Randomized rendez-vous with limited memory

We present a tradeoff between the expected time for two identical agents to rendez-vous on a synchronous, anonymous, oriented ring and the memory requirements of the agents. In particular, we show that there exists a 2t state agent, which can achieve rendez-vous on an n node ring in expected time O( n 2/2 t ∈+∈2 t ) and that any t/2 state agent requires expected time Ω( n 2/2 t ). As a corollary we observe that Θ(loglogn) bits of memory are necessary and sufficient to achieve rendez-vous in linear time

Asymptotic structural properties of quasi-random saturated structures of RNA

Background: RNA folding depends on the distribution of kinetic traps in the landscape of all secondary structures. Kinetic traps in the Nussinov energy model are precisely those secondary structures that are saturated, meaning that no base pair can be added without introducing either a pseudoknot or base triple. In previous work, we investigated asymptotic combinatorics of both random saturated structures and of quasi-random saturated structures, where the latter are constructed by a natural stochastic process.Results: We prove that for quasi-random saturated structures with the uniform distribution, the asymptotic expected number of external loops is O(logn) and the asymptotic expected maximum stem length is O(logn), while under the Zipf distribution, the asymptotic expected number of external loops is O(log2n) and the asymptotic expected maximum stem length is O(logn/log logn).Conclusions: Quasi-random saturated structures are generated by a stochastic greedy method, which is simple to implement. Structural features of random saturated structures appear to resemble those of quasi-random saturated structures, and the latter appear to constitute a class for which both the generation of sampled structures as well as a combinatorial investigation of structural features may be simpler to undertake

Routing on delay tolerant sensor networks

Delay (or disruption) tolerant sensor networks may be modeled as Markovian evolving graphs [1]. We present experimental evidence showing that considering multiple (possibly not shortest) paths instead of one fixed (greedy) path can decrease the expected time to deliver a packet on such a network by as much as 65 per cent depending on the probability that an edge exists in a given time interval. We provide theoretical justification for this result by studying a special case of the Markovian evolving grid graph. We analyze a natural algorithm for routing on such networks and show that it is possible to improve the expected time of delivery by up to a factor of two depending upon the probability of an edge being up during a time step and the relative positions of the source and destination. Furthermore we show that this is optimal, i.e., no other algorithm can achieve a better expected running time. As an aside, our results give high probability bounds for Knuth's toilet paper problem [11]

Station layouts in the presence of location constraints

In wireless communication, the signal of a typical broadcast station is transmited from a broadcast center p and reaches objects at a distance, say, R from it. In addition there is a radius r, r < R, such that the signal originating from the center of the station is so strong that human habitation within distance r from the center p should be avoided. Thus every station determines a region which is an “annulus of permissible habitation". We consider the following station layout (SL) problem: Cover a given (say, rectangular) planar region which includes a collection of orthogonal buildings with a minimum number of stations so that every point in the region is within the reach of a station, while at the same time no building is within the dangerous range of a station. We give algorithms for computing such station layouts in both the one-and two-dimensional cases

Linear search with terrain-dependent speeds

We revisit the linear search problem where a robot, initially placed at the origin on an infinite line, tries to locate a stationary tar-get placed at an unknown position on the line. Unlike previous studies, in which the robot travels along the line at a constant speed, we con-sider settings where the robot’s speed can depend on the direction of travel along the line, or on the profile of the terrain, e.g. when the line is inclined, and the robot can accelerate. Our objective is to design search algorithms that achieve good competitive ratios for the time spent by the robot to complete its search versus the time spent by an omniscient robot that knows the location of the target. We consider several new robot mobility models in which the speed of the robot depends on the terrain. These include (1) different con-stant speeds for different directions, (2) speed with constant acceleration and/or variability depending on whether a certain segment has already been searched, (3) speed dependent on the incline of the terrain. We pro-vide both upper and lower bounds on the competitive ratios of search algorithms for these models, and in many cases, we derive optimal algo-rithms for the search time

The Minangkabau Healers And Healing Methods: A Structural Analysis

In this thesis the researcher wants to illustrate the healing methods of the Minangkabau in West Sumatra. It looks at one village of the interior and describes the different healing methods of the Minangkabau in that village. The aim is to illustrate the different ways of treatment and to analyze it in a structural way by following the ideas of Claude Levi-Strauss and Josselin de Jong. For many anthropologists, structuralism and its methodology are outdated, but this thesis intends to show that a structural approach is still fruitful and could contribute to analyze traditional healing methods. Furthermore, this thesis will illustrate that there are different types of healers with their own ways of treatment within one village society and its network. The research objectives are to explore the Minangkabau healers and their healing methods. The different types of healers, healing methods and plants should be categorized. This thesis will also examine whether Frederick Errington’s hypothesis that the Minangkabau are sign-oriented is correct in the field of healing. The Minangkabau society is both part of Southeast Asia and part of the Islamic world and therefore this research shows in how far these healing methods are embedded within a greater context. The research discovers that there are three types of healers who still play an important role in the health of the local population. There are three elements of healing methods that play a certain role. Unique patterns of the Minangkabau healing methods are described by the researcher and give an impression why traditional healing methods are still relevant

Weak coverage of a rectangular barrier

Assume n wireless mobile sensors are initially dispersed in an ad hoc manner in a rectangular region. They are required to move to final locations so that they can detect any intruder crossing the region in a direction parallel to the sides of the rectangle, and thus provide weak bar-rier coverage of the region. We study three optimization problems related to the movement of sensors to achieve weak barrier coverage: minimizing the number of sensors moved (MinNum), minimizing the average distance moved by the sensors (MinSum), and minimizing the maximum distance moved by the sensors (

HUBUNGAN ANTARA PENGETAHUAN, SIKAP, PRAKTEK KELUARGA TENTANG PEMBERANTASAN SARANG NYAMUK (PSN) DENGAN KEJADIAN DEMAM BERDARAH DENGUE DI WILAYAH KERJA PUSKESMAS TLOGOSARI WETAN KOTA SEMARANG

Background: Dengue hemorrhagic fever (DHF) is an infectious disease caused by dengue virus through vector of Aedes aegypti mosquito. Untill now it is one of public health problem in Indonesia. Based on data which came from Semarang Health Service, the amount of DBD case in area of Puskesmas Tlogosari was still high, it was 118 cases in 2010. This research has purpose to find the association between knowledge, attitude, practice of family about removing breeding place of mosquito with case of dengue hemorrhagic fever in area of Puskesmas Tlogosari Wetan Semarang City. Methods: This research was an observational analytic research applying case control design. In this research, the sample criterias were case sample and control sample. The case samples were mothers who had family member that had DHF and the control samples were mothers who had family member that never had DHF. Both cases must had domicile in area of Puskesmas Tlogosari Wetan Semarang City. The total members of case sample were 50 members and for control members were 50 members. Data collection was conducted by interview the sample using a questionnaire which had been tested for validity and reliability. The data in this research were tested with Chi square which has level of significant (alfa) 5%. Result: In the case samples, we found that 50% of case samples had bad characteristic knowledge, 76% did not support the program of removing breeding place of mosquito, and 36% had bad practice of removing breeding place of mosquito. There are significant association between knowledge, attitude, practice of family about removing breeding place of mosquito with case of dengue hemorrhagic fever. Conclusion: Knowledge, attitude, and practice of family about removing breeding place of mosquito have significant association with case of dengue hemorrhagic fever

Labeled versus unlabeled distributed Cayley networks

We consider labelings (i.e. assignments of labels to the links that give the network a globally consistent orientation) on anonymous Cayley networks NG constructed from a set G of generators of a group G. Such networks can be endowed with a natural labeling LG to form the oriented Cayley network, denoted by NG[LG]. We show that in general oriented Cayley networks are more powerful than unoriented Cayley networks, in the sense that the former can compute more Boolean functions than the latter. We also give a characterization of those Abelian groups G which have a canonical set of generators G such that the network NG computes more Boolean functions than the network NG[LG]