Shapiro delay in the PSR J1640+2224 binary system

We present the results of precision timing observations of the binary millisecond pulsar PSR J1640+2224. Combining the pulse arrival time measurements made with the Effelsberg 100-m radio telescope and the Arecibo 305-m radio telescope, we have extended the existing timing model of the pulsar to search for a presence of the effect of a general-relativistic Shapiro delay in the data. At the currently attainable precision level, the observed amplitude of the effect constrains the companion mass to m_2=0.15^{+0.08}_{-0.05} M_\sun, which is consistent with the estimates obtained from optical observations of the white dwarf companion and with the mass range predicted by theories of binary evolution. The measured shape of the Shapiro delay curve restricts the range of possible orbital inclinations of the PSR J1640+2224 system to $78^{\circ}\le i\le 88^{\circ}$. The pulsar offers excellent prospects to significantly tighten these constraints in the near future.Comment: 12 pages, 4 figures, accepted for publication in Ap

A 2.1 Solar Mass Pulsar Measured by Relativistic Orbital Decay

PSR J0751+1807 is a millisecond pulsar in a circular 6 hr binary system with a helium white dwarf secondary. Through high precision pulse timing measurements with the Arecibo and Effelsberg radio telescopes, we have detected the decay of its orbit due to emission of gravitational radiation. This is the first detection of the relativistic orbital decay of a low-mass, circular binary pulsar system. The measured rate of change in orbital period, corrected for acceleration biases, is dP_b/dt=(-6.4+-0.9)x10^-14. Interpreted in the context of general relativity, and combined with measurement of Shapiro delay, it implies a pulsar mass of 2.1+-0.2 solar masses, the most massive pulsar measured. This adds to the emerging trend toward relatively high neutron star masses in neutron star--white dwarf binaries. Additionally, there is some evidence for an inverse correlation between pulsar mass and orbital period in these systems. We consider alternatives to the general relativistic analysis of the data, and we use the pulsar timing data to place limits on violations of the strong equivalence principle.Comment: 9 pages, Submitted to Ap

Forms of Understanding of XAI-Explanations

Explainability has become an important topic in computer science and artificial intelligence, leading to a subfield called Explainable Artificial Intelligence (XAI). The goal of providing or seeking explanations is to achieve (better) 'understanding' on the part of the explainee. However, what it means to 'understand' is still not clearly defined, and the concept itself is rarely the subject of scientific investigation. This conceptual article aims to present a model of forms of understanding in the context of XAI and beyond. From an interdisciplinary perspective bringing together computer science, linguistics, sociology, and psychology, a definition of understanding and its forms, assessment, and dynamics during the process of giving everyday explanations are explored. Two types of understanding are considered as possible outcomes of explanations, namely enabledness, 'knowing how' to do or decide something, and comprehension, 'knowing that' -- both in different degrees (from shallow to deep). Explanations regularly start with shallow understanding in a specific domain and can lead to deep comprehension and enabledness of the explanandum, which we see as a prerequisite for human users to gain agency. In this process, the increase of comprehension and enabledness are highly interdependent. Against the background of this systematization, special challenges of understanding in XAI are discussed

Телемедицина: перспективы развития

Необходимость развития в условиях цифровой экономики такого направления как телемедицина кажется необходимостью, однако существует противоречие между существующими проблемами в системе организации здравоохранения Российской Федерации и возможностями доступности к услугам телемедицины. Анализ показал, что данное направление востребовано, необходимо, существует ряд сервисов, предлагающих услуги по телемедицине, однако нормативно-правовая база не позволяет в полной мере организовать полноценную работу по предоставлению телемедицинских услуг, в том числе, бесплатных