10,917 research outputs found
Implementing Energy Efficiency & ESD from a Development Perspective
This note discusses the difficulties currently being experienced in implementing Ecological Sustainable Development (ESD) from a development perspective. It looks at what motivates developers and examines what is needed, either through mandatory measures or incentives to change the development culture in Australia. The note draws on experience from a number of current and recently completed projects and incorporates input from developers. It also includes discussion on the evolving outcomes of current industry initiatives aimed specifically at changing development processes and culture in Australia. The note focuses on new buildings. The way in which new buildings are financed and delivered generally differs significantly from retrofit projects being undertaken by building owners. Building owners can more easily factor long term operational costs of their buildings into their retrofit project financing. Typically, building developers are not the long-term owners, operators or tenants of the buildings that they deliver. Their projects are normally sold before or soon after completion to unrelated parties such as property trusts, superannuation funds, and other investors. It is this discontinuity in development and ownership of new buildings that creates perhaps the single biggest challenge to the uptake of ESD for the property industry
The stability of coronal and prominence magnetic fields
The significance of the localized instabilities is not yet fully understood. The nonlinear coupling of these modes may give rise to an explosive instability, with the modes coupling to longer wavelengths. On the other hand, if the modes saturate early, than the main effect of the instability may be an enhancement of transport coefficients. Nonetheless, the equation provides a simple test for the stability of cylindrical magnetic fields
A numerical model of standard to blowout jets
We report on three-dimensional (3D) MHD simulations of the formation of jets produced during the emergence and eruption of solar magnetic fields. The interaction between an emerging and an ambient magnetic field in the solar atmosphere leads to (external) reconnection and the formation of "standard" jets with an inverse Y-shaped configuration. Eventually, low-atmosphere (internal) reconnection of sheared fieldlines in the emerging flux region produces an erupting magnetic flux rope and a reconnection jet underneath it. The erupting plasma blows out the ambient field and, moreover, it unwinds as it is ejected into the outer solar atmosphere. The fast emission of the cool material that erupts together with the hot outflows due to external/internal reconnection form a wider "blowout" jet. We show the transition from "standard" to "blowout" jets and report on their 3D structure. The physical plasma properties of the jets are consistent with observational studies.Peer reviewe
MHD mode conversion in a stratified atmosphere
Mode conversion in the region where the sound and Alfven speeds are equal is
a complex process, which has been studied both analytically and numerically,
and has been seen in observations. In order to further the understanding of
this process we set up a simple, one-dimensional model, and examine wave
propagation through this system using a combination of analytical and numerical
techniques. Simulations are carried out in a gravitationally stratified
atmosphere with a uniform, vertical magnetic field for both isothermal and
non-isothermal cases. For the non-isothermal case a temperature profile is
chosen to mimic the steep temperature gradient encountered at the transition
region. In all simulations, a slow wave is driven on the upper boundary, thus
propagating down from low-beta to high-beta plasma across the mode-conversion
region. In addition, a detailed analytical study is carried out where we
predict the amplitude and phase of the transmitted and converted components of
the incident wave as it passes through the mode-conversion region. A comparison
of these analytical predictions with the numerical results shows good
agreement, giving us confidence in both techniques. This knowledge may be used
to help determine wave types observed and give insight into which modes may be
involved in coronal heating.Comment: 7 pages, 5 figure
MHD Mode Conversion around a 2D Magnetic Null Point
Mode conversion occurs when a wave passes through a region where the sound
and Alfven speeds are equal. At this point there is a resonance, which allows
some of the incident wave to be converted into a different mode. We study this
phenomenon in the vicinity of a two-dimensional, coronal null point. As a wave
approaches the null it passes from low- to high-beta plasma, allowing
conversion to take place. We simulate this numerically by sending in a slow
magnetoacoustic wave from the upper boundary; as this passes through the
conversion layer a fast wave can clearly be seen propagating ahead. Numerical
simulations combined with an analytical WKB investigation allow us to determine
and track both the incident and converted waves throughout the domain.Comment: 4 pages, 2 figure
Diversity and structure of human T-Cell receptor Ī²-chain variable region genes
The nucleotide sequences of 27 T-cell receptor Ī² cDNA clones isolated from a human peripheral lymphocyte library were determined and compared to five additional published sequences. These cDNA clones represent 22 distinct T-cell receptor Ī²-chain variable region (VĪ²) gene segment sequences, which fall into 15 different VĪ² gene subfamilies, each containing six or fewer members. From this analysis, we estimate that the repertoire of expressed human VĪ² genes is <59, apparently much smaller than the immunoglobulin heavy chain and light chain variable region (VH and VL) repertoires. Variability plots comparing these human VĪ² regions with each other and with published mouse VĪ² regions provide evidence for only four hypervariable regions homologous to those seen in comparisons of immunoglobulin V regions. Somatic hypermutation appears to be used infrequently, if at all, in these VĪ² genes
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The rats in Hawaiian sugarcane
Heavy losses In Hawaiian sugarcane are caused by Polynesian rats (Rattus exulans), Norway rats (R. norvegicus), and black rats (R. rattus). Relative population levels, movement patterns, damage to sugarcane, and suggested timing of control during five stages of the 2-year crop cycle are described. The progress toward the registering of zinc phosphide for use in crops and the development of other rodenticides are mentioned
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