A physical approach to modelling large-scale galactic magnetic fields

A convenient representation of the structure of the large-scale galactic magnetic field is required for the interpretation of polarization data in the sub-mm and radio ranges, in both the Milky Way and external galaxies. We develop a simple and flexible approach to construct parametrised models of the large-scale magnetic field of the Milky Way and other disc galaxies, based on physically justifiable models of magnetic field structure. The resulting models are designed to be optimised against available observational data. Representations for the large-scale magnetic fields in the flared disc and spherical halo of a disc galaxy were obtained in the form of series expansions whose coefficients can be calculated from observable or theoretically known galactic properties. The functional basis for the expansions is derived as eigenfunctions of the mean-field dynamo equation or of the vectorial magnetic diffusion equation. The solutions presented are axially symmetric but the approach can be extended straightforwardly to non-axisymmetric cases. The magnetic fields are solenoidal by construction, can be helical, and are parametrised in terms of observable properties of the host object, such as the rotation curve and the shape of the gaseous disc. The magnetic field in the disc can have a prescribed number of field reversals at any specified radii. Both the disc and halo magnetic fields can separately have either dipolar or quadrupolar symmetry. The model is implemented as a publicly available software package GalMag which allows, in particular, the computation of the synchrotron emission and Faraday rotation produced by the model's magnetic field. The model can be used in interpretations of observations of magnetic fields in the Milky Way and other spiral galaxies, in particular as a prior in Bayesian analyses. (Abridged.)Comment: 20 pages, 14 figures. Accepted for publication in A&

Влияние политики налогообложения сигарет на бюджетные поступления и употребление сигарет в Узбекистане

BACKGROUND: In 2012,Uzbekistanratified the Framework Convention on Tobacco Control, which states that price and tax measures are an effective means of reducing tobacco consumption. We aimed to explore the effect of taxation policies on revenues and cigarette consumption.METHODS: Data on tax rates, revenues, cigarette sales were taken from national reports. To forecast potential revenues, a scenario analysis was performed.RESULTS: In 1991-2004, ad valorem excise system was in place in Uzbekistan, which was later replaced by the specific excise system. In 1997-2011, the nominal average excise has increased by a factor of twenty, but in real terms, after a sharp increase in 1999, average excise declined annually and increased only in 2010-2011. Annual cigarette sales per capita of adult population in 1999-2007 constituted 17-25 cigarette packs, while in 2008-2011 it increased to 30-37 packs. Four scenarios of excise tax increases in 2012 were developed: one actual scenario based on the rates effective in Uzbekistan in 2012, and three hypothetical ones anticipating excise rates increase by 1.5, 2 and 3-fold. With actual excise increase in 2012, the inflation-adjusted budget revenues would grow by 5%, and with three hypothetical - by 17%, 35% and 66% respectively, despite the decline of tax-paid cigarette sales.CONCLUSION: Stabilization or reduction in cigarette excises in Uzbekistan in 2002-2008 led to a decline in real excise revenues and the growth of cigarette sales. In 1999 and 2010-2011, excises were significantly increased and the real revenues have risen, despite the decline in cigarette sales. As cigarette prices are low, the illegal outflow of cigarettes from Uzbekistan apparently exceeds the illegal inflow. A significant increase in cigarette excise (1.5-3 fold) can both increase budget revenues and reduce cigarette consumption, with greater increase yielding more benefits.KEYWORDS: Uzbekistan; tobacco; excise; cigarettes; revenue.В 2012 году Узбекистан ратифицировал Рамочную конвенцию по борьбе против табака, которая гласит, что ценовые и налоговые меры являются эффективным средством сокращения потребления табака. Нашей целью было изучить влияние налоговой политики на поступления в бюджет и потребление сигарет в стране.МЕТОДЫ: Данные о налоговых ставках, поступлениях в бюджет, продажах сигарет были взяты из национальных отчетов. Для прогнозирования потенциальных поступлений в бюджет был проведен анализ нескольких вариантов повышения ставки акциза.РЕЗУЛЬТАТЫ: В 1991-2004 годах в Узбекистане применялась адвалорная система акцизов, которая впоследствии была заменена специфической системой акцизов. В 1997-2011 годах номинальная средняя ставка акциза выросла в двадцать раз, но в реальном выражении, после резкого увеличения в 1999 году, средняя ставка акциза ежегодно снижалась и возросла лишь в 2010-2011 годах. Годовой объем продаж сигарет на душу взрослого населения в 1999-2007 годах составлял 17-25 пачек сигарет, в то время как в 2008-2011 годах он вырос до 30-37 пачек. Были рассчитаны четыре сценария повышения акцизных налогов в 2012 году: один фактический сценарий, основанный на ставке, действовавшей в Узбекистане в 2012 году, и три гипотетических, которые предполагали рост ставки акциза в 1,5, 2 и 3 раза. При фактическом росте акцизных ставок в 2012 году, поступления в бюджет, с учетом инфляции, вырастут на 5%, а при трех гипотетических вариантах – на 17%, 35% и 66% соответственно, несмотря на снижение объема продаж облагаемых налогом сигарет.ВЫВОДЫ: Стабилизация или снижение акцизов на сигареты в Узбекистане в 2002-2008 годах привели к снижению реальных поступлений в бюджет и к росту продаж сигарет. В 1999 и 2010-2011 годах акцизы были значительно увеличены и реальные доходы выросли, несмотря на снижение продаж сигарет. Из-за низкой цены сигарет незаконный вывоз сигарет из Узбекистана, по-видимому, превышает незаконный ввоз. Значительный рост ставок акциза (в 1,5-3 раза) способен как увеличить бюджетные доходы, так и уменьшить потребление сигарет, при этом, чем больше будет этот рост, тем больше преимуществ получит страна.КЛЮЧЕВЫЕ СЛОВА: Узбекистан; табак; акциз; сигареты; поступления в бюджет

Statistical properties of Faraday rotation measure from large-scale magnetic fields in intervening disc galaxies

To constrain the large-scale magnetic field strengths in cosmologically distant galax- ies, we derive the probability distribution function of Faraday rotation measure (RM) when random lines of sight pass through a sample of disc galaxies, with axisymmetric large-scale magnetic fields. We find that the width of the RM distribution of the galaxy sample is directly related to the mean large-scale field strength of the galaxy population, provided the dispersion within the sample is lower than the mean value. In the absence of additional constraints on parameters describing the magneto-ionic medium of the intervening galaxies, and in the situation where RMs produced in the intervening galaxies have already been statistically isolated from other RM contributions along the lines of sight, our simple model of the magneto-ionic medium in disc galaxies suggests that the mean large-scale magnetic field of the population can be measured to within ~ 50% accuracy.Comment: 4 pages, Proceedings of FM8 "New Insights in Extragalactic Magnetic Fields", XXXth General Assembly of the IAU, Vienna, August 20-31, 201