The Multiple Origin of Blue Straggler Stars: Theory vs. Observations

In this chapter we review the various suggested channels for the formation and evolution of blue straggler stars (BSSs) in different environments and their observational predictions. These include mass transfer during binary stellar evolution - case A/B/C and D (wind Roche-lobe overflow) mass transfer, stellar collisions during single and binary encounters in dense stellar cluster, and coupled dynamical and stellar evolution of triple systems. We also explore the importance of the BSS and binary dynamics in stellar clusters. We review the various observed properties of BSSs in different environments (halo and bulge BSSs, BSSs in globular clusters and BSSs in old open clusters), and compare the current observations with the theoretical predictions for BSS formation. We try to constrain the likely progenitors and processes that play a role in the formation of BSSs and their evolution. We find that multiple channels of BSS formation are likely to take part in producing the observed BSSs, and we point out the strengths and weaknesses of each the formation channel in respect to the observational constraints. Finally we point out directions to further explore the origin of BSS, and highlight eclipsing binary BSSs as important observational tool.Comment: Chapter 11, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe

Three-Dimensional Regulation of Radial Glial Functions by Lis1-Nde1 and Dystrophin Glycoprotein Complexes

Lis1-Nde1 integrates cerebral cortical neurogenesis with neuronal migration by stabilizing the basal-lateral surface of radial glial cells

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics

Star Formation and Dynamics in the Galactic Centre

The centre of our Galaxy is one of the most studied and yet enigmatic places in the Universe. At a distance of about 8 kpc from our Sun, the Galactic centre (GC) is the ideal environment to study the extreme processes that take place in the vicinity of a supermassive black hole (SMBH). Despite the hostile environment, several tens of early-type stars populate the central parsec of our Galaxy. A fraction of them lie in a thin ring with mild eccentricity and inner radius ~0.04 pc, while the S-stars, i.e. the ~30 stars closest to the SMBH (<0.04 pc), have randomly oriented and highly eccentric orbits. The formation of such early-type stars has been a puzzle for a long time: molecular clouds should be tidally disrupted by the SMBH before they can fragment into stars. We review the main scenarios proposed to explain the formation and the dynamical evolution of the early-type stars in the GC. In particular, we discuss the most popular in situ scenarios (accretion disc fragmentation and molecular cloud disruption) and migration scenarios (star cluster inspiral and Hills mechanism). We focus on the most pressing challenges that must be faced to shed light on the process of star formation in the vicinity of a SMBH.Comment: 68 pages, 35 figures; invited review chapter, to be published in expanded form in Haardt, F., Gorini, V., Moschella, U. and Treves, A., 'Astrophysical Black Holes'. Lecture Notes in Physics. Springer 201

Health care in Kaunas 1918 – 1940

Šio tyrimo tikslas yra išnagrinėti sveikatos priežiūros sistemos veikimą Kaune 1918 – 1940 m. ir nustatyti kaip sveikatos priežiūra funkcionavo Kauno mieste. Lietuva atgavusi nepriklausomybę turėjo formuoti sveikatos priežiūros politiką, kuri siekė pagalbos suteikimo gyventojams sergantiems įvairiomis ligomis. Vienas iš daugelio neatidėliotinų uždavinių buvo sveikatos priežiūros užtikrinimas Kaune. Pokarinis badas, žemas higienos lygis ir nepritekliai, visose gyvenimo srityse ypač skaudžiai palietė Kauno gyventojus. Karo pasekmė buvo epidemijos – vidurių šiltinė, dėmėtoji šiltinė, gripo epidemija. Dažnai lydėjo šių ligų komplikacijos, vaistų stoka ir nepakankamas kvalifikuotų gydytojų skaičius. Tačiau nepriklausomybės pradžioje vyravo daugybę sunkumų – tvarkos, finansiniai, administraciniai. Negana to, Kaunas tapęs laikinąją sostine turėjo pasirūpinti nuolatos augančiu gyventojų skaičiumi. Todėl imtasi rūpintis viešosiomis ligoninėmis, steigtos privačios ligoninės. Ilgainiui Kaune sveikatos priežiūros galimybes teko plėsti – didinti lovų skaičių, įkurti naujas ligonines. Ligoninėse pagal galimybes buvo taikomi įvairūs gydymo metodai, stengiamasi padėti sunkiomis ligomis sergantiems. Nagrinėjamu laikotarpiu Lietuvoje susirūpinta ganėtinai prastai funkcionuojančia sveikatos priežiūros sistema. Šiame darbe pateikiama sveikatos priežiūros padėtis, jos valstybinis organizavimas. Kauno ligoninių veikla, ligonių laikymo sąlygos. Įvardinamos 22 metų laikotarpyje iškilusios problemos suteikiant medicininę pagalbą ligoniams. Tiriama Kaune veikusio universiteto vykdyta klinikinė veikla, buvo atsižvelgiama į gydytojų visuomeninę ir kitų įstaigų kaip vaistinių veiklą. Taip pat atsižvelgiama į gydytojų susirūpinamą tuo metu paplitusiomis ligomis, kovo su jomis, sveikatos priežiūros administravimą Kaune.The purpose of this study is to analyze the system of the health care in Kaunas city (1918 – 1940). It seeks to identify how health care system where able to function in independent country. From the first years of independence there was some huge challenges – financial situation and administration wasn’t ready to deal with health care issues quickly. Those difficulties effected Kaunas city health care system. Overall the health care policies and improvements in public and private hospitals moved further, building and reconstructing new facilities, opening private care centres. Under new medical care model a new treatment methods were applied, always trying to help to those who had serious physical, mental and other health problems. The issue of this paper related with Kaunas city slow but stable evolution of health care based on new government laws that helped doctors, pharmacist and hospitals staff who worked in Kaunas in 1918 – 1940. This work contains all hospitals and university clinics, who were working in independent Kaunas city. Trying to underline how everything was done. In this manner, there is a closer look how hospitals were build, in what kind of status the building was, then how patients were kept and all this data are compared with other hospitals that used to or still worked at that time. Then underling the problems that were 22 years period, which were trying to deliver a proper help for ill patients. Investigating practises in hospitals was related to hospital staff. The most important factor was the doctors who worked there, who manage to put some new ideas in treatment methods and in research for effective way to treat patients. Then looking throw the fight against infectious diseases and other health care problems in city. Analysing what kind relationships doctors with government had. This work exploring how ill patients in Kaunas were accepted and how treatment worked based on the statistical data. In this study dozens of the health care organizations and associations were in Kaunas city who try to maintain proper work of hospitals, pharmacies and social care systems