Female Middle School Principals\u27 Voices: Implications for School Leadership Preparation

This study was an attempt to add the voices of women to the discourse of sch.ool leadership. It focused on the nature of the middle school leadership experiences of three female middle school principals, their social interactions based on gen- der role expectations and their own leadership perspectives. Findings suggest that middle school leadership is characterized as challenging and sacrificial, that participants initially deny the effect of gender on their performance, but that so- cial stereotypes influence people\u27s perceptions about female principals, and that they tend to be more collaborative and nurturing than their male counterparts. Further, servant leadership and instructional leadership are the two leadership perspectives embraced by female middle school principals

Theoretical aspects of high--Q^2 deep inelastic scattering

We present an overview of the theory of high--Q^2 deep inelastic scattering. We focus in particular on the theoretical uncertainties in the predictions for neutral and charged current cross sections obtained by extrapolating from lower Q^2.Comment: 10 (Latex) pages, including 6 embedded figures, uses epsfig.sty, ioplppt.sty and iopl12.sty; Plenary talk presented at the 3rd UK Phenomenology Workshop on HERA Physics, Durham, September 1998, to be published in the Proceeding

Detection of X-ray galaxy clusters based on the Kolmogorov method

The detection of clusters of galaxies in large surveys plays an important part in extragalactic astronomy, and particularly in cosmology, since cluster counts can give strong constraints on cosmological parameters. X-ray imaging is in particular a reliable means to discover new clusters, and large X-ray surveys are now available. Considering XMM-Newton data for a sample of 40 Abell clusters, we show that their analysis with a Kolmogorov distribution can provide a distinctive signature for galaxy clusters. The Kolmogorov method is sensitive to the correlations in the cluster X-ray properties and can therefore be used for their identification, thus allowing to search reliably for clusters in a simple way

Low-carbon fuels for aviation

The aviation industry is responsible for 2.1% of global CO2 emissions and represents 12% of CO2 emissions from all transport sources. Aviation is a particularly difficult sector to decarbonise because alternative fuels are relatively expensive, produce highly distributed greenhouse gas emissions in their production and combustion, and should preferably be compatible with existing aviation infrastructure. Emissions from aviation also include nitrogen oxides (NOx), water vapour, particulates, carbon monoxide, unburned hydrocarbons, and sulfur oxides (SOx). These have a 2-3 times greater climate change impact than CO2 alone. The non-CO2 emissions of alternative low-carbon aviation fuels can differ significantly from those of kerosene and have not been fully evaluated. Biofuels • Bio-jet fuels are currently the most technologically mature option for low-carbon aviation fuels because some of these feedstocks and processes are already deployed at scale for other uses. • Bio-jet fuels must be blended with kerosene to achieve certification and can then be used with existing aviation infrastructure. This blending proportionally decreases any potential CO2 emission saving. • Bio-jet fuels can be made from a range of feedstocks, which are restricted in the UK to waste materials. UK biofuel feedstock availability is sufficient for only a small proportion of UK aviation fuel demand (<20%). With blending, their contribution to CO2 emissions saving is much less (<<10%). • Life cycle assessment scenarios show very variable impacts on CO2 emissions for biofuel processes: only some deliver emissions savings compared to fossil fuel kerosene. Calculations for forest residues appear to show consistent savings in CO2 emissions compared to jet fuel, but these do not take account of the difference in timescale between emission and re-absorption, leading to a major underestimation of emissions. The diversion of agricultural and forestry waste to bio-jet fuel production will have detrimental effects, for example on soil quality. Power-to-Liquid fuels • PtL fuels must be blended with kerosene to achieve certification and can then be used with existing aviation infrastructure. This blending proportionally decreases any potential CO2 emission saving. • PtL fuels are currently not produced at scale. Significant technological development is required to reduce production costs and increase production scale. • Use of PtL fuels in aviation would require a very significant increase of UK low-carbon electricity generation and storage capacity to power production of green hydrogen and CO2 from direct air capture. • Life cycle assessment scenarios show that PtL fuels could have 3-10 times lower emissions impact than fossil fuel kerosene if renewable electricity and CO2 from direct air capture are used to produce the fuel. Hydrogen • Hydrogen cannot be used as a drop-in fuel for aircraft, and its use will require significant redesign of aviation infrastructure. • The greenhouse gas emissions impact of hydrogen depends on its mode of production. Currently, global hydrogen production is mostly from fossil fuel sources, with much less than 1% generated from low-carbon sources. • Increasing low-carbon hydrogen production via electrolysis (green hydrogen) will require the building of additional low-carbon electricity generation capacity. • Low-carbon hydrogen production via methane reforming with carbon capture and storage (blue hydrogen) should use natural gas obtained from producers with low emissions intensity. The goal of policy will be to promote whichever technologies achieve the desired sustainability targets. A molecular science and engineering approach combines an understanding of molecular behaviour with a problem-solving mindset derived from engineering. This approach is crucial to the development and the eventual deployment of the fuel technologies discussed in this paper

Observation of thundercloud-related gamma rays and neutrons in Tibet

During the 2010 rainy season in Yangbajing (4300 m above sea level) in Tibet, China, a long-duration count enhancement associated with thunderclouds was detected by a solar-neutron telescope and neutron monitors installed at the Yangbajing Comic Ray Observatory. The event, lasting for ∼40  min, was observed on July 22, 2010. The solar-neutron telescope detected significant γ-ray signals with energies >40  MeV in the event. Such a prolonged high-energy event has never been observed in association with thunderclouds, clearly suggesting that electron acceleration lasts for 40 min in thunderclouds. In addition, Monte Carlo simulations showed that >10  MeV γ rays largely contribute to the neutron monitor signals, while >1  keV neutrons produced via a photonuclear reaction contribute relatively less to the signals. This result suggests that enhancements of neutron monitors during thunderstorms are not necessarily clear evidence for neutron production, as previously thought

Optical followup of galaxy clusters detected by the South Pole Telescope

The South Pole Telescope (SPT) is a 10 meter telescope operating at mm wavelengths. It has recently completed a three-band survey covering 2500 sq. degrees. One of the survey's main goals is to detect galaxy clusters using Sunyaev-Zeldovich effect and use these clusters for a variety of cosmological and astrophysical studies such as the dark energy equation of state, the primordial non-gaussianity and the evolution of galaxy populations. Since 2005, we have been engaged in a comprehensive optical and near-infrared followup program (at wavelengths between 0.4 and 5 {\mu}m) to image high-significance SPT clusters, to measure their photometric redshifts, and to estimate the contamination rate of the candidate lists. These clusters are then used for various cosmological and astrophysical studies.Comment: For TAUP 2011 proceeding

Resonant Subband Landau Level Coupling in Symmetric Quantum Well

Subband structure and depolarization shifts in an ultra-high mobility GaAs/Al_{0.24}Ga_{0.76}As quantum well are studied using magneto-infrared spectroscopy via resonant subband Landau level coupling. Resonant couplings between the 1st and up to the 4th subbands are identified by well-separated anti-level-crossing split resonance, while the hy-lying subbands were identified by the cyclotron resonance linewidth broadening in the literature. In addition, a forbidden intersubband transition (1st to 3rd) has been observed. With the precise determination of the subband structure, we find that the depolarization shift can be well described by the semiclassical slab plasma model, and the possible origins for the forbidden transition are discussed.Comment: 4 pages, 2 figure