Nuclear fission: The "onset of dissipation" from a microscopic point of view

Semi-analytical expressions are suggested for the temperature dependence of those combinations of transport coefficients which govern the fission process. This is based on experience with numerical calculations within the linear response approach and the locally harmonic approximation. A reduced version of the latter is seen to comply with Kramers' simplified picture of fission. It is argued that for variable inertia his formula has to be generalized, as already required by the need that for overdamped motion the inertia must not appear at all. This situation may already occur above T=2 MeV, where the rate is determined by the Smoluchowski equation. Consequently, comparison with experimental results do not give information on the effective damping rate, as often claimed, but on a special combination of local stiffnesses and the friction coefficient calculated at the barrier.Comment: 31 pages, LaTex, 9 postscript figures; final, more concise version, accepted for publication in PRC, with new arguments about the T-dependence of the inertia; e-mail: [email protected]

Masses, Oxygen and Carbon abundances in CHEPS dwarf stars

Reproduced with permission from Astronomy & Astrophysics. © 2019 ESOContext. We report the results from the determination of stellar masses, carbon, and oxygen abundances in the atmospheres of 107 stars from the Calan-Hertfordshire Extrasolar Planet Search (CHEPS) programme. Our stars are drawn from a population with a significantly super-solar metallicity. At least 10 of these stars are known to host orbiting planets. Aims. In this work, we set out to understand the behaviour of carbon and oxygen abundance in stars with different spectral classes, metallicities, and V sin i within the metal-rich stellar population. Methods. Masses of these stars were determined using data from Gaia DR2. Oxygen and carbon abundances were determined by fitting the absorption lines. We determined oxygen abundances with fits to the 6300.304 Å O I line, and we used 3 lines of the C I atom and 12 lines of the C 2 molecule for the determination of carbon abundances. Results. We determine masses and abundances of 107 CHEPS stars. There is no evidence that the [C/O] ratio depends on V sin i or the mass of the star within our constrained range of masses, i.e. 0.82 5 km s -1) are massive stars.Peer reviewedFinal Published versio

Pharmacovigilance [Pharmacovigilance update]

The main pharmacovigilance updates in 2020 are reviewed. Remdesivir in COVID-19: relatively safe but turns out to be less effective than expected. Hydroxychloroquine in COVID-19 : lack of efficacy and risk of arrhythmias. Cytokines storm in COVID-19: may impact pharmacokinetics. VEGF inhibitors: risk of aneurysm and artery dissection. Tofacitinib: dose-dependant risk of venous thromboembolic events. Ondansetron in the first trimester of pregnancy : a highly debated risk of orofacial cleft defects. Fingolimod : contraindicated during pregnancy due to suspected risk of congenital malformations. Ranitidine: global market withdrawal due to contamination with nitrosamines. Ulipristal for uterine fibroids : market withdrawal due to risk of severe liver injury. Ingenol mebutate : market withdrawal due to paradoxical risk of skin cancers

Схожість насіння та біометричні показники плодів павловнії повстис¬тої Paulownia Tomentosa Steud. різного географічного походження

Paulownia tomentosa Steud. – rapid growing wood breed, capable to regenerate many times by sprout shoots after the cutting of tree and accelerating the growth of subsequent generations, it is a perspective for plantation cultivation in Ukraine. The purpose of the work is to investigate the germination quality of the seeds of the Paulownia tomentosa and the biometric indicators of the fruits and seeds, depending on the geographical origin of the trees, to evaluate the possibility of using the zoned seeds for the cultivation of high quality planting material. Biometric indicators were determined on the basis of measurements of the size of the fruits obtained in different geographical regions of Ukraine (Lviv, Transcarpathian and Odessa oblasts). To determine the effect of temperature on crop quality, germination of seeds was carried out at two temperature regimes: +15…20 °С and +21…25 °С. To determine the effect of the duration of pre-wetting on similarity indicators, seeds were soaked in water with a temperature of +20 °С 24 and 48 hours. In the conditions of the Odessa region, Paulownia tomentosa forms larger fruits, the weight of which is dominated by a mass of fruits from the Transcarpathian and Lviv regions by 24 and 38 %. Seeds of this origin are heavier and are characterized by higher sprouting rates and the friendly appearance of seed germinations. In the temperature mode of sprouting + 20…25 °С, the technical germination of the Paulownia tomentosa seeds varies from 88 to 99 %, regardless of geographical origin. At pre-soaked seeds in water for 48 hours are increasing of germination by 4–5 %, when soaked for 24 hours – by 1–3 % compared to the control (without soaking). The energy of seed germination is increased by 10–40 % and by 8–27 %. In the seeds harvested in Odessa average of seed rest is the smallest and ranges from 6.4 to 7.3 days, which indicates a very high seed germination rate. The decrease in the temperature of germination of the Paulownia tomentosa seeds leads to a decrease in all similarity indicators. The technical germination of the seeds varies in the range of 66–79 %; compared with the germination at a temperature of + 20… 25 °С decreases in the studied index is 20–23 %. Preliminary soaking of seedlings at lower temperatures also has a positive effect on seed germination. Seeds of Paulownia tomentosa are characterized by a high technical germination, regardless of geographical origin. The temperature decreasing significantly slows the seed germination process and causes a decrease in germination indexes. The increase in the duration of the pre-wetting is due to an increase in the technical germination and energy of seed germination. In general, the studied seed of three origins is characterized by high crop qualities and can be used for growing seedling material.Наведено результати дослідження біометричних показників плодів та насіння Paulownia tomentosa Steud., заготовлених із дерев, що зростають у ґрунтово-кліматичних умовах Одеської, Закарпатської та Львівської областей. Встановлено, що в умовах Одеської області павловнія повстиста формує більші плоди. Насіння цього походження характеризується значною швидкістю проростання та дружністю появи сходів. Досліджено вплив змінного температурного режиму пророщування на посівні якості насіння різного географічного походження. Встановлено, що зниження температури пророщування спричиняє зменшення енергії проростання, лабораторної та абсолютної схожості насіння, збільшує середній насінний спокій. Оцінено вплив тривалості попереднього намочування на схожість насіння. Виявлено, що попереднє намочування насіння істотно підвищує показники схожості, його тривалість пов'язується з показниками енергії проростання, технічної та абсолютної схожості. Встановлено, що серед трьох походжень насіння найвища технічна схожість характерна для насіння з Львівської області. Насіння з Одеської області має найвищу енергію проростання. Загалом досліджуване насіння всіх трьох походжень характеризується високими посівними якостями, що свідчить про можливість використання районованого насіння для вирощування садивного матеріалу і створення насаджень з притаманною для материнських рослин біологічною стійкістю, зокрема до впливу низьких температур у конкретних ґрунтово-кліматичних умовах

Mean first passage time for nuclear fission and the emission of light particles

The concept of a mean first passage time is used to study the time lapse over which a fissioning system may emit light particles. The influence of the "transient" and "saddle to scission times" on this emission are critically examined. It is argued that within the limits of Kramers' picture of fission no enhancement over that given by his rate formula need to be considered.Comment: 4 pages, RevTex, 4 postscript figures; with correction of misprints; appeared in Phys. Rev. Lett.90.13270

Statistical fluctuations for the fission process on its decent from saddle to scission

We reconsider the importance of statistical fluctuations for fission dynamics beyond the saddle in the light of recent evaluations of transport coefficients for average motion. The size of these fluctuations are estimated by means of the Kramers-Ingold solution for the inverted oscillator, which allows for an inclusion of quantum effects.Comment: 12 pages, Latex, 5 Postscript figures; submitted to PRC e-mail: [email protected] www home page: http://www.physik.tu-muenchen.de/tumphy/e/T36/hofmann.htm

A detailed study of Lithium in 107 CHEPS dwarf stars

Reproduced with permission from Astronomy & Astrophysics, © ESO 2018.Context. We report results from lithium abundance determinations using high resolution spectral analysis of the 107 metal-rich stars from the Calan-Hertfordshire Extrasolar Planet Search programme. Aims. We aim to set out to understand the lithium distribution of the population of stars taken from this survey. Methods. The lithium abundance taking account of non-local thermodynamical equilibrium effects was determined from the fits to the Li I 6708 Å resonance doublet profiles in the observed spectra. Results. We find that a) fast rotators tend to have higher lithium abundances; b) log N(Li) is higher in more massive and hot stars; c) log N(Li) is higher in stars of lower log g; d) stars with the metallicities >0.25 dex do not show the lithium lines in their spectra; e) most of our planet hosts rotate slower; and f) a lower limit of lithium isotopic ratio is 7Li/ 6Li > 10 in the atmospheres of two stars with planets (SWP) and two non-SWP stars. Conclusions. Measurable lithium abundances were found in the atmospheres of 45 stars located at distances of 20-170 pc from the Sun, for the other 62 stars the upper limits of log N(Li) were computed. We found well defined dependences of lithium abundances on T eff, V sin i, and less pronounced for the log g. In case of V sin i we see two sequences of stars: with measurable lithium and with the upper limit of log N(Li). About 10% of our targets are known to host planets. Only two SWP have notable lithium abundances, so we found a lower proportion of stars with detectable Li among known planet hosts than among stars without planets. However, given the small sample size of our planet-host sample, our analysis does not show any statistically significant differences in the lithium abundance between SWP and stars without known planets.Peer reviewe

Mean-field description of ground-state properties of drip-line nuclei. (I) Shell-correction method

A shell-correction method is applied to nuclei far from the beta stability line and its suitability to describe effects of the particle continuum is discussed. The sensitivity of predicted locations of one- and two-particle drip lines to details of the macroscopic-microscopic model is analyzed.Comment: 22 REVTeX pages, 13 uuencoded postscript figures available upon reques

Особливості росту біогрупи гіркокаштана звичайного у Зіболківському лісництві ДП "Жовківське лісове господарство"

A short description of the horse chestnut is given. It was established that the of introducent's plantation in the Zibolkivsky forestry of the State Enterprise "Zhovkva Forestry" was established at the beginning of the 20th century and is associated with the name of the outstanding public figure of the Galychyna in those times – Oleksandr Skarbek. The productivity indices of planting of the investigated breed are determined. It is established that at the age of 95 years the plantation of the horse chestnut, reaching an average height of 19.5 m and an average diameter of 44.3 cm, are forming a stock of 1 hectare – 600 m3. The peculiarities of the natural renewal of the introducent have been studied and the changes in the processes of natural renewal occurrence in the investigated plant have been investigated and the main factors influencing this process are established. A comparative analysis of the natural regeneration of the horse chestnut and sycamore maple (Acer pseudoplatanus L.) under the cover of the introducent tree stand is made. It was established horse chestnut lags behind in growth, quantity and vitality, and, being in conditions of excessive shading, "falls" from the growth to the age of 8 years. The amount of vital undergrowth of the horse chestnut is not satisfactory, and its distribution is uneven. It is established that horse chestnut is not an aggressive breed in relation to local tree species, and its undergrowth is not able to compete with the undergrowth of aboriginal species. The conducted researches show that horse chestnut in the conditions of the wet hornbeam pine sudibrova (mixed oakery) of the Small Polissya of Ukraine has reached the highest level of acclimatization – naturalization, which confirms the ability of the species to a natural renewal. The unique 109-year-old plantation of the horse chestnut in Zibolkivsky forestry of the State Enterprise "Zhovkva Forestry" is a valuable historical monument and a natural object requiring a guard regime and its further use as an educational and cultural-aesthetic object. The initiated research is aimed at establishing prospects for the use of breeds in the forest-cultivated production of the region, determining the degree of naturalization of the species and the aggressiveness of its behavior regarding the autochthonous tree species in indigenous forest types.Наведено коротку характеристику гіркокаштана звичайного та досліджено історію створення насадження за участю інтродуцента у Зіболківському лісництві ДП "Жовківське лісове господарство" на початку ХХ ст. Визначено особливості росту досліджуваної породи. Встановлено, що у віці 95 років дерева гіркокаштана звичайного досягають середньої висоти 19,5 м та середнього діаметра 44,3 см. Вивчено процеси природного поновлення інтродуцента та досліджено основні чинники, що впливають на формування підросту. Зроблено порівняльний аналіз природного поновлення гіркокаштана звичайного та клена-явора під наметом деревостану інтродуцента. Встановлено, що самосів гіркокаштана відстає в рості, кількості та життєвості і, перебуваючи в умовах надмірного затінення, "випадає" із підросту до 8-річного віку. Проведені дослідження свідчать, що гіркокаштан звичайний в умовах вологої грабово-соснової судіброви Малого Полісся України досяг найвищого рівня акліматизації – натуралізації, що підтверджує здатність виду до природного поновлення. Розпочаті дослідження мають на меті встановлення перспектив використання породи у лісокультурному виробництві регіону, визначення ступеня натуралізації виду та агресивності його поведінки щодо автохтонних деревних видів рослин у корінних типах лісу

On nuclear transport at small excitations

Numerical computations of transport coefficients at low temperatures are presented for shapes typically encountered in nuclear fission. The influence of quantum effects of the nucleonic degrees of freedom is examined, with pair correlations included. Consequences for global collective motion are studied for the case of the decay rate. The range of temperatures is specified above which this motion may be described as a quantal diffusion process.Comment: 8 pages, LaTex, 2 postscript figures; final version with small editorial changes, Phys. Rev. Lett. 82 (1999) 4603; e-mail: [email protected]; [email protected]