Greedy Randomized Adaptive Search and Variable Neighbourhood Search for the minimum labelling spanning tree problem

This paper studies heuristics for the minimum labelling spanning tree (MLST) problem. The purpose is to find a spanning tree using edges that are as similar as possible. Given an undirected labelled connected graph, the minimum labelling spanning tree problem seeks a spanning tree whose edges have the smallest number of distinct labels. This problem has been shown to be NP-hard. A Greedy Randomized Adaptive Search Procedure (GRASP) and a Variable Neighbourhood Search (VNS) are proposed in this paper. They are compared with other algorithms recommended in the literature: the Modified Genetic Algorithm and the Pilot Method. Nonparametric statistical tests show that the heuristics based on GRASP and VNS outperform the other algorithms tested. Furthermore, a comparison with the results provided by an exact approach shows that we may quickly obtain optimal or near-optimal solutions with the proposed heuristics

Pilot, Rollout and Monte Carlo Tree Search Methods for Job Shop Scheduling

Greedy heuristics may be attuned by looking ahead for each possible choice, in an approach called the rollout or Pilot method. These methods may be seen as meta-heuristics that can enhance (any) heuristic solution, by repetitively modifying a master solution: similarly to what is done in game tree search, better choices are identified using lookahead, based on solutions obtained by repeatedly using a greedy heuristic. This paper first illustrates how the Pilot method improves upon some simple well known dispatch heuristics for the job-shop scheduling problem. The Pilot method is then shown to be a special case of the more recent Monte Carlo Tree Search (MCTS) methods: Unlike the Pilot method, MCTS methods use random completion of partial solutions to identify promising branches of the tree. The Pilot method and a simple version of MCTS, using the $\varepsilon$-greedy exploration paradigms, are then compared within the same framework, consisting of 300 scheduling problems of varying sizes with fixed-budget of rollouts. Results demonstrate that MCTS reaches better or same results as the Pilot methods in this context.Comment: Learning and Intelligent OptimizatioN (LION'6) 7219 (2012

Ambulante Rehabilitation nach zerebralem Insult im Gefüge medizinischer und pflegerischer Nachsorge:eine Querschnittsuntersuchung

Es liegen in Deutschland wenig Daten über Umfang, Prädiktoren und Patientenzufriedenheit mit ambulanter Rehabilitation, über ärztliche Nachsorge und pflegerische Betreuung nach zerebralem Insult vor. In dieser Querschnittsstudie werden o.g. Parameter ermittelt und Vernetzungen zwischen ambulanter Rehabilitation mit ärztlicher und pflegerischer Nachsorge dargestellt. So wurde vor dem Hintergrund steigender Patientenzahlen und sozioökonomischer Fragen zum ersten Mal eine Basis für weiterführende Untersuchungen geschaffen, mit denen eine Erstellung verbindlicher Leitlinien für die Langzeitversorgung für Insultpatienten gelingen soll

Veränderungen des Knochens in Abhängigkeit der Strahlendosis in Bezug auf die Insertion enossaler dentaler Implantate

Bei Patienten nach tumorbedingten Resektionen und Strahlenbelastung finden osseointegrierte Implantate Anwendung, da resektionsbedingte Veränderungen die Anatomie des Prothesenlagers für herausnehmbaren Zahnersatz beeinträchtigen. Diese Patienten sollten mit Implantaten in Abhängigkeit von der Strahlendosis rehabilitiert werden. Bei 32 Patienten mit verschiedener Strahlenbelastung wurden Knochenzylinder gewonnen und diese mit Hämatoxylin-Eosin und Lowcross puffer von Willebrandt /Faktor VIII gefärbt. Anschließend wurden histomorphometrisch der prozentuale Osteoidanteil, die quantitative Osteozyten- und Gefäßanzahl ausgewertet. Der Osteoidanteil unterschied sich statistisch nicht signifikant. Signifikant hingegen waren weniger Gefäße und Osteozyten nach Bestrahlung im Gegensatz zu unbestrahlten Patienten. Eine Strahlentherapie induziert eine Fibrose, ohne die quantitative Knochenmasse zu verändern. Es kommt jedoch zum einem Vaskularisations- und Vitalitätsverlust

Discrete Particle Swarm Optimization for the minimum labelling Steiner tree problem

Particle Swarm Optimization is an evolutionary method inspired by the social behaviour of individuals inside swarms in nature. Solutions of the problem are modelled as members of the swarm which fly in the solution space. The evolution is obtained from the continuous movement of the particles that constitute the swarm submitted to the effect of the inertia and the attraction of the members who lead the swarm. This work focuses on a recent Discrete Particle Swarm Optimization for combinatorial optimization, called Jumping Particle Swarm Optimization. Its effectiveness is illustrated on the minimum labelling Steiner tree problem: given an undirected labelled connected graph, the aim is to find a spanning tree covering a given subset of nodes, whose edges have the smallest number of distinct labels

Root cortex development is fine-tuned by the interplay of MIGs, SCL3 and DELLAs during arbuscular mycorrhizal symbiosis

Root development is a crucial process that determines the ability of plants to acquire nutrients, adapt to the substrate and withstand changing environmental conditions. Root plasticity is controlled by a plethora of transcriptional regulators that allow, in contrast to tissue development in animals, post-embryonic changes that give rise to new tissue and specialized cells. One of these changes is the accommodation in the cortex of hyperbranched hyphae of symbiotic arbuscular mycorrhizal (AM) fungi, called arbuscules. Arbuscule-containing cells undergo massive reprogramming to coordinate developmental changes with transport processes. Here we describe a novel negative regulator of arbuscule development, MIG3. MIG3 induces and interacts with SCL3, both of which modulate the activity of the central regulator DELLA, restraining cortical cell growth. As in a tug-of-war, MIG3-SCL3 antagonizes the function of the complex MIG1-DELLA, which promotes the cell expansion required for arbuscule development, adjusting cell size during the dynamic processes of the arbuscule life cycle. Our results in the legume plant Medicago truncatula advance the knowledge of root development in dicot plants, showing the existence of additional regulatory elements not present in Arabidopsis that fine-tune the activity of conserved central modules

Biomarkers as Proxies to Analyse Land-Use History in Northern Jordan

In the semi-arid 'Decapolis region' in northern Jordan, due severe land degradation in the past, 'barren' and 'impoverished' landscapes can be found today. It is widely believed that land degradation in these regions was caused by ancient land use, e.g. overgrazing due to ‘Arab mismanagement'. However, the connection of degradation with land use is far from certain. The 'Decapolis region' is located in an approximately 100 km wide transition zone from Mediterranean to steppe and desert climate. Therefore, the landscape in this region is highly sensitive to climate variations. A major sedimentation phase in the late 6th century AD appears to represent a significant climate change towards more aridity, and might be connected with a cluster of heavy rainfall events in northern Jordan. In fact, more recent studies have found that periods of predominantly pastoral land use in northern Jordan were connected with natural reforestation. Since a dating of sedimentation alone does not deliver clues about the precise reason of deposition, a multidisciplinary team is analyzing the land-use history in the ‘Decapolis’ region. This presentation focusses on ongoing biomarker analyses. Samples were selected considering geoarchaeological data, including phosphorus concentrations, archaeological data, including distribution of potsherds and other fragments on ancient fields and data of further disciplines. Vegetation changes are investigated by analyses of n-alkanes and terpenoids. Manuring with faeces is analysed by specific steroids that are indicative for faeces deposition. Preliminary results showed a high input of omnivorous (pigs, humans) faeces in some areas. Manuring with faeces of herbivores seemed to be less important

RiCRN1, a crinkler effector from the arbuscular mycorrhizal fungus rhizophagus irregularis, functions in arbuscule development

Arbuscular mycorrhizal (AM) symbiosis is one of the most prominent and beneficial plant–microbe interactions that facilitates mineral nutrition and confers tolerance to biotic and abiotic stresses. AM fungi colonize the root cortex and develop specialized structures called arbuscules where the nutrient exchange takes place. Arbuscule development is a highly controlled and coordinated process requiring the involvement of many plant proteins recruited at that interface. In contrast, much less is known about the fungal proteins involved in this process. Here, we have identified an AM fungal effector that participates in this developmental step of the symbiosis. RiCRN1 is a crinkler (CRN) effector that belongs to a subfamily of secreted CRN proteins from R. irregularis. CRNs have been so far only functionally characterized in pathogenic microbes and shown to participate in processes controlling plant cell death and immunity. RiCRN1 accumulates during symbiosis establishment parallel to MtPT4, the gene coding for an arbuscule-specific phosphate transporter. Expression in Nicotiana benthamiana leaves and in Medicago truncatula roots suggest that RiCRN1 is not involved in cell death processes. RiCRN1 dimerizes and localizes to nuclear bodies, suggesting that, similar to other CRNs, it functions in the plant nucleus. Downregulation of RiCRN1 using host-induced gene silencing led to an impairment of the symbiosis in M. truncatula and to a reduction of MtPT4, while ectopic expression of RiCRN1, surprisingly, led to a drastic reduction in arbuscule size that correlated with a decrease not only in MtPT4 but also in MtBCP1, a marker for initial stages of arbuscule development. Altogether, our results suggest that a tightly regulated expression in time and space of RiCRN1 is critical for symbiosis progression and for the proper initiation of arbuscule development