Adaptive fast multipole methods on the GPU

We present a highly general implementation of fast multipole methods on graphics processing units (GPUs). Our two-dimensional double precision code features an asymmetric type of adaptive space discretization leading to a particularly elegant and flexible implementation. All steps of the multipole algorithm are efficiently performed on the GPU, including the initial phase which assembles the topological information of the input data. Through careful timing experiments we investigate the effects of the various peculiarities of the GPU architecture.Comment: Software available at http://user.it.uu.se/~stefane/freeware.htm

ИЗУЧЕНИЕ ПОКАЗАТЕЛЕЙ БЕЗОПАСНОСТИ ЗЕРНОВОГО ПРОДУКТА «ЗЛАКОВЫЙ БАТОНЧИК»

The study of food products is the most important method for creating proves of their food safety based on generally accepted scientific ideas and current international and national legal norms of food safety. At the stage of laboratory research it is possible to objectively prove the efficiency and safety of new types of food products while their consumption according to certain health indications among the relevant group of people, including staff working in hazardous industrial environment. In the Russian Federation the procedure for assessing the safety and running the laboratory tests of food products are regulated by the Federal Laws on the Quality and Safety of Food Products, regulations on provision of public catering services, methodological recommendations for assessing the risk to public health in case of exposure to microbial factors contained in food products, as well as technical regulations of the Customs Union on food safety. The authors have developed regulatory and technical documentation for the cereal product “Cereal bar” and presented data on its safety when consumed. Conclusions about the product are made on the basis of a study of its chronic toxicity. It has been established that the ingredients composition of the cereal bar, included in the diet of laboratory animals, provided a positive effect on their body condition, weight gain and did not cause abnormal changes in the volume of internal organs and the development of pathologies that could indicate a side effect of the product. During study of the hematological and biochemical parameters, no significant differences were found between the data of the control group and experimental group of the animals. The conducted studies of the cereal product “Cereal bar” confirm the absence of a potential risk of developing chronic toxicity in case of introduction of the cereal bar to the animals’ diets and its consumption over a long period of time.Исследование пищевых продуктов является важнейшим инструментом построения доказательной базы их безопасности исходя из общепринятых научных представлений и действующих международных и национальных правовых норм. На этапе лабораторных исследований можно объективно доказать эффективность и безопасность новых видов пищевой продукции при применении по определенным показаниям у соответствующего контингента лиц, в том числе работающих во вредных производственных условиях. В Российской Федерации порядок оценки безвредности и проведение лабораторных исследований продуктов питания регламентируются Федеральными законами о качестве и безопасности пищевых продуктов, постановлениями об оказании услуг общественного питания, методическими рекомендациями по оценке риска здоровью населения при воздействии факторов микробной природы, содержащихся в пищевых продуктах, а также техническим регламентом Таможенного союза о безопасности пищевой продукции. Авторами разработана нормативно-техническая документация на зерновой продукт «Злаковый батончик» и представлены данные о его безвредности при употреблении в пищу Выводы о продукте сделаны на основе изучения его хронической токсичности. Установлено, что ингредиентный состав злакового батончика, включенного в рацион питания лабораторных животных, положительно влияет на прирост массы их тела и не вызывает аномального изменения объема внутренних органов и развития патологий, которые могли бы свидетельствовать о побочном действии продукта. В процессе изучения гематологических и биохимических показателей не найдено достоверных отличий между данными контрольной и опытных групп животных. Проведенные исследования зернового продукта «Злаковый батончик» подтверждают отсутствие потенциальной опасности развития хронической токсичности при добавлении его в рационы питания и употреблении в течение длительного периода времени

Computational Physics on Graphics Processing Units

The use of graphics processing units for scientific computations is an emerging strategy that can significantly speed up various different algorithms. In this review, we discuss advances made in the field of computational physics, focusing on classical molecular dynamics, and on quantum simulations for electronic structure calculations using the density functional theory, wave function techniques, and quantum field theory.Comment: Proceedings of the 11th International Conference, PARA 2012, Helsinki, Finland, June 10-13, 201

The astrometric Gaia-FUN-SSO observation campaign of 99 942 Apophis

Astrometric observations performed by the Gaia Follow-Up Network for Solar System Objects (Gaia-FUN-SSO) play a key role in ensuring that moving objects first detected by ESA's Gaia mission remain recoverable after their discovery. An observation campaign on the potentially hazardous asteroid (99 942) Apophis was conducted during the asteroid's latest period of visibility, from 12/21/2012 to 5/2/2013, to test the coordination and evaluate the overall performance of the Gaia-FUN-SSO . The 2732 high quality astrometric observations acquired during the Gaia-FUN-SSO campaign were reduced with the Platform for Reduction of Astronomical Images Automatically (PRAIA), using the USNO CCD Astrograph Catalogue 4 (UCAC4) as a reference. The astrometric reduction process and the precision of the newly obtained measurements are discussed. We compare the residuals of astrometric observations that we obtained using this reduction process to data sets that were individually reduced by observers and accepted by the Minor Planet Center. We obtained 2103 previously unpublished astrometric positions and provide these to the scientific community. Using these data we show that our reduction of this astrometric campaign with a reliable stellar catalog substantially improves the quality of the astrometric results. We present evidence that the new data will help to reduce the orbit uncertainty of Apophis during its close approach in 2029. We show that uncertainties due to geolocations of observing stations, as well as rounding of astrometric data can introduce an unnecessary degradation in the quality of the resulting astrometric positions. Finally, we discuss the impact of our campaign reduction on the recovery process of newly discovered asteroids.Comment: Accepted for publication in A&

A structural comparison of human serum transferrin and human lactoferrin

The transferrins are a family of proteins that bind free iron in the blood and bodily fluids. Serum transferrins function to deliver iron to cells via a receptor-mediated endocytotic process as well as to remove toxic free iron from the blood and to provide an anti-bacterial, low-iron environment. Lactoferrins (found in bodily secretions such as milk) are only known to have an anti-bacterial function, via their ability to tightly bind free iron even at low pH, and have no known transport function. Though these proteins keep the level of free iron low, pathogenic bacteria are able to thrive by obtaining iron from their host via expression of outer membrane proteins that can bind to and remove iron from host proteins, including both serum transferrin and lactoferrin. Furthermore, even though human serum transferrin and lactoferrin are quite similar in sequence and structure, and coordinate iron in the same manner, they differ in their affinities for iron as well as their receptor binding properties: the human transferrin receptor only binds serum transferrin, and two distinct bacterial transport systems are used to capture iron from serum transferrin and lactoferrin. Comparison of the recently solved crystal structure of iron-free human serum transferrin to that of human lactoferrin provides insight into these differences

The astrometric Gaia-FUN-SSO observation campaign of 99942 Apophis

© 2015 ESO. Aims. Astrometric observations performed by the Gaia Follow-Up Network for Solar System Objects (Gaia-FUN-SSO) play a key role in ensuring that moving objects first detected by ESA's Gaia mission remain recoverable after their discovery. An observation campaign on the potentially hazardous asteroid (99 942) Apophis was conducted during the asteroid's latest period of visibility, from 12/21/2012 to 5/2/2013, to test the coordination and evaluate the overall performance of the Gaia-FUN-SSO. Methods. The 2732 high quality astrometric observations acquired during the Gaia-FUN-SSO campaign were reduced with the Platform for Reduction of Astronomical Images Automatically (PRAIA), using the USNO CCD Astrograph Catalogue 4 (UCAC4) as a reference. The astrometric reduction process and the precision of the newly obtained measurements are discussed. We compare the residuals of astrometric observations that we obtained using this reduction process to data sets that were individually reduced by observers and accepted by the Minor Planet Center. Results. We obtained 2103 previously unpublished astrometric positions and provide these to the scientific community. Using these data we show that our reduction of this astrometric campaign with a reliable stellar catalog substantially improves the quality of the astrometric results. We present evidence that the new data will help to reduce the orbit uncertainty of Apophis during its close approach in 2029. We show that uncertainties due to geolocations of observing stations, as well as rounding of astrometric data can introduce an unnecessary degradation in the quality of the resulting astrometric positions. Finally, we discuss the impact of our campaign reduction on the recovery process of newly discovered asteroids