known whether the kidneys can recover this lost function and the impact that more than a single exposure to a level within these ranges can have on renal function. These results suggest that lithium level monitoring should be undertaken at least every 3 months, in line with current UK guidelines and not be reduced further until the impact of more than one exposure to these lithium levels has been fully established

Shape and symmetry determine two-dimensional melting transitions of hard regular polygons

The melting transition of two-dimensional (2D) systems is a fundamental problem in condensed matter and statistical physics that has advanced significantly through the application of computational resources and algorithms. 2D systems present the opportunity for novel phases and phase transition scenarios not observed in 3D systems, but these phases depend sensitively on the system and thus predicting how any given 2D system will behave remains a challenge. Here we report a comprehensive simulation study of the phase behavior near the melting transition of all hard regular polygons with $3\leq n\leq 14$ vertices using massively parallel Monte Carlo simulations of up to one million particles. By investigating this family of shapes, we show that the melting transition depends upon both particle shape and symmetry considerations, which together can predict which of three different melting scenarios will occur for a given $n$. We show that systems of polygons with as few as seven edges behave like hard disks; they melt continuously from a solid to a hexatic fluid and then undergo a first-order transition from the hexatic phase to the fluid phase. We show that this behavior, which holds for all $7\leq n\leq 14$, arises from weak entropic forces among the particles. Strong directional entropic forces align polygons with fewer than seven edges and impose local order in the fluid. These forces can enhance or suppress the discontinuous character of the transition depending on whether the local order in the fluid is compatible with the local order in the solid. As a result, systems of triangles, squares, and hexagons exhibit a KTHNY-type continuous transition between fluid and hexatic, tetratic, and hexatic phases, respectively, and a continuous transition from the appropriate "x"-atic to the solid. [abstract truncated due to arxiv length limitations]

Epistemological movements in communication: reference tables

Data SetThis publication supports the chapter EpistemologicalMovements in Communication: An Analysis o f Empirical and Rhetorical/Critical Scholarship to be published in the NCA Centennial Volume. It provides the extended data tables that could not be presented in the chapter because of space limitations. It does not stand alone and save for a few explanatory notes, is not presented to be read independently of the chapter. We request that any citation of the material here reference this work as a supplement to the chapter. The opportunity to misinterpret the data is otherwise quite high

COINING PHRASES FOR DOLLARS: JAY-Z, ECONOMIC LITERACY, AND THE EDUCATIONAL IMPLICATIONS OF HIP-HOP’S ENTREPRENEURIAL ETHOS

Previous research examining Hip-Hop and education has almost exclusively examined Hip-Hop’s connection to literacy and literary education, Morrell, 2002; Hill, 2009; Fisher, 2007 Lee & Majors, 2003). The paper examines the educational implications of Hip-Hip’s entrepreneurial ethos. This paper examines data collected over a five year period from 8th grade through four years of high school looking at the Hip-Hop practices of 12 youths in the group, “Bassline Entertainment.” Using the lyrics of Jay-Z as a thematic frame, this paper delineates the manner in which the entrepreneurial ethos of Hip-Hop helped convince these young artists of the relevance of a college education.  This paper found that the educational relevance of Hip-Hop culture emerged from the fact that the youth were engaged in an entrepreneurial endeavor. In contrast to previous research on Hip-Hop and education which viewed the students’ texts as literary documents, the students of Bassline Entertainment perceived their Hip-Hop texts as commodities or commodified texts. Thus, the Hip-Hop lyrical and musical composition for the Bassline students was inherently incomplete. It was only complete once it was marketed or sold in the manner in which it gained access to an audience. Consequently, an additional and extended array of skills and competencies became relevant to the Bassline Students, persuasive letter-writing skills to intellectual property attorneys in order to get the samples on their CD’s cleared, web design and digital graphics to promote their music, event planning and promotion to create performance opportunities, as well as videography and film to create videos for their work. Within this framework, the extended skill development afforded by a college education became personally relevant to the Bassline artists. In the end, each of the members of the Bassline Entertainment group applied for and was accepted into a four-year post-secondary college or University

The Extended Mind/ Walk, Hands, Eyes (Edinburgh) Exhibition Guide

First paragraph: The Extended Mind is based on the idea that our bodies, objects, language, institutions, other people and environments, expand our capacity to think, feel and orient ourselves in the world. This idea, that cognition is not simply something that takes place in the brain, is often called distributed cognition. A curatorial and academic endeavour, the exhibition grows from a collaboration between Talbot Rice Gallery and a research project called The History of Distributed Cognition