Multi-step Fermi normal coordinates

We generalize the concept of Fermi normal coordinates adapted to a geodesic to the case where the tangent space to the manifold at the base point is decomposed into a direct product of an arbitrary number of subspaces, so that we follow several geodesics in turn to find the point with given coordinates. We compute the connection and the metric as integrals of the Riemann tensor. In the case of one subspace (Riemann normal coordinates) or two subspaces, we recover some results previously found by Nesterov, using somewhat different techniques.Comment: 9 pages, 4 figure

Effect of steel hardness on soot wear

Due to incomplete combustion, high levels of soot can accumulate in engine lubricants between drain intervals. This soot can promote wear of engine parts such as timing chains and cam followers. One standard approach to reducing wear is to increase the hardness of the rubbing components used. According to the Archard wear equation, wear rate should be broadly inversely proportional to hardness. To explore this approach for controlling soot wear, wear tests have been conducted in a High Frequency Reciprocating Rig (HFRR) with HFRR steel discs of various hardness against a hard steel ball. Carbon black (soot surrogate) dispersions in model lubricants based on solutions of ZDDP and dispersant in GTL base oils have been studied. Wear volumes have been measured and wear scars and tribofilms analysed using scanning white light interferometry and SEM-EDS. It is found that, while most oils show wear that reduces with increasing hardness, for blends that contain both ZDDP and carbon black, wear rate markedly increases with disc hardness as the latter approaches the hardness of the ball. The results support the prevalence of a corrosive-abrasive wear mechanism when carbon black and ZDDP are both present in a lubricant and suggests that selection of very hard surfaces may not be a useful way to control soot

Comparative geomorphological observations in two groups of alluvial fans of Sperchios and Eurotas regions, Greece

Στην παρούσα εργασία μελετήθηκαν συγκριτικά δύο ομάδες αλλουβιακών ριπιδίων του ελληνικού χώρου, η πρώτη στην περιοχή του ποταμού Σπερχειού και η δεύτερη στην περιοχή του ποταμού Ευρώτα. Fia το σκοπό αυτό μετρήθηκαν συγκεκριμένα μορφομετρικά χαρακτηριστικά των λεκανών απορροής των ρεμάτων Τσερλιά, Ξεριά, Γοργοπόταμου, Κερασιά, Ρέτσα και Κάκαρη, καθώς και των ριπιδίων τους, έγινε σύγκριση των μετρήσεων αυτών και βγήκαν συμπεράσματα για το σχηματισμό και την εξέλιξη των ριπιδίων. Παράλληλα έγιναν επιμήκεις τομές της κεντρικής κοίτης των ρεμάτων, πραγματοποιήθηκε κροκαλομετρία εντός της κοίτης των ριπιδίων και αποτυπώθηκαν οι οδοντώσεις των ισοϋψών των ριπιδίων. Κατά την κροκαλομετρία έγινε φανερό ότι το μέσο μέγεθος Μ μειώνεται από την κορυφή προς τη βάση των ριπιδίων. Από τη μελέτη των οδοντώσεων των ισοϋψών προέκυψε ότι τα ριπίδια στην περιοχή του Ευρώτα έχουν υποστεί μεγαλύτερη διάβρωση από αυτά της περιοχής του Σπερχειού. Απ' όλα τα παραπάνω συμπεραίνεται ότι τα μελετούμενα ριπίδια παρουσιάζουν σημαντικές διαφορές τόσο μεταξύ τους (κυρίως για την περιοχή του Σπερχειού) όσο και μεταξύ των δύο περιοχών μελέτης. Αυτό οφε^ται κυρίως στον ρηξιγενή τεκτονισμό, την επικρατούσα λιθολογία και το κλίμα. Οι παράγοντες αυτοί είναι εκείνοι που κυρίως καθορίζουν τη γένεση και εξέλιξη των ριπιδίων και επηρεάζουν το σχήμα, την έκταση και τα επιμέρους χαρακτηριστικά τουςIn the present study two groups of alluvial fans from two different regions in Greece were comparetively studied, the first in the region of Sperchios river and the second in the region ofEurotas river. Distinct morphometric characteristics of the drainage basins of the tributaries Ts er lias, Xerias, Gorgopotamos, Kerasias, Retsas and Kakaris, as well as their fans were measured and compared. Furthermore ,the longitudinal stream profiles were mapped, pebble measurements were made and contour crenulations of the fans were studied. In gravelometry, it was found that the mean size M of the pebbles decreases from the apex to the apron of the fan. The crenulation analysis showed that the fans of the streams ofEurotas region have undergone greater erosion than those of Sperchios region. Remarkable differences exist between the fans of the two regions. These results lead to the conclusion that recent tectonism, the prevailing lithology and climate are responsible for the formation and evolution of the fans and also influence their shape, area and all the other morphometric characteristic

Biopsychosocial Intervention for Stroke Carers (BISC): protocol for a feasibility randomized controlled trial

Introduction Reducing length of hospital stay for stroke survivors often creates a shift in the responsibility of care towards informal carers. Adjustment to the caregiving process is experienced by many carers as overwhelming, complex and demanding, and can have a detrimental impact on mental and physical health and wellbeing. National policy guidelines recommend that carers’ needs are considered and addressed; despite this, few interventions have been developed and empirically evaluated. We developed a biopsychosocial intervention in collaboration with carers of stroke survivors. Our aim is to determine whether the intervention can be delivered in a group setting and evaluated using a randomised controlled trial (RCT). Methods and Analysis Feasibility randomised controlled trial (RCT) and nested qualitative interview study. We aim to recruit up to 40 stroke carers within one year of the stroke onset. Carers are randomised to usual care or usual care plus biopsychosocial intervention. Each intervention group will consist of five stroke carers. The intervention will focus on: psychoeducation, psychological adjustment to stroke, strategies for reducing unwanted negative thoughts and emotions, and problem solving strategies. The main outcome is the feasibility of conducting an RCT. Carer outcomes at six months include: anxiety and depression, quality of life, and carer strain. Data is also collected from stroke survivors at baseline and six months including: level of disability, anxiety and depression, and quality of life. Ethics and Dissemination Favourable ethical opinion was provided by East Midlands – Nottingham2 Research Ethics Committee (14/EMI/1264). This study will determine whether delivery of the biopsychosocial intervention is feasible and acceptable to stroke carers within a group format. It will also determine whether it is feasible to evaluate the effects of the biopsychosocial intervention in an RCT. We will disseminate our findings through peer-reviewed publications and presentations at national and international conferences

The role of mobility in the dynamics of the COVID-19 epidemic in Andalusia

Metapopulation models have been a popular tool for the study of epidemic spread over a network of highly populated nodes (cities, provinces, countries) and have been extensively used in the context of the ongoing COVID-19 pandemic. In the present work, we revisit such a model, bearing a particular case example in mind, namely that of the region of Andalusia in Spain during the period of the summer-fall of 2020 (i.e., between the first and second pandemic waves). Our aim is to consider the possibility of incorporation of mobility across the province nodes focusing on mobile-phone time dependent data, but also discussing the comparison for our case example with a gravity model, as well as with the dynamics in the absence of mobility. Our main finding is that mobility is key towards a quantitative understanding of the emergence of the second wave of the pandemic and that the most accurate way to capture it involves dynamic (rather than static) inclusion of time-dependent mobility matrices based on cell-phone data. Alternatives bearing no mobility are unable to capture the trends revealed by the data in the context of the metapopulation model considered herein

A Biopsychosocial Intervention for Stroke Carers (BISC): development and description of the intervention

Objective: Family members of stroke survivors are often not supported for their caring role, with many reporting adjustment difficulties. This paper describes the development and content of a group-based intervention for informal carers of stroke survivors.Method: The intervention is based on the theoretical foundation of the biopsychosocial model with the aim to understand and address the physical, psychological and social factors of caring for stroke survivors. Findings from a comprehensive literature review and a qualitative study with carers and stroke professionals were synthesized to guide the intervention development. The Template for Intervention Description and Replication (TIDieR) checklist was used as a framework to describe the intervention.Results: The intervention integrates cognitive-behavioural approaches via the identification of the biopsychosocial (physical, emotional, social) factors that can have an impact on the well-being of carers. It includes education on stroke-specific topics and advice on coping strategies. It consists of six two-hour group sessions facilitated in a community setting. It provides information and support on adjusting to the caring role in the first year post-stroke. Intervention materials were designed for addressing carers’ specific needs using psychological techniques, such as problem-solving, goal setting and relaxation exercises.Conclusion: We have underlined the importance for describing and reporting the process of intervention development for complex interventions in the context of stroke rehabilitation. An intervention addressing the needs of informal stroke carers (Biopsychosocial Intervention for Stroke Carers; BISC) has been developed and described. BISC was further evaluated in a single-centre feasibility randomized controlled trial

Educational programme management methodology for research projects

Smart grids and intelligent energy systems play a pivotal role in fostering the sustainable advancement of our civilization. Over the past few decades, power systems, like many other sectors, have undergone a rapid digital transformation. This rapid development necessitates a proactive response from universities, research institutes, industry stakeholders in relation to educational programmes. Educators must rapidly adapt their curricula and teaching methodologies to effectively train the next generation of engineering professionals. While curriculum crafting for new educational programs is inherently challenging, another layer of complexity arises when research collaborations in large consortia are tasked with delivering high-quality education within a given project scope and time frame. This paper outlines a methodology for establishing an educational strategy for such research projects. This approach takes into account the available resources and expertise of the project participants, while embracing modern, learner-centric educational methodologies. It also ensures alignment with broader objectives or frameworks. Furthermore, the strategy incorporates a dynamic evaluation process that runs concurrently with the educational activities. Finally, the ERIGrid 2.0 H2020 project upon which the proposed methodology was developed, is presented as a case study