Infrared Photometry and Dust Absorption in Highly Inclined Spiral Galaxies

We present JHK surface photometry of 15 highly inclined, late-type (Sab-Sc) spirals and investigate the quantitative effects of dust extinction. Using the (J - H, H - K) two-color diagram, we compare the color changes along the minor axis of each galaxy to the predictions from different models of radiative transfer. Models in which scattering effects are significant and those with more than a small fraction of the light sources located near the edge of the dust distribution do not produce enough extinction to explain the observed color gradients across disk absorption features. The optical depth in dust near the plane as deduced from the color excess depends sensitively on the adopted dust geometry, ranging from tau = 4 to 15 in the visual band. This suggests that a realistic model of the dust distribution is required, even for infrared photometry, to correct for dust extinction in the bulges of nearly edge-on systems.Comment: Accepted for publication in the March 1996 AJ. LaTex source which generates 27 pages of text and tables (no figures). Complete (text + figs) compressed Postscript preprint is also available at ftp://bessel.mps.ohio-state.edu/pub/terndrup/inclined.ps.Z (854 Mbyte

Language practices in school-based Grade R classrooms

The investigation on language practices aimed at establishing how the language of learning policy formulated by the Department of Education in South Africa was interpreted at classroom level. The study focused on language activities in schoolbased Grade R classes to observe how learners’ home language was used as the language of learning. Evidence from literature indicates that the success of any policy depends to a significant extent on the implementation strategy adopted to promote such a policy, especially at district and school levels. The outcome of this investigationestablished that key factors were not sufficiently considered in the implementation strategy at district and school levels. Learners’ diverse linguistic backgrounds, teachers’ expertise and the lack of suitable learning materials all compromised the success of the language of learning policy

The value of continuous professional development: Teachers' perceptions

The central argument is that in the presentation of workshops for teachers, presenters should focus on the principles underlying continuous professional development (CPD), since teachers are likely to be more willing to attend workshops if they are worth the time spent and the sacrifices made. In a workshop, on supporting learners with learning difficulties, such principles were therefore applied. A hands-on presentation was used to ensure that the teachers fully understood the use of the suggested teaching methods. The teachers were then asked to complete a questionnaire to determine their perceptions of how they had experienced the workshop. The questionnaire focused on the various CPD principles applied in the workshop, as well as the personal value and expected effect of the workshop on their teaching approach. In general, the teachers reported that regardless of their teaching position, qualifications, gender, or age they had experienced the CPD workshop positively. Keywords: continuous professional development; in-service training; learning difficulties; teaching methods; workshop South African Journal of Education Vol. 27 (1) 2007: pp. 53-6

Semiclassical and Quantum Black Holes and their Evaporation, de Sitter and Anti-de Sitter Regimes, Gravitational and String Phase Transitions

An effective string theory in physically relevant cosmological and black hole space times is reviewed. Explicit computations of the quantum string entropy, partition function and quantum string emission by black holes (Schwarzschild, rotating, charged, asymptotically flat, de Sitter dS and AdS space times) in the framework of effective string theory in curved backgrounds provide an amount of new quantum gravity results as: (i) gravitational phase transitions appear with a distinctive universal feature: a square root branch point singularity in any space time dimensions. This is of the type of the de Vega - Sanchez transition for the thermal self-gravitating gas of point particles. (ii) There are no phase transitions in AdS alone. (iii) For $dS$ background, upper bounds of the Hubble constant H are found, dictated by the quantum string phase transition.(iv) The Hawking temperature and the Hagedorn temperature are the same concept but in different (semiclassical and quantum) gravity regimes respectively. (v) The last stage of black hole evaporation is a microscopic string state with a finite string critical temperature which decays as usual quantum strings do in non-thermal pure quantum radiation (no information loss).(vi) New lower string bounds are given for the Kerr-Newman black hole angular momentum and charge, which are entirely different from the upper classical bounds. (vii) Semiclassical gravity states undergo a phase transition into quantum string states of the same system, these states are duals of each other in the precise sense of the usual classical-quantum (wave-particle) duality, which is universal irrespective of any symmetry or isommetry of the space-time and of the number or the kind of space-time dimensions.Comment: review paper, no figures. to appear in Int Jour Mod Phys

An accurate equation of state for the one component plasma in the low coupling regime

An accurate equation of state of the one component plasma is obtained in the low coupling regime $0 \leq \Gamma \leq 1$. The accuracy results from a smooth combination of the well-known hypernetted chain integral equation, Monte Carlo simulations and asymptotic analytical expressions of the excess internal energy $u$. In particular, special attention has been brought to describe and take advantage of finite size effects on Monte Carlo results to get the thermodynamic limit of $u$. This combined approach reproduces very accurately the different plasma correlation regimes encountered in this range of values of $\Gamma$. This paper extends to low $\Gamma$'s an earlier Monte Carlo simulation study devoted to strongly coupled systems for $1 \leq \Gamma \leq 190$ ({J.-M. Caillol}, {J. Chem. Phys.} \textbf{111}, 6538 (1999)). Analytical fits of $u(\Gamma)$ in the range $0 \leq \Gamma \leq 1$ are provided with a precision that we claim to be not smaller than $p= 10^{-5}$. HNC equation and exact asymptotic expressions are shown to give reliable results for $u(\Gamma)$ only in narrow $\Gamma$ intervals, i.e. $0 \leq \Gamma \lesssim 0.5$ and $0 \leq \Gamma \lesssim 0.3$ respectively

Semiclassical thermodynamics of scalar fields

We present a systematic semiclassical procedure to compute the partition function for scalar field theories at finite temperature. The central objects in our scheme are the solutions of the classical equations of motion in imaginary time, with spatially independent boundary conditions. Field fluctuations -- both field deviations around these classical solutions, and fluctuations of the boundary value of the fields -- are resummed in a Gaussian approximation. In our final expression for the partition function, this resummation is reduced to solving certain ordinary differential equations. Moreover, we show that it is renormalizable with the usual 1-loop counterterms.Comment: 24 pages, 5 postscript figure

Bone Conduction Audio Communication System for Musicians

poster abstractMusicians often perform their music live with an in-ear device to monitor select audio signals and specific tempos. While wearing conventional earphones as audio monitors enables musicians to coordinate rhythmically, it weakens the user’s awareness to their surrounding acoustic environment by closing off one, if not both ears. Disorientation is common for many musicians, such as saxophonists, violinists, and singers due the inability to fully hear one’s own musical instrument and surrounding ambient environment. This presents the necessity of a better solution for musicians. Bone conduction is an open ear design that allows audio transmission to be heard through vibrations of the bone while allowing the ambient sound of a stage environment to be heard by live performers. Bone conduction, as a means of audio transmission, is a method of sonic communication already shown of value. It is currently implemented in hardware produced by the military and law enforcement. Unfortunately, military oriented products and solutions are not readily available or adaptable to the on-stage performance. Hence, designing a peripheral device specific for live musicians is needed. In our model/research, actual transmission of conducting signals was done with a BCE-1 22x 14mm bone conducting exciter in conjunction with a CBL ASSY 3.5mm slim adapter and ample THHN building wire. The adapter was soldered onto the exciter, which may be powered through the 3.5 mm output of user defined signal generating device of the user’s preference. Future testing of the device will be performed and ultimately used in live performance during one of Dr. Robin Cox’s ensemble rehearsals in the IUPUI Department of Music & Arts Technology

Correlated Binomial Models and Correlation Structures

We discuss a general method to construct correlated binomial distributions by imposing several consistent relations on the joint probability function. We obtain self-consistency relations for the conditional correlations and conditional probabilities. The beta-binomial distribution is derived by a strong symmetric assumption on the conditional correlations. Our derivation clarifies the 'correlation' structure of the beta-binomial distribution. It is also possible to study the correlation structures of other probability distributions of exchangeable (homogeneous) correlated Bernoulli random variables. We study some distribution functions and discuss their behaviors in terms of their correlation structures.Comment: 12 pages, 7 figure