835 research outputs found

    Classical Cepheids, what else?

    Full text link
    We present new and independent estimates of the distances to the Magellanic Clouds (MCs) using near-infrared (NIR) and optical--NIR period--Wesenheit (PW) relations. The slopes of the PW relations are, within the dispersion, linear over the entire period range and independent of metal content. The absolute zero points were fixed using Galactic Cepheids with distances based on the infrared surface-brightness method. The true distance modulus we found for the Large Magellanic Cloud---(mM)0=18.48±0.01±0.10(m-M)_0 = 18.48 \pm 0.01 \pm 0.10 mag---and the Small Magellanic Cloud---(mM)0=18.94±0.01±0.10(m-M)_0 = 18.94 \pm 0.01 \pm 0.10 mag---agree quite well with similar distance determinations based on robust distance indicators. We also briefly discuss the evolutionary and pulsation properties of MC Cepheids

    Simulacija udarnih valnih opterećenja u OpenFOAM-u

    Get PDF
    Tema ovog rada je primjena numeričkih proračuna udarnih valnih opterećenja na nepomične konstrukcije pomorske tehnike. Korišten je programski paket Naval Hydro Pack u programu OpenFOAM. Korišten je model dvofaznog strujanja sa slobodnom površinom pomoću “Volume of Fluid” metode i “Level Set” metode. Jednadžbe su diskretizirane metodom kontrolnih volumena. Ukratko je prikazan način modeliranja valova pomoću relaksacijskih zona. Proveden je proračun opterećenja kvadratnog stupa uslijed udarnog vodenog vala te su rezultati uspoređeni s eksperimentalnim vrijednostima. Prikazan je način generiranja ekstremnog vala (engl. „freak wave“) pomoću fokusiranja valnih komponenti standardnog spektra energije valova. Provedena je simulacija ekstremnog vala te su prikazani rezultati proračuna

    On the distance of the Magellanic Clouds using Cepheid NIR and optical-NIR Period Wesenheit Relations

    Full text link
    We present the largest near-infrared (NIR) data sets, JHKsJHKs, ever collected for classical Cepheids in the Magellanic Clouds (MCs). We selected fundamental (FU) and first overtone (FO) pulsators, and found 4150 (2571 FU, 1579 FO) Cepheids for Small Magellanic Cloud (SMC) and 3042 (1840 FU, 1202 FO) for Large Magellanic Cloud (LMC). Current sample is 2--3 times larger than any sample used in previous investigations with NIR photometry. We also discuss optical VIVI photometry from OGLE-III. NIR and optical--NIR Period-Wesenheit (PW) relations are linear over the entire period range (0.0<logPFU1.650.0<\log P_{\rm FU} \le1.65 ) and their slopes are, within the intrinsic dispersions, common between the MCs. These are consistent with recent results from pulsation models and observations suggesting that the PW relations are minimally affected by the metal content. The new FU and FO PW relations were calibrated using a sample of Galactic Cepheids with distances based on trigonometric parallaxes and Cepheid pulsation models. By using FU Cepheids we found a true distance moduli of 18.45±0.02(random)±0.10(systematic)18.45\pm0.02{\rm(random)}\pm0.10{\rm(systematic)} mag (LMC) and 18.93±0.02(random)±0.10(systematic)18.93\pm0.02{\rm(random)}\pm0.10{\rm(systematic)} mag (SMC). These estimates are the weighted mean over ten PW relations and the systematic errors account for uncertainties in the zero-point and in the reddening law. We found similar distances using FO Cepheids (18.60±0.03(random)±0.10(systematic)18.60\pm0.03{\rm(random)}\pm0.10{\rm(systematic)} mag [LMC] and 19.12±0.03(random)±0.10(systematic)19.12\pm0.03{\rm(random)}\pm0.10{\rm(systematic)} mag [SMC]). These new MC distances lead to the relative distance, Δμ=0.48±0.03\Delta\mu=0.48\pm0.03 mag (FU, logP=1\log P=1) and Δμ=0.52±0.03\Delta\mu=0.52\pm0.03 mag (FO, logP=0.5\log P=0.5),which agrees quite well with previous estimates based on robust distance indicators.Comment: 17 pages, 7 figure

    Primjena Naval Hydro Paketa za Proračun Valnih Opterećenja

    Get PDF
    Ovaj rad prikazuje mogućnosti primjene programskog paketa NavalHydro u programu OpenFOAM na probleme određivanja valnih opterećenja u brodogradnji. Diskretizacija Navier-Stokesovih jednadžbi se provodi metodom kontrolnih volumena, dok se za praćenje slobodne površine koristi „Volume of Fluid“ metoda. Paket NavalHydro prilagođen je provođenju proračuna gdje su prisutni značajni utjecaji slobodne površine, što ga čini pogodnim za određivanje valnih opterećenja. U ovom radu je prikazan proračun opterećenja vertikalnog cilindra uslijed nailaska harmonijskih valova. Rezultati su uspoređeni s eksperimentalnim podacima. Uz to je prikazana simulacija ekstremnog vala (eng. „freak wave“), koja pokazuje mogućnost određivanja opterećenja uslijed ovakvih pojava

    Gender influence on professional satisfaction and gender issue perception among young oncologists. A survey of the Young Oncologists Working Group of the Italian Association of Medical Oncology (AIOM)

    Get PDF
    Background: The professional gender gap is increasingly recognised in oncology. We explored gender issues perception and gender influence on professional satisfaction/gratification among young Italian oncologists. Methods: Italian oncologists aged 6440 years and members of the Italian Association of Medical Oncology were invited to participate in an online survey addressing workload/burnout, satisfaction in professional abilities and relations, relevant factors for professional gratification, and gender barriers. \u3c72 test for general association or \u3c72 test for trend was used to analyse the data. Results: 201 young oncologists participated in the survey: 67% female, 71% aged 30-40 years, 41% still in training and 82% without children. Women and men were equally poorly satisfied by the relations with people occupying superior hierarchical positions. There was heterogeneity between women and men in current (p=0.011) and expected future (p=0.007) satisfaction in professional abilities: women were more satisfied by current empathy and relations with colleagues and were more confident in their future managerial and team leader skills. The most important elements for professional gratification indicated by all participants were, in general, work-life balance (36%) and intellectual stimulation/research (32%); specifically for women, work-life balance (48%) and intellectual stimulation/research (20%); and specifically for men, career (29%) and social prestige/recognition (26%). Heterogeneity within the same gender emerged. For example, the elements indicated by men as the most important were intellectual stimulation/research (39%) and work-life balance (21%) in general, versus social prestige/recognition (24%) and career (24%), respectively, specifically for men (p<0.0001). More women versus men perceived gender issue as an actual problem (60% vs 38%, p=0.03); men underestimated gender barriers to women's career (p=0.011). Conclusions: Satisfaction in professional abilities varied by gender. Work-life balance is important for both women and men. Stereotypes about gender issues may be present. Gender issue is an actual problem for young oncologists, mostly perceived by women

    A lack of classical Cepheids in the inner part of the Galactic disk

    Full text link
    Recent large-scale infrared surveys have been revealing stellar populations in the inner Galaxy seen through strong interstellar extinction in the disk. In particular, classical Cepheids with their period-luminosity and period-age relations are useful tracers of Galactic structure and evolution. Interesting groups of Cepheids reported recently include four Cepheids in the Nuclear Stellar Disk (NSD), about 200 pc around the Galactic Centre, found by Matsunaga et al. and those spread across the inner part of the disk reported by Dekany and collaborators. We here report our discovery of nearly thirty classical Cepheids towards the bulge region, some of which are common with Dekany et al., and discuss the large impact of the reddening correction on distance estimates for these objects. Assuming that the four Cepheids in the NSD are located at the distance of the Galactic Centre and that the near-infrared extinction law, i.e. wavelength dependency of the interstellar extinction, is not systematically different between the NSD and other bulge lines-of-sight, most of the other Cepheids presented here are located significantly further than the Galactic Centre. This suggests a lack of Cepheids in the inner 2.5 kpc region of the Galactic disk except the NSD. Recent radio observations show a similar distribution of star-forming regions.Comment: 8 pages, 4 figures, accepted for publication in MNRA
    corecore