Determination of Electron Flux Spectra in a Solar Flare with an Augmented Regularization Method: Application to Rhessi Data

Kontar et al. (2004) have shown how to recover mean source electron spectra in solar flares through a physical constraint regularization analysis of the bremsstrahlung photon spectra I() that they produce. They emphasize the use of non-square inversion techniques, and preconditioning combined with physical properties of the spectra to achieve the most meaningful solution to the problem. Higher-order regularization techniques may be used to generate forms with certain desirable properties (e.g., higher-order derivatives). They further note that such analysis may be used to infer properties of the electron energy spectra at energies well above the maximum photon energy observed. In this paper we apply these techniques to data from a solar flare observed by RHESSI on 26 February, 2002. Results using different orders of regularization are presented and compared for various time intervals. Clear evidence is presented for a change in the value of the high-energy cutoff in the mean source electron spectrum with time. We also show how the construction of the injected electron spectrum F₀(E₀) (assuming that Coulomb collisions in a cold target dominate the electron transport) is facilitated by the use of higher-order regularization methods.     

Pelagia noctiluca"Blooming" in the Strait of Messina: Preliminary Studies on the Applicability of Two Methods for Isolating Nematocytes

Abstract. Nematocytes are the specialized stinging cells of cnidarians. So far, Pelagia noctiluca (Cnidaria, Scyphozoa) nematocytes have never been isolated. Taking in account the notable increase in the population of Pelagia noctiluca ("blooming") in the Strait of Messina in 1999, we performed preliminary studies on the applicability of two different methods for isolating nematocytes from tentacles and mouth arms: a chemical method, namely SCN treatment, and a physical one, namely heat dissociation. These approaches have already been employed to isolate nematocytes from Aiptasia diaphana (Anthozoa). Membrane integrity was assessed by the cytological Trypan blue test. To evaluate cell viability, the capacity to regulate cell volume was investigated under 35 % hyposmotic shock by image computer processing of sagittal sections. The results show that heat dissociation is unsuitable to isolate nematocytes because the cell membrane was damaged as revealed by cytological test. On the other hand, SCN treatment yields 90% anatomically intact, isolated nematocytes from tentacles, but not from mouth arms. Nematocytes isolated by SCN exhibit volume regulation mechanisms (RVD). These results are compared with those described in Aiptasia diaphana (Anthozoa), which lives in a different habitat.     

An Evaluation of Information Meetings as a Tool for Addressing Fear of Large Carnivores

Managing authorities in Scandinavia arrange public information meetings when members of the public express fear because wolves or brown bears approach human settlements. This study aimed to increase the understanding of the potential effect of information meetings on self-reported fear of wolves and brown bears. In total, 198 participants completed questionnaires before and after the information meetings. Nine follow-up interviews were held 1 year later. The quantitative analyses revealed that participants who found the information credible reported a significant increase in social trust and a decrease in vulnerability and fear. The qualitative analyses pointed to the importance of information content and meta-communication, for example, nonverbal cues. It is proposed that, among participants who find the information credible, information meetings may change the appraisal of wolves and brown bears, and therefore they might prove useful as an intervention to address fear of these animals.     

Time dependent photon transport in a three dimensional interstellar cloud with stochastic clumps

We consider time dependent photon transport in a three dimensional interstellar cloud which occupies a three dimensional regionV. One or more clumps of given shapes are present withinV and their positions are determined by a suitable set of stochastic variables. Iff is the photon number density in the cloud or in the clumps, then our mathematical model leads to two coupled initial value problems for the average photon density over the stochastic variables f and forf ^* =f -f. By using the theory of semigroups, we prove existence and uniqueness of a strongly continuous solution and examine the small fluctuation approximation of such a solution.     

Sull'andamento annuo della pressione atmosferica in relazione con l'altezza sul mare

Riassunto Viene esteso agli Osservatori del Monte Rosa lo studio di alcune regolarità quantitative segnalate daConrad nell'andamento annuo della pressione atmosferica in funzione dell'altezza sul mare, con risultati probativi.

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Summary Some regularities in the yearly variation of the air-pressure, as related with the height above the sea level, have been reported byConrad. These regularities are confirmed by the air-pressure data from the meteorological Observatories of the Monte Rosa.

     

High-temperature behaviour of melilite: in situ X-ray diffraction study of gehlenite–åkermanite–Na melilite solid solution

High-temperature X-ray diffraction experiments have been performed on melilite solid solutions, on single crystal and powder samples. In åkermanite–gehlenite series, the volumetric thermal expansion increases from gehlenite, 26.5(2) E-06 K-1, to åkermanite, 31.2(1) E-06 K-1. The variation is related to the cation content in the tetrahedral T1 site of the structure, and the linear expansion along the a axis has the greatest variation as a function of composition. The expansion perpendicular to the tetrahedral layers does not present any significant variation as a function of composition. In the åkermanite–Na melilite series, the presence of Na in the [8]-coordinated site strongly increases the linear expansion along the c axis, while the volumetric expansion decreases from åkermanite to Na melilite, whose value can be extrapolated to 27.4 E-06 K-1     

The growth of “black crusts” on calcareous building stones in Palermo (Sicily): a first appraisal of anthropogenic and natural sulphur sources

Chemical, mineralogical and isotopic composition (³⁴S/³²S) analyses were carried out on “black crusts” developed on the old buildings of Palermo (Sicily) with the aim to distinguish between natural and anthropogenic sulphur sources. Furthermore individual samples of total suspended particulate (TSP) were collected and analysed in order to estimate the influence of air pollution on the decay process of calcareous stones in a typical southern Mediterranean coastal environment. SEM/EDS analysis, X-ray diffractometry, IR spectroscopy and liquid chromatography led to the compositional characterization of “black crusts” and airborne particulate matter in the city. Sulphur isotopic compositions of gypsum-bearing crusts showed a prevailing contribution of anthropogenic sources (vehicle exhaust and other combustion processes). Natural sulphur and/or sulphate sources (biogenic and/or sea-spray) were shown to play a secondary role. These data can be considered a starting point for the determination of the rate of growth of “black crusts” in a coastal Mediterranean urban environment like Palermo. In the future, they might be useful to local authorities for planning more efficient maintenance action in order to slow as much as possible the rate of decay of the monumental heritage of the city.     

Assessment of the Enhanced Geothermal System Resource Base of the United States

This paper describes an assessment of the enhanced geothermal system (EGS) resource base of the conterminous United States, using constructed temperature at depth maps. The temperature at depth maps were computed from 3 to 10 km, for every km. The methodology is described. Factors included are sediment thickness, thermal conductivity variations, distribution of the radioactive heat generation and surface temperature based on several geologic models of the upper 10 km of the crust. EGS systems are extended in this paper to include coproduced geothermal energy, and geopressured resources. A table is provided that summarizes the resource base estimates for all components of the EGS geothermal resource. By far, the conduction-dominated components of EGS represent the largest component of the U.S. resource. Nonetheless, the coproduced resources and geopressured resources are large and significant targets for short and intermediate term development. There is a huge resource base between the depths of 3 and 8 km, where the temperature reaches 150–250°C. Even if only 2% of the conventional EGS resource is developed, the energy recovered would be equivalent to roughly 2,500 times the annual consumption of primary energy in the U.S. in 2006. Temperatures above 150°C at those depths are more common in the active tectonic regions of the western conterminous U.S., but are not confined to those areas. In the central and eastern U.S. there are identified areas of moderate size that are of reasonable grade and probably small areas of much higher grade than predicted by this analyses. However because of the regional (the grid size is 5′ × 5′) scale of this study such potentially promising sites remain to be identified. Several possible scenarios for EGS development are discussed. The most promising and least costly may to be developments in abandoned or shut-in oil and gas fields, where the temperatures are high enough. Because thousands of wells are already drilled in those locations, the cost of producing energy from such fields could be significantly lowered. In addition many hydrocarbon fields are producing large amounts of co-produced water, which is necessary for geothermal development. Although sustainability is not addressed in this study, the resource is so large that in at least some scenarios of development the geothermal resource is sustainable for long periods of time.