Magnetic games between a planet and its host star: the key role of topology

Magnetic interactions between a star and a close-in planet are postulated to be a source of enhanced emissions and to play a role in the secular evolution of the orbital system. Close-in planets generally orbit in the sub-alfv\'enic region of the stellar wind, which leads to efficient transfers of energy and angular momentum between the star and the planet. We model the magnetic interactions occurring in close-in star-planet systems with three-dimensional, global, compressible magneto-hydrodynamic numerical simulations of a planet orbiting in a self-consistent stellar wind. We focus on the cases of magnetized planets and explore three representative magnetic configurations. The Poynting flux originating from the magnetic interactions is an energy source for enhanced emissions in star-planet systems. Our results suggest a simple geometrical explanation for ubiquitous on/off enhanced emissions associated with close-in planets, and confirm that the Poynting fluxes can reach powers of the order of $10^{19}$ W. Close-in planets are also showed to migrate due to magnetic torques for sufficiently strong stellar wind magnetic fields. The topology of the interaction significantly modifies the shape of the magnetic obstacle that leads to magnetic torques. As a consequence, the torques can vary by at least an order of magnitude as the magnetic topology of the interaction varies.Comment: 15 pages, 6 figures, accepted for publication in The Astrophysical Journa

A quantitative assessment of the ecological value of sycamore maple habitats in the French Alps

La naturalité est un critère important pour l'évaluation de mesures conservatoires des écosystèmes. Au niveau local, une telle évaluation doit être basée sur des indicateurs objectifs et quantifiables sur le terrain. Dans cette étude, nous avons utilisé une méthode multicritères basée sur la différence entre Valeur Naturelle (NV) et Valeur Conservatoire (CV) pour quantifier la valeur écologique des érablaies de versant à érable sycomore (Acer pseudoplatanus L.) par comparaison avec les peuplements mixtes de hêtraie-sapinière-pessière avoisinants. En effet, les naturalistes ainsi que l'Union Européenne considèrent que les érablaies de versant ont une valeur de conservation et de naturalité élevée. Nos résultats montrent que les valeurs naturelle et de conservation sont significativement plus élevées pour l'érablaie que pour la forêt mixte avoisinante et que cette évaluation ne dépend pas de facteurs abiotiques tels que l'altitude ou l'exposition. En fait, la naturalité de structure et de composition des érablaies de versant sont plus fortes que celles des forêts mixtes et permettent de différencier les deux habitats en termes de valeur écologique. Les gestionnaires peuvent facilement utiliser cette méthode pour évaluer la valeur écologique de petits habitats en zone de montagne, ce qui permet d'établir des orientations sylvicoles pour une gestion conservatoire et proche de la nature. / Naturalness is an important criterion in nature conservation assessment. At the stand-level, such assessment must be based on objective and quantifiable indicators measurable in the field. In this study, we used a multi-criterion method based on the difference between a Natural Value(NV) and a Conservation Value (CV) to quantify the ecological value of sycamore maple patches compared to the surrounding mixed forests. Indeed, sycamore habitats are considered of high natural and conservation value both by naturalists and by European institutions. Our results showed that the natural and conservation values were significantly higher for the sycamore forests than for the surrounding mixed forests and that this assessment did not depend on abiotic factors such as elevation or aspect. Actually, naturalness of structure and composition in the sycamore habitats was higher than for mixed forests and allowed us to differentiate between the two habitats. Managers could easily use this method in order to assess the ecological value of small habitats in mountainous regions and to provide guidelines for close-to-nature and conservation-related silviculture.FORET DE MONTAGNE;ECOLOGIE FORESTIERE;EVALUATION;PROTECTION DE LA NATURE;ACER PSEUDOPLATANUS;METHODOLOGIE;HABITAT;VALEUR ECOLOGIQUE;NATURALITE;ALPES FRANCAISES;CHARTREUSE MASSIF;ACER PSEUDOPLATANUS;CHARTREUSE;INDICATORS;NATURALNESS;ECOLOGICAL VALUE

Експериментальне дослідження застосування нестероїдних протизапальних препаратів при використанні низькоінтенсивного інфрачервоного лазерного випромінювання

Topicality. The combined application of nonsteroidal anti-inflammatory drugs (NSAIDs) and low-intensity infrared laser radiation (LIIRLR) for treatment of osteoarthrosis has remained an actual task. Aim to study the NSAIDs usage under LIIRLR application in experiments in rats.Materials and Methods. The time for LIIRLR application (15 min after drug administration) was chosen according to our previous studies on diclofenac sodium (DNa) pharmacokinetics in rats blood plasma. To study the NSAIDs application at the influence of LIIRLR, white beedless male rats (n=15) of 250-300 g were used in the experiments. The animals were divided into 3 groups. Rats of group the 1were received purified water (per os) and exposed to LIIRLR. Rats of group the 2 were received DNa at a dose of ED50 (per os, 8 mg/kg). Rats of group the 3 were influenced of LIIRLR and in 15 min received DNa (per os, 8 mg/kg). For DNa extraction from rat plasma samples, the method of solid-phase extraction was used. Concentration of DNa was determined by method of high-performance liquid chromatography (HPLC).Results. It was established that at the combined use LIIRLR and DNa the drug concentration in the rats blood serum was 1.7 fold higher in comparison to DNa application alone.Conclusions. It is proved, that the method of combine application of LIIRLRand NSAIDs (in 15 min) was more effective than the use of NSAIDs alone.Актуальность. Комбинированное применение нестероидных противовоспалительных препаратов (НПВП) и низкоинтенсивного инфракрасного лазерного излучения (НИЛИ) для лечения остеоартроза является актуальной задачей.Цель работы − изучить применение НПВП при использовании НИЛИ в эксперименте на крысах.Материалы и методы. Время применения НИЛИ (15 мин после введения препарата) было установлено при исследовании фармакокинетики диклофенака натрия (ДNa) в плазме крови крыс. Для изучения применения НПВС при воздействии НИЛИ были использованы нелинейные белые крысы-самцы (n = 15) массой 250-300 г. Животные в эксперименте были разделены на 3 группы. Первой группе крыс вводили воду очищенную (per os) иподвергали влиянию НИЛИ. Второй группе крыс вводили ДNa в дозе ЕД50 (per os, 8 мг/кг). Крыс третьей группы подвергали влиянию НИЛИ и через 15 мин вводили ДNa (per os, 8 мг/кг). Для извлечения ДNa из образцов плаз-мы крови крыс был использован метод твердофазной экстракции. Концентрацию ДNa определяли с помощью метода высокоэффективной жидкостной хроматографии (ВЭЖХ).                                         Результаты и их обсуждение. Установлено, что при схеме комбинированного использования НИЛИ и ДNa по отношению к применению ДNa концентрация препарата в плазме крови крыс повышалась в 1,7 раза.                         Выводы. Доказано, что приведенный метод комбинированного использования НИЛИ и НПВП (через 15 мин) более эффективный, чем применение НПВП.Актуальність. Комбіноване застосування нестероїдних протизапальних препаратів (НПЗП) і низькоінтенсивного інфрачервоного лазерного випромінювання (НІЛВ) для лікування остеоартрозу є актуальним завданням.Мета роботи − вивчити застосування НПЗП при використанні НІЛВ в експерименті на щурах.Матеріали та методи. Час використання НІЛВ (15 хв після введення препарату) був встановлений при дослідженні фармакокінетики диклофенаку натрію (ДNa) у плазмі крові щурів. Для вивчення застосування НПЗПпри впливі НІЛВ були використані нелінійні білі щури-самці (n = 15) масою 250-300 г. Тварини в експерименті були розділені на 3 групи. Першій групі щурів вводили воду очищену (per os) та піддавали впливу НІЛВ. Другійгрупі щурів вводили ДNa у дозі ЕД50 (per os, 8 мг/кг). Щурів третьої групи піддавали впливу НІЛВ та через 15 хв вводили ДNa (per os, 8 мг/кг). Для екстрагування ДNa із зразків плазми крові щурів був використаний методтвердофазової екстракції. Концентрацію ДNa визначали за методом високоефективної рідинної хроматографії (ВЕРХ).Результати та їх обговорення. Встановлено, що при схемі комбінованого використання НІЛВ та ДNa по відношенню до застосування ДNa концентрація препарату у плазмі крові щурів підвищувалась в 1,7 рази.Висновки. Доведено, що наведений метод комбінованого використання НІЛВ та НПЗП (через 15 хв) є більш ефективним, ніж застосування НПЗП

Galaxy Selection and Clustering and Lyman alpha Absorber Identification

The effects of galaxy selection on our ability to constrain the nature of weak Ly\alpha absorbers at low redshift are explored. Current observations indicate the existence of a population of gas-rich, low surface brightness (LSB) galaxies, and these galaxies may have large cross sections for Ly\alpha absorption. Absorption arising in LSB galaxies may be attributed to HSB galaxies at larger impact parameters from quasar lines of sight, so that the observed absorption cross sections of galaxies may seem unreasonably large. Thus it is not possible to rule out scenarios where LSB galaxies make substantial contributions to Ly\alpha absorption using direct observations. Less direct tests, where observational selection effects are taken into account using simulations, should make it possible to determine the nature of Ly\alpha absorbers by observing a sample of ~100 galaxies around quasar lines of sight with well-defined selection criteria. Such tests, which involve comparing simulated and observed plots of the unidentified absorber fractions and absorbing galaxy fractions versus impact parameter, can distinguish between scenarios where absorbers arise in particular galaxies and those where absorbers arise in gas tracing the large scale galaxy distribution. Care must be taken to minimize selection effects even when using these tests. Results from such tests are likely to depend upon the limiting neutral hydrogen column density. While not enough data are currently available to make a strong conclusion about the nature of moderately weak absorbers, evidence is seen that such absorbers arise in gas that is around or between galaxies that are often not detected in surveys.Comment: 15 pages, 10 figures, accepted to the Astrophysical Journa

Damped Lyman Alpha Systems at z<1.65: The Expanded SDSS HST Sample

We present results of our HST Cycle 11 Survey for low-redshift (z<1.65) DLAs in the UV spectra of quasars selected from the SDSS Early Data Release. These quasars have strong intervening MgII-FeII systems which are known signatures of high column density neutral gas. In total, UV observations of Ly-alpha absorption in 197 MgII systems with z<1.65 and rest equivalent width (REW) W2796 \ge 0.3A have now been obtained. The main results are: (1) 36(+/- 6)% of systems with W2796 \ge 0.5 A and FeII W2600 \ge 0.5 A are DLAs. This increases to 42(+/- 7)% for systems with W2796/W2600 0.1 A. (2) The mean N(HI) of MgII systems with 0.3 A \le W2796 < 0.6 A is a factor of ~36 lower than that of systems with W2796 \ge 0.6 A. (3) The DLA incidence per unit redshift is consistent with no evolution for z <~ 2 (Omega_L=0.7, Omega_M = 0.3), but exhibits significant evolution for z >~ 2. (4) Omega_{DLA} is constant for 0.5<z<5.0 to within the uncertainties. This is larger than Omega_{gas}(z=0) by a factor of ~2. (5) The slope of the N(HI) distribution does not change significantly with redshift. However, the low redshift distribution is marginally flatter due to the higher fraction of high N(HI) systems in our sample. (6) Finally, using the precision of MgII survey statistics, we find that there may be evidence of a decreasing Omega_{DLA} from z=0.5 to z=0. We reiterate the conclusion of Hopkins, Rao, & Turnshek that very high columns of neutral gas might be missed by DLA surveys because of their very small cross sections, and therefore, that Omega_{DLA} might not include the bulk of the neutral gas mass in the Universe. (Abridged)Comment: Accepted for publication in ApJ. 22 pages, 22 figure