Context.Accretion and ejection are complex and related processes that vary on various timescales in young stars. Aims.We intend to investigate the accretion and outflow dynamics and their interaction ...from observations of the classical T Tauri star AA Tau. Methods.From a long time series of high resolution ($R=115\,000$) HARPS spectra and simultaneous broad-band photometry, we report new evidence for magnetospheric accretion as well as ejection processes in the nearly edge-on classical T Tauri star AA Tau. Results.AA Tau's light curve is modulated with a period of 8.22 d. The recurrent luminosity dips are due to the periodic occultation of the central star by the magnetically-warped inner disk edge located at about 9 $R_\star$. Balmer line profiles exhibit a clear rotational modulation of high-velocity redshifted absorption components with a period of 8.22 days as well, with a maximum strength when the main accretion funnel flow passes through the line of sight. At the same time, the luminosity of the system decreases by about 1 mag, indicative of circumstellar absorption of the stellar photosphere by the magnetically-warped, corotating inner disk edge. The photospheric and He I radial velocities also exhibit periodic variations, and the veiling is modulated by the appearance of the accretion shock at the bottom of the accretion funnel. Diagnostics of hot winds and their temporal behaviour are also presented. Conclusions.The peculiar geometry of the young AA Tau system (nearly edge-on) allows us to uniquely probe the acretion-ejection region close to the star. We find that most spectral and photometric diagnostics vary as expected from models of magnetically-channelled accretion in young stars, with a large scale magnetosphere tilted by 20° onto the star's spin axis. We also find evidence for time variability of the magnetospheric accretion flow on a timescale of a few rotational periods.
Pancreatic ductal adenocarcinoma (PDAC) has the worst prognosis among solid malignancies and improved therapeutic strategies are needed to improve outcomes. Patient-derived xenografts (PDX) and ...patient-derived organoids (PDO) serve as promising tools to identify new drugs with therapeutic potential in PDAC. For these preclinical disease models to be effective, they should both recapitulate the molecular heterogeneity of PDAC and validate patient-specific therapeutic sensitivities. To date however, deep characterization of the molecular heterogeneity of PDAC PDX and PDO models and comparison with matched human tumour remains largely unaddressed at the whole genome level. We conducted a comprehensive assessment of the genetic landscape of 16 whole-genome pairs of tumours and matched PDX, from primary PDAC and liver metastasis, including a unique cohort of 5 'trios' of matched primary tumour, PDX, and PDO. We developed a pipeline to score concordance between PDAC models and their paired human tumours for genomic events, including mutations, structural variations, and copy number variations. Tumour-model comparisons of mutations displayed single-gene concordance across major PDAC driver genes, but relatively poor agreement across the greater mutational load. Genome-wide and chromosome-centric analysis of structural variation (SV) events highlights previously unrecognized concordance across chromosomes that demonstrate clustered SV events. We found that polyploidy presented a major challenge when assessing copy number changes; however, ploidy-corrected copy number states suggest good agreement between donor-model pairs. Collectively, our investigations highlight that while PDXs and PDOs may serve as tractable and transplantable systems for probing the molecular properties of PDAC, these models may best serve selective analyses across different levels of genomic complexity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
We homogeneously analyse ∼3.2 × 105 photometric measurements for ∼1100 transit light curves belonging to 17 exoplanet hosts. The photometric data cover 16 years (2004–2019) and include ...amateur and professional observations. Old archival light curves were reprocessed using up-to-date exoplanetary parameters and empirically debiased limb-darkening models. We also derive self-consistent transit and radial-velocity fits for 13 targets. We confirm the non-linear transit timing variation (TTV) trend in the WASP-12 data at a high significance, and with a consistent magnitude. However, Doppler data reveal hints of a radial acceleration of about −7.5 ± 2.2 m s−1 yr−1, indicating the presence of unseen distant companions, and suggesting that roughly 10 per cent of the observed TTV was induced via the light-travel (or Roemer) effect. For WASP-4, a similar TTV trend suspected after the recent TESS observations appears controversial and model dependent. It is not supported by our homogeneous TTV sample, including 10 ground-based EXPANSION light curves obtained in 2018 simultaneously with TESS. Even if the TTV trend itself does exist in WASP-4, its magnitude and tidal nature are uncertain. Doppler data cannot entirely rule out the Roemer effect induced by possible distant companions.
We present the results of a photometric monitoring campaign of three well-studied FU Orionis systems (FU Orionis, V1057 Cygni and V1515 Cygni) undertaken at Maidanak Observatory between 1981 and ...2003. When combined with photometric data in the literature, this data base provides a valuable resource for searching for short time-scale variability—both periodic and aperiodic—as well as for studying the secular evolution of these systems. In the case of V1057 Cyg (which is the system exhibiting the largest changes in brightness since it went into outburst) we compare the photometric data with time-dependent models. We show that prior to the end of the ‘plateau’ stage in 1996, the evolution of V1057 Cyg in the V–(B–V) colour—magnitude diagram is well represented by disc instability models in which the outburst is triggered by some agent—such as an orbiting planet—in the inner disc. Following the end of the plateau phase in 1996, the dimming and irregular variations are consistent with occultation of the source by a variable dust screen, which has previously been interpreted in terms of dust condensation events in the observed disc wind. Here we instead suggest that this effect results from the interaction between the wind and an infalling dusty envelope, the existence of this envelope having been previously invoked in order to explain the mid-infrared emission of FU Orionis systems. We discuss how this model may explain some of the photometric and spectroscopic characteristics of FU Orionis systems in general.
The article presents the research of genus Crataegus L. diversity in the territory of the Nakhchivan Autonomous Republic. We provided comparative analysis of specimens from the herbarium of the ...Institute of Botany of Azerbaijan National Academy of Sciences, Institute of Bioresources of Nakhchivan Section of Azerbaijan National Academy of Sciences, and Nakhchivan State University to clarify the current state of the genus Crataegus L. in the flora of the Nakhichivan Autonomous Republic. Based on the analysis of field data and collected herbarium during 2004-2015 and literature data we revealed 22 species of the genus in the flora of the Nakhichevan Autonomous Republic at present time. We also fixed that some 17 wildgrowing species occur in natural conditions, among them Crataegus chlorocarpa Lenne et C. Koch, C. ferganensis Pojark., C. sanguinea Pall., C. songarica C. Koch, C. turkestanica Pojark. were introducted into the culture and used in the landscaping of parks and gardens. We also considered the data on synonyms species, patterns of distribution among high-altitude zones, habitats as well as period of flowering and fruiting.
Opposition effect of Trojan asteroids Shevchenko, V.G.; Belskaya, I.N.; Slyusarev, I.G. ...
Icarus (New York, N.Y. 1962),
2012, 2012-01-00, 20120101, Letnik:
217, Številka:
1
Journal Article
Recenzirano
► We have obtained detailed magnitude–phase relations for three Jupiter Trojans. ► The magnitude–phase relations are linear down to phase angle of 0.1–0.2°. ► We have not revealed any noticeable ...opposition brightening for the V and R bands. ► Such behavior is inherent for dark surfaces where single scattering plays main role.
CCD-photometry of three Jupiter Trojan asteroids were carried out to study their opposition effect. We obtained well-sampled magnitude–phase curves for (588) Achilles, (884) Priamus, and (1143) Odysseus in the maximal attainable phase angle range down to 0.1–0.2°. The magnitude–phase relations have a linear behavior in all observed range of phase angles and do not show any non-linear opposition brightening. We have not found any confident differences between phase slopes measured in B, V and R bands. The values of the measured phase slopes of Trojans are different from available data for Centaurs. They are within the range of phase slopes measured for some low-albedo main belt asteroids, also exhibit a linear behavior down to small phase angles. An absence of non-linear opposition brightening puts constraints on the surface properties of the studied objects, assuming very dark surfaces where single scattering plays dominating role.
We also determined the rotation periods, amplitudes, the values of color indexes B–V and V–R, and the absolute magnitudes of these asteroids.
Background: Sonographic measurement of optic nerve sheath diameter (ONSD) can reflect intracranial pressure (ICP) indirectly and determine the neurology intensive care unit (NICU) requirement and ...mortality in acute ischemic stroke (AIS). Aim: To demonstrate the effectiveness of ONSD to determine mortality, morbidity, and NICU requirement on patients with the AIS. Methods: The sonographic ONSD measurements were performed on each patient with AIS, over 18 years old. All patients were categorized according to the Oxfordshire Community Stroke Project (OCSP) classification system. MRI images were examined for increased ICP, and the patients were categorized into two groups as increased ICP (i-ICP) and normal ICP. The ONSD results were evaluated in terms of classifications, outcomes, and prognosis of the patients. Results: One hundred and five patients were included and 31 (35.2%) were in the i-ICP group. The median ONSDs were 5.26 mm in the i-ICP group and 4.62 mm in the normal ICP group (P < 0.001). The median ONSDs were 5.13 mm in the NICU group and 4.69 mm in the neurology ward (NW) group (P = 0.001). The total anterior circulation infarction (TACI) subgroup had higher ONSDs than the others (TACI: 5.27 mm; PACI: 4.73 mm; POCI: 4.77 mm; and LACI: 4.64 mm, P < 0.001). The NICU requirements were higher in the TACI subgroup. The median ONSD was 5.42 mm in the deceased group (survived: 4.77 mm, P < 0.001). Conclusion: ONSD may be favorable for predicting the increased ICP and the NICU requirement in OCSP subgroups. Moreover, ONSD can be used to foresee the mortality of AIS.
Beginning of operation of the first Russian–Cuban Observatory telescope, a wide-field 20-cm robotic telescope installed at the observational site optical station in Havana, Republic of Cuba, is ...reported. The general view of the telescope is shown and attached equipment is described. The “first light” obtained using a 20-cm telescope is demonstrated and briefly discussed. Multi-task observational projects supposed to be conducted using mentioned RCO telescope are described. Russian–Cuban complexication scheme is described and some of its features are briefly discussed.
We clarified the current state of genus Crataegus L. in the flora of the Nakhchivan Autonomous Republic (Azerbaijan) using a comparative analysis of herbarium specimens from the Azarbaijan herbariums ...and data collected during the expeditions in 2004–2018. We succeed in adding some important data on the flora of Nakhchivan Autonomous Republic and Azerbaijan, we also enhanced the previous research with chromosome and morphological analysis. We identified 17 wild species of Crataegus genus in the Nakhchivan Autonomous Republic (C. pentagyna Waldst. et Kit. ex Willd., 1800, C. zangezura Pojark., 1939, C. orientalis Pall. ex Bieb., 1808, C. pojarkoviae Kossych, 1964, C. tournefortii Griseb., 1843, C. szovitsii Pojark., 1939, C. pontica C. Koch, 1853, C. meyeri Pojark., 1939, C. eriantha Pojark., 1939, C. atrosanguinea Pojark., 1939, C. caucasica C. Koch, 1853, C. pallasii Griseb., 1843, C. rhipidophylla Gand. (С. curvisepala Lindm.; C. kyrtostyla Pojark.) 1871, C. pseudoheterophylla Pojark., 1939, C. monogyna Jacq., 1775, C. x armena Pojark., 1939, and C. x cinovskisii Kassumova), which will contribute to five introduced cultural species used in the greenery. We also clarified the status of interserial and intersection hybrids using the chromosome and morphological analysis. The article includes the complete list of Crataegus L. species with information about synonyms of the species, patterns of distribution, habitat, latitude and elevation, flowering and fruiting phenology.
The Whole Earth Blazar Telescope (WEBT) collaboration has collected a large amount of optical and radio data on BL Lacertae in the last years, which, when added to literature data, allow to construct ...well-sampled light curves of the source from 1968 to the end of 2003. These optical and radio data are here analysed with three statistical methods designed for unevenly-sampled data trains in order to search for possible periodicities. While the main radio outbursts repeat every similar to 8 years, with a possible progressive stretching of the period, the evidence of an optical periodicity is much less clear. Radio light curves from 4.8 to 37 GHz are well correlated, with variations at the higher frequencies leading the lower-frequency ones by a few weeks for contiguous bands, up to a few months when considering the largest frequency separations. The radio behaviour reveals the presence of two different components, the softer-spectrum one constituting the bulk of the radio emission. On the other hand, the harder component shows itself as radio events which appear enhanced at the higher frequencies and seem to have optical counterparts. Cross-correlation between the optical light curve and radio hardness ratios indicates a radio time delay of more than 3 months. Thus, our analysis suggests a scenario where flux variations propagate towards less and less opaque regions, giving rise to related optical and hard radio events and, in more extended zones, to soft events apprently uncorrelated with the former ones.
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