An Investigation of the Large-scale Variability of the Apparently Single Wolf-Rayet Star WR 1

In recent years, much studies have focused on determining the origin of the large-scale line-profile and/or photometric patterns of variability displayed by some apparently single Wolf-Rayet stars, with the existence of an unseen (collapsed?) companion or of spatially extended wind structures as potential candidates. We present observations of WR 1 which highlight the unusual character of the variations in this object. Our narrowband photometric observations reveal a gradual increase of the stellar continuum flux amounting to Delta v = 0.09 mag followed by a decline on about the same timescale (3-4 days). Only marginal evidence for variability is found during the 11 following nights. Strong, daily line-profile variations are also observed but they cannot be easily linked to the photometric variations. Similarly to the continuum flux variations, coherent time-dependent changes are observed in 1996 in the centroid, equivalent width, and skewness of He II 4686. Despite the generally coherent nature of the variations, we do not find evidence in our data for the periods claimed in previous studies. While the issue of a cyclical pattern of variability in WR 1 is still controversial, it is clear that this object might constitute in the future a cornerstone for our understanding of the mechanisms leading to the formation of largely anisotropic outflows in Wolf-Rayet stars.Comment: 11 pages, 9 figures, accepted for publication in Astronomy & Astrophysic

Nuclear star cluster formation in energy-space

In a virialized stellar system, the mean-square velocity is a direct tracer of the energy per unit mass of the system. Here, we exploit this to estimate and compare root-mean-square velocities for a large sample of nuclear star clusters and their host (late- or early-type) galaxies. Traditional observables, such as the radial surface brightness and second-order velocity moment profiles, are subject to short-term variations due to individual episodes of matter infall and/or star formation. The total mass, energy and angular momentum, on the other hand, are approximately conserved. Thus, the total energy and angular momentum more directly probe the formation of galaxies and their nuclear star clusters, by offering access to more fundamental properties of the nuclear cluster-galaxy system than traditional observables. We find that there is a strong correlation, in fact a near equality, between the root-mean-square velocity of a nuclear star cluster and that of its host. Thus, the energy per unit mass of a nuclear star cluster is always comparable to that of its host galaxy. We interpret this as evidence that nuclear star clusters do not form independently of their host galaxies, but rather that their formation and subsequent evolution are coupled. We discuss how our results can potentially be used to offer a clear and observationally testable prediction to distinguish between the different nuclear star cluster formation scenarios, and/or quantify their relative contributions.Comment: 12 pages, 3 figures, 4 tables; accepted for publication in MNRA

Экология в жизни современных спортсменов

Основным свойством экологии человека является ее естественное состояние, которое отражает индивидуально приспособительные реакции каждого человека в обществе и способность его наиболее качественно осуществлять социально-биологическую функцию в определенных условиях и в конкретной местности. Для каждого человека качество популяционного здоровья отражается степенью вероятности на протяжении всей жизни человека, а также характеризует его возможности и жизненные позиции как социального организма в целом

Properties of the Chandra Sources in M81

The Chandra X-ray Observatory obtained a 50-ks observation of the central region of M81 using the ACIS-S in imaging mode. The global properties of the 97 x-ray sources detected in the inner 8.3x8.3 arcmin field of M81 are examined. Roughly half the sources are concentrated within the central bulge. The remainder are distributed throughout the disk with the brightest disk sources lying preferentially along spiral arms. The average hardness ratios of both bulge and disk sources are consistent with power law spectra of index Gamma~1.6 indicative of a population of x-ray binaries. A group of much softer sources are also present. The background source-subtracted logN-logS distribution of the disk follows a power law of index ~ -0.5 with no change in slope over three decades in flux. The logN-logS distribution of the bulge follows a similar shape but with a steeper slope above ~4.0e+37 ergs/s. There is unresolved x-ray flux from the bulge with a radial profile similar to that of the bulge sources. This unresolved flux is softer than the average of the bulge sources and extrapolating the bulge logN-logS distribution towards weaker sources can only account for 20% of the unresolved flux. No strong time variability was observed for any source with the exception of one bright, soft source.Comment: 5 pages, 3 color PS figures, to appear in ApJ

Local height probabilities in a composite Andrews-Baxter-Forrester model

We study the local height probabilities in a composite height model, derived from the restricted solid-on-solid model introduced by Andrews, Baxter and Forrester, and their connection with conformal field theory characters. The obtained conformal field theories also describe the critical behavior of the model at two different critical points. In addition, at criticality, the model is equivalent to a one-dimensional chain of anyons, subject to competing two- and three-body interactions. The anyonic-chain interpretation provided the original motivation to introduce the composite height model, and by obtaining the critical behaviour of the composite height model, the critical behaviour of the anyonic chains is established as well. Depending on the overall sign of the hamiltonian, this critical behaviour is described by a diagonal coset-model, generalizing the minimal models for one sign, and by Fateev-Zamolodchikov parafermions for the other.Comment: 34 pages, 5 figures; v2: expanded introduction, references added and other minor change

Collaborative Deep Learning for Recommender Systems

Collaborative filtering (CF) is a successful approach commonly used by many recommender systems. Conventional CF-based methods use the ratings given to items by users as the sole source of information for learning to make recommendation. However, the ratings are often very sparse in many applications, causing CF-based methods to degrade significantly in their recommendation performance. To address this sparsity problem, auxiliary information such as item content information may be utilized. Collaborative topic regression (CTR) is an appealing recent method taking this approach which tightly couples the two components that learn from two different sources of information. Nevertheless, the latent representation learned by CTR may not be very effective when the auxiliary information is very sparse. To address this problem, we generalize recent advances in deep learning from i.i.d. input to non-i.i.d. (CF-based) input and propose in this paper a hierarchical Bayesian model called collaborative deep learning (CDL), which jointly performs deep representation learning for the content information and collaborative filtering for the ratings (feedback) matrix. Extensive experiments on three real-world datasets from different domains show that CDL can significantly advance the state of the art

Effect of H on the crystalline and magnetic structures of the YCo3-H(D) system. I. YCo3 from neutron powder diffraction and first-principles calculations

This paper reports investigations into the influence of hydrogen on the magnetic properties of the YCo3-H system. We report results on the magnetic structure and magnetic transitions of YCo3 using a combination of neutron powder diffraction measurements and first-principles full potential augmented plane wave + local orbital calculations under the generalized gradient approximation. The ferromagnetic and ferrimagnetic structures are examined on an equal footing. However, we identify that, no matter which structure is used as the starting point, the neutron diffraction data always refines down to the ferrimagnetic structure with the Co2 atoms having antiparallel spins. In the ab initio calculations, the inclusion of spin-orbit coupling is found to be important in the prediction of the correct magnetic ground state. Here, the results suggest that, for zero external field and sufficiently low temperatures, the spin arrangement of YCo3 is ferrimagnetic rather than ferromagnetic as previously believed. The fixed spin moment calculation technique has been employed to understand the two successive field-induced magnetic transitions observed in previous magnetization measurements under increasing ultrahigh magnetic fields. We find that the magnetic transitions start from the ferrimagnetic phase �0.61�B/Co� and terminate with the ferromagnetic phase �1.16�B/Co�, while the spin on the Co2 atoms progressively changes from antiparallel ferrimagnetic to paramagnetic and then to ferromagnetic. Our neutron diffraction measurements, ab initio calculations, and the high field magnetization measurements are thus entirely self-consistent

Современное состояние и перспективы развития ООПТ Томской области

В работе дана характеристика сети особо охраняемых природных территорий Томской области, ее роли в поддержании эколого-хозяйственного баланса области. Определены этапы формирования сети ООПТ. Дан анализ географического разнообразия сети ООПТ и представленности ее в административных районах области. Определена роль сети ООПТ в сохранении редких и исчезающих видов растений и животных. Разработана и реализована методика комплексной оценки эффективности сети ООПТ. Предложены пути ее развития и оптимизации.In work the characteristic of the network of specially protected natural territories of the Tomsk region, its role in maintaining ecological and economic balance of the region. The stages of forming a network of protected areas. The analysis of the geographic diversity of the PA network and its representation in the administrative districts of the region. Defined the role of the network of protected areas in the conservation of rare and endangered species of plants and animals. Developed and implemented a methodology of comprehensive evaluation of the effectiveness of the PA network. The proposed ways of its development and optimization