Lidar measurements of thermal structure

Rayleigh backscatter observations at 532 nm and 355 nm of relative atmospheric density above Aberystwyth on a total of 93 nights between Dec. 1982 and Feb. 1985 were used to derive the height variation of temperature in the upper stratosphere and mesosphere. Preliminary results for height up to about 25 km were also obtained from observations of Raman backscattering from nitrogen molecules. Comparisons were carried out for stratospheric heights with satellite borne measurements; good agreement was found between equivalent black body temperatures derived from the lidar observations and those obtained from nadir measurements in three channels of the stratosphere sounder units on NOAA satellites; the lidar based atmospheric temperatures have shown general agreement with but a greater degree of structure than the limb sounding measurements obtained using the SAMS experiment on the NOAA-7 satellite. In summer, stratospheric and mesospheric temperatures showed a smooth height variation similar to that of the CIRA model atmosphere. In contrast, the winter data showed a great variability with height, and marked temperature changes both from night to night and within a given night

Non-extremal black hole solutions from the c-map

We construct new static, spherically symmetric non-extremal black hole solutions of four-dimensional ${\cal N}=2$ supergravity, using a systematic technique based on dimensional reduction over time (the c-map) and the real formulation of special geometry. For a certain class of models we actually obtain the general solution to the full second order equations of motion, whilst for other classes of models, such as those obtainable by dimensional reduction from five dimensions, heterotic tree-level models, and type-II Calabi-Yau compactifications in the large volume limit a partial set of solutions are found. When considering specifically non-extremal black hole solutions we find that regularity conditions reduce the number of integration constants by one half. Such solutions satisfy a unique set of first order equations, which we identify. Several models are investigated in detail, including examples of non-homogeneous spaces such as the quantum deformed $STU$ model. Though we focus on static, spherically symmetric solutions of ungauged supergravity, the method is adaptable to other types of solutions and to gauged supergravity.Comment: 57 pages. Minor changes to the introduction, typos corrected and references added. Accepted for publication in JHE

Observations of stratospheric aerosols associated with the El Chichon eruption

Lidar observations of aerosols were carried out at Aberystwyth between Nov. 1982 and Dec. 1985 using a frequency doubled and frequency tripled Nd/Yag laser and a receiver incorporating a 1 m diameter in a Newtonian telescope configuration. In analyses of the experimental data attention is paid to the magnitude of the coefficient relating extinction and backscatter, the choice being related to the possible presence of aerosols in the upper troposphere and the atmospheric densities employed in the normalisation procedure. The aerosol loading showed marked day to day changes in early months and an overall decay was apparent only after April 1983, this decay being consistent with an e sup -1 time of about 7 months. The general decay was accompanied by a lowering of the layer but layers of aerosols were shown intermittently at heights above the main layer in winter months. The height variations of photon counts corrected for range, or of aerosol backscatter ratio, showed clear signatures of the tropopause. A strong correlation was found between the heights of the tropopause identified from the lidar measurements and from radiosonde-borne temperature measurements. A notable feature of the observations is the appearance of very sharp height gradients of backscatter ratio which seem to be produced by differential advection

The effect of resin/hardener stoichiometry on the electrical properties of silicon nitride/epoxy nanocomposites

The effect of resin/hardener stoichiometry was investigated for both unfilled epoxy and nanocomposite samples. The results indicate that incorporating silicon nitride nanofiller, which contains amine groups on its surface, has a significant influence on the resin/hardener reaction. At 2 wt.% of nanofiller, it was estimated that the powder contains amine groups equivalent to around 5 wt.% of the hardener mass, which results in the displacement of the optimum resin/hardener mass ratio by the same amount (~5 wt.%). The dielectric spectra showed that the B relaxation is directly related to the hydroxyether groups that are generated by the reaction between the epoxy and the amine groups. Therefore, the relaxation strength is proportional to the crosslinking density and consequently related to the glass transition temperature. The DC conductivity increases considerably as a result of incorporating silicon nitride nanofiller when not compensating for its impact on the resin/hardener stoichiometry. This might be related to the increase in the amine content of the material caused by the amine groups existing on the surface of the nanoparticles. When the stoichiometry effect is taken into account, the DC conductivity decreased to a value that is comparable to that of the unfilled polymer

On the dielectric performance of modified epoxy networks

Epoxy resins represent a commonly used basis for insulation materials and have been used in many different electrical applications. The formation of these systems involves reactions between a hardener, such as an amine-curing system, and an epoxy terminated resin. Recent studies have reported that epoxy resin systems can exhibit enhanced physical properties when the stoichiometry of the resin is varied using reactive diluent. This has been attributed to the increased free volume within the molecular structures within the epoxy resin network. The work described here set out to investigate this hypothesis concerning the potential benefits of varying the network structure of epoxy resin through the inclusion of monofunctional reactive diluents within the epoxy formulation. This research is of potential significance because any modification of the epoxy resin network results in modified thermal, mechanical and electrical properties and, consequently, represents a potential mean of tailoring overall performance to suit particular applications

Predicting the cost of the consequences of a large nuclear accident in the UK

Nuclear accidents have the potential to lead to significant off-site effects that require actions to minimise the radiological impacts on people. Such countermeasures may include sheltering, evacuation, restrictions on the sale of locally-grown food, and long-term relocation of the population amongst others. Countries with nuclear facilities draw up emergency preparedness plans, and put in place such provisions as distributing instructions and iodine prophylaxis to the local population. Their plans are applied in simulated exercises on a regular basis. The costs associated with emergency preparedness and the safety provisions to reduce the likelihood of an accident, and/or mitigate the consequences, are justified on the basis of the health risks and accident costs averted. There is, of course, only limited actual experience to indicate the likely costs so that much of the costing of accidents is based on calculations. This paper reviews the methodologies used, in particular the approach that has been developed in the UK, to appraise the costs of a hypothetical nuclear accident. Results of analysing a hypothetical nuclear accident at a fictitious reactor site within the United Kingdom are discussed in relation to the accidents at Three Mile Island 2, Chernobyl and Fukushima Dai-ichi

Do jumbo-CD holders care about anything?

Uninsured deposits represent a theoretically appealing but relatively untested alternative to subordinated debt for incorporating market discipline into banking supervision. To make the deposit market a useful supervisory tool, it is necessary to know what types of risk are priced by depositors and in what proportions. Using a clustering technique to select from among a large set of potential regressors, as well as a carefully chosen set of control variables, we attempt to determine the types of risk that cause uninsured depositors to react in both the price and quantity dimensions. As a benchmark for economic significance, we estimate similar regressions on supervisory ratings. We find that, in contrast to government supervisors, depositors have not priced most types of risk since 1997. Indeed, the only risk variables that consistently come up as statistically significant are those that measure capital adequacy. Our interpretation of these results is that, because aggregate banking conditions are good, it is not worth depositors' effort to investigate individual bank quality very carefully. We conclude that, in the current economic and regulatory environment, the market is content to delegate most of its monitoring and discipline to the government. To the extent that it does monitor, it only monitors capital. The jumbo-CD market is thus not likely to be of much supervisory use, particularly given that examiners already have good information about capital levels. The depositor emphasis on capital also supports the conjecture that market discipline was responsible for much of the recent capital build-up.Bank deposits ; Bank supervision

Symbolism over Substance? Large Law Firms and Corporate Social Responsibility

First draft of a paper which now appears in the journal 'Legal Ethics' Volume 18(2) This paper considers the individual CSR policies of the top 100 English Law firms (as ranked by the trade publication 'The Lawyer'), what the firms categorise as constituting CSR activity and the public disclosures they make. The research highlights that few firms explain why they are committed to CSR and the quality of disclosures varied so widely that meaningful comparison was not possible