859 research outputs found

    Electronic filing : what practitioners of small and medium size accounting firms are saying

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    Problems presently exist within the government's Electronic Filing System. Since the government has a goal of becoming a paperless tax return filing system, they need to be aware of these problems. A survey of practitioners was conducted in order to understand the problems that practitioners are experiencing with the system, and possible solutions. All major issues were addressed with possible solutions. The aim of the paper was to make the IRS aware of the problems and I took the side of the devil's advocate showing all the major problems that could be found with the Electronic Filing System.B.A. (Bachelor of Arts

    Tjernobyl och rennäringen - Lägesrapport från Sverige

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    Status report about Chernobyl and reindeer husbandry in Sweden including participants' discussion.Abstract in Swedish / Sammanfattning: Den 1 juli hojdes grånsvårdet for Cs-137 i bl a renkott från 300 till 1 500 Bq/kg. Efter hojningen av grånsvårdet friklassades nåstan alla samebyar i Norrbottens lån under sarvslakten. Samtliga fjållsamebyar i Norrbottens lån utom den sydligaste år tills vidare helt friklassade. Tre samebyar i sodra delen av Jåmtlands lån var friklassade under sarvslakten. I ovrigt omfattas all renslakt i Våsterbottens och Jåmtlands lån av kontroll betråffande Cs-137. Under juli - aug i år var cesiumhalten lågre ån vid motsvarande tidpunkt i f jol (tabell 1 och figur 1). Under juli - aug slaktades drygt 1 000 renar i skogslandet i sodra delen av Våsterbottens lån (tabell 3). Fr.o.m. andra veckan i juli godkåndes de fiesta slaktkropparna. Halveringstiden for Cs-137 i renarna, som betade i skogslandet kring inlandsbanan i sodra delen av Våsterbottenslån, har beråknats till ca en vecka. Genom tidigarelåggning av sarvslakter i Våsterbottens lån (tabell 3) och norra delen av Jåmtlands lån (tabell 5) minskades kassationen med ett par tusen slaktkroppar. Under senare delen av september steg cesiumhalten till ungefår samma nivå som i f jol. En långsiktig prognos har utarbetats betråffande halten Cs-137 i renar på naturbete. Prognosen visar att omfattande åtgårder kommer att behova vidtagas under de nårmaste 15 - 25 åren om ren-kottet från samebyarna i sodra delen av Våsterbottens lån och norra delen av Jåmtlands lån skall kunna god-kånnas som livsmedel vid ett riktvårde på 1 500 Bq Cs-137/kg kott

    Van der Waals Density Functional for General Geometries

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    A scheme within density functional theory is proposed that provides a practical way to generalize to unrestricted geometries the method applied with some success to layered geometries [H. Rydberg, et al., Phys. Rev. Lett. 91, 126402 (2003)]. It includes van der Waals forces in a seamless fashion. By expansion to second order in a carefully chosen quantity contained in the long range part of the correlation functional, the nonlocal correlations are expressed in terms of a density-density interaction formula. It contains a relatively simple parametrized kernel, with parameters determined by the local density and its gradient. The proposed functional is applied to rare gas and benzene dimers, where it is shown to give a realistic description.Comment: 4 pages, 4 figure

    On cloud ice induced absorption and polarisation effects in microwave limb sounding

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    Microwave limb sounding in the presence of ice clouds was studied by detailed simulations, where clouds and other atmospheric variables varied in three dimensions and the full polarisation state was considered. Scattering particles were assumed to be horizontally aligned oblate spheroids with a size distribution parameterized in terms of temperature and ice water content. A general finding was that particle absorption is significant for limb sounding, which is in contrast to the down-looking case, where it is usually insignificant. Another general finding was that single scattering can be assumed for cloud optical paths below about 0.1, which is thus an important threshold with respect to the complexity and accuracy of retrieval algorithms. The representation of particle sizes during the retrieval is also discussed. Concerning polarisation, specific findings were as follows: Firstly, no significant degree of circular polarisation was found for the considered particle type. Secondly, for the ±45° polarisation components, differences of up to 4 K in brightness temperature were found, but differences were much smaller when single scattering conditions applied. Thirdly, the vertically polarised component has the smallest cloud extinction. An important goal of the study was to derive recommendations for future limb sounding instruments, particularly concerning their polarisation setup. If ice water content is among the retrieval targets (and not just trace gas mixing ratios), then the simulations show that it should be best to observe any of the ±45° and circularly polarised components. These pairs of orthogonal components also make it easier to combine information measured from different positions and with different polarisations

    First Odin sub-mm retrievals in the tropical upper troposphere: ice cloud properties

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    International audienceMore accurate global measurements of the amount of ice in thicker clouds are needed to validate atmospheric models and sub-mm radiometry can be an important component in this respect. A cloud ice retrieval scheme for the first such instrument in space, Odin-SMR, is presented here. Several advantages of sub-mm observations are shown, such as low influence of particle shape and orientation, and a high dynamic range of the retrievals. In the case of Odin-SMR, only cloud ice above ?12.5 km can be measured. The present retrieval scheme gives a detection threshold of about 4 g/m2 above 12.5 km and does not saturate even for thickest observed clouds (>500 g/m2). The main retrieval uncertainties are the assumed particle size distribution and cloud inhomogeneity effects. The overall retrieval accuracy is estimated to be ~75%. The retrieval error is judged to have large random components and to be significantly lower than this value for averaged results, but high fixed errors can not be excluded. However, a firm lower value can always be provided. Initial results are found to be consistent with similar Aura MLS retrievals, but show important differences to corresponding data from atmospheric models. This first retrieval algorithm is limited to lowermost Odin-SMR tangent altitudes, and further development should improve the detection threshold and the vertical resolution. It should also be possible to decrease the retrieval uncertainty associated with cloud inhomogeneities by detailed analysis of other data sets

    Enhanced dispersion interaction between quasi-one dimensional conducting collinear structures

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    Recent investigations have highlighted the failure of a sum of R6R^{-6} terms to represent the dispersion interaction in parallel metallic, anisotropic, linear or planar nanostructures [J. F. Dobson, A. White, and A. Rubio, Phys. Rev. Lett. 96, 073201 (2006) and references therein]. By applying a simple coupled plasmon approach and using electron hydrodynamics, we numerically evaluate the dispersion (non-contact van der Waals) interaction between two conducting wires in a collinear pointing configuration. This case is compared to that of two insulating wires in an identical geometry, where the dispersion interaction is modelled both within a pairwise summation framework, and by adding a pinning potential to our theory leading to a standard oscillator-type model of insulating dielectric behavior. Our results provide a further example of enhanced dispersion interaction between two conducting nanosystems compared to the case of two insulating ones. Unlike our previous work, this calculation explores a region of relatively close coupling where, although the electronic clouds do not overlap, we are still far from the asymptotic region where a single power law describes the dispersion energy. We find that strong differences in dispersion attraction between metallic and semiconducting / insulating cases persist into this non-asymptotic region. While our theory will need to be supplemented with additional short-ranged terms when the electronic clouds overlap, it does not suffer from the short-distance divergence exhibited by purely asymptotic theories, and gives a natural saturation of the dispersion energy as the wires come into contact.Comment: 10 pages, 5 figures. Added new extended numerical calculations, new figures, extra references and heavily revised tex

    Comparison between the first Odin-SMR, Aura MLS and CloudSat retrievals of cloud ice mass in the upper tropical troposphere

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    International audienceEmerging microwave satellite techniques are expected to provide improved global measurements of cloud ice mass. CloudSat, Aura MLS and Odin-SMR fall into this category and first cloud ice retrievals from these instruments are compared. The comparison is made for partial ice water columns above 12 km, following the SMR retrieval product. None of the instruments shows significant false cloud detections and a consistent view of the geographical distribution of cloud ice is obtained, but differences on the absolute levels exist. CloudSat gives the lowest values, with an overall mean of 2.12 g/m2. A comparable mean for MLS is 4.30 g/m2. This relatively high mean can be an indication of overestimation of the vertical altitude of cloud ice by the MLS retrievals. The vertical response of SMR has also some uncertainty, but this does not affect the comparison between MLS and CloudSat. SMR observations are sensitive to cloud inhomogeneities inside the footprint and some compensation is required. Results in good agreement with CloudSat, both in regard of the mean and probability density functions, are obtained for a weak compensation, while a simple characterisation of the effect indicates the need for stronger compensation. The SMR mean was found to be 1.89/2.62/4.10 g/m2 for no/selected/strongest compensation, respectively. Assumptions about the particle size distribution are a consideration for all three instruments, and constitute the dominating retrieval uncertainty for CloudSat. The comparison indicates a retrieval accuracy of about 40% (3.1±1.2 g/m2). This number is already very small compared to uncertainties of cloud ice parametrisation in atmospheric models, but can be decreased further through a better understanding of main retrieval error sources

    Comparison between early Odin-SMR, Aura MLS and CloudSat retrievals of cloud ice mass in the upper tropical troposphere

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    International audienceEmerging microwave satellite techniques are expected to provide improved global measurements of cloud ice mass. CloudSat, Aura MLS and Odin-SMR fall into this category and early cloud ice retrievals from these instruments are compared. The comparison follows the SMR retrieval product and is made for partial ice water columns above 12 km. None of the retrievals shows a significant degree of false cloud detections, the ratio between local mean values from the instruments is fairly constant and a consistent view of the geographical distribution of cloud ice is obtained. However, important differences on the absolute levels exist, where the overall mean is 9.6, 4.2 and 3.7 g m?2 for CloudSat, SMR and MLS, respectively. Assumptions about the particle size distribution (PSD) are a consideration for all three instruments and constitute the dominating retrieval uncertainty for CloudSat. The mean for CloudSat when applying the same PSD as for MLS and SMR was estimated to 6.3 g m?2. A second main consideration for MLS and SMR are the effects caused by the poorer spatial resolution: a possible vertical misplacement of retrieved values and an impact of cloud inhomogeneities. The latter effect was found to be the dominating retrieval uncertainty for SMR, giving a possible mean value range of 2.3?8.9 g m?2. The comparison indicates a common retrieval accuracy in the order of 70%. Already this number should suffice for improved validations of cloud ice parametrisation schemes in atmospheric models, but a substantially better consistency between the datasets should be attainable through an increased understanding of main retrieval error sources

    Nature and chemical abundances of a sample of Lyman-α emitter objects at high redshift

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    We built a grid of photoionization models and compiled already available observational emission line intensities (1000 53. Values for C/O abundance ratio derived for the LAEs seem to be consistent with those derived for local star forming objects with similar metallicities, while an overabundance of N/O was found for most of the LAEs.Instituto de Astrofísica de La Plat
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