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The paper describes a sensitivity function calculation method for few-view X-ray computed tomography of strongly absorbing objects. It is based on a probabilistic interpretation of energy transport through the object from a source to a detector. A PRIZMA code package is used to track photons. The code is developed at FSUE “RFNC–VNIITF named after Academ. E. I. Zababakhin” and implements a stochastic Monte Carlo method. The value of the sensitivity function in a discrete cell of the reconstruction region is assumed to be directly proportional to the fraction of photon trajectories which cross the cell from all those recorded by the detector. The method’s efficiency is validated through a numerical experiment on the reconstruction of a section of a spherical heavy-metal phantom with an air cavity and a density difference of 25 Ṫhe proposed method is shown to outperform the method based on projection approximation in case of reconstruction from 9 views.

Erratum to the paper [Konovalov, Alexander; Smoktunowicz, Agata; Vendramin, Leandro. On skew braces and their ideals. Exp. Math. 30 (2021), no. 1, 95–104. DOI: 10.1080/10586458.2018.1492476.].

Background: Pineal cysts (PCs) are benign lesions commonly found on intracranial imaging. Despite their high prevalence, there is no clear consensus on the most appropriate management of patients with PCs, especially those with symptomatic nonhydrocephalic cysts. Methods: A retrospective analysis was performed on 142 patients with PCs (103 surgical cases and 39 conservatively managed cases). Data were examined, including clinical presentation, imaging findings, ophthalmological status, natural course, postoperative outcomes, and complications. Results: Surgical group: the most common symptom was headache (92%), followed by signs of intracranial hypertension due to hydrocephalus (22%). New radiological feature of PCs was found in 11 patients. From 71 patients with long-term follow-up, headache completely resolved in 44 (62%) patients; marked improvement was observed in 20 (29%); in 7 (9%) – headache remained unchanged. The most common postoperative complication was neuro-ophthalmological disorders (23%), with a tendency for resolution in the long-term follow-up period. Neuro-ophthalmological symptoms at last follow-up included upward gaze palsy (6%) and skew deviation (5%), followed by convergence disorders (3%) and eyelid-retraction (2%). Natural course group: PC size remained stable in 34 (87%) patients during the follow-up period. The patient’s gender or age was not a significant predictor of cyst growth (P = 0.4, P = 0.56). Conclusion: The majority of patients with a newly diagnosed PC remain clinically and radiologically stable. Patients with nonhydrocephalic PCs and intractable headaches experience significant relief in headache symptoms, but are at risk of mild to moderate neuro-ophthalmological disorders. The natural course of PCs and factors promoting their growth still remains poorly defined.

For pediatric patients with high‐grade gliomas, standard‐of‐care treatment includes surgery, chemotherapy, and radiation therapy; however, most patients ultimately succumb to their disease. With advances in genomic characterization of pediatric high‐grade gliomas, the use of targeted therapies in combination with current treatment modalities offer the potential to improve survival in this patient population. In this report, we present the case of a 3‐year‐old girl with glioblastoma who continues to experience an exceptional and durable response (>2 years) to the poly (ADP‐ribose) polymerase (PARP) inhibitor olaparib. Our patient presented with persistent and progressive seizure activity that upon workup was the result of a large heterogeneously enhancing, mixed cystic and solid mass in the left frontal‐parietal‐temporal region. Histopathologic analysis of resected tumor tissue confirmed the diagnosis of glioblastoma, and comprehensive genomic profiling demonstrated absence of any BRAF or H3F3A mutations. Genomic profiling, however, did reveal a probable germline heterozygous BRCA2 Lys3326Ter (K3226*) nonsense variant. After debulking surgery, the patient received standard‐of‐care treatment with radiation and temozolomide. Nine months later the PARP inhibitor olaparib was administered in combination with temozolomide for 16 cycles. This regimen was well tolerated by the patient and serial imaging showed reduction in tumor size. Since completion of the regimen, the patient remains neurologically intact with no evidence of tumor recurrence. To our knowledge, this represents the first case of a pediatric glioblastoma that maintains a durable response to a therapeutic strategy that included the PARP inhibitor olaparib and more generally highlights the potential clinical utility of incorporating these agents into the treatment of pediatric high‐grade gliomas. Key Points Germline mutations detected in pediatric gliomas may represent a cancer predisposition syndrome.Integrating molecular testing into routine clinical care for pediatric patients with glioma is critical to identify therapeutic targets and patients with a cancer predisposition syndrome.Patients with glioma with defects in DNA repair pathway components (e.g., BRCA1/2) may show increased responsiveness to poly (ADP‐ribose) polymerase (PARP) inhibitors.Combining PARP inhibitors with temozolomide (standard‐of‐care treatment) revealed no adverse events or toxicities over the course of 18 months., This article reports the first case of a pediatric glioblastoma that maintained a durable response to a therapeutic strategy that included the PARP inhibitor olaparib, highlighting the potential clinical utility of incorporating these agents into the treatment of pediatric high‐grade gliomas.

Literate computing has emerged as an important tool for computational studies and open science, with growing folklore of best practices. In this work, we report two case studies - one in computational magnetism and another in computational mathematics - where domain-specific software was exposed to the Jupyter environment. This enables high-level control of simulations and computation, interactive exploration of computational results, batch processing on HPC resources, and reproducible workflow documentation in Jupyter notebooks. In the first study, Ubermag drives existing computational micromagnetics software through a domain-specific language embedded in Python. In the second study, a dedicated Jupyter kernel interfaces with the GAP system for computational discrete algebra and its dedicated programming language. In light of these case studies, we discuss the benefits of this approach, including progress toward more reproducible and reusable research results and outputs, notably through the use of infrastructure such as JupyterHub and Binder., Comment: 11 pages, 3 figures

The prime graph question asks whether the Gruenberg–Kegel graph of an integral group ring [Formula: see text], i.e. the prime graph of the normalized unit group of [Formula: see text], coincides with that one of the group [Formula: see text]. In this note, we prove for finite groups [Formula: see text] a reduction of the prime graph question to almost simple groups. We apply this reduction to finite groups [Formula: see text] whose order is divisible by at most three primes and show that the Gruenberg–Kegel graph of such groups coincides with the prime graph of [Formula: see text].

Lightning talk presented at Collaborations Workshop 2019 organised by the Software Sustainability Institute.

The author examines the current Russian civil law with a focus on a key principle of bona fides (goodfaith). The appearance of the principle is appreciated as a guarantee of stability and social orientationof the law. By making a brief historical overview, the author supports the normative consolidation ofthe principle, which is declared in the Conception of Civil Legislation. Besides, the author stressesthe principle in question not only for the legal regulation of property and binding relations but alsothe practical rationale of the principle as a pillar of civil legislation. Food faith is defined by the authoras an intention of a party to a civil transaction to prevent at a maximum the possibility of violation byconduct of legal rights and judicial interests of other parties, perform their rights strictly under thecontent, scope and purpose. Besides, the author takes up the comparative analysis of good faithto show that the concept covers mostly reasonableness and fairness of the actions of the parties tocivil relations. At that, the author notes that non-inclusion of the principles of reasonableness andjustice to the pre-requisites of civil law deems a justified classified default. The author concludes with remarking a tendency of judicial practice to broaden the application of the good faith principle. Thelatter seems relevant to court only if it cannot deliver a fair decision only by interpreting and applyingthe existing the applicable rule of law.

The first-named author is partially supported by CCP CoDiMa (EP/M022641/1) and the OpenDreamKit Horizon 2020 European Research Infrastructures project (#676541). The second-named author is supported by the ERC Advanced grant 320974. The third-named author is supported by PICT-201-0147, MATH-AmSud 17MATH-01 and ERC Advanced grant 320974. We define combinatorial representations of finite skew braces and use this idea to produce a database of skew braces of small size. This database is then used to explore different concepts of the theory of skew braces such as ideals, series of ideals, prime and semiprime ideals, Baer and Wedderburn radicals and solvability. The paper contains several questions. Postprint

Broad-coverage knowledge bases (KBs) such as Wikipedia, Freebase, Microsoft's Satori and Google's Knowledge Graph contain structured data describing real-world entities. These data sources have become increasingly important for a wide range of intelligent systems: from information retrieval and question answering, to Facebook's Graph Search, IBM's Watson, and more. Previous work on learning to populate knowledge bases from text has, for the most part, made the simplifying assumption that facts remain constant over time. But this is inaccurate -- we live in a rapidly changing world. Knowledge should not be viewed as a static snapshot, but instead a rapidly evolving set of facts that must change as the world changes. In this paper we demonstrate the feasibility of accurately identifying entity-transition-events, from real-time news and social media text streams, that drive changes to a knowledge base. We use Wikipedia's edit history as distant supervision to learn event extractors, and evaluate the extractors based on their ability to predict online updates. Our weakly supervised event extractors are able to predict 10 KB revisions per month at 0.8 precision. By lowering our confidence threshold, we can suggest 34.3 correct edits per month at 0.4 precision. 64% of predicted edits were detected before they were added to Wikipedia. The average lead time of our forecasted knowledge revisions over Wikipedia's editors is 40 days, demonstrating the utility of our method for suggesting edits that can be quickly verified and added to the knowledge graph.

We identify all small groups of order up to 288 in the GAP Library for which the Zassenhaus conjecture on rational conjugacy of units of finite order in the integral group ring cannot be established by an existing method. The groups must first survive all theoretical sieves and all known restrictions on partial augmentations (the HeLP$^+$ method). Then two new computational methods for verifying the Zassenhaus conjecture are applied to the unresolved cases, which we call the quotient method and the partially central unit construction method. To the cases that remain we attempt an assortment of special arguments available for units of certain orders and the lattice method. In the end, the Zassenhaus conjecture is verified for all groups of order less than 144 and we give a list of all remaining cases among groups of orders 144 to 287., 10 pages

Symbolic computation has underpinned a number of key advances in Mathematics and Computer Science. Applications are typically large and potentially highly parallel, making them good candidates for parallel execution at a variety of scales from multi-core to high-performance computing systems. However, much existing work on parallel computing is based around numeric rather than symbolic computations. In particular, symbolic computing presents particular problems in terms of varying granularity and irregular task sizes that do not match conventional approaches to parallelisation. It also presents problems in terms of the structure of the algorithms and data. This paper describes a new implementation of the free open-source GAP computational algebra system that places parallelism at the heart of the design, dealing with the key scalability and cross-platform portability problems. We provide three system layers that deal with the three most important classes of hardware: individual shared memory multi-core nodes, mid-scale distributed clusters of multi-core nodes and full-blown high-performance computing systems, comprising large-scale tightly connected networks of multi-core nodes. This requires us to develop new cross-layer programming abstractions in the form of new domain-specific skeletons that allow us to seamlessly target different hardware levels. Our results show that, using our approach, we can achieve good scalability and speedups for two realistic exemplars, on high-performance systems comprising up to 32000 cores, as well as on ubiquitous multi-core systems and distributed clusters. The work reported here paves the way towards full-scale exploitation of symbolic computation by high-performance computing systems, and we demonstrate the potential with two major case studies. © 2016 The Authors. Concurrency and Computation: Practice and Experience Published by John Wiley & Sons Ltd.

Slides for the talk at theAI away day of the School of Computer Science, University of St Andrews

The article deals with the issues of quality improvement at the life cycle stages of means of automated monitoring of electrochemical protection of technical systems. The possibility of production of automated control facilities with robustness properties in relation to changes in external influences and environmental conditions is considered, which improve the quality of the process of electrochemical protection of technical systems. The article considers the stages of the process of designing the means for automated control of the electrochemical protection process. A set of local criteria for the formation of an integral quality criterion for solving the problem of choosing the optimal options for the location of the means for automated control of the electrochemical protection process is determined.