Dynamics of wide binary stars: A case study for testing Newtonian dynamics in the low acceleration regime

Extremely wide binary stars represent ideal systems to probe Newtonian dynamics in the low acceleration regimes (<10e-10 m/s/s) typical of the external regions of galaxies. Here we present a study of 60 alleged wide binary stars with projected separation ranging from 0.004 to 1 pc, probing gravitational accelerations well below the limit were dark matter or modified dynamics theories set in. Radial velocities with accuracy ~100 m/s were obtained for each star, in order to constrain their orbital velocity, that, together with proper motion data, can distinguish bound from unbound systems. It was found that about half of the observed pairs do have velocity in the expected range for bound systems, out to the largest separations probed here. In particular, we identified five pairs with projected separation >0.15 pc that are useful for the proposed test. While it would be premature to draw any conclusion about the validity of Newtonian dynamics at these low accelerations, our main result is that very wide binary stars seem to exist in the harsh environment of the solar neighborhood. This could provide a tool to test Newtonian dynamics versus modified dynamics theories in the low acceleration conditions typical of galaxies. In the near future the GAIA satellite will provide data to increase significantly the number of wide pairs that, with the appropriate follow up spectroscopic observations, will allow the implementation of this experiment with unprecedented accuracy.Comment: Accepted for publication on International Journal of Modern Physics

Integration of computation methods into radiation sterilization process

Authors have developed the computer technology for simulation of practical tasks in radiation sterilization process in accordance with Method 1, Standard ISO 11137 and IAEA Code of Practice. The technology was realized on the base of the RT-Office modules for modeling by Monte Carlo method of an absorbed dose in an irradiated heterogeneous targets with electron beam (EB), X-ray and gamma-ray and specialized software ModeSAL. The software ModeSAL was used for simulation and comparative analysis of a sterility assurance level (SAL) and a sterilizing dose for bioburden to achieve a required SAL in an irradiated product. The mathematical approach of the technology is based on the detailed and precise consideration of a self-consistent physical and geometrical models of calculation an EB, X-ray and gamma-ray dose maps in an irradiated product, a SAL, a sterilizing dose and the spatial and time uncertainties for dose provided to an irradiated product. The analysis of interrelations between parameters of EB radiation facility and values of a SAL and a sterilizing dose are considered. Разработана компьютерная технология для решения практических задач процесса радиационной стерилизации в соответствии со стандартом ISO 11137 и кодами практики МАГАТЭ. Технология реализована на основе модулей RT-Office и специализированного программного обеспечения ModeSAL. Модули RT-Office предназначены для расчета методом Монте-Карло поглощенной дозы в гетерогенных мишенях, облучаемых пучками электронов, тормозным или гамма излучением. Программное обеспечение ModeSAL использовалось для моделирования и сравнительного анализа уровня стерильности и стерилизационной дозы для микробной контаминации в облучаемом продукте. Математический подход технологии основан на детальном и корректном учете самосогласованных физических и геометрических моделей расчета поля дозы электронов, тормозного и гамма излучения, уровня стерильности и стерилизационной дозы а также пространственных и временных неоднородностей дозы в облучаемой мишени. Проводится анализ взаимосвязи между параметрами радиационного оборудования пучков электронов и величинами уровня стерильности и стерилизационной дозы

Cold Chain Energy Analysis for Sustainable Food and Beverage Supply

Perishable goods, such as chilled and frozen foods, have a short shelf life and high sensitivity to their surrounding environment (e.g., temperature, humidity, and light intensity). For this reason, they must be distributed within a specific time and require special equipment and facilities (e.g., refrigeration and dehumidification systems) throughout the entire chain from farm to fork to ensure slow deterioration and to deliver safe and high-quality products to consumers. Cold chains can last for short periods, such as a few hours, or for several months or even years (e.g., frozen food products) depending on the product and the target market. A huge amount of energy is required to preserve quality by maintaining the desired temperature level over time. The required energy is also affected by inventory management policies (e.g., warehouse filling levels affect the cooling demand per unit of a product) and the behavior of the operators (e.g., number and duration of door openings). Furthermore, waste entails the loss of energy and other resources consumed for processing and storing these products. The aim of the present study is to propose a quantitative approach in order to map the energy flows throughout the cold chain in the food and beverage sector and to evaluate the overall energy performance. The results of the energy flow mapping give decisionmakers insights into the minimum energy required by the cold chain and allow them to prioritize energy efficiency measures by detecting the most energy consuming stages of the cold chain. The implementation of a holistic approach, shifting from a single-company perspective to chain assessment, leads to a global optimum and to an increased implementation rate of energy efficiency measures due to the reduced barriers perceived by different actors of the cold chain

Relativistic model of hidden bottom tetraquarks

The relativistic model of the ground state and excited heavy tetraquarks with hidden bottom is formulated within the diquark-antidiquark picture. The diquark structure is taken into account by calculating the diquark-gluon vertex in terms of the diquark wave functions. Predictions for the masses of bottom counterparts to the charm tetraquark candidates are given.Comment: 6 page

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 359)

This bibliography lists 164 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during Jan. 1992. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance