Within-the-hour variability: levels and their probabilities

The study of foF2 data measured every 5-min and of TEC measurements made every 10-min shows that the within-the-hour variability is different in the two parameters. Deciles of this variability for foF2 and for TEC are determined together with the probabilities of exceeding a given level of variability. Furthermore, considering hourly values, it is found that the variability in TEC is like an «intrinsic noise» throughout the day of the order of less than 5% of the hourly value; but at sunrise and often at sunset large values take place. A seasonal dependence is evident. Besides, a within-the-hour variability in foF2 is always present with large values at sunrise or sunset depending on the season, and also during disturbed ionospheric conditions

Individual rules for trail pattern formation in Argentine ants (Linepithema humile)

We studied the formation of trail patterns by Argentine ants exploring an empty arena. Using a novel imaging and analysis technique we estimated pheromone concentrations at all spatial positions in the experimental arena and at different times. Then we derived the response function of individual ants to pheromone concentrations by looking at correlations between concentrations and changes in speed or direction of the ants. Ants were found to turn in response to local pheromone concentrations, while their speed was largely unaffected by these concentrations. Ants did not integrate pheromone concentrations over time, with the concentration of pheromone in a 1 cm radius in front of the ant determining the turning angle. The response to pheromone was found to follow a Weber's Law, such that the difference between quantities of pheromone on the two sides of the ant divided by their sum determines the magnitude of the turning angle. This proportional response is in apparent contradiction with the well-established non-linear choice function used in the literature to model the results of binary bridge experiments in ant colonies (Deneubourg et al. 1990). However, agent based simulations implementing the Weber's Law response function led to the formation of trails and reproduced results reported in the literature. We show analytically that a sigmoidal response, analogous to that in the classical Deneubourg model for collective decision making, can be derived from the individual Weber-type response to pheromone concentrations that we have established in our experiments when directional noise around the preferred direction of movement of the ants is assumed.Comment: final version, 9 figures, submitted to Plos Computational Biology (accepted

Революція в освіті: використання комп'ютерного моделювання та хмарних смарт-технологій для сприяння успішному відкритому навчанню

The article presents the proceedings of two workshops: Cloud-based Smart Technologies for Open Education Workshop (CSTOE 2022) and Illia O. Teplytskyi Workshop on Computer Simulation in Education (CoSinE 2022) held in Kyiv, Ukraine, on December 22, 2022. The CoSinE workshop focuses on computer simulation in education, including topics such as computer simulation in STEM education, AI in education, and modeling systems in education. The CSTOE workshop deals with cloud-based learning resources, platforms, and infrastructures, with topics including personalized learning and research environment design, big data and smart data in open education and research, machine learning for open education and research, and more. The article includes a summary of successful cases and provides directions for future research in each workshop’s respective topics of interest. The proceedings consist of several peer-reviewed papers that present a state-of-the-art overview and provide guidelines for future research. The joint program committee consisted of members from universities and research institutions worldwide.У статті представлено матеріали двох семінарів: Семінару "Хмарні смарт-технології для відкритої освіти" (CSTOE 2022) та Семінару Іллі О. Теплицького з комп'ютерного моделювання в освіті (CoSinE 2022), що відбулися в Києві, Україна, 22 грудня 2022 року. Семінар CoSinE присвячений комп'ютерному моделюванню в освіті, включаючи такі теми, як комп'ютерне моделювання в STEM-освіті, штучний інтелект в освіті та системи моделювання в освіті. Семінар CSTOE присвячений хмарним навчальним ресурсам, платформам та інфраструктурам, включаючи такі теми, як дизайн персоналізованого навчального та дослідницького середовища, великі дані та інтелектуальні дані у відкритій освіті та дослідженнях, машинне навчання для відкритої освіти та досліджень тощо. Стаття містить короткий опис успішних кейсів і пропонує напрямки для майбутніх досліджень у відповідних темах кожного семінару, що представляють інтерес. Збірник матеріалів складається з декількох рецензованих статей, які представляють сучасний огляд і надають рекомендації для майбутніх досліджень. Спільний програмний комітет складається з представників університетів та науково-дослідних установ з усього світу

Highly time-resolved chemical speciation and source apportionment of organic aerosol components in Delhi, India, using extractive electrospray ionization mass spectrometry

In recent years, the Indian capital city of Delhi has been impacted by very high levels of air pollution, especially during winter. Comprehensive knowledge of the composition and sources of the organic aerosol (OA), which constitutes a substantial fraction of total particulate mass (PM) in Delhi, is central to formulating effective public health policies. Previous source apportionment studies in Delhi identified key sources of primary OA (POA) and showed that secondary OA (SOA) played a major role but were unable to resolve specific SOA sources. We address the latter through the first field deployment of an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) in Delhi, together with a high-resolution aerosol mass spectrometer (AMS). Measurements were conducted during the winter of 2018/19, and positive matrix factorization (PMF) was used separately on AMS and EESI-TOF datasets to apportion the sources of OA. AMS PMF analysis yielded three primary and two secondary factors which were attributed to hydrocarbon-like OA (HOA), biomass burning OA (BBOA-1 and BBOA-2), more oxidized oxygenated OA (MO-OOA), and less oxidized oxygenated OA (LO-OOA). On average, 40 % of the total OA mass was apportioned to the secondary factors. The SOA contribution to total OA mass varied greatly between the daytime (76.8 %, 10:00–16:00 local time (LT)) and nighttime (31.0 %, 21:00–04:00 LT). The higher chemical resolution of EESI-TOF data allowed identification of individual SOA sources. The EESI-TOF PMF analysis in total yielded six factors, two of which were primary factors (primary biomass burning and cooking-related OA). The remaining four factors were predominantly of secondary origin: aromatic SOA, biogenic SOA, aged biomass burning SOA, and mixed urban SOA. Due to the uncertainties in the EESI-TOF ion sensitivities, mass concentrations of EESI-TOF SOA-dominated factors were related to the total AMS SOA (i.e. MO-OOA + LO-OOA) by multiple linear regression (MLR). Aromatic SOA was the major SOA component during the daytime, with a 55.2 % contribution to total SOA mass (42.4 % contribution to total OA). Its contribution to total SOA, however, decreased to 25.4 % (7.9 % of total OA) during the nighttime. This factor was attributed to the oxidation of light aromatic compounds emitted mostly from traffic. Biogenic SOA accounted for 18.4 % of total SOA mass (14.2 % of total OA) during the daytime and 36.1 % of total SOA mass (11.2 % of total OA) during the nighttime. Aged biomass burning and mixed urban SOA accounted for 15.2 % and 11.0 % of total SOA mass (11.7 % and 8.5 % of total OA mass), respectively, during the daytime and 15.4 % and 22.9 % of total SOA mass (4.8 % and 7.1 % of total OA mass), respectively, during the nighttime. A simple dilution–partitioning model was applied on all EESI-TOF factors to estimate the fraction of observed daytime concentrations resulting from local photochemical production (SOA) or emissions (POA). Aromatic SOA, aged biomass burning, and mixed urban SOA were all found to be dominated by local photochemical production, likely from the oxidation of locally emitted volatile organic compounds (VOCs). In contrast, biogenic SOA was related to the oxidation of diffuse regional emissions of isoprene and monoterpenes. The findings of this study show that in Delhi, the nighttime high concentrations are caused by POA emissions led by traffic and biomass burning and the daytime OA is dominated by SOA, with aromatic SOA accounting for the largest fraction. Because aromatic SOA is possibly more toxic than biogenic SOA and primary OA, its dominance during the daytime suggests an increased OA toxicity and health-related consequences for the general public.</p

Prognostic value of adenosine stress cardiovascular magnetic resonance in patients with low-risk chest pain

<p>Abstract</p> <p>Background</p> <p>Approximately 5% of patients with an acute coronary syndrome are discharged from the emergency room with an erroneous diagnosis of non-cardiac chest pain. Highly accurate non-invasive stress imaging is valuable for assessment of low-risk chest pain patients to prevent these errors. Adenosine stress cardiovascular magnetic resonance (AS-CMR) is an imaging modality with increasing application. The goal of this study was to evaluate the negative prognostic value of AS-CMR among low-risk acute chest pain patients.</p> <p>Methods</p> <p>We studied 103 patients, mean 56.7 ± 12.3 years of age, with chest pain and no electrocardiographic evidence of ischemia and negative cardiac biomarkers of necrosis, who were admitted to the Cardiac Decision Unit of our institution. All patients underwent AS-CMR. A negative AS-CMR was defined as absence of all the following: regional wall motion abnormalities at rest; perfusion defects during stress (adenosine) and rest; and myocardial scar on late gadolinium enhancement images. The patients were followed for a mean of 277 (range 161-462) days. The primary end point was defined as the combination of cardiac death, nonfatal acute myocardial infarction, re-hospitalization for chest pain, obstructive coronary artery disease (>50% coronary stenosis on invasive angiography) and coronary revascularization.</p> <p>Results</p> <p>In 14 patients (13.6%), AS-CMR was positive. The remaining 89 patients (86.4%), who had negative AS-CMR, were discharged. No patient with negative AS-CMR reached the primary end-point during follow-up. The negative predictive value of AS-CMR was 100%.</p> <p>Conclusion</p> <p>AS-CMR holds promise as a useful tool to rule out significant coronary artery disease in patients with low-risk chest pain. Patients with negative AS-CMR have an excellent short and mid-term prognosis.</p

A data-driven approach to optimising the encoding for multi-shell diffusion MRI with application to neonatal imaging

Diffusion MRI has the potential to provide important information about the connectivity and microstructure of the human brain during normal and abnormal development, non-invasively and in vivo. Recent developments in MRI hardware and reconstruction methods now permit the acquisition of large amounts of data within relatively short scan times. This makes it possible to acquire more informative multi-shell data, with diffusion-sensitisation applied along many directions over multiple b-value shells. Such schemes are characterised by the number of shells acquired, and the specific b-value and number of directions sampled for each shell. However, there is currently no clear consensus as to how to optimise these parameters. In this work, we propose a means of optimising multi-shell acquisition schemes by estimating the information content of the diffusion MRI signal, and optimising the acquisition parameters for sensitivity to the observed effects, in a manner agnostic to any particular diffusion analysis method that might subsequently be applied to the data. This method was used to design the acquisition scheme for the neonatal diffusion MRI sequence used in the developing Human Connectome Project, which aims to acquire high quality data and make it freely available to the research community. The final protocol selected by the algorithm, and currently in use within the dHCP, consists of 20 b = 0 images and DW images at b = 400, 1000, 2600 s/mm2 with 64, 88, and 128 directions per shell respectively

Surgical outcome after spinal fractures in patients with ankylosing spondylitis

<p>Abstract</p> <p>Background</p> <p>Ankylosing spondylitis is a rheumatic disease in which spinal and sacroiliac joints are mainly affected. There is a gradual bone formation in the spinal ligaments and ankylosis of the spinal diarthroses which lead to stiffness of the spine.</p> <p>The diffuse paraspinal ossification and inflammatory osteitis of advanced Ankylosing spondylitis creates a fused, brittle spine that is susceptible to fracture. The aim of this study is to present the surgical experience of spinal fractures occurring in patients suffering from ankylosing spondylitis and to highlight the difficulties that exist as far as both diagnosis and surgical management are concerned.</p> <p>Methods</p> <p>Twenty patients suffering from ankylosing spondylitis were operated due to a spinal fracture. The fracture was located at the cervical spine in 7 cases, at the thoracic spine in 9, at the thoracolumbar junction in 3 and at the lumbar spine in one case. Neurological defects were revealed in 10 patients. In four of them, neurological signs were progressively developed after a time period of 4 to 15 days. The initial radiological study was negative for a spinal fracture in twelve patients. Every patient was assessed at the time of admission and daily until the day of surgery, then postoperatively upon discharge.</p> <p>Results</p> <p>Combined anterior and posterior approaches were performed in three patients with only posterior approaches performed on the rest. Spinal fusion was seen in 100% of the cases. No intra-operative complications occurred. There was one case in which superficial wound inflammation occurred. Loosening of posterior screws without loss of stability appeared in two patients with cervical injuries.</p> <p>Frankel neurological classification was used in order to evaluate the neurological status of the patients. There was statistically significant improvement of Frankel neurological classification between the preoperative and postoperative evaluation. 35% of patients showed improvement due to the operation performed.</p> <p>Conclusion</p> <p>The operative treatment of these injuries is useful and effective. It usually succeeds the improvement of the patients' neurological status. Taking into consideration the cardiovascular problems that these patients have, anterior and posterior stabilization aren't always possible. In these cases, posterior approach can be performed and give excellent results, while total operation time, blood loss and other possible complications are decreased.</p

Конференція ACNS "Хмарні та імерсивні технології в освіті": звіт

This article serves as an introduction to a collection of selected papers presented at the ACNS Conference on Cloud and Immersive Technologies in Education (CITEd 2022), which took place in Kyiv, Ukraine, on December 21-22, 2022. The collection provides valuable insights into the latest advancements in cloud and immersive technologies in the field of education. The introductory text offers an overview of the conference events and provides concise summaries of the selected papers, offering a glimpse into the diverse topics and research areas covered. These selected papers reflect the cutting-edge research and innovative approaches showcased at CITEd 2022, making them a valuable resource for educators, researchers, and practitioners interested in exploring the potential of cloud and immersive technologies in education.Ця стаття слугує вступом до збірки вибраних доповідей, представлених на конференції ACNS з хмарних та імерсивних технологій в освіті (CITEd 2022), яка відбулася в Києві, Україна, 21-22 грудня 2022 року. Збірник містить цінну інформацію про останні досягнення в галузі хмарних та імерсивних технологій в освіті. Вступний текст пропонує огляд подій конференції та містить стислі резюме вибраних доповідей, які дають уявлення про різноманітні теми та дослідницькі напрямки, охоплені конференцією. Ці доповіді відображають передові дослідження та інноваційні підходи, представлені на CITEd 2022, що робить їх цінним ресурсом для освітян, дослідників і практиків, зацікавлених у вивченні потенціалу хмарних та імерсивних технологій в освіті