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

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

Linguistic stratigraphy in the central Solomon Islands: Lexical evidence of early Papuan/Austronesian interaction

The extent to which linguistic borrowing can be used to shed light on the existence and nature of early contact between Papuan and Oceanic speakers is examined. The question is addressed by taking one Papuan language, Lavukaleve, spoken in the Russell Islands, central Solomon Islands and examining lexical borrowings between it and nearby Oceanic languages, and with reconstructed forms of Proto Oceanic. Evidence from ethnography, culture history and archaeology, when added to the linguistic evidence provided in this study, indicates long-standing cultural links between other (non-Russell) islands. The composite picture is one of a high degree of cultural contact with little linguistic mixing, i.e., little or no changes affecting the structure of the languages and actually very little borrowed vocabulary

Assisting the Long-Term Unemployed: Results from a Randomized Trial

Welfare reform in Australia centres on the concept of both economic and social participation. The policy concern is that people who fail to participate in economic and social life may become entrenched in disadvantage. In 2000 - 2001, a randomized trial was conducted by the Department of Family and Community Services in order to assess whether an intensive interview with successive follow-ups would result in increased economic and social participation for unemployed individuals who had been on income support for more than five years. We find evidence that participation in the trial led to a reduction in average weekly hours of work, but increased the amount of hours spent in study or training programs and the proportion of individuals engaged in such programs. We also find evidence of increased social integration associated with participation in the trial

Asymptotic solutions for the asymmetric flow in a channel with porous retractable walls under a transverse magnetic field

The self-similarity solutions of the Navier-Stokes equations are constructed for an incompressible laminar flow through a uniformly porous channel with retractable walls under a transverse magnetic field. The flow is driven by the expanding or contracting walls with different permeability. The velocities of the asymmetric flow at the upper and lower walls are different in not only the magnitude but also the direction. The asymptotic solutions are well constructed with the method of boundary layer correction in two cases with large Reynolds numbers, i.e., both walls of the channel are with suction, and one of the walls is with injection while the other one is with suction. For small Reynolds number cases, the double perturbation method is used to construct the asymptotic solution. All the asymptotic results are finally verified by numerical results.</p

The hierarchical response of human corneal collagen to load

Fibrillar collagen in the human cornea is integral to its function as a transparent lens of precise curvature, and its arrangement is now well-characterised in the literature. While there has been considerable effort to incorporate fibrillar architecture into mechanical models of the cornea, the mechanical response of corneal collagen to small applied loads is not well understood. In this study the fibrillar and molecular response to tensile load was quantified using small and wide angle X-ray scattering (SAXS/WAXS), and digital image correlation (DIC) photography was used to calculate the local strain field that gave rise to the hierarchical changes. A molecular scattering model was used to calculate the tropocollagen tilt relative to the fibril axis and changes associated with applied strain. Changes were measured in the D-period, molecular tilt and the orientation and spacing of the fibrillar and molecular networks. These measurements were summarised into hierarchical deformation mechanisms, which were found to contribute at varying strains. The change in molecular tilt is indicative of a sub-fibrillar “spring-like” deformation mechanism, which was found to account for most of the applied strain under physiological and near-physiological loads. This deformation mechanism may play an important functional role in tissues rich in fibrils of high helical tilt, such as skin and cartilage

Activation in Lavukaleve pronouns: oia versus foia

The first part of this paper describes an unusual system of anaphoric reference tracking in Lavukaleve, a Papuan language of the Solomon Islands. Lavukaleve has two demonstrative pronouns which can be used to make anaphoric reference in narratives. One of these demonstrative pronouns is used to make anaphoric reference to a semi-activated participant, and the other to an activated participant. The second part of the paper situates Lavukaleve's activation-based system of reference tracking in a general typology of reference tracking. Other languages which have reference tracking systems based on the cognitive status of the referent are discussed, and the close connection between these and obviation systems is pointed out

Body part terms in Lavukaleve, a Papuan language of the Solomon Islands

This paper explores body part terms in Lavukaleve, a Papuan isolate spoken in the Solomon Islands. The full set of body part terms collected so far is presented, and their grammatical properties are explained. It is argued that Lavukaleve body part terms do not enter into partonomic relations with each other, and that a hierarchical structure of body part terms does not apply for Lavukaleve. It is shown too that some universal claims which have been made about the expression of terms relating to limbs are contradicted in Lavukaleve, which has only one general term covering arm, hand, leg and (for some people) foot

Languages in contact: An exploration of stability and change in the Solomon Islands

The Papuan-Oceanic world has long been considered a hotbed of contact-induced linguistic change, and there have been a number of studies of deep linguistic influence between Papuan and Oceanic languages (like those by Thurston and Ross). This paper assesses the degree and type of contact-induced language change in the Solomon Islands, between the four Papuan languages—Bilua (spoken on Vella Lavella, Western Province), Touo (spoken on southern Rendova, Western Province), Savosavo (spoken on Savo Island, Central Province), and Lavukaleve (spoken in the Russell Islands, Central Province)—and their Oceanic neighbors. First, a claim is made for a degree of cultural homogeneity for Papuan and Oceanic-speaking populations within the Solomons. Second, lexical and grammatical borrowing are considered in turn, in an attempt to identify which elements in each of the four Papuan languages may have an origin in Oceanic languages—and indeed which elements in Oceanic languages may have their origin in Papuan languages. Finally, an assessment is made of the degrees of stability versus change in the Papuan and Oceanic languages of the Solomon Islands