New fine structure cooling rate

One of the dominant electron cooling processes in the ionosphere is caused by electron impact induced fine structure transitions among the ground state levels of atomic oxygen. This fine structure cooling rate is based on theoretical cross sections. Recent advances in the numerical cross section determinations to include polarization effects and more accurate representations of the atomic target result in new lower values. These cross sections are employed in this paper to derive a new fine structure cooling rate which is between 40% and 60% of the currently used rate. A new generalized formula is presented for the cooling rate (from which the fine structure cooling rate is derived), valid for arbitrary mass and temperature difference of the colliding particles and arbitrary inelastic energy difference

Thermal electron heating rate: A derivation

The thermal electron heating rate is an important heat source term in the ionospheric electron energy balance equation, representing heating by photoelectrons or by precipitating higher energy electrons. A formula for the thermal electron heating rate is derived from the kinetic equation using the electron-electron collision operator as given by the unified theory of Kihara and Aono. This collision operator includes collective interactions to produce a finite collision operator with an exact Coulomb logarithm term. The derived heating rate O(e) is the sum of three terms, O(e) = O(p) + S + O(int), which are respectively: (1) primary electron production term giving the heating from newly created electrons that have not yet suffered collisions with the ambient electrons; (2) a heating term evaluated on the energy surface m(e)/2 = E(T) at the transition between Maxwellian and tail electrons at E(T); and (3) the integral term representing heating of Maxwellian electrons by energetic tail electrons at energies ET. Published ionospheric electron temperature studies used only the integral term O(int) with differing lower integration limits. Use of the incomplete heating rate could lead to erroneous conclusions regarding electron heat balance, since O(e) is greater than O(int) by as much as a factor of two

Probe and radar electron temperatures in an isotropic, nonequilibrium plasma

Electron temperatures measured by electrostatic probes and radar backscatter in isotropic, nonequilibrium plasma for studying planetary atmosphere

Solar Irradiance Observed from PVO and Inferred Solar Rotation

Solar irradiance in the extreme ultraviolet flux (EUV) has been monitored for 11 years by the Pioneer Venus Orbiter (PVO). Since the experiment moves around the Sun with the orbital rate of Venus rather than that of Earth, the measurement gives us a second viewing location from which to begin unravelling which irradiance variations are intrinsic to the Sun, and which are merely rotational modulations whose periods depend on the motion of the observer. Researchers confirm an earlier detection, made with only 8.6 years of data, that the EUV irradiance is modulated by rotation rates of two families of global oscillation modes. One family is assumed to be r-modes occupying the convective envelope and sharing its rotation, while the other family (g-modes) lies in the radiative interior which as a slower rotation. Measured power in r-modes of low angular harmonic number indicates that the Sun's envelope rotated about 0.7 percent faster near the last solar maximum (1979 thru 1982) than it did during the next rise to maximum (1986 to 1989). No change was seen in the g-mode family of lines, as would be expected from the much greater rotational inertia of the radiative interior

The effect of an isotopic non-equilibrium plasma on electron temperature measurements

Electron temperatures determined by electrostatic probe, diffuse resonance, and radar backscatter techniques in an isotropic two temperature plasma are presented. Plasma models corresponding to the addition of a minor component of energetic electrons, and models corresponding to a process that cools a fraction of the ionospheric electrons are considered. The diffuse resonance temperature is found to lie between the probe and radar backscatter temperatures. The isotropic models corresponding to the addition of energetic electrons cannot support the reported discrepancies between radio wave and probe electron temperature measurements. Temperature differences similar to the observed differences can be produced by models with a fraction of the electrons at a temperature cooler than that of the main component of electrons

Three-particle collisions in a gas of hard spheres

Three particle collisions in gas of hard sphere

Motivating the baby boomer generation: an application of the theory of planned behaviour, exercise behaviour, and stages of change on physical activity intentions

The Baby Boom Generation, born between 1946 and 1964, is creating a shift in Canada towards an aging population. In 2031, 22.8% of the population will be over the age of 65, compared to 14.1 in 2011 (Statistics Canada, 2010). Although it is well known that physical activity is an integral aspect of healthy aging (Swan, Friis, & Turner, 2008) and that the benefits of physical activity far outweigh the risks, less than 50% of baby boomers participated in regular physical activity in 2010 (Statistics Canada, 2011). Theoretical research using the Theory of Planned Behaviour (TPB) and the Stages of Change Model (SCM) has been used extensively in the behavioural health field. To our knowledge, no study has focused on the baby boom population specifically and their behaviour and intentions toward physical activity. Method: One-hundred and seventy male and female baby boomers (aged 45 to 66) participated in the study. Using questionnaires, stage of change (SCM), demographics, attitudes, subjective norm, perceived behavioural control, behavioural beliefs, normative beliefs, control beliefs (Theory of Planned Behaviour; TPB) and exercise behaviour (Godin Leisure Time Exercise Questionnaire; GLTEQ) were assessed. Results: Stepwise regression analyses indicated that the TPB constructs predicted 35.6% of physical activity intention, and intention predicted 29.4% of physical activity behaviour. Statistical differences were seen between the SCM contemplators and preparers and the action and maintainers on the TPB constructs. Conclusions: The TPB produced important theoretical insight into the physical activity intentions and behaviours of baby boomers based on participants’ stage of change. PBC and attitudes were the strongest predictors of intention. These findings suggest that these constructs should be targeted in interventions designed to increase physical activity participation in the baby boom population

Conditions for Aeronomic Applicability of the Classical Electron Heat Conduction Formula

Conditions for the applicability of the classical formula for heat conduction in the electrons in ionized gas are investigated. In a fully ionised gas ( V(sub en) much greater than V(sub ei)), when the mean free path for electron-electron (or electron-ion) collisions is much larger than the characteristic thermal scale length of the observed system, the conditions for applicability break down. In the case of the Venus ionosphere this breakdown is indicated for a large fraction of the electron temperature data from altitudes greater than 180 km, for electron densities less than 10(exp 4)/cc cm. In a partially ionised gas such that V(sub en) much greater than V(sub ei) there is breakdown of the formula not only when the mean free path of electrons greatly exceeds the thermal scale length, but also when the gradient of neutral particle density exceeds the electron thermal gradient. It is shown that electron heat conduction may be neglected in estimating the temperature of joule heated electrons by observed strong 100 Hz electric fields when the conduction flux is limited by the saturation flux. The results of this paper support our earlier aeronomical arguments against the hypothesis of planetary scale whistlers for the 100 Hz electric field signal. In turn this means that data from the 100 Hz signal may not be used to support the case for lightning on Venus

Use of Langmuir probes in non-Maxwellian space plasmas

Disturbance of the Maxwellian plasma may occur in the vicinity of a spacecraft due to photoemission, interactions between the spacecraft and thermospheric gases, or electron emissions from other devices on the spacecraft. Significant non-Maxwellian plasma distributions may also occur in nature as a mixture of ionospheric and magnetospheric plasmas or secondaries produced by photoionization in the thermosphere or auroral precipitation. The general formulas for current collection (volt–ampere curves) by planar, cylindrical, and spherical Langmuir probes in isotropic and anisotropic non-Maxwellian plasmas are examined. Examples are given of how one may identify and remove the non-Maxwellian components in the Langmuir probe current to permit the ionospheric parameters to be determined. Theoretical volt–ampere curves presented for typical examples of non-Maxwellian distributions include: two-temperature plasmas and a thermal plasma with an energetic electron beam. If the nonionospheric electrons are Maxwellian at a temperature distinct from that of the ionosphere electrons, the volt–ampere curves can be fitted directly to obtain the temperatures and densities of both electron components without resorting to techniques that attempt to derive the plasma distribution from the current by taking derivatives. For an arbitrary isotropic distribution, the current for retarded particles is shown to be identical for the three geometries. For anisotropic distributions, the three probe geometries are not equally suited for measuring the ionospheric electron temperature and density or for determining the distribution function in the presence of non-Maxwellian background electrons. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70117/2/RSINAK-70-7-3015-1.pd

Genetic diversity and colonization patterns of Onnia tomentosa and Phellinus tremulae (Hymenochaetaceae, Aphyllophorales) in the boreal forest near Thunder Bay, northwestern Ontario

Forest health is impacted greatly by fungi, particularly those that cause disease in living trees. By examining genetic diversity within populations of pathogenic fungi and their patterns of colonization it is possible to gain a greater understanding of host-pathogen interactions. Two common pathogens in the boreal forest are Onnia tomentosa, causal agent of a root-rot disease in spruce known as stand opening disease, and Phellinus tremulae, causal agent of white heart rot in stems of trembling aspen. Both fungi are members of the Hymenochaetaceae in the Basidiomycota. Two black spruce (Picea mariana) plantations located north of Nipigon were examined for Onnia tomentosa. Spatial coordinates of 124 basidiomata were taken, and the basidiomata collected from plots that had received different commercial thinning treatments. Using extracted DNA from each of the basidiomata, it was possible to measure genetic diversity and consequently genet size. One hundred and sixteen genetically distinct individuals were found suggesting that the majority of the basidiomata represented unique genets. The distribution pattern was mapped. Stand thinning appears to negatively impact colonization of spruce by O. tomentosa compared with that observed in unthinned control stands. In an ancillary study, a stand of trembling aspen (Populus tremuloides) located at Silver Mountain (74 km SW of Thunder Bay) was examined for Phellinus tremulae. Four infected trees were harvested and each stem cut into 50 cm sections with the top 5 cm from each section removed as a cookie. From each cookie, isolations of P. tremulae were made onto agar media and somatic compatibility techniques were utilized to determine size and distribution of genets in each tree. Two trees contained two genets of P. tremulae, one tree contained a single genet, while the remaining tree failed to yield any isolations of P. tremulae at all