Detecting Fixed Patterns in Chordal Graphs in Polynomial Time

The Contractibility problem takes as input two graphs G and H, and the task is to decide whether H can be obtained from G by a sequence of edge contractions. The Induced Minor and Induced Topological Minor problems are similar, but the first allows both edge contractions and vertex deletions, whereas the latter allows only vertex deletions and vertex dissolutions. All three problems are NP-complete, even for certain fixed graphs H. We show that these problems can be solved in polynomial time for every fixed H when the input graph G is chordal. Our results can be considered tight, since these problems are known to be W[1]-hard on chordal graphs when parameterized by the size of H. To solve Contractibility and Induced Minor, we define and use a generalization of the classic Disjoint Paths problem, where we require the vertices of each of the k paths to be chosen from a specified set. We prove that this variant is NP-complete even when k=2, but that it is polynomial-time solvable on chordal graphs for every fixed k. Our algorithm for Induced Topological Minor is based on another generalization of Disjoint Paths called Induced Disjoint Paths, where the vertices from different paths may no longer be adjacent. We show that this problem, which is known to be NP-complete when k=2, can be solved in polynomial time on chordal graphs even when k is part of the input. Our results fit into the general framework of graph containment problems, where the aim is to decide whether a graph can be modified into another graph by a sequence of specified graph operations. Allowing combinations of the four well-known operations edge deletion, edge contraction, vertex deletion, and vertex dissolution results in the following ten containment relations: (induced) minor, (induced) topological minor, (induced) subgraph, (induced) spanning subgraph, dissolution, and contraction. Our results, combined with existing results, settle the complexity of each of the ten corresponding containment problems on chordal graphs.     

Deciding k-Colorability of P 5-Free Graphs in Polynomial Time

The problem of computing the chromatic number of a P ₅-free graph (a graph which contains no path on 5 vertices as an induced subgraph) is known to be NP-hard. However, we show that for every fixed integer k, there exists a polynomial-time algorithm determining whether or not a P ₅-free graph admits a k-coloring, and finding one, if it does.     

Vocal-based emotion recognition using random forests and decision tree

This paper proposes a new vocal-based emotion recognition method using random forests, where pairs of the features on the whole speech signal, namely, pitch, intensity, the first four formants, the first four formants bandwidths, mean autocorrelation, mean noise-to-harmonics ratio and standard deviation, are used in order to recognize the emotional state of a speaker. The proposed technique adopts random forests to represent the speech signals, along with the decision-trees approach, in order to classify them into different categories. The emotions are broadly categorised into the six groups, which are happiness, fear, sadness, neutral, surprise, and disgust. The Surrey Audio-Visual Expressed Emotion database is used. According to the experimental results using leave-one-out cross-validation, by means of combining the most significant prosodic features, the proposed method has an average recognition rate of \(66.28\%\), and at the highest level, the recognition rate of \(78\%\) has been obtained, which belongs to the happiness voice signals. The proposed method has \(13.78\%\) higher average recognition rate and \(28.1\%\) higher best recognition rate compared to the linear discriminant analysis as well as \(6.58\%\) higher average recognition rate than the deep neural networks results, both of which have been implemented on the same database.     

Finding Induced Paths of Given Parity in Claw-Free Graphs

The Parity Path problem is to decide if a given graph contains both an induced path of odd length and an induced path of even length between two specified vertices. In the related problems Odd Induced Path and Even Induced Path, the goal is to determine whether an induced path of odd, respectively even, length between two specified vertices exists. Although all three problems are NP-complete in general, we show that they can be solved in $\mathcal{O}(n^{5})$ time for the class of claw-free graphs. Two vertices s and t form an even pair in G if every induced path from s to t in G has even length. Our results imply that the problem of deciding if two specified vertices of a claw-free graph form an even pair, as well as the problem of deciding if a given claw-free graph has an even pair, can be solved in $\mathcal{O}(n^{5})$ time and $\mathcal{O}(n^{7})$ time, respectively. We also show that we can decide in $\mathcal{O}(n^{7})$ time whether a claw-free graph has an induced cycle of given parity through a specified vertex. Finally, we show that a shortest induced path of given parity between two specified vertices of a claw-free perfect graph can be found in $\mathcal {O}(n^{7})$ time.     

On the Role of C Addition on α Precipitation in a β Titanium Alloy

The onset of α nucleation in a carbon containing β-titanium alloy has been investigated by coupling atom probe tomography (APT) with transmission electron microscopy. The analysis of the APT results indicates that in addition to ω precipitates that can act as potential α nucleation sites, carbon atoms tend to form clusters within the β-matrix, which in turn give rise to additional nucleation sites for α, resulting in finer scale α precipitates due to increased nucleation density.     

Brain Mechanisms of Exercise-Induced Hypoalgesia: To Find a Way Out from “Fear-Avoidance Belief”

It is well known that exercise produces analgesic effects (exercise-induced hypoalgesia (EIH)) in animal models and chronic pain patients, but the brain mechanisms underlying these EIH effects, especially concerning the emotional aspects of pain, are not yet fully understood. In this review, we describe drastic changes in the mesocorticolimbic system of the brain which permit the induction of EIH effects. The amygdala (Amyg) is a critical node for the regulation of emotions, such as fear and anxiety, which are closely associated with chronic pain. In our recent studies using neuropathic pain (NPP) model mice, we extensively examined the association between the Amyg and EIH effects. We found that voluntary exercise (VE) activated glutamate (Glu) neurons in the medial basal Amyg projecting to the nucleus accumbens (NAc) lateral shell, while it almost completely suppressed NPP-induced activation of GABA neurons in the central nucleus of the Amyg (CeA). Furthermore, VE significantly inhibited activation of pyramidal neurons in the ventral hippocampus-CA1 region, which play important roles in contextual fear conditioning and the retrieval of fear memory. This review describes novel information concerning the brain mechanisms underlying EIH effects as a result of overcoming the fear-avoidance belief of chronic pain.     

Towards Designing a Trusted Routing Solution in Mobile Ad Hoc Networks

Designing a trusted and secure routing solution in an untrustworthy scenario is always a challenging problem. Lack of physical security and low trust levels among nodes in an ad hoc network demands a secure end-to-end route free of any malicious entity. This is particularly challenging when malicious nodes collude with one another to disrupt the network operation. In this paper we have designed a secure routing solution to find an end-to-end route free of malicious nodes with collaborative effort from the neighbors. We have also extended the solution to secure the network against colluding malicious nodes, which, to the best of our knowledge, is the first such solution proposed. We have also proposed a framework for computing and distributing trusts that can be used with out trusted routing protocol. Our proposed framework is unique and different from the other schemes in that it tries to analyze the psychology of the attacker and quantifies the behavior in the computational model. Extensive simulation has been carried out to evaluate the design of our protocol. Partially funded by Department of Defense Award No. H98230-04-C-0460, Department of Transportation Project No. FL-26-7102-00 and National Science Foundation Grant Nos. ANI-0123950 and CCR-0196557. Tirthankar Ghosh is a PhD candidate in the Telecommunications and Information Technology Institute at Florida International University. His area of research is routing security and trust computation in wireless ad hoc and sensor networks. He received his Bachelor of Electrical Engineering from Jadavpur University, India and Masters in Computer Engineering from Florida International University. Dr. Niki Pissinou received her Ph.D. in Computer Science from the University of Southern California, her M.S. in Computer Science from the University of California at Riverside, and her B.S.I.S.E. in Industrial and Systems Engineering from The Ohio State University. She is currently a tenured professor and the director of the Telecommunication & Information Technology Institute at FIU. Previously Dr. Pissinou was a tenured faculty at the Center for Advanced Computer Studies at the University of Louisiana at Lafayette where she was also the director of the Telecommunication & Information & Technology Laboratory partially funded by NASA, and the co-director of the NOMAD: A Wireless and Nomadic Laboratory partially funded by NSF, and the Advanced Network Laboratory. Dr. Pissinou is active in the fields computer networks, information technology and distributed systems. Dr. Kami (Sam) Makki has earned his Ph.D. in Computer Science from the University of Queensland in Brisbane Australia, his Masters degree in Computer Science and Engineering from the University of New South Wales in Sydney Australia, and his Bachelor and Masters Degrees in Civil Engineering from the University of Tehran Iran. Before joining the department of Electrical Engineering and Computer Science at the University of Toledo he has held a number of academic positions and research appointments at the Queensland University of Technology in Brisbane, Royal Melbourne Institution of Technology in Melbourne and at The University of Queensland in Brisbane Australia. He is an active researcher in the fields of distributed systems, databases, mobile and wireless communications, and has more than 30 publications in peerreviewed journals and international proceedings. He has served as a chair and technical program committee member and reviewer for a number of IEEE and ACM sponsored technical conferences and has received a number of achievement awards.     

Theoretical studies of the pressure-induced zinc-blende to cinnabar phase transition in CdTe and thermodynamical properties of each phase

Luminescence of CdTe quantum dots embedded in ZnTe is quenched at pressure of about 4.5 GPa in the high-pressure experiments. This pressure-induced quenching is attributed to the “zinc-blende–cinnabar” phase transition in CdTe, which was confirmed by the first-principles calculations. Theoretical analysis of the pressure at which the phase transition occurs for CdTe was performed using the CASTEP module of Materials Studio package with both generalized gradient approximation (GGA) and local density approximation (LDA). The calculated phase transition pressures are equal to about 4.4 GPa and 2.6 GPa, according to the GGA and LDA calculations, respectively, which is in a good agreement with the experimental value. Theoretically estimated value of the pressure coefficient of the band-gap luminescence in zinc-blende structure is in very good agreement with that recently measured in the QDs structures. The calculated Debye temperature, elastic constants and specific heat capacity for the zinc-blend structure agree well with the experimental data; the data for the cinnabar phase are reported here for the first time to the best of the authors' knowledge.     

Logistics cost analysis of rice straw for biomass power generation in Thailand

The logistics of the fuel supply have a large impact on the economy of a biomass power generation facility, especially for low density biomass fuels like straw. A detailed cost analysis of a typical rice straw logistics process for two baling options in three regions of Thailand shows that the costs for all logistics operations vary from a minimum of 18.75 USD/t for small rectangular bales in the Northern region of Thailand to maximum 19.89 USD/t for large rectangular bales in the North-eastern region. The difference in costs is not very significant due to the higher ownership and operating costs of the equipment for using large rectangular bales; however, the specific fuel consumption cost is substantially lower by around 17.5% and a total transport cost reduction is about 31.5%. Analysis of the logistics economies of scale for projected power plant capacities of 2-35 MW_e showed that each doubling the capacity of the energy facility increases the specific costs of the logistics operations only by around 4% in all regions.     

The impact of liberalisation of the electricity market on the hard coal mining sector in Poland

The liberalisation of the electricity market changed the conditions of operation not only for the power industry, but also for related sectors. One of the particularly sensitive industries in Poland is coal mining, which is the result of coal-based structure of electricity generation. As it is more difficult, in the liberalised market, to burden consumers with all the costs, electricity producers are eager to transfer the risk of operation to the suppliers. That increases uncertainty about the future of the hard coal industry. The aim of this paper was to quantitatively estimate the impact that liberalisation of the electricity markets may have on the coal mining sector in Poland. First of all, the possible areas of that impact were identified. Then the model, which involved detailed relations in the impact areas identified, was developed and employed to evaluate the performance of the mining sector. The comparison of scenarios of a monopolistic electricity sector with a liberalised one enabled an estimation of the scale of the impact on the mining sector to be made. The results showed that liberalisation causes decreased coal consumption and decreased operating profits in coal companies. However, some savings in electricity costs are possible for coal producers.