Deep imaging survey of young, nearby austral stars: VLT/NACO near-infrared Lyot-coronographic observations

Context. High contrast and high angular resolution imaging is the optimal search technique for substellar companions to nearby stars at physical separations larger than typically 10 AU. Two distinct populations of substellar companions, brown dwarfs and planets, can be probed and characterized. As a result, fossile traces of processes of formation and evolution can be revealed by physical and orbital properties, both for individual systems and as an ensemble. Aims. Since November 2002, we have conducted a large, deep imaging, survey of young, nearby associations of the southern hemisphere. Our goal is detection and characterization of substellar companions with projected separations in the range 10–500 AU. We have observed a sample of 88 stars, primarily G to M dwarfs, younger than 100 Myr, and within 100 pc of Earth. Methods. The VLT/NACO adaptive optics instrument of the ESO Paranal Observatory was used to explore the faint circumstellar environment between typically 0.1 and 10". Diffraction-limited observations in H and K_s-band combined with Lyot-coronagraphy enabled us to reach primary star-companion brightness ratios as small as 10^(-6). The existence of planetary mass companions could therefore be probed. We used a standardized observing sequence to precisely measure the position and flux of all detected sources relative to their visual primary star. Repeated observations at several epochs enabled us to discriminate comoving companions from background objects. Results. We report the discovery of 17 new close (0.1–5.0") multiple systems. HIP 108195 AB and C (F1 III-M6), HIP 84642 AB (a~14 AU, K0-M5) and TWA22 AB (a~1.8 AU; M6-M6) are confirmed comoving systems. TWA22 AB is likely to be a rare astrometric calibrator that can be used to test evolutionary model predictions. Among our complete sample, a total of 65 targets were observed with deep coronagraphic imaging. About 240 faint companion candidates were detected around 36 stars. Follow-up observations with VLT or HST for 83% of these stars enabled us to identify a large fraction of background contaminants. Our latest results that pertain to the substellar companions to GSC 08047-00232, AB Pic and 2M1207 (confirmed during this survey and published earlier), are reviewed. Finally, a statistical analysis of our complete set of coronagraphic detection limits enables us to place constraints on the physical and orbital properties of giant planets between typically 20 and 150 AU

Compliance error compensation in robotic-based milling

The paper deals with the problem of compliance errors compensation in robotic-based milling. Contrary to previous works that assume that the forces/torques generated by the manufacturing process are constant, the interaction between the milling tool and the workpiece is modeled in details. It takes into account the tool geometry, the number of teeth, the feed rate, the spindle rotation speed and the properties of the material to be processed. Due to high level of the disturbing forces/torques, the developed compensation technique is based on the non-linear stiffness model that allows us to modify the target trajectory taking into account nonlinearities and to avoid the chattering effect. Illustrative example is presented that deals with robotic-based milling of aluminum alloy

Experimental study of super-rotation in a magnetostrophic spherical Couette flow

We report measurements of electric potentials at the surface of a spherical container of liquid sodium in which a magnetized inner core is differentially rotating. The azimuthal angular velocities inferred from these potentials reveal a strong super-rotation of the liquid sodium in the equatorial region, for small differential rotation. Super-rotation was observed in numerical simulations by Dormy et al. [1]. We find that the latitudinal variation of the electric potentials in our experiments differs markedly from the predictions of a similar numerical model, suggesting that some of the assumptions used in the model - steadiness, equatorial symmetry, and linear treatment for the evolution of both the magnetic and velocity fields - are violated in the experiments. In addition, radial velocity measurements, using ultrasonic Doppler velocimetry, provide evidence of oscillatory motion near the outer sphere at low latitude: it is viewed as the signature of an instability of the super-rotating region

ОЦІНКА ЯКОСТІ ВОДИ У ПРИРОДНИХ ДЖЕРЕЛАХ М. ЛЬВОВА

Abstract. The main purpose of freshwater ecosystems is to provide drinking needs meeting the water quality requirements for health. Pure raw water is needed not only for drinking, but also for many technological purposes. Good raw water causes the reduce of water treatment costs. Therefore, the quality of water in natural sources is an important factor not only for drinking water supply or for achieving higher economic impact of production, but it also contributes to the development of biodiversity, which is beneficial for the environment and society. Water supply of Lviv is provided exclusively from underground sources located at a distance of 20 to 80 km, so it is of high quality everywhere, but differs in chemical composition, and properties. However, it is widely believed that water from natural sources is better than tap water. In the territory of Lviv, Bryukhovychi and Vinnyky there are more than ten such springs, water from which is used by the inhabitants of the city and villages. The aim of the work is to determine whether the water from springs located in the city is suitable for drinking needs. As a result of the conducted research, it was found that water from springs located in Lviv is not suitable for drinking. According to the research results, in all spring water samples the content of calcium and magnesium is significantly higher than in the sample taken from the city water supply network. The total water hardness in all sources exceeds MPC. The content of sulfates, chlorides, nitrates, nitrites and ammonium ions in all spring water samples is much higher than in tap water. The content of total ammonium ion in water from source # 3 almost reaches the limit of MPC (0.95MPC). Lead content in all samples taken from springs exceeds the MPC.Головним призначенням прісноводних екосистем є забезпечення питних потреб, з дотриманням вимог щодо якості води з метою охорони здоров'я. Якісна свіжа вода потрібна не лише для забезпечення питних потреб населення, але й для багатьох технологічних цілей. Чим чистішою є вода у джерелі, тим меншими будуть витрати на водопідготовку. Отже, якість води у природних джерелах є важливим фактором не лише для питного водопостачання чи для досягнення вищого економічного ефекту виробництв, а й також сприяє розвитку біо-різноманіття, що у свою чергу є корисним як для навколишнього середовища, так і для суспільства в цілому. Водопостачання міста Львова здійснюється виключно з підземних джерел, розміщених на відстані від 20 до 80 км, відтак всюди вона якісна, але різниться хімічним складом, а тому і властивостями. Проте досить поширеною серед мешканців міста є думка, що вода з природних джерел є кращою за водопровідну. На території Львова, Брюхович та Винник є більше десяти таких джерел, вода з яких використовується мешканцями міста і сіл. Мета роботи. На основі проведених досліджень визначити чи придатна для питних потреб вода у джере-лах розташованих на території міста. Внаслідок проведених досліджень було встановлено, що вода з джерел, розташованих на території міста Львова, непридатна для використання для питних потреб. Як показали результати досліджень, у всіх пробах джерельної води вміст кальцію та магнію є суттєво вищим, ніж у пробі, відібраній у водопровідній мережі міста. Показники загальної жорсткості у воді з усіх джерел значно перевищують ГДК. Вміст сульфатів, хлоридів, нітратів, нітритів та іонів амонію у всіх пробах джерельної води значно вищий, ніж у водопровідній. Вміст сумарного амоній-іону у воді з джерела №3 майже сягає граничної межі норми (0,95ГДК). Вміст свинцю у всіх пробах відібраних із джерел перевищує ГДК

Implementing EEG hyperscanning setups.

Hyperscanning refers to obtaining simultaneous neural recordings from more than one person (Montage et al., 2002 [1]), that can be used to study interactive situations. In particular, hyperscanning with Electroencephalography (EEG) is becoming increasingly popular since it allows researchers to explore the interactive brain with a high temporal resolution. Notably, there is a 40-year gap between the first instance that simultaneous measurement of EEG activity was mentioned in the literature (Duane and Behrendt, 1965 [2]), and the first actual description of an EEG hyperscanning setup being implemented (Babiloni et al., 2006 [3]). To date, specific EEG hyperscanning devices have not yet been developed and EEG hyperscanning setups are not usually described with sufficient detail to be easily reproduced. Here, we offer a step-by-step description of solutions to many of these technological challenges. Specifically, we describe and provide customized implementations of EEG hyperscanning setups using hardware and software from different companies: Brain Products, ANT, EGI, and BioSemi. •Necessary details to set up a functioning EEG hyperscanning protocol are provided.•The setups allow independent measures and measures of synchronization between the signals of two different brains.•Individual electrical Ground and Reference is obtained in all discussed systems

Giant Planet Companion to 2MASSW J1207334-393254

We report new VLT/NACO imaging observations of the young, nearby brown dwarf 2MASSW J1207334-393254 and its suggested planetary mass companion (2M1207 b). Three epochs of VLT/NACO measurements obtained over nearly one year show that the planetary mass companion candidate shares the same proper motion and, with a high confidence level, is not a stationary background object. This result confirms the status of 2M1207 b as of planetary mass (5 times the mass of Jupiter) and the first image of a planetary mass companion in a different system than our own. This discovery offers new perspectives for our understanding of chemical and physical properties of planetary mass objects as well as their mechanisms of formation.Comment: 4 pages, 2 figures. accepted in Astronomy & Astrophysic

Electrochromic and electrofluorochromic properties of a new boron dipyrromethene–ferrocene conjugate

A new boron dipyrromethene–ferrocene (BODIPY–Fc) conjugate with pentafluorophenyl as the meso substituent and two Fc termini was synthesized and its spectroscopic and electrochemical features were analyzed. An intramolecular charge transfer from the donor Fc to the acceptor BODIPY has been predicted by theory and confirmed experimentally, leading to efficient fluorescence quenching when the dyad is in the neutral state. Fluorescence can be triggered by oxidizing both ferrocenyl units either chemically or electrochemically. Eventually, a fully reversible fluorescence switch is evidenced by coupling TIRF microscopy with electrolysis in an electrochemical cell