Fluid mixing technique increases the gain and output power of carbon dioxide laser systems

High speed flowing gas system provides uniform mixing in short times compared to flow transit times and carbon dioxide vibrational relaxation times. This system minimizes the effects of surrounding surfaces and provides a uniformly high gain that is independent of dimensions transverse to the flow direction

Notes on the statistical analysis of some loomweights from Pompeii

Recent work, in the field, on the dimensions and weights of loomweights from excavations in Insula VI.I, Pompeii suggested – to our surprise – that there was structure in the form of evidence of bi-modality in the weights. The paper has two purposes. One is to illustrate a variety of statistical methods that were used to confirm the validity of our observations. The other is to discuss what the archaeological implications of this might be. A more general point is that if more attention is given to what are often regarded as “uninteresting” artefacts some interesting results may emerge - specifically, it can be asked whether loomweights have chronological significance for interpreting archaeological sites (at Pompeii at least)

On the value of life

The national budget affects life and death via its allocations in areas such as traffic safety, flood control, public health and the like. When the cost-effectiveness of an intervention is evaluated, common effect measures are the number of lives extended (saved) and the expected lifeyears gained. The latter are usually adjusted for quality of life, giving QALYs, and discounted. In models that support decision making on the national aggregates, the subjects can be reduced to representative agents that are scored only on these dimensions. The lives extended measure is impartial to age and sex. The lifeyears measures deals better with the relative impact but is biased in age and sex, since young people have a higher life expectancy than the old and women have a higher life expectancy than men, and policy advice might reflect that bias. It seems advisable to devise a measure that is more impartial and fair with respect to the age groups and the sexes. An alternative is to value a single life at 100%, and to measure the lifeyears gain with respect to that 100%. In addition, rather than fine-tune policy with interpersonal utility comparisons, one could choose a utility norm for the representative agent. A possible norm for time preference and diminishing marginal utility of life is the square root. The square root is easier to communicate than logarithmic utility or some rate of discount, but has comparable effect. A life of 100 years then has value 10, a life of 25 years has value 5, so that by age 25 half of life is passed. The considerations of both 100% range and square root utility lead to the following age & sex adjusted gain measure. When a person has age a, experiences an event (accident, disease) with a life expectancy of d years, but might have an intervention such that the life expectancy could become e, then the current effect measures are the single life saved and the absolute lifeyears gain x = e - d, but the proposed compromise gain measure is g[x | a, d] = Sqrt[x / (a + d + x)]. The square root gives the utility of the representative agent, g gives the impact for interpersonal comparison, and aggregate utility is found by summing the a over the individuals i. For example, saving (from acute death, d = 0) a baby (a = 0) has the same value, namely 1, whether it is a boy (life expectancy at birth, x = 75.94) or girl (x = 80.71) (data Statistics Netherlands 2002). As another example, let the unit share s = x / (a + e) be 25% for one person and 81% for another person so that the last person would weigh more than three times as much in this respect. For above gain measure, g = Sqrt[s] and the weight ratio becomes 50% / 90%, so that the last person now weighs less than half so that there is more equality. The paper compares various gain measures within the context of social welfare maximization.

Notes on some statistical aspects of pottery quantification

The quantification of finds assemblages from excavations, as an aid to the comparative study of assemblages and sites, is a developing and increasingly important aspect of post-excavation analysis. In the area of pottery studies a major influence has been the work of Clive Orton and Paul Tyers, culminating in the recent release of the 'pie-slice' package for computer analysis. Much of the published literature is either highly technical, or of an expository nature which needs a great deal of the technical material and underlying assumptions to be taken on trust. The present paper is intended to be intermediate between these two levels. We address some of the more complex or less obvious issues involved in application of the pie-slice 'philosophy'. A worked example is given to highlight aspects of some of the assumptions and calculations involved. Some attention is given to what can be done outside the pie-slice package. One concern is the analysis of assemblages that have been quantified using estimated vessel equivalents (eves), but not in a manner that allows conversion to pottery information equivalents (pies) in the pie-slice package

Nonequilibrium electrical conductivity measurements in argon and helium seeded plasmas

In a previous paper, the authors presented experimental values of electrical conductivity measured in a plasma composed of argon gas seeded with potassium vapor. The measurements were made at atmospheric pressure with a neutral gas temperature of 2000° ± 100°K and with a number of values of seed concentration in the range 0.2 to 0.8 mole %. The effect of nonequilibrium heating of the electron gas-excited potassium system was investigated for a range of current densities between 0.8 and 80 amp/cm^2. These data were in good agreement with values of the conductivity calculated by a scheme, outlined in Ref. 1, which included the effects of energy loss from the system, composed of the electron gas and the electronically excited states of potassium due to radiation from the excited potassium atoms. In addition, the pulsed technique used to measure the conductivity in response to a step function application of the electric field made possible the determination of the relaxation times for the ionization process

Recombination, ionization, and nonequilibrium electrical conductivity in seeded plasmas

New data are presented which provide direct experimental confirmation of the validity of a physical model which has been widely employed to predict the electrical conductivity of dense, two-temperature, seeded plasmas. Experimental measurements of electron temperature, and ionization and recombination rates are presented for partially ionized plasmas of potassium-seeded argon. Experimental conditions were chosen to cover those ranges of interest in connection with proposed magnetohydrodynamic energy conversion devices for which nonequilibrium electrical conductivity measurements have been previously reported, e.g., translational atom temperatures of about 2000°K, total atom densities near 10^(18)/cm^3, potassium densities of about 10^(16)/cm^3, electron densities from 10^(13)/cm^3 to 10^(15)/cm^3, and electron temperatures from 2200 to 3500°K. Measured values of electron-electron-ion recombination coefficients for potassium show good agreement with theoretical values based upon the Gryzinski classical inelastic-collision cross-section expressions. Observed ionization rates and relaxation characteristics appear to be adequately explained by a similar formulation for the ionization process