7 research outputs found
Neon abundances in mercury-manganese stars: Radiative accelerators and non-LTE calculations
No full textWe make new non-local thermodynamic equilibrium calculations to deduce the abundances of neon from visible-region echelle spectra of selected Ne i lines in seven normal stars and 20 HgMn stars. We find that the best strong blend-free Ne line that can be used at the lower end of the effective temperature Teff range is λ6402, although several other potentially useful Ne i lines are found in the red region of the spectra of these stars. The mean neon abundance in the normal stars (log A=8.10) is in excellent agreement with the standard abundance of neon (8.08). However, in HgMn stars neon is almost universally underabundant, ranging from marginal deficits of 0.1–0.3 dex to underabundances of an order of magnitude or more. In many cases, the lines are so weak that only upper limits can be established. The most extreme example found is υ Her with an underabundance of at least 1.5 dex. These underabundances are qualitatively expected from radiative acceleration calculations, which show that Ne has a very small radiative acceleration in the photosphere, and that it is expected to undergo gravitational settling if the mixing processes are sufficiently weak and there is no strong stellar wind. According to theoretical predictions, the low Ne abundances place an important constraint on the intensity of such stellar winds, which must be less than 10−14 M⊙ yr−1 if they are non-turbulent
Exotic branes in Exceptional Field Theory: E <inf>7(7)</inf> and beyond
No full text© 2018, The Author(s). In recent years, it has been widely argued that the duality transformations of string and M-theory naturally imply the existence of so-called ‘exotic branes’ — low codimension objects with highly non-perturbative tensions, scaling as gsα for α ≤ −3. We argue that their intimate link with these duality transformations make them an ideal object of study using the general framework of Double Field Theory (DFT) and Exceptional Field Theory (EFT) — collectively referred to as ExFT. Parallel to the theme of dualities, we also stress that these theories unify known solutions in string- and M-theory into a single solution under ExFT. We argue that not only is there a natural unifying description of the lowest codimension objects, many of these exotic states require this formalism as a consistent supergravity description does not exist
Exotic branes in Exceptional Field Theory: E <inf>7(7)</inf> and beyond
No full text© 2018, The Author(s). In recent years, it has been widely argued that the duality transformations of string and M-theory naturally imply the existence of so-called ‘exotic branes’ — low codimension objects with highly non-perturbative tensions, scaling as gsα for α ≤ −3. We argue that their intimate link with these duality transformations make them an ideal object of study using the general framework of Double Field Theory (DFT) and Exceptional Field Theory (EFT) — collectively referred to as ExFT. Parallel to the theme of dualities, we also stress that these theories unify known solutions in string- and M-theory into a single solution under ExFT. We argue that not only is there a natural unifying description of the lowest codimension objects, many of these exotic states require this formalism as a consistent supergravity description does not exist
Potential energy surfaces fur rare gas open shell van der Waals complexes: How well can {ab initio} theory predict them?
No full text1) A.D. Eposti, H.J. Werner, J. Chem. Phys. 93(5), 3351 (1990)Author Institution: Department of Chemistry, Emory UniversityIn the past few years many {ab initio} calculations have been performed to calculate potential energy surfaces for closed and open shell van der Waals complexes. The level of theory used ranges from SCF,CASSF, MRCI, to perturbation methods. To date, the most successful calculations for an open-shell system were made for . The calculated potential energy surface for the state was in good agreement with the surface deducted from spectroscopic data However, the {ab initio} calculations appeared to underestimate the depth of the state potential surfaces. In the present work we report new CEPA potential surfaces for -Rg complexes with Rg=He, Ne and Kr. For -Ne and -Kr, comparisons between the rovibronic energies predicted from the surfaces, and those measured experimentally, will be presented. For OH-He, predications of the binding energies and geometries will be reported
Is Sustainable Development of Deserts Feasible?
No full textHot deserts that presently cover about one-fifth of the land area of our planet are rapidly devouring more and more arable lands mostly due to anthropogenic causes. We propose an interdisciplinary approach to revitalizing and commercializing hot deserts, which is based on systems thinking and Russian and NASA space technology experience in designing life-support systems for long-duration flights. We formulate ten principles for the design of sustainable life support systems in deserts, which can make the development of the deserts feasible. It is discussed how the principles can be employed to design and operate desert’s eco-industrial parks with greenhouses in which the transpired and evaporated moisture is collected and condensed. The potential benefits of setting up the eco-industrial parks in deserts include the slowdown and eventual reversal of the desertification trend, the migration of many industrial production facilities from mild-climate regions to deserts, the increased availability of potable water and food in deserts, the development of poor African countries, and the emergence of new investment markets
Tri-vector deformations in d = 11 supergravity
No full text© 2019, The Author(s). We construct a d = 11 supergravity analogue of the open-closed string map in the context of SL(5) Exceptional Field Theory (ExFT). The deformation parameter tri-vector Ω generalizes the non-commutativity bi-vector parameter Θ of the open string. When applied to solutions in d = 11, this map provides an economical way of performing TsT deformations, and may be used to recover d = 10 Yang-Baxter deformations after dimensional reduction. We present a generalization of the Classical Yang-Baxter Equation (CYBE) for rank 3 objects, which emerges from d = 11 supergravity and the SL(5) ExFT. This equation is shown to reduce to the d = 10 CYBE upon dimensional reduction
Определение суммарного содержания некоторых вторичных метаболитов в различных органах дагестанских образцов Capparis herbacea Willd.
No full textRelevance, material and methods. Purpose of the work: comparative assessment of the content of the sum of phenolic compounds exhibiting antioxidant activity in various organs of herbaceous capers C. herbacea Willd. The 4 samples of C. herbaceawere collected from natural populations of Dagestan during the flowering and fruiting phases in the summer of 2019. The collected raw materials were divided into fractions (organs), dried in the shade to an air-dry mass, then subjected to further analysis to determine the total content of flavonoids, anthocyanins by the spertrophotometric method on SF-56; the total content of antioxidants by the amperometric method on the instrument of express analysis "Color-Yauza-001-AAA ".Results. During the analysis, good indicators were obtained for the content of the studied compounds. Thus, in terms of the content of flavonoids, the greatest variation is seen in the stems of herbaceous capers (0.34-0.86%) compared to their content in leaves and inflorescences (2.67-2.97% and 2.45-2.90%, respectively). The amount of anthocyanins varies in all organs within the range of 0.05-0.23%. The smallest spread is observed in the total content of antioxidants in the fruits of herbaceous capers (21.35-21.40 mg/l), while in inflorescences this indicator varies greatly (27.44-42.19 mg/l). It is noteworthy that the samples with a high value of antioxidants showed a low content of flavonoids, thereby indicating that flavonoids are not the main components in the antioxidant system of the studied caper species. An important condition determining the variability of the content of phenolic compounds in various plant organs is a complex of abiotic environmental factors. The study of this factor (altitude gradient) revealed a significant relationship with the accumulation of flavonoids in all organs, which has a multi-vector nature (correlation coefficient r*= 0.57; 0.56; -0.47), respectively, in stems, leaves, and inflorescences (P<0,05). A positive relationship in the accumulation of anthocyanins is observed with the height in caper leaves. In all other cases, the connection is random. In addition, the analysis of variance revealed that a large difference in the variability of the studied compounds is observed between individual groups of plants in the absence of intragroup variability.Актуальность, материал и методика. Цель работы: сравнительная оценка содержания суммы фенольных соединений, в различных органах каперсов C. herbaceaWilld. Было собрано 4 образца C. herbaceaв природных популяциях Дагестана в фазу цветения и плодоношения летом 2019 года. Собранное сырье было разделено по фракциям (органы), высушено в тени до воздушно-сухой массы, затем подвергнуто дальнейшему анализу на определение суммарного содержания флавоноидов, антоцианов спектрофотометрическим методом на СФ-56; суммарное содержание антиоксидантов – амперометрическим методом на приборе экспресс-анализа «Цвет-Яуза - 001-ААА».Результаты. По содержанию флавоноидов наибольший разброс обнаружен в стеблях (0,34-0,86%) по сравнению с их содержанием в листьях и соцветиях (2,67-2,97% и 2,45-2.90%, соответственно). Сумма антоцианов варьирует по всем органам в пределах 0,05-0,23%. Наименьший разброс наблюдается в суммарном содержании антиоксидантов в плодах каперсов травянистых (21,35-21,40 мг/л), в то время как в соцветиях этот показатель сильно разнится (27,44-42,19 мг/л). Образцы с высоким значением антиоксидантов показали низкое содержание флавоноидов, тем самым указывая на то, что в антиоксидантной системе изучаемого вида каперсов флавоноиды не являются главными компонентами. Важным условием, определяющим изменчивость содержания фенольных соединений в различных органах растений, является комплекс абиотических факторов среды. Изучение этого фактора (высотный градиент) выявило существенную связь с накоплением флавоноидов во всех органах, имеющий разновекторный характер (коэффициент корреляции r*=0,57; 0,56; -0,47), соответственно в стеблях, листьях, соцветиях (P<0,05). Положительную связь с высотой над уровнем моря в накоплении антоцианов наблюдали в листьях каперсов. Во всех остальных случаях связь имеет случайный характер. Дисперсионный анализ позволил выявить, что большая разница изменчивости изучаемых соединений наблюдается между отдельными группами растений при отсутствии внутригрупповой изменчивости. Полученные результаты могут быть интересны в объяснении механизмов влияния разных абиотических факторов на изменчивость накопления вторичных метаболитов. Важно также и выявление образцов каперсов травянистых, которые могут быть источниками фенольных соединений, обладающих антиоксидантной функцией, для дальнейшего использования их в пищевой промышленности, в частности
