A demonstration of Tribler : peer-to-peer television

The success of Peer-to-Peer Television (P2P-TV) systems depends on the inducement of users to cooperate massively and voluntarily. To operationalize our proposed applications of incentives based on psychological backgrounds, we discuss a demonstration of our own P2P-TV system called Tribler. It is a system for downloading, video-on-demand (VoD), and live streaming of Television content. This paper discusses the demonstration of Tribler version 4.0 as the first operationalization of relevant psychological backgrounds

A demonstration of Tribler : peer-to-peer television

The success of Peer-to-Peer Television (P2P-TV) systems depends on the inducement of users to cooperate massively and voluntarily. To operationalize our proposed applications of incentives based on psychological backgrounds, we discuss a demonstration of our own P2P-TV system called Tribler. It is a system for downloading, video-on-demand (VoD), and live streaming of Television content. This paper discusses the demonstration of Tribler version 4.0 as the first operationalization of relevant psychological backgrounds

Temporal evolution of the Evershed flow in sunspots. II. Physical properties and nature of Evershed clouds

Context: Evershed clouds (ECs) represent the most conspicuous variation of the Evershed flow in sunspot penumbrae. Aims: We determine the physical properties of ECs from high spatial and temporal resolution spectropolarimetric measurements. Methods: The Stokes profiles of four visible and three infrared spectral lines are subject to inversions based on simple one-component models as well as more sophisticated realizations of penumbral flux tubes embedded in a static ambient field (uncombed models). Results: According to the one-component inversions, the EC phenomenon can be understood as a perturbation of the magnetic and dynamic configuration of the penumbral filaments along which these structures move. The uncombed inversions, on the other hand, suggest that ECs are the result of enhancements in the visibility of penumbral flux tubes. We conjecture that the enhancements are caused by a perturbation of the thermodynamic properties of the tubes, rather than by changes in the vector magnetic field. The feasibility of this mechanism is investigated performing numerical experiments of thick penumbral tubes in mechanical equilibrium with a background field. Conclusions: While the one-component inversions confirm many of the properties indicated by a simple line parameter analysis (Paper I of this series), we tend to give more credit to the results of the uncombed inversions because they take into account, at least in an approximate manner, the fine structure of the penumbra.Comment: Accepted for publication in A&

CRISP Spectropolarimetric Imaging of Penumbral Fine Structure

We discuss penumbral fine structure in a small part of a pore, observed with the CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope (SST), close to its diffraction limit of 0.16 arcsec. Milne-Eddington inversions applied to these Stokes data reveal large variations of field strength and inclination angle over dark-cored penumbral intrusions and a dark-cored light bridge. The mid-outer part of this penumbra structure shows 0.3 arcsec wide spines, separated by 1.6 arcsec (1200 km) and associated with 30 deg inclination variations. Between these spines, there are no small-scale magnetic structures that easily can be be identified with individual flux tubes. A structure with nearly 10 deg more vertical and weaker magnetic field is seen midways between two spines. This structure is co-spatial with the brightest penumbral filament, possibly indicating the location of a convective upflow from below.Comment: Accepted for publication in ApJL 17 Oct 2008. One Figure adde

Аналіз тенденцій рівня розвитку економічних процесів підприємства

Подано методичні розробки щодо визначення ймовірної зміни рівнів розвитку економічних процесів машинобудівних підприємств залежно від рівня ефективності матеріальної мотивації персоналу на період 2010 р. Імовірну зміну рівня розвитку економічного процесу визначено за допомогою ланцюгів Маркова, що передбачає реалізацію шести послідовних етапів. Ключові слова: підприємства машинобудування, ланцюги Маркова, економічні процеси.Представлены методические разработки по определению вероятного изменения уровня развития экономических процессов предприятий машиностроения в зависимости от уровня эффективности материальной мотивации персонала на период 2010 г. Вероятное изменение уровня развития экономического процесса определено с помощью цепей Маркова, что предусматривает реализацию шести последовательных этапов. Ключевые слова: предприятия машино-стро¬ения, цепи Маркова, экономические процессы.The paper presents methodical developments on determination of probable changes in the level of machine-build enterprises’ economic processes development depending on the level of personnel’s material motivation efficiency for the period of 2010. Probable changes in the level of economic processes development are determined by using Markov’s chains which provide six stages. Keywords: machine-building enterprises, Markov chains, economic processes

Downward pumping of magnetic flux as the cause of filamentary structures in sunspot penumbrae

The structure of a sunspot is determined by the local interaction between magnetic fields and convection near the Sun's surface. The dark central umbra is surrounded by a filamentary penumbra, whose complicated fine structure has only recently been revealed by high-resolution observations. The penumbral magnetic field has an intricate and unexpected interlocking-comb structure and some field lines, with associated outflows of gas, dive back down below the solar surface at the outer edge of the spot. These field lines might be expected to float quickly back to the surface because of magnetic buoyancy, but they remain submerged. Here we show that the field lines are kept submerged outside the spot by turbulent, compressible convection, which is dominated by strong, coherent, descending plumes. Moreover, this downward pumping of magnetic flux explains the origin of the interlocking-comb structure of the penumbral magnetic field, and the behaviour of other magnetic features near the sunspot

Oncogenic RAS sensitizes cells to drug-induced replication stress via transcriptional silencing of P53

Cancer cells often experience high basal levels of DNA replication stress (RS), for example due to hyperactivation of oncoproteins like MYC or RAS. Therefore, cancer cells are considered to be sensitive to drugs that exacerbate the level of RS or block the intra S-phase checkpoint. Consequently, RS-inducing drugs including ATR and CHK1 inhibitors are used or evaluated as anti-cancer therapies. However, drug resistance and lack of biomarkers predicting therapeutic efficacy limit efficient use. This raises the question what determines sensitivity of individual cancer cells to RS. Here, we report that oncogenic RAS does not only enhance the sensitivity to ATR/CHK1 inhibitors by directly causing RS. Instead, we observed that HRAS(G12V) dampens the activation of the P53-dependent transcriptional response to drug-induced RS, which in turn confers sensitivity to RS. We demonstrate that inducible expression of HRAS(G12V) sensitized cells to ATR and CHK1 inhibitors. Using RNA-sequencing of FACS-sorted cells we discovered that P53 signaling is the sole transcriptional response to RS. However, oncogenic RAS attenuates the transcription of P53 and TGF-beta pathway components which consequently dampens P53 target gene expression. Accordingly, live cell imaging showed that HRAS(G12V) exacerbates RS in S/G2-phase, which could be rescued by stabilization of P53. Thus, our results demonstrate that transcriptional control of P53 target genes is the prime determinant in the response to ATR/CHK1 inhibitors and show that hyperactivation of the MAPK pathway impedes this response. Our findings suggest that the level of oncogenic MAPK signaling could predict sensitivity to intra-S-phase checkpoint inhibition in cancers with intact P53

On the validity of the 630 nm Fe I nm lines for the magnetometry of the internetwork quiet Sun

The purpose of this work is to analyze the reliability of the magnetic field strengths inferred from the 630 nm pair of Fe I lines at internetwork quiet Sun regions. Some numerical experiments have been performed that demonstrate the inability of these lines to recover the magnetic field strength in such low flux solar regions. It is shown how different model atmospheres, with magnetic field strengths ranging from few hundred Gauss to kiloGauss, give rise to Stokes profiles that can not be distinguished. The reasons for this degeneracy are discussed.Comment: Accepted for publication in A&

Resolving the Azimuthal Ambiguity in Vector Magnetogram Data with the Divergence-Free Condition: Application to Discrete Data

We investigate how the divergence-free property of magnetic fields can be exploited to resolve the azimuthal ambiguity present in solar vector magnetogram data, by using line-of-sight and horizontal heliographic derivative information as approximated from discrete measurements. Using synthetic data we test several methods that each make different assumptions about how the divergence-free property can be used to resolve the ambiguity. We find that the most robust algorithm involves the minimisation of the absolute value of the divergence summed over the entire field of view. Away from disk centre this method requires the sign and magnitude of the line-of-sight derivatives of all three components of the magnetic field vector.Comment: Solar Physics, in press, 20 pages, 11 figure