Impedance Method Used To Calculate Initial Switching Currents in Transmission Networks and Generator Real Power

Switching-on of transmission network elements can bring about high inrush currents in the network elements (lines and transformers) as well as sudden changes in real power of generating units. In order to reduce those disadvantageous effects in modern power systems switching operations are controlled by protection devices referred to as synchro-check. Optimal setting of the synchro-check parameters requires the application of adequate criteria and an efficient method for calculating current changes in lines and generators that result from switching operations. This article proposes a new calculation method based on a nodal impedance matrix. Such a matrix is commonly used for short-circuit analyses. The advantage of the proposed method is that a short-circuit software with an adequate extension can be also applied to the analysis of switching operations

Freelance Workers—Experiencing a Career Outside an Organization

This article focuses on the issues of everyday work as a self-employed, professional freelancer in Poland. The appearance of this specific category of workers on the labor market is connected with certain major changes on the economic, technological, and socio-cultural levels. The career of a freelancer is sometimes considered to be an antithesis of a corporate career. The key points are: working on one’s own, functioning outside the traditional organizational structures, HR management and supervision, promotion procedures, corporate career paths, et cetera. For a freelancer, the organization is not “an employer,” but rather “a client” or “a business partner.” The manager of the organization is not “his boss” and the employees are not his “colleagues.” As we can observe, most of the typical boundaries of a career are blurred here and that is one of the reasons why it arouses curiosity as an unusual phenomenon. The article aims to present a sociological perspective regarding the career of a freelancer in Poland. A framework of symbolic interactionism and grounded theory were applied to the author’s research (conducted in 2009-14) on which the article is based. Its first part focuses on the theoretical background and the methods that were used to collect and analyze data. The second part includes some of the author’s findings and conclusions on a freelance career from the interactionist perspective, as well as a discussion about the possible agreement and discrepancies between the author’s understanding of freelance against the widely discussed concept of precarity

GLISSANDO: GLauber Initial-State Simulation AND mOre

GLISSANDO is a Glauber Monte-Carlo generator for early-stages of relativistic heavy-ion collisions, written in c++ and interfaced to Root. Several models are implemented: the wounded-nucleon model, the binary collisions model, the mixed model, and the model with hot-spots. Subtleties of the distribution of nucleon in the nucleus are discussed. The original geometric distribution of sources in the transverse plane can be superimposed with a statistical distribution simulating the dispersion in the generated transverse energy in each individual collision. The program generates inter alia the fixed axes (standard) and variable-axes (participant) two-dimensional profiles of the density of sources in the transverse plane and their Fourier components. These profiles can be used in further analyses of physical phenomena, such as the the jet quenching, event-by-event hydrodynamics, or analysis of the elliptic flow and its fluctuations. Characteristics of the event (multiplicities, eccentricities, Fourier coefficients, etc.) are evaluated and stored in a file for further off-line studies. A number of scripts is provided for that purpose. Supplied variants of the code can also be used for the proton-nucleus and deuteron-nucleus collisions.Comment: Updated ver. 1.6 of the code available at http://www.pu.kielce.pl/homepages/mryb/GLISSANDO

Understanding in-video dropouts and interaction peaks in online lecture videos

With thousands of learners watching the same online lecture videos, analyzing video watching patterns provides a unique opportunity to understand how students learn with videos. This paper reports a large-scale analysis of in-video dropout and peaks in viewership and student activity, using second-by-second user interaction data from 862 videos in four Massive Open Online Courses (MOOCs) on edX. We find higher dropout rates in longer videos, re-watching sessions (vs first-time), and tutorials (vs lectures). Peaks in re-watching sessions and play events indicate points of interest and confusion. Results show that tutorials (vs lectures) and re-watching sessions (vs first-time) lead to more frequent and sharper peaks. In attempting to reason why peaks occur by sampling 80 videos, we observe that 61% of the peaks accompany visual transitions in the video, e.g., a slide view to a classroom view. Based on this observation, we identify five student activity patterns that can explain peaks: starting from the beginning of a new material, returning to missed content, following a tutorial step, replaying a brief segment, and repeating a non-visual explanation. Our analysis has design implications for video authoring, editing, and interface design, providing a richer understanding of video learning on MOOCs

The homotopy type of the loops on (n−1)(n-1)-connected (2n+1)(2n+1)-manifolds

For $n\geq 2$ we compute the homotopy groups of $(n-1)$-connected closed manifolds of dimension $(2n+1)$. Away from the finite set of primes dividing the order of the torsion subgroup in homology, the $p$-local homotopy groups of $M$ are determined by the rank of the free Abelian part of the homology. Moreover, we show that these $p$-local homotopy groups can be expressed as a direct sum of $p$-local homotopy groups of spheres. The integral homotopy type of the loop space is also computed and shown to depend only on the rank of the free Abelian part and the torsion subgroup.Comment: Trends in Algebraic Topology and Related Topics, Trends Math., Birkhauser/Springer, 2018. arXiv admin note: text overlap with arXiv:1510.0519

Winter Bird Assemblages in Rural and Urban Environments: A National Survey

Urban development has a marked effect on the ecological and behavioural traits of many living organisms, including birds. In this paper, we analysed differences in the numbers of wintering birds between rural and urban areas in Poland. We also analysed species richness and abundance in relation to longitude, latitude, human population size, and landscape structure. All these parameters were analysed using modern statistical techniques incorporating species detectability. We counted birds in 156 squares (0.25 km2 each) in December 2012 and again in January 2013 in locations in and around 26 urban areas across Poland (in each urban area we surveyed 3 squares and 3 squares in nearby rural areas). The influence of twelve potential environmental variables on species abundance and richness was assessed with Generalized Linear Mixed Models, Principal Components and Detrended Correspondence Analyses. Totals of 72 bird species and 89,710 individual birds were recorded in this study. On average (±SE) 13.3 ± 0.3 species and 288 ± 14 individuals were recorded in each square in each survey. A formal comparison of rural and urban areas revealed that 27 species had a significant preference; 17 to rural areas and 10 to urban areas. Moreover, overall abundance in urban areas was more than double that of rural areas. There was almost a complete separation of rural and urban bird communities. Significantly more birds and more bird species were recorded in January compared to December. We conclude that differences between rural and urban areas in terms of winter conditions and the availability of resources are reflected in different bird communities in the two environments

Bone Morphogenic Proteins are Immunoregulatory Cytokines Controlling FOXP3+ T\u3csub\u3ereg\u3c/sub\u3e Cells

Bone morphogenic proteins (BMPs) are members of the transforming growth factor β (TGF-β) cytokine family promoting differentiation, homeostasis, and self-renewal of multiple tissues. We show that signaling through the bone morphogenic protein receptor 1α (BMPR1α) sustains expression of FOXP3 in Treg cells in peripheral lymphoid tissues. BMPR1α signaling promotes molecular circuits supporting acquisition and preservation of Treg cell phenotype and inhibiting differentiation of pro-inflammatory effector Th1/Th17 CD4+ T cell. Mechanistically, increased expression of KDM6B (JMJD3) histone demethylase, an antagonist of the polycomb repressive complex 2, underlies lineage-specific changes of T cell phenotypes associated with abrogation of BMPR1α signaling. These results reveal that BMPs are immunoregulatory cytokines mediating maturation and stability of peripheral FOXP3+ regulatory T cells (Treg cells) and controlling generation of iTreg cells. Thus, we establish that BMPs, a large cytokine family, are an essential link between stromal tissues and the adaptive immune system involved in sustaining tissue homeostasis by promoting immunological tolerance

Simulations of X-ray spectral/timing properties in a propagation model of variability of accreting black holes

A phenomenological model of X-ray variability of accreting black holes is considered, where the variable emission is attributed to multiple active regions/perturbations moving radially towards the central black hole. The hard X-rays are produced by inverse Compton upscattering of soft photons coming from reprocessing/thermalization of the same hard X-rays. The heating rate of the Comptonizing plasma is assumed to scale with the rate of dissipation of gravitational energy while the supply of soft photons is assumed to diminish towards the center. Two scenarios are considered: (1) an inner hot flow with outer truncated standard accretion disc and (2) an accretion disc with an active corona and a thick hot ionized skin. A variant of the model is also considered, which is compatible with the currently discussed multi-Lorentzian description of power spectral densities of X-ray lightcurves. In the inner hot flow scenario the model can reproduce the observed Fourier frequency resolved spectra observed in X-ray binaries, in particular the properties of the reprocessed component as functions of Fourier frequency. In the accretion disc with ionized skin scenario the reduction of soft photons due to the ionized skin is insufficient to produce the observed characteristics.Comment: 8 pages, MNRAS, replaced with the accepted version, minor changes in formulae in Sec. 3.

Hot spot imaging in cardiovascular diseases:an information statement from SNMMI, ASNC, and EANM

This information statement from the Society of Nuclear Medicine and Molecular Imaging, American Society of Nuclear Cardiology, and European Association of Nuclear Medicine describes the performance, interpretation, and reporting of hot spot imaging in nuclear cardiology. The field of nuclear cardiology has historically focused on cold spot imaging for the interpretation of myocardial ischemia and infarction. Hot spot imaging has been an important part of nuclear medicine, particularly for oncology or infection indications, and the use of hot spot imaging in nuclear cardiology continues to expand. This document focuses on image acquisition and processing, methods of quantification, indications, protocols, and reporting of hot spot imaging. Indications discussed include myocardial viability, myocardial inflammation, device or valve infection, large vessel vasculitis, valve calcification and vulnerable plaques, and cardiac amyloidosis. This document contextualizes the foundations of image quantification and highlights reporting in each indication for the cardiac nuclear imager.</p