Shortest Reconfiguration of Colorings Under Kempe Changes

International audienc

Reconfiguration of Spanning Trees with Degree Constraint or Diameter Constraint

We investigate the complexity of finding a transformation from a given spanning tree in a graph to another given spanning tree in the same graph via a sequence of edge flips. The exchange property of the matroid bases immediately yields that such a transformation always exists if we have no constraints on spanning trees. In this paper, we wish to find a transformation which passes through only spanning trees satisfying some constraint. Our focus is bounding either the maximum degree or the diameter of spanning trees, and we give the following results. The problem with a lower bound on maximum degree is solvable in polynomial time, while the problem with an upper bound on maximum degree is PSPACE-complete. The problem with a lower bound on diameter is NP-hard, while the problem with an upper bound on diameter is solvable in polynomial time

Reconfiguration of Spanning Trees with Many or Few Leaves

Let G be a graph and T?,T? be two spanning trees of G. We say that T? can be transformed into T? via an edge flip if there exist two edges e ? T? and f in T? such that T? = (T??e) ? f. Since spanning trees form a matroid, one can indeed transform a spanning tree into any other via a sequence of edge flips, as observed in [Takehiro Ito et al., 2011]. We investigate the problem of determining, given two spanning trees T?,T? with an additional property ?, if there exists an edge flip transformation from T? to T? keeping property ? all along. First we show that determining if there exists a transformation from T? to T? such that all the trees of the sequence have at most k (for any fixed k ? 3) leaves is PSPACE-complete. We then prove that determining if there exists a transformation from T? to T? such that all the trees of the sequence have at least k leaves (where k is part of the input) is PSPACE-complete even restricted to split, bipartite or planar graphs. We complete this result by showing that the problem becomes polynomial for cographs, interval graphs and when k = n-2

Guillain-Barré syndrome complicated by posterior reversible encephalopathy syndrome and reversible cerebral vasoconstriction syndrome

Introduction: Guillain-Barré syndrome is an immune-mediated inflammatory polyneuritis characterised by rapidly progressive flaccid paralysis. Guillain-Barré syndrome may present with posterior reversible encephalopathy syndrome or reversible cerebral vasoconstriction syndrome in rare cases. Case description: A woman in her 60s with a history of follicular lymphoma presented with a one-week history of difficulty walking and thunderclap headaches. The patient was diagnosed with Guillain-Barré syndrome based on neurological examination, cerebrospinal fluid analysis and nerve conduction findings. Further diagnosis of posterior reversible encephalopathy and reversible cerebral vasoconstriction syndromes was based on imaging findings and headache history. The patient was treated with intravenous immunoglobulin and amlodipine, and symptoms improved. Discussion: We reviewed the literature on Guillain-Barré syndrome associated with posterior reversible encephalopathy and/or reversible cerebral vasoconstriction syndrome. The underlying pathophysiology may involve dysautonomia resulting in unstable blood pressure, and hyponatraemia causing endothelial dysfunction. The SNOOP mnemonic highlights the ‘red flags’. This SNOOP mnemonic suggests the possibility of secondary headaches that require imaging studies. In this case, the patient exhibited three SNOOP symptoms: S (history of malignancy: follicular lymphoma), O (sudden-onset headache) and O (over 50 years old). Conclusion: This case highlights the importance of considering coexisting central neurological disorders in patients with Guillain-Barré syndrome

Validity and reproducibility of food photographic estimation for evaluating meals in evacuation shelters

Objective: The primary goal was to evaluate the validity of food photographic estimation for nutritional assessment compared with weighed food record (WFR). Methods: We evaluated the validity and reproducibility of photographic estimation of foods provided in evacuation shelters. We analyzed 35 meals served at 12 shelters in Kumamoto Prefecture in Japan, affected by a heavy rain disaster in 2020. In this context, we compared 21 senior students' portion size estimation by food photographs to WFR. In addition, we assigned five meals for each of the 21 senior students, and the same meal photograph was estimated by three students to test reproducibility. Results: No statistically significant difference was detected between the two methods regarding energy, the total grams of meal, the protein, and vitamins B1, B2, and C, except for salt. In addition, the students who never self-cooked underestimated the total grams. Conclusion: Food photographic estimation could simplify the nutritional assessment in evacuation shelters. However, unclear photographs and food items served by weight could weaken the estimation accuracy. According to previous studies and the applied postestimation questionnaire, photographs taken from specified angles and reference food photobooks for portion size estimation may improve accuracy

Newly Developed TV-Based Cognitive Training Games Improve Car Driving Skills, Cognitive Functions, and Mood in Healthy Older Adults: Evidence From a Randomized Controlled Trial

Background: Cognitive training in a laboratory improves car driving skills of older car drivers. However, it remains unclear whether other types of cognitive training at home have beneficial effects on driving skills. Using our developed cognitive training games that can be played on a television with a set-top box in a person’s home, we investigated the effects of a 6-week cognitive training program on driving skills, which included on-road evaluation (primary outcome), and cognitive functions and emotional states (secondary outcome) in older people.Methods: In this double-blinded randomized control trial (RCT), 60 older licensed drivers were randomly assigned into one of the two groups: a cognitive training game for car driving (CTCD) group and an active control cognitive training game (ACT) group. Participants in the CTCD group played the CTCD (processing speed, dual attention, and speed prediction) for 20 min in five sessions per week for 6 weeks. Participants in the ACT group played the ACT (selecting the larger number; selecting a number from largest to smallest; play a game of rock, article, scissors) for 20 min in five sessions per week for 6 weeks. We measured driving skills, various cognitive functions, and emotional states before and after the 6-week intervention period.Results: Our main results showed that compared to the ACT group, the CTCD group demonstrated improved driving skills (adjusted p = 0.034). Moreover, the CTCD group demonstrated improved inhibition (stroop, adjusted p = 0.042: reverse Stroop, adjusted p = 0.043) and processing speed performance symbol search (SS), adjusted p = 0.049; digit symbol coding (adjusted p = 0.047), compared to the ACT group. The CTCD group scored higher on vigor–activity mood (adjusted p = 0.041) as measured using the Profile of Mood State.Discussion: This randomized controlled trial provides scientific evidence for the benefits of the 6-week CTCD program on driving skills and cognitive functions, such as processing speed, inhibition, and vigor–activity mood, in healthy older people. Our results suggest that cognitive training is useful to improve the driving skills of older adults.Trial registration: This trial was registered at The University Hospital Medical Information Network Clinical Trials Registry (UMIN 000029769). Registered 31 October 2017, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R00003401