18 research outputs found

    The mass and density of the dwarf planet (225088) 2007 OR10

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    The satellite of (225088) 2007 OR10 was discovered on archival Hubble Space Telescope images and along with new observations with the WFC3 camera in late 2017 we have been able to determine the orbit. The orbit's notable eccentricity, e\approx0.3, may be a consequence of an intrinsically eccentric orbit and slow tidal evolution, but may also be caused by the Kozai mechanism. Dynamical considerations also suggest that the moon is small, Deff_{eff} << 100 km. Based on the newly determined system mass of 1.75x1021^{21} kg, 2007 OR10 is the fifth most massive dwarf planet after Eris, Pluto, Haumea and Makemake. The newly determined orbit has also been considered as an additional option in our radiometric analysis, provided that the moon orbits in the equatorial plane of the primary. Assuming a spherical shape for the primary this approach provides a size of 1230±\pm50 km, with a slight dependence on the satellite orbit orientation and primary rotation rate chosen, and a bulk density of 1.75±\pm0.07 g cm3^{-3} for the primary. A previous size estimate that assumed an equator-on configuration (1535225+75^{+75}_{-225} km) would provide a density of 0.920.14+0.46^{+0.46}_{-0.14} g cm3^{-3}, unexpectedly low for a 1000 km-sized dwarf planet.Comment: Accepted for publication in Icaru

    An UXor among FUors: Extinction-related Brightness Variations of the Young Eruptive Star V582 Aur

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    V582 Aur is an FU Ori-type young eruptive star in outburst since similar to 1985. The eruption is currently in a relatively constant plateau phase, with photometric and spectroscopic variability superimposed. Here we will characterize the progenitor of the outbursting object, explore its environment, and analyze the temporal evolution of the eruption. We are particularly interested in the physical origin of the two deep photometric dips, one that occurred in 2012 and one that is ongoing since 2016. We collected archival photographic plates and carried out new optical, infrared, and millimeter-wave photometric and spectroscopic observations between 2010 and 2018, with a high sampling rate during the current minimum. Besides analyzing the color changes during fading, we compiled multiepoch spectral energy distributions and fitted them with a simple accretion disk model. Based on pre-outburst data and a millimeter continuum measurement, we suggest that the progenitor of the V582 Aur outburst is a low-mass T Tauri star with average properties. The mass of an unresolved circumstellar structure, probably a disk, is 0.04M(circle dot). The optical and near-infrared spectra demonstrate the presence of hydrogen and metallic lines, show the CO band head in absorption, and exhibit a variable Ha profile. The color variations strongly indicate that both the similar to 1 yr long brightness dip in 2012 and the current minimum since 2016 are caused by increased extinction along the line of sight. According to our accretion disk models, the reddening changed from A(V) = 4.5 to 12.5mag, while the accretion rate remained practically constant. Similarly to the models of the UXor phenomenon of intermediate- and low-mass young stars, orbiting disk structures could be responsible for the eclipses

    Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

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    In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

    Discovery of a satellite of the large trans-neptunian object (225088) 2007 OR10

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    2007 OR10 is currently the third largest known dwarf planet in the trans-Neptunian region, with an effective radiometric diameter of ∼1535 km. It has a slow rotation period of ∼45 hr that was suspected to be caused by tidal interactions with a satellite undetected at that time. Here, we report on the discovery of a likely moon of 2007 OR10, identified on archival Hubble Space Telescope WFC3/UVIS system images. Although the satellite is detected at two epochs, this does not allow an unambiguous determination of the orbit and the orbital period. A feasible 1.5-5.8 • 1021 kg estimate for the system mass leads to a likely 35-100 day orbital period. The moon is about 4.2 fainter than 2007 OR10 in HST images that corresponds to a diameter of 237 km assuming equal albedos with the primary. Due to the relatively small size of the moon, the previous size and albedo estimates for the primary remains unchanged. With this discovery all trans-Neptunian objects larger than 1000 km are now known to harbor satellites, an important constraint for moon formation theories in the young solar system. © 2017. The American Astronomical Society. All rights reserved.The research leading to these results has received funding from the European Unions Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 687378; from the GINOP-2.3.2-15-2016-00003 grant of the National Research, Development and Innovation Office (Hungary); and from the LP2012-31 grant of the Hungarian Academy of Sciences. Funding from Spanish grant AYA-2014-56637-C21-P is acknowledged, as is the Proyecto de Excelencia de la Junta de Andaluca, J.A. 2012-FQM1776.Peer reviewe

    Agricultural economics and transition: What was expected, what we observed, the lessons learned Proceedings (Volume I / II)

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    Over fifteen years have elapsed since the transition from the centrally planned economic system started in the early 1990’s. During this time agricultural and rural areas of Central and Eastern Europe have undergone profound structural changes with wide variations in the degree of transformation and in the rate of success in creating a competitive market and private ownership based food and agricultural system. By becoming member of the European Union the "transition" in its traditional interpretation has been concluded in ten of the Central East European countries. The transition to market based agriculture, however, is far from completion in Southern and Eastern Europe and especially in the CIS countries. International Association of Agricultural Economists (IAAE) and European Association of Agricultural Economists (EAAE) in collaboration with the Corvinus University of Budapest and with a number of other institutions in Hungary organized an inter-conference seminar on the subject of agricultural transition in Central and Eastern Europe and Central Asia. The major objective of the seminar was to discuss and draw conclusions on the role of agricultural policy in the transition process in the light of actual progress and current situation in Central and East European countries and in formal Soviet States. In addition the contribution of agricultural economics – both from the West and from the East – as a discipline and a profession to the transition process in agriculture were discussed. A specific objective was to identify priorities and means to strengthen the agricultural economics profession in the transition countries and determine research and educational priorities for the future. The seminar was attended by 118 participants representing 26 countries from Europe, North America and Asia. The Seminar was the largest professional meeting organized by the two associations in 2007. Over 110 abstracts were submitted and evaluated by the International Program Committee. In the two day program of the meeting, 8 presentations were made during the 3 plenary sessions, 66 papers were presented in the 15 contributed paper sessions in 8 subject categories. In addition there were 15 posters discussed in the poster session and the findings of a World Bank study on distortions of agricultural incentives in the region was the subject of a pre-conference workshop. Plenary speakers included Ulrich Koester, Johan Swinnen, Jerzy Wilkin, Zvi Lerman, Eugenia Serova and József Popp-Gábor Udovecz. At the end of the seminar David Colman, President of IAAE gave a global assessment of the status of agricultural economics discipline and profession, while Csaba Csáki, former President of IAAE made summary comments on major issues discussed during the seminar. This volume includes the plenary and contributed papers presented at the seminar and submitted for publications by the authors as well as the abstracts of the poster papers discussed. The seminar was supported and sponsored by a number of organizations and persons. All of their contributions have to be greatly acknowledged. First the two international organizations IAAE and EAAE have to be mentioned, which provided overall organizational framework and logistical support. The IAAE provided in addition a generous grant to support the participation of young agricultural economists from Central and Eastern Europe on the seminar. On the Hungarian side the Corvinus University of Budapest, the Szent István University of Gödöllő, the Research Institute for Agricultural Economics, the Hungarian Agricultural Economics Association, the Hungarian Association of Agricultural Sciences and the Hungarian Ministry of Agriculture and Rural Development were the major material and organizational supporters. The International Program committee was chaired by David Colman and Csaba Csáki and included Ulrich Koester, Joe Swinnen, Eugenia Serova and Jerzy Wilkin. The local Organizing committee was chaired by Csaba Forgács and István Szűcs and included Zoltán Lakner, András Nábrádi, József Popp, József Tóth, Gábor Udovecz, László Vajda, László Villányi, Krisztina Fodor, Attila Jámbor and Tamás Mizik. Finally IAMO, Halle facilitated the publication of this proceedings
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