Different properties of coronary stents

Stents are mesh structured implants which are used to support the vessel wall in the balloon expanded vessel part. Several methods were developed and applied for the determination of mechanical properties of coronary stents, as a part of a complex pre-clinical in vitro diagnostic system: radiopacity, flaring, metallic surface area and fatigue tests. Three pieces of equipment were assembled for the examination of fatigue properties. The first method simulates the bending stress in the coronary arteries; the second method simulates the effect of the cylindrical mechanical strain which is equivalent to the systolic and diastolic pulse in the coronary arteries; and the third method is using the energy of the ultrasound concentrating to the stent. After fatigue tests stereomicroscopy, optical microscopy, scanning electron microscopy were used for the determination of surface quality and condition. The most frequent failures were scratches, pits and small shrinkage of materials originated from the manufacturing and finishing processes. Because of fatigue tests slip lines occurred in the critical curves, grain boundaries were outlined, the surface of the struts become rough, but these mutations do not affect the functionality of the stents

Elmélet és tapasztalat viszonya a Hubble-állandó meghatározására irányuló tudományos kutatásban (Tudományfilozófiai esettanulmány)

A XX. század tudományfilozófiája a logikai pozitivizmus nagyratörő és optimista programjával kezdődött, mely nem kevesebbet tűzött ki célul maga elé, minthogy a korábbi sikertelen kísérletek után végre eredményesen kidolgozza a szilárd, biztos tudomány filozófiai alapjait és módszertanát, s ezáltal végre elérje azt a célt, melyet még Bacon és Descartes fogalmazott meg, s amelyre az újkori filozófia – egyik fő föladataként – mindaddig sikertelenül törekedett [v.ö. pl.: Schlick 1972; Schlick 1972a]. Az optimizmus természetesen nem abból fakadt, hogy a logikai pozitivizmus képviselői túlértékelték volna saját képességeiket: az egész program azon nyugodott, hogy a Frege, Wittgenstein, s különösképpen Russell és Whitehead által kidolgozott új logika – a szimbolikus logika – olyan eszközzel szolgált a filozófiai ismeretelmélet számára, amelyet a korábbi korok képviselői nélkülöztek [v.ö.: Carnap 1972a]. S ha a XX. századi tudományfilozófia kezdetét e program megszületésével azonosíthatjuk, e tudományfilozófia története tulajdonképpen nem más, mint a - Russell mellett elsősorban a Bécsi Kör és a hozzá kapcsolódó filozófusok által reprezentált - logikai pozitivizmus törekvésének fokozatos ellehetetlenülése és fölbomlása, optimizmusuk illuzórikus voltának lelepleződése. [A Bécsi Kör történetéről lásd Altrichter Ferenc bevezetőjét „A Bécsi Kör” című kötethez, a Bécsi Kör törekvéseinek illuzórikus voltáról pedig Fehér Márta A Tudományfejlődés kérdőjelei című könyvét, valamint a Magyar Filozófiai Szemlében megjelent tanulmányát: Altrichter 1972; Fehér 1983; Fehér 198

White dwarf period tables – I. Pulsators with hydrogen-dominated atmospheres

We collected all known white dwarf pulsators with hydrogen-dominated atmospheres and list their main photometric and atmospheric parameters together with their pulsation periods and amplitudes observed at different epochs. Exploring the pulsating white dwarf related literature with the systematic use of the SIMBAD and the NASA’s Astrophysics Data System (ADS) databases. Four tables listing seven ZZ Ceti stars in detached white dwarf plus main-sequence binaries, seven extremely low-mass DA pulsators, three hot DAVs and 180 ZZ Ceti stars

KIC 2831097. A short orbital-period candidate RR Lyrae binary

KIC 2831097 was discovered to be a first-overtone RR Lyrae pulsator based on 4-year Kepler photometry (Sódor et al. 2017, MNRAS, 465, L1). The data show strong, 0.1 d amplitude systematic phase variations that can be explained by light travel-time effect caused by an about 2-year period orbital motion in a binary system, superimposed on a linear pulsation-period decrease. To verify the binary hypothesis, several well-timed radial-velocity observations will be sufficient

KIC 9533489: a genuine γ Doradus – δ Scuti Kepler hybrid pulsator with transit events

Context Several hundred candidate hybrid pulsators of type A–F have been identified from space-based observations. Their large number allows both statistical analyses and detailed investigations of individual stars. This offers the opportunity to study the full interior of the genuine hybrids, in which both low-radial-order p- and high-order g-modes are self-excited at the same time. However, a few other physical processes can also be responsible for the observed hybrid nature, related to binarity or to surface inhomogeneities. The finding that most δ Scuti stars also show long-period light variations represents a real challenge for theory. Aims We aim at determining the pulsation frequencies of KIC 9533489, to search for regular patterns and spacings among them, and to investigate the stability of the frequencies and the amplitudes. An additional goal is to study the serendipitously detected transit events: is KIC 9533489 the host star? What are the limitations on the physical parameters of the involved bodies? Methods Fourier analysis of all the available Kepler light curves. Investigation of the frequency and period spacings. Determination of the stellar physical parameters from spectroscopic observations. Modelling of the transit events. Results The Fourier analysis of the Kepler light curves revealed 55 significant frequencies clustered into two groups, which are separated by a gap between 15 and 27 d −1. The light variations are dominated by the beating of two dominant frequencies located at around 4 d −1 . The amplitudes of these two frequencies show a monotonic long-term trend. The frequency spacing analysis revealed two possibilities: the pulsator is either a highly inclined moderate rotator (v ≈ 70 km s −1 , i > 70 ◦ ) or a fast rotator (v ≈ 200 km s −1 ) with i ≈ 20 ◦ . The transit analysis disclosed that the transit events, which occur with a ≈ 197 d period may be caused by a 1.6 R_Jup body orbiting a fainter star, which would be spatially coincident with KIC 9533489

Ground-Based Observations of the ZZ Ceti Star HS 1625+1231

We present the results of our detailed light curve analysis of the ZZ Ceti star HS 1625+1231. We collected photometric time series data at Konkoly Observatory on 14 nights, and performed Fourier analysis of these data sets. We detected 11 significant frequencies, where six of them are found to be independent pulsation modes in the 514-881 s period range. By utilizing these frequencies, we performed preliminary asteroseismic investigations to give constraints on the main physical parameters, and to derive seismic distances for the star. Finally, we compared the astrometric distance provided by the Gaia EDR3 data with those seismic distances. Our selected model, considering both the spectroscopic measurements and the distance value provided by Gaia, has Teff=11 000 K and M*=0.60 M⊙

Sex, skull length, breed, and age predict how dogs look at faces of humans and conspecifics

The gaze of other dogs and humans is informative for dogs, but it has not been explored which factors predict face-directed attention. We used image presentations of unfamiliar human and dog heads, facing the observer (portrait) or facing away (profile), and measured looking time responses. We expected dog portraits to be aversive, human portraits to attract interest, and tested dogs of different sex, skull length and breed function, which in previous work had predicted human-directed attention. Dog portraits attracted longer looking times than human profiles. Mesocephalic dogs looked at portraits longer than at profiles, independent of the species in the image. Overall, brachycephalic dogs and dogs of unspecified breed function (such as mixed breeds) displayed the longest looking times. Among the latter, females observed the images for longer than males, which is in line with human findings on sex differences in processing faces. In a subsequent experiment, we tested whether dog portraits functioned as threatening stimuli. We hypothesized that dogs will avoid food rewards or approach them more slowly in the presence of a dog portrait, but found no effect of image type. In general, older dogs took longer to approach food placed in front of the images and mesocephalic dogs were faster than dogs of other skull length types. The results suggest that short-headed dogs are more attentive to faces, while sex and breed function predict looking times through complex interactions