Journal articles on the topic 'Uniquely labelled graphs'

Each action of a finitely generated group on a set uniquely defines a labelled directed graph called the Schreier graph of the action. Schreier graphs are used mainly as a tool to establish geometrical and dynamical properties of corresponding group actions. In particilar, they are widely used in order to check amenability of different classed of groups. In the present paper Schreier graphs are utilized to construct new examples of faithful actions of free products of groups. Using Schreier graphs of group actions a sufficient condition for a group action to be faithful is presented. This result is applied to finite automaton actions on spaces of words i.e. actions defined by finite automata over finite alphabets. It is shown how to construct new faithful automaton presentations of groups upon given such a presentation. As an example a new countable series of faithful finite automaton presentations of free products of finite groups is constructed. The obtained results can be regarded as another way to construct new faithful actions of groups as soon as at least one such an action is provided.

Recognizing topological analogy between the parts of semantic network seems to be very important step in the process of semantic categorization and interpretation of data that are embedded into the semantic network. Considering the semantic network as a set of graphs, recognition of topological analogy between the parts of semantic network can be treated as maximum common subgraph problem which falls in the group of exact graph matching problems. In this paper authors propose a new algorithm for maximum common subgraph detection aimed to a specific semantic network called Active Semantic Model (ASM). This semantic network can be represented as the set of labeled directed multigraphs with unique node labels. The structure of these graphs is specific because associations or edges are labeled with several attributes and some of them are related to nodes connected by edge. That kind of association-oriented structure enables associations or edges to play key role in the process of semantic categorization and interpretation of data. Furthermore, this kind of structure enables modeling semantic contexts in a form of semantically designated graphs (of associations). Proposed algorithm is capable of recognizing simultaneously maximum common subgraph of input graph and each of the graphs representing different contexts in ASM semantic network.

AbstractFor integers l ≥ 1, d ≥ 0 we study (undirected) graphs with vertices 1, …, n such that the vertices can be partitioned into l parts such that every vertex has at most d neighbours in its own part. The set of all such graphs is denoted Pn (l, d). We prove a labelled first-order limit law, i.e., for every first-order sentence φ, the proportion of graphs in Pn (l, d) that satisfy φ converges as n → ∞. By combining this result with a result of Hundack, Prömel and Steger [12] we also prove that if 1 ≤ s1 ≤ … ≤ sl are integers, then Forb() has a labelled first-order limit law, where Forb() denotes the set of all graphs with vertices 1, …, n, for some n, in which there is no subgraph isomorphic to the complete (l + 1 )-partite graph with parts of sizes 1, s1, …, sl. In the course of doing this we also prove that there exists a first-order formula ξ, depending only on l and d, such that the proportion of ∈ Pn (l, d) with the following property approaches 1 as n → ∞: there is a unique partition of {1, …, n} into l parts such that every vertex has at most d neighbours in its own part, and this partition, viewed as an equivalence relation, is defined by ξ.

We give a concrete formula for the unique faithful trace on the finite simple non-AF labeled graph [Formula: see text]-algebra [Formula: see text] associated to the Thue–Morse sequence [Formula: see text]. Our result provides an alternative proof of the existence of a labeled graph [Formula: see text]-algebra that is not Morita equivalent to any graph [Formula: see text]-algebras. Furthermore, we compute the [Formula: see text]-groups of [Formula: see text] using the path structure of the Thue–Morse sequence.

We consider a problem introduced by Mossel and Ross (‘Shotgun assembly of labeled graphs’, arXiv:1504.07682). Suppose a random n × n jigsaw puzzle is constructed by independently and uniformly choosing the shape of each ‘jig’ from q possibilities. We are given the shuffled pieces. Then, depending on q, what is the probability that we can reassemble the puzzle uniquely? We say that two solutions of a puzzle are similar if they only differ by a global rotation of the puzzle, permutation of duplicate pieces, and rotation of rotationally symmetric pieces. In this paper, we show that, with high probability, such a puzzle has at least two non-similar solutions when 2 ⩽ q ⩽ 2e−1/2n, all solutions are similar when q ⩾ (2+ϵ)n, and the solution is unique when q = ω(n).

As in many natural language processing tasks, data-driven models based on supervised learning have become the method of choice for semantic role labeling. These models are guaranteed to perform well when given sufficient amount of labeled training data. Producing this data is costly and time-consuming, however, thus raising the question of whether unsupervised methods offer a viable alternative. The working hypothesis of this article is that semantic roles can be induced without human supervision from a corpus of syntactically parsed sentences based on three linguistic principles: (1) arguments in the same syntactic position (within a specific linking) bear the same semantic role, (2) arguments within a clause bear a unique role, and (3) clusters representing the same semantic role should be more or less lexically and distributionally equivalent. We present a method that implements these principles and formalizes the task as a graph partitioning problem, whereby argument instances of a verb are represented as vertices in a graph whose edges express similarities between these instances. The graph consists of multiple edge layers, each one capturing a different aspect of argument-instance similarity, and we develop extensions of standard clustering algorithms for partitioning such multi-layer graphs. Experiments for English and German demonstrate that our approach is able to induce semantic role clusters that are consistently better than a strong baseline and are competitive with the state of the art.

In this paper, we introduce an algorithm that assigns an essentially unique key called the Universal Chemical Key (UCK) to molecular structures. The molecular structures are represented as labeled graphs whose nodes abstract atoms and whose edges abstract bonds. The algorithm was tested on 236,917 compounds obtained from the National Cancer Institute (NCI) database of chemical compounds. On this database, the UCK algorithm assigned unique keys for chemicals with distinct molecular structures.

Assessing the impact of chemicals on the environment and addressing subsequent issues are two central challenges to their safe use. Environmental data are continuously expanding, requiring flexible, scalable, and extendable data management solutions that can harmonize multiple data sources with potentially differing nomenclatures or levels of specificity. Here, we present the methodological steps taken to construct a rule-based labeled property graph database, the “Meta-analysis of the Global Impact of Chemicals” (MAGIC) graph, for potential environmental impact chemicals (PEIC) and its subsequent application harmonizing multiple large-scale databases. The resulting data encompass 16,739 unique PEICs attributed to their corresponding chemical class, stereo-chemical information, valid synonyms, use types, unique identifiers (e.g., Chemical Abstract Service registry number CAS RN), and others. These data provide researchers with additional chemical information for a large amount of PEICs and can also be publicly accessed using a web interface. Our analysis has shown that data harmonization can increase up to 98% when using the MAGIC graph approach compared to relational data systems for datasets with different nomenclatures. The graph database system and its data appear more suitable for large-scale analysis where traditional (i.e., relational) data systems are reaching conceptional limitations.

Unstable nets, by definition, display vertex collisions in any barycentric representation, among which are approximate models for the associated crystal structures. This means that different vertex lattices happen to superimpose when every vertex of a periodic net is located at the centre of gravity of its first neighbours. Non-crystallographic nets are known to be unstable, but crystallographic nets can also be unstable and general conditions for instability are not known. Moreover, examples of unstable nets are still scarce. This article presents a systematic analysis of unstable 3-periodic nets of genus 4, satisfying the restrictions that, in a suitable basis, (i) their labelled quotient graph contains a spanning tree with zero voltage and (ii) voltage coordinates belong to the set {−1, 0, 1}. These nets have been defined by a unique circuit of null voltage in the quotient graph. They have been characterized through a shortest path between colliding vertices. The quotient graph and the nature of the net obtained after identification of colliding vertices, if known, are also provided. The complete list of the respective unstable nets, with a detailed description of the results, can be found in the supporting information.

AbstractThe cloning and sequencing of two specific molecular markers linked to grape (Vitis vinifera) seedless gene indicated that the full lengths of the markers, 39970524-5-564 (GenBank accession number: AY327513) and 39970524-6-1538 (GenBank accession number: AY327514), were 564 bp and 1538 bp, respectively. The restriction sites of sequences 39970524-5-564 and 39970524-6-1538 were analysed with Wingene231 software. The results indicated that there were 29 and 130 restriction sites in 39970524-5-564 and 39970524-6-1538, respectively, digested by restriction enzymes with recognition sites of six or more than six bases. There was no cleavage site in 39970524-5-564 and there was one site at 135 bp of 39970524-6-1538 when these two markers were digested by EcoRI. Both markers can not be digested by HindIII. Therefore, the full length of 39970524-5-564 and of the two bands of 39970524-6-1538 (1400 bp and 135 bp) could be cut out from the pGEMR-T Easy Vector by EcoRI. The labelled DNA of 39970524-5-564, used as a probe for Southern blotting with genomic DNA from Red Globe, Flame Seedless, Thompson Seedless, four seedless hybrids and three seeded hybrids, showed a unique hybrid band present in all seedless individuals, but absent in all seeded individuals. It was further indicated that the specific marker 39970524-5-564 was derived from the genome of seedless grapes.

Abstract In vivo thrombosis imaging systems have been developed that show localized smallscale and short-acting thrombotic events in arterioles and venules; however, these microvascular models may not accurately simulate thrombogenesis in large vessels. A new quantitative imaging system was developed for evaluation of electrolytic-injury models of thrombus induction in large vessels of mice (carotid arteries and femoral veins). Laser-induced fluorophore emissions of membrane-labeled platelets and labeled fibrin-specific monoclonal antibodies were captured with time-lapse video recordings. Platelets were seen to accrue slowly after thrombus induction in both arteries and veins, peaking at approximately 15–45 minutes. In arteries, platelets accumulated more rapidly and to a greater extent than fibrin. Surprisingly, platelet accumulation in veins was substantial, occurring diffusely throughout the thrombus. Arterial thrombus dissolution occurred most often via large embolic events, sometimes occurring cyclically every 5–20 minutes by regrowth and re-embolization. In contrast, the rate of thrombus dissolution in veins was more gradual and appeared as micro-embolic events. Standard heparin anticoagulation inhibited venous thrombus growth by reducing fibrin development by 75% without affecting platelet accumulation. In contrast, blocking platelet aggregation at the αIIb/β3 receptor (with RGD-based mimetics) resulted in a 43% reduction in platelets and a surprising 5-fold increase in fibrin accumulation, suggesting the possibility of temporal competition between platelets and fibrin under venous conditions of thrombus formation. In established thrombi, newly activated platelets, identified by exposure of the active site of the αIIb/β3 receptor (using JON/A, a fluorophore-labeled antibody specific to activated αIIb/β3), were seen to roll in small aggregates across the outer margin of the thrombus mass in both arteries and veins for over 30 minutes, indicating continual dynamic platelet aggregation in both vessel types. Fibrin accrual was most intense at the margins of acute thrombotic stimuli and co-localized with fluorophore-labeled anti-Factor Xa and with Factor Va/VIIIa (identified using labeled activated protein C), which suggests that fibrin polymerization predominates adjacent to sites of these assembled coagulation complexes. In summary, the time-lapse nature of this video imaging system provides a unique and quantifiable method for determining how coagulation and platelet aggregation develop and are modulated in vivo within the same thrombus. Its use for the study of large vessel thrombosis often corroborated long-held tenets of platelet activity and coagulation, while revealing several novel findings: platelets are major contributors to venous thrombosis; arteries and veins have profound differences in thrombus dissolution/embolization patterns; inhibiting platelet aggregation may augment fibrin clot formation; platelet aggregation is a dynamic process in both arteries and veins, continually in flux on the thrombus surface for at least 30 minutes; and fibrin forms local to sites of coagulation complex assembly. Figure Figure Graph illustrating single traces for representative electrolytically-induced, free-radical-mediated thrombi in mouse carotid arteries (EAT) and femoral veins (EVT) over 60 minutes, for anti-fibrin (FBN) and platelet (Plt) labels. The y-axis displays arbitrary units for the product of total thrombus area and average fluorophore intensity within the thrombus.

Internet of Things (IoT) is regarded as a next-generation wave of Information Technology (IT) after the widespread emergence of the Internet and mobile communication technologies. IoT supports information exchange and networked interaction of appliances, vehicles and other objects, making sensing and actuation possible in a low-cost and smart manner. On the other hand, cyber-physical systems (CPS) are described as the engineered systems which are built upon the tight integration of the cyber entities (e.g., computation, communication, and control) and the physical things (natural and man-made systems governed by the laws of physics). The IoT and CPS are not isolated technologies. Rather it can be said that IoT is the base or enabling technology for CPS and CPS is considered as the grownup development of IoT, completing the IoT notion and vision. Both are merged into closed-loop, providing mechanisms for conceptualizing, and realizing all aspects of the networked composed systems that are monitored and controlled by computing algorithms and are tightly coupled among users and the Internet. That is, the hardware and the software entities are intertwined, and they typically function on different time and location-based scales. In fact, the linking between the cyber and the physical world is enabled by IoT (through sensors and actuators). CPS that includes traditional embedded and control systems are supposed to be transformed by the evolving and innovative methodologies and engineering of IoT. Several applications areas of IoT and CPS are smart building, smart transport, automated vehicles, smart cities, smart grid, smart manufacturing, smart agriculture, smart healthcare, smart supply chain and logistics, etc. Though CPS and IoT have significant overlaps, they differ in terms of engineering aspects. Engineering IoT systems revolves around the uniquely identifiable and internet-connected devices and embedded systems; whereas engineering CPS requires a strong emphasis on the relationship between computation aspects (complex software) and the physical entities (hardware). Engineering CPS is challenging because there is no defined and fixed boundary and relationship between the cyber and physical worlds. In CPS, diverse constituent parts are composed and collaborated together to create unified systems with global behaviour. These systems need to be ensured in terms of dependability, safety, security, efficiency, and adherence to real‐time constraints. Hence, designing CPS requires knowledge of multidisciplinary areas such as sensing technologies, distributed systems, pervasive and ubiquitous computing, real-time computing, computer networking, control theory, signal processing, embedded systems, etc. CPS, along with the continuous evolving IoT, has posed several challenges. For example, the enormous amount of data collected from the physical things makes it difficult for Big Data management and analytics that includes data normalization, data aggregation, data mining, pattern extraction and information visualization. Similarly, the future IoT and CPS need standardized abstraction and architecture that will allow modular designing and engineering of IoT and CPS in global and synergetic applications. Another challenging concern of IoT and CPS is the security and reliability of the components and systems. Although IoT and CPS have attracted the attention of the research communities and several ideas and solutions are proposed, there are still huge possibilities for innovative propositions to make IoT and CPS vision successful. The major challenges and research scopes include system design and implementation, computing and communication, system architecture and integration, application-based implementations, fault tolerance, designing efficient algorithms and protocols, availability and reliability, security and privacy, energy-efficiency and sustainability, etc. It is our great privilege to present Volume 21, Issue 3 of Scalable Computing: Practice and Experience. We had received 30 research papers and out of which 14 papers are selected for publication. The objective of this special issue is to explore and report recent advances and disseminate state-of-the-art research related to IoT, CPS and the enabling and associated technologies. The special issue will present new dimensions of research to researchers and industry professionals with regard to IoT and CPS. Vivek Kumar Prasad and Madhuri D Bhavsar in the paper titled "Monitoring and Prediction of SLA for IoT based Cloud described the mechanisms for monitoring by using the concept of reinforcement learning and prediction of the cloud resources, which forms the critical parts of cloud expertise in support of controlling and evolution of the IT resources and has been implemented using LSTM. The proper utilization of the resources will generate revenues to the provider and also increases the trust factor of the provider of cloud services. For experimental analysis, four parameters have been used i.e. CPU utilization, disk read/write throughput and memory utilization. Kasture et al. in the paper titled "Comparative Study of Speaker Recognition Techniques in IoT Devices for Text Independent Negative Recognition" compared the performance of features which are used in state of art speaker recognition models and analyse variants of Mel frequency cepstrum coefficients (MFCC) predominantly used in feature extraction which can be further incorporated and used in various smart devices. Mahesh Kumar Singh and Om Prakash Rishi in the paper titled "Event Driven Recommendation System for E-Commerce using Knowledge based Collaborative Filtering Technique" proposed a novel system that uses a knowledge base generated from knowledge graph to identify the domain knowledge of users, items, and relationships among these, knowledge graph is a labelled multidimensional directed graph that represents the relationship among the users and the items. The proposed approach uses about 100 percent of users' participation in the form of activities during navigation of the web site. Thus, the system expects under the users' interest that is beneficial for both seller and buyer. The proposed system is compared with baseline methods in area of recommendation system using three parameters: precision, recall and NDGA through online and offline evaluation studies with user data and it is observed that proposed system is better as compared to other baseline systems. Benbrahim et al. in the paper titled "Deep Convolutional Neural Network with TensorFlow and Keras to Classify Skin Cancer" proposed a novel classification model to classify skin tumours in images using Deep Learning methodology and the proposed system was tested on HAM10000 dataset comprising of 10,015 dermatoscopic images and the results observed that the proposed system is accurate in order of 94.06\% in validation set and 93.93\% in the test set. Devi B et al. in the paper titled "Deadlock Free Resource Management Technique for IoT-Based Post Disaster Recovery Systems" proposed a new class of techniques that do not perform stringent testing before allocating the resources but still ensure that the system is deadlock-free and the overhead is also minimal. The proposed technique suggests reserving a portion of the resources to ensure no deadlock would occur. The correctness of the technique is proved in the form of theorems. The average turnaround time is approximately 18\% lower for the proposed technique over Banker's algorithm and also an optimal overhead of O(m). Deep et al. in the paper titled "Access Management of User and Cyber-Physical Device in DBAAS According to Indian IT Laws Using Blockchain" proposed a novel blockchain solution to track the activities of employees managing cloud. Employee authentication and authorization are managed through the blockchain server. User authentication related data is stored in blockchain. The proposed work assists cloud companies to have better control over their employee's activities, thus help in preventing insider attack on User and Cyber-Physical Devices. Sumit Kumar and Jaspreet Singh in paper titled "Internet of Vehicles (IoV) over VANETS: Smart and Secure Communication using IoT" highlighted a detailed description of Internet of Vehicles (IoV) with current applications, architectures, communication technologies, routing protocols and different issues. The researchers also elaborated research challenges and trade-off between security and privacy in area of IoV. Deore et al. in the paper titled "A New Approach for Navigation and Traffic Signs Indication Using Map Integrated Augmented Reality for Self-Driving Cars" proposed a new approach to supplement the technology used in self-driving cards for perception. The proposed approach uses Augmented Reality to create and augment artificial objects of navigational signs and traffic signals based on vehicles location to reality. This approach help navigate the vehicle even if the road infrastructure does not have very good sign indications and marking. The approach was tested locally by creating a local navigational system and a smartphone based augmented reality app. The approach performed better than the conventional method as the objects were clearer in the frame which made it each for the object detection to detect them. Bhardwaj et al. in the paper titled "A Framework to Systematically Analyse the Trustworthiness of Nodes for Securing IoV Interactions" performed literature on IoV and Trust and proposed a Hybrid Trust model that seperates the malicious and trusted nodes to secure the interaction of vehicle in IoV. To test the model, simulation was conducted on varied threshold values. And results observed that PDR of trusted node is 0.63 which is higher as compared to PDR of malicious node which is 0.15. And on the basis of PDR, number of available hops and Trust Dynamics the malicious nodes are identified and discarded. Saniya Zahoor and Roohie Naaz Mir in the paper titled "A Parallelization Based Data Management Framework for Pervasive IoT Applications" highlighted the recent studies and related information in data management for pervasive IoT applications having limited resources. The paper also proposes a parallelization-based data management framework for resource-constrained pervasive applications of IoT. The comparison of the proposed framework is done with the sequential approach through simulations and empirical data analysis. The results show an improvement in energy, processing, and storage requirements for the processing of data on the IoT device in the proposed framework as compared to the sequential approach. Patel et al. in the paper titled "Performance Analysis of Video ON-Demand and Live Video Streaming Using Cloud Based Services" presented a review of video analysis over the LVS \& VoDS video application. The researchers compared different messaging brokers which helps to deliver each frame in a distributed pipeline to analyze the impact on two message brokers for video analysis to achieve LVS & VoS using AWS elemental services. In addition, the researchers also analysed the Kafka configuration parameter for reliability on full-service-mode. Saniya Zahoor and Roohie Naaz Mir in the paper titled "Design and Modeling of Resource-Constrained IoT Based Body Area Networks" presented the design and modeling of a resource-constrained BAN System and also discussed the various scenarios of BAN in context of resource constraints. The Researchers also proposed an Advanced Edge Clustering (AEC) approach to manage the resources such as energy, storage, and processing of BAN devices while performing real-time data capture of critical health parameters and detection of abnormal patterns. The comparison of the AEC approach is done with the Stable Election Protocol (SEP) through simulations and empirical data analysis. The results show an improvement in energy, processing time and storage requirements for the processing of data on BAN devices in AEC as compared to SEP. Neelam Saleem Khan and Mohammad Ahsan Chishti in the paper titled "Security Challenges in Fog and IoT, Blockchain Technology and Cell Tree Solutions: A Review" outlined major authentication issues in IoT, map their existing solutions and further tabulate Fog and IoT security loopholes. Furthermore, this paper presents Blockchain, a decentralized distributed technology as one of the solutions for authentication issues in IoT. In addition, the researchers discussed the strength of Blockchain technology, work done in this field, its adoption in COVID-19 fight and tabulate various challenges in Blockchain technology. The researchers also proposed Cell Tree architecture as another solution to address some of the security issues in IoT, outlined its advantages over Blockchain technology and tabulated some future course to stir some attempts in this area. Bhadwal et al. in the paper titled "A Machine Translation System from Hindi to Sanskrit Language Using Rule Based Approach" proposed a rule-based machine translation system to bridge the language barrier between Hindi and Sanskrit Language by converting any test in Hindi to Sanskrit. The results are produced in the form of two confusion matrices wherein a total of 50 random sentences and 100 tokens (Hindi words or phrases) were taken for system evaluation. The semantic evaluation of 100 tokens produce an accuracy of 94\% while the pragmatic analysis of 50 sentences produce an accuracy of around 86\%. Hence, the proposed system can be used to understand the whole translation process and can further be employed as a tool for learning as well as teaching. Further, this application can be embedded in local communication based assisting Internet of Things (IoT) devices like Alexa or Google Assistant. Anshu Kumar Dwivedi and A.K. Sharma in the paper titled "NEEF: A Novel Energy Efficient Fuzzy Logic Based Clustering Protocol for Wireless Sensor Network" proposed a a deterministic novel energy efficient fuzzy logic-based clustering protocol (NEEF) which considers primary and secondary factors in fuzzy logic system while selecting cluster heads. After selection of cluster heads, non-cluster head nodes use fuzzy logic for prudent selection of their cluster head for cluster formation. NEEF is simulated and compared with two recent state of the art protocols, namely SCHFTL and DFCR under two scenarios. Simulation results unveil better performance by balancing the load and improvement in terms of stability period, packets forwarded to the base station, improved average energy and extended lifetime.

Binary relations derived from labeled rooted trees play an import role in mathematical biology as formal models of evolutionary relationships. The (symmetrized) Fitch relation formalizes xenology as the pairs of genes separated by at least one horizontal transfer event. As a natural generalization, we consider symmetrized Fitch maps, that is, symmetric maps $\varepsilon$ that assign a subset of colors to each pair of vertices in $X$ and that can be explained by a tree $T$ with edges that are labeled with subsets of colors in the sense that the color $m$ appears in $\varepsilon(x,y)$ if and only if $m$ appears in a label along the unique path between $x$ and $y$ in $T$. We first give an alternative characterization of the monochromatic case and then give a characterization of symmetrized Fitch maps in terms of compatibility of a certain set of quartets. We show that recognition of symmetrized Fitch maps is NP-complete. In the restricted case where $|\varepsilon(x,y)|\leq 1$ the problem becomes polynomial, since such maps coincide with class of monochromatic Fitch maps whose graph-representations form precisely the class of complete multi-partite graphs.

In the field of graph theory, the complete graph of vertices is a simple undirected graph such that every pair of distinct vertices is connected by a unique edge. In the present work, we introduce planar subgraph of with maximal number of edges . Generally, does not admit prime labeling. We present an algorithm to obtain prime-labeled subgraphs of . We conclude the paper by stating two conjectures based on labeling of . In particular, the planar subgraph admits anti-magic labeling but does not admit edge magic total labeling.

A signed graph is a graph where each edge is labeled as either positive or negative. A circle is positive if the product of edge labels is positive. The frustration index is the least number of edges that need to be removed so that every remaining circle is positive. The maximum frustration of a graph is the maximum frustration index over all possible sign labellings. We prove two results about the maximum frustration of a complete bipartite graph $K_{l,r}$, with $l$ left vertices and $r$ right vertices. First, it is bounded above by\[ \frac{lr}{2}\left(1-\frac{1}{2^{l-1}}\binom{l-1}{\lfloor \frac{l-1}{2}\rfloor}\right).\] Second, there is a unique family of signed $K_{l,r}$ that reach this bound. Using this fact, exact formulas for the maximum frustration of $K_{l,r}$ are found for $l \leq 7$.

AbstractGenome wide optical maps are high resolution restriction maps that give a unique numeric representation to a genome. They are produced by assembling hundreds of thousands of single molecule optical maps, which are called Rmaps. Unfortunately, there are very few choices for assembling Rmap data. There exists only one publicly-available non-proprietary method for assembly and one proprietary software that is available via an executable. Furthermore, the publicly-available method, by Valouev et al. (Proc Natl Acad Sci USA 103(43):15770–15775, 2006), follows the overlap-layout-consensus (OLC) paradigm, and therefore, is unable to scale for relatively large genomes. The algorithm behind the proprietary method, Bionano Genomics’ Solve, is largely unknown. In this paper, we extend the definition of bi-labels in the paired de Bruijn graph to the context of optical mapping data, and present the first de Bruijn graph based method for Rmap assembly. We implement our approach, which we refer to as rmapper, and compare its performance against the assembler of Valouev et al. (Proc Natl Acad Sci USA 103(43):15770–15775, 2006) and Solve by Bionano Genomics on data from three genomes: E. coli, human, and climbing perch fish (Anabas Testudineus). Our method was able to successfully run on all three genomes. The method of Valouev et al. (Proc Natl Acad Sci USA 103(43):15770–15775, 2006) only successfully ran on E. coli. Moreover, on the human genome rmapper was at least 130 times faster than Bionano Solve, used five times less memory and produced the highest genome fraction with zero mis-assemblies. Our software, rmapper is written in C++ and is publicly available under GNU General Public License at https://github.com/kingufl/Rmapper.

Let $\mathbf{p}$ be a configuration of $n$ points in $\mathbb{R}^{d}$ for some $n$ and some $d\geqslant 2$ . Each pair of points has a Euclidean distance in the configuration. Given some graph $G$ on $n$ vertices, we measure the point-pair distances corresponding to the edges of $G$ . In this paper, we study the question of when a generic $\mathbf{p}$ in $d$ dimensions will be uniquely determined (up to an unknowable Euclidean transformation) from a given set of point-pair distances together with knowledge of $d$ and $n$ . In this setting the distances are given simply as a set of real numbers; they are not labeled with the combinatorial data that describes which point pair gave rise to which distance, nor is data about $G$ given. We show, perhaps surprisingly, that in terms of generic uniqueness, labels have no effect. A generic configuration is determined by an unlabeled set of point-pair distances (together with $d$ and $n$ ) if and only if it is determined by the labeled distances.

Here we describe a problem class with combined architecture, plant, and control design for dynamic engineering systems. The design problem class is characterized by architectures comprised of linear physical elements and nested co-design optimization problems employing linear-quadratic dynamic optimization. The select problem class leverages a number of existing theory and tools and is particularly effective due to the symbiosis between labeled graph representations of architectures, dynamic models constructed from linear physical elements, linear-quadratic dynamic optimization, and the nested co-design solution strategy. A vehicle suspension case study is investigated and a specifically constructed architecture, plant, and control design problem is described. The result was the automated generation and co-design problem evaluation of 4374 unique suspension architectures. The results demonstrate that changes to the vehicle suspension architecture can result in improved performance, but at the cost of increased mechanical complexity. Furthermore, the case study highlights a number of challenges associated with finding solutions to the considered class of design problems. One such challenge is the requirement to use simplified design problem elements/models; thus, the goal of these early-stage studies are to identify new architectures that are worth investigating more deeply. The results of higher-fidelity studies on a subset of high-performance architectures can then be used to select a final system architecture. In many aspects, the described problem class is the simplest case applicable to graph-representable, dynamic engineering systems.

Abstract Background Understanding complex associations between psychopathology and chronic illness is instrumental in facilitating both research and treatment progress. The current study is the first and only network-based study to provide such an encompassing view of unique associations between a multitude of mental and physical health-related domains. Methods The current analyses were based on the Singapore Mental Health Study, a cross-sectional study of adult Singapore residents. The study sample consisted of 6616 respondents, of which 49.8% were male and 50.2% female. A network structure was constructed to examine associations between psychopathology, alcohol use, gambling, major chronic conditions, and functioning. Results The network structure identified what we have labeled a Cartesian graph: a network visibly split into a psychopathological domain and a physical health domain. The borders between these domains were fuzzy and bridged by various cross-domain associations, with functioning items playing an important role in bridging chronic conditions to psychopathology. Conclusions Current results deliver a comprehensive overview of the complex relation between psychopathology, functioning, and chronic illness, highlighting potential pathways to comorbidity.

Abstract Objectives Exosomes are endogenous nanoparticles that participate in cell-to-cell communication through the transfer of cargos such RNAs, lipids and proteins from donor cells to recipient cells. Previously, we showed that mammals absorb exosomes from milk. Ultrasonication causes a transient disruption of the exosome membranes, leading to loss of microRNAs. When mice were fed diets based on the AIN-93G formulation, modified to contain a physiological amount of milk exosomes (exosome and RNA-sufficient diet, ERS) or sonicated exosomes (exosome and RNA-depleted diet, ERD), we observed a loss of circulating and tissue microRNAs and phenotypes such as aberrant purine metabolism. The objective of this study was to conduct a comprehensive analysis ofthe effects of sonication on exosomes cargos and bioavailability, thereby generating insights into mechanisms through which ERD elicits phenotypes. Methods Exosomes were isolated from ultrasonicated (USE) and non-sonicated (NSE) bovine milk by ultracentrifugation and authenticated following guidelines of the International Society for Extracellular Vesicles. MicroRNAs were analyzed by small RNA-sequencing. Lipids and proteins were analyzed by LC/MS-MS. Intestinal transport was assessed using FM 4-64-labeled exosomes in primary human small intestine cells (FHs cells). Bioavailability of exosomes transfected with IRDye-labeled miR-320a was assessed using oral gavage in C57BL/6 mice.The unpaired t-test was used for statistical analysis P < 0.05 was considered statistically significant. Results Ultrasonication affected the vesicle count and exosome morphology. Western blot analysis detected marker proteins only in NSE. The content of microRNAs was about 93% lower in USE than NSE. Significant difference was noted for lipid and protein identities between NSE and USE. Reduced uptake of USE by intestinal cells and loss of cargo accumulation in murine livers and pancreas for USE compared to NSE (Fig. 1-5). Conclusions Ultrasonication causesa loss of microRNAs in milk exosomes. The unique patterns of proteins and lipids likely is due to an exchangeof membranes between exosomes and other vesicles during ultrasonication, which might explain the lower bioavailability of USE compared to NSE. We currently test the exchange of lipids during ultrasonication. Funding Sources NIFA, NIH, Gates Foundation, PureTech, Inc. and USDA Hatch and Multistate. J.Z. is a consultant for PureTech. Supporting Tables, Images and/or Graphs

In a TED talk in June 2009, media scholar Clay Shirky cited the devastating earthquake that struck the Sichuan province of China in May 2008 as an example of how media flows are changing. He explained how the first reports of the quake came not from traditional news media, but from local residents who sent messages on QQ, China’s largest social network, and on Twitter, the world’s most popular micro-blogging service. "As the quake was happening, the news was reported," said Shirky. This was neither a unique nor isolated incident. It has become commonplace for the people caught up in the news to provide the first accounts, images and video of events unfolding around them. Studies in participatory journalism suggest that professional journalists now share jurisdiction over the news in the sense that citizens are participating in the observation, selection, filtering, distribution and interpretation of events. This paper argues that the ability of citizens to play “an active role in the process of collecting, reporting, analysing and disseminating news and information” (Bowman and Willis 9) means we need to reassess the meaning of ‘ambient’ as applied to news and journalism. Twitter has emerged as a key medium for news and information about major events, such as during the earthquake in Chile in February 2010 (see, for example, Silverman; Dickinson). This paper discusses how social media technologies such as Twitter, which facilitate the immediate dissemination of digital fragments of news and information, are creating what I have described as “ambient journalism” (Hermida). It approaches real-time, networked digital technologies as awareness systems that offer diverse means to collect, communicate, share and display news and information in the periphery of a user's awareness. Twitter shares some similarities with other forms of communication. Like the telephone, it facilitates a real-time exchange of information. Like instant messaging, the information is sent in short bursts. But it extends the affordances of previous modes of communication by combining these features in both a one-to-many and many-to-many framework that is public, archived and searchable. Twitter allows a large number of users to communicate with each other simultaneously in real-time, based on an asymmetrical relationship between friends and followers. The messages form social streams of connected data that provide value both individually and in aggregate. News All Around The term ‘ambient’ has been used in journalism to describe the ubiquitous nature of news in today's society. In their 2002 study, Hargreaves and Thomas said one of the defining features of the media landscape in the UK was the easy availability of news through a host of media platforms, such as public billboards and mobile phones, and in spaces, such as trains and aircraft. “News is, in a word, ambient, like the air we breathe,” they concluded (44). The availability of news all around meant that citizens were able to maintain an awareness of what was taking place in the world as they went about their everyday activities. One of the ways news has become ambient has been through the proliferation of displays in public places carrying 24-hour news channels or showing news headlines. In her book, Ambient Television, Anna McCarthy explored how television has become pervasive by extending outside the home and dominating public spaces, from the doctor’s waiting room to the bar. “When we search for TV in public places, we find a dense, ambient clutter of public audio-visual apparatuses,” wrote McCarthy (13). In some ways, the proliferation of news on digital platforms has intensified the presence of ambient news. In a March 2010 Pew Internet report, Purcell et al. found that “in the digital era, news has become omnipresent. Americans access it in multiple formats on multiple platforms on myriad devices” (2). It seems that, if anything, digital technologies have increased the presence of ambient news. This approach to the term ‘ambient’ is based on a twentieth century model of mass media. Traditional mass media, from newspapers through radio to television, are largely one-directional, impersonal one-to-many carriers of news and information (McQuail 55). The most palpable feature of the mass media is to reach the many, and this affects the relationship between the media and the audience. Consequently, the news audience does not act for itself, but is “acted upon” (McQuail 57). It is assigned the role of consumer. The public is present in news as citizens who receive information about, and interpretation of, events from professional journalists. The public as the recipient of information fits in with the concept of ambient news as “news which is free at the point of consumption, available on demand and very often available in the background to people’s lives without them even looking” (Hargreaves and Thomas 51). To suggest that members of the audience are just empty receptacles to be filled with news is an oversimplification. For example, television viewers are not solely defined in terms of spectatorship (see, for example, Ang). But audiences have, traditionally, been kept well outside the journalistic process, defined as the “selecting, writing, editing, positioning, scheduling, repeating and otherwise massaging information to become news” (Shoemaker et al. 73). This audience is cast as the receiver, with virtually no sense of agency over the news process. As a result, journalistic communication has evolved, largely, as a process of one-way, one-to-many transmission of news and information to the public. The following section explores the shift towards a more participatory media environment. News as a Social Experience The shift from an era of broadcast mass media to an era of networked digital media has fundamentally altered flows of information. Non-linear, many-to-many digital communication technologies have transferred the means of media production and dissemination into the hands of the public, and are rewriting the relationship between the audience and journalists. Where there were once limited and cost-intensive channels for the distribution of content, there are now a myriad of widely available digital channels. Henry Jenkins has written about the emergence of a participatory culture that “contrasts with older notions of passive media spectatorship. Rather than talking about media producers and consumers occupying separate roles, we might now see them as participants who interact with each other according to a new set of rules that none of us fully understands” (3). Axel Bruns has coined the term “produsage” (2) to refer to the blurred line between producers and consumers, while Jay Rosen has talked about the “people formerly know as the audience.” For some, the consequences of this shift could be “a new model of journalism, labelled participatory journalism,” (Domingo et al. 331), raising questions about who can be described as a journalist and perhaps, even, how journalism itself is defined. The trend towards a more participatory media ecosystem was evident in the March 2010 study on news habits in the USA by Pew Internet. It highlighted that the news was becoming a social experience. “News is becoming a participatory activity, as people contribute their own stories and experiences and post their reactions to events” (Purcell et al. 40). The study found that 37% of Internet users, described by Pew as “news participators,” had actively contributed to the creation, commentary, or dissemination of news (44). This reflects how the Internet has changed the relationship between journalists and audiences from a one-way, asymmetric model of communication to a more participatory and collective system (Boczkowski; Deuze). The following sections considers how the ability of the audience to participate in the gathering, analysis and communication of news and information requires a re-examination of the concept of ambient news. A Distributed Conversation As I’ve discussed, ambient news is based on the idea of the audience as the receiver. Ambient journalism, on the other hand, takes account of how audiences are able to become part of the news process. However, this does not mean that citizens are necessarily producing journalism within the established framework of accounts and analysis through narratives, with the aim of providing accurate and objective portrayals of reality. Rather, I suggest that ambient journalism presents a multi-faceted and fragmented news experience, where citizens are producing small pieces of content that can be collectively considered as journalism. It acknowledges the audience as both a receiver and a sender. I suggest that micro-blogging social media services such as Twitter, that enable millions of people to communicate instantly, share and discuss events, are an expression of ambient journalism. Micro-blogging is a new media technology that enables and extends society's ability to communicate, enabling users to share brief bursts of information from multiple digital devices. Twitter has become one of the most popular micro-blogging platforms, with some 50 million messages sent daily by February 2010 (Twitter). Twitter enables users to communicate with each other simultaneously via short messages no longer than 140 characters, known as ‘tweets’. The micro-blogging platform shares some similarities with instant messaging. It allows for near synchronous communications from users, resulting in a continuous stream of up-to-date messages, usually in a conversational tone. Unlike instant messaging, Twitter is largely public, creating a new body of content online that can be archived, searched and retrieved. The messages can be extracted, analysed and aggregated, providing a measure of activity around a particular event or subject and, in some cases, an indication of the general sentiment about it. For example, the deluge of tweets following Michael Jackson's death in July 2009 has been described as a public and collective expression of loss that indicated “the scale of the world’s shock and sadness” (Cashmore). While tweets are atomic in nature, they are part of a distributed conversation through a social network of interconnected users. To paraphrase David Weinberger's description of the Web, tweets are “many small pieces loosely joined,” (ix). In common with mass media audiences, users may be very widely dispersed and usually unknown to each other. Twitter provides a structure for them to act together as if in an organised way, for example through the use of hashtags–the # symbol–and keywords to signpost topics and issues. This provides a mechanism to aggregate, archive and analyse the individual tweets as a whole. Furthermore, information is not simply dependent on the content of the message. A user's profile, their social connections and the messages they resend, or retweet, provide an additional layer of information. This is called the social graph and it is implicit in social networks such as Twitter. The social graph provides a representation of an individual and their connections. Each user on Twitter has followers, who themselves have followers. Thus each tweet has a social graph attached to it, as does each message that is retweeted (forwarded to other users). Accordingly, social graphs offer a means to infer reputation and trust. Twitter as Ambient Journalism Services such as Twitter can be considered as awareness systems, defined as computer-mediated communication systems “intended to help people construct and maintain awareness of each others’ activities, context or status, even when the participants are not co-located” (Markopoulos et al., v). In such a system, the value does not lie in the individual sliver of information that may, on its own, be of limited value or validity. Rather the value lies in the combined effect of the communication. In this sense, Twitter becomes part of an ambient media system where users receive a flow of information from both established media and from each other. Both news and journalism are ambient, suggesting that “broad, asynchronous, lightweight and always-on communication systems such as Twitter are enabling citizens to maintain a mental model of news and events around them” (Hermida 5). Obviously, not everything on Twitter is an act of journalism. There are messages about almost every topic that often have little impact beyond an individual and their circle of friends, from random thoughts and observations to day-to-day minutiae. But it is undeniable that Twitter has emerged as a significant platform for people to report, comment and share news about major events, with individuals performing some of the institutionalised functions of the professional journalist. Examples where Twitter has emerged as a platform for journalism include the 2008 US presidential elections, the Mumbai attacks in November of 2008 and the January 2009 crash of US Airways flight (Lenhard and Fox 2). In these examples, Twitter served as a platform for first-hand, real-time reports from people caught up in the events as they unfolded, with the cell phone used as the primary reporting tool. For example, the dramatic Hudson River landing of the US Airways flight was captured by ferry passenger Janis Krum, who took a photo with a cell phone and sent it out via Twitter.One of the issues associated with services like Twitter is the speed and number of micro-bursts of data, together with the potentially high signal to noise ratio. For example, the number of tweets related to the disputed election result in Iran in June 2009 peaked at 221,774 in one hour, from an average flow of between 10,000 and 50,000 an hour (Parr). Hence there is a need for systems to aid in selection, organisation and interpretation to make sense of this ambient journalism. Traditionally the journalist has been the mechanism to filter, organise and interpret this information and deliver the news in ready-made packages. Such a role was possible in an environment where access to the means of media production was limited. But the thousands of acts of journalism taking place on Twitter every day make it impossible for an individual journalist to identify the collective sum of knowledge contained in the micro-fragments, and bring meaning to the data. Rather, we should look to the literature on ambient media, where researchers talk about media systems that understand individual desires and needs, and act autonomously on their behalf (for example Lugmayr). Applied to journalism, this suggests a need for tools that can analyse, interpret and contextualise a system of collective intelligence. An example of such a service is TwitterStand, developed by a group of researchers at the University of Maryland (Sankaranarayanan et al.). The team describe TwitterStand as “an attempt to harness this emerging technology to gather and disseminate breaking news much faster than conventional news media” (51). In their paper, they describe in detail how their news processing system is able to identify and cluster news tweets in a noisy medium. They conclude that “Twitter, or most likely a successor of it, is a harbinger of a futuristic technology that is likely to capture and transmit the sum total of all human experiences of the moment” (51). While such a comment may be something of an overstatement, it indicates how emerging real-time, networked technologies are creating systems of distributed journalism.Similarly, the US Geological Survey (USGS) is investigating social media technologies as a way quickly to gather information about recent earthquakes. It has developed a system called the Twitter Earthquake Detector to gather real-time, earthquake-related messages from Twitter and filter the messages by place, time, and keyword (US Department of the Interior). By collecting and analysing the tweets, the USGS believes it can access anecdotal information from citizens about a quake much faster than if it only relied on scientific information from authoritative sources.Both of these are examples of research into the development of tools that help users negotiate and regulate the streams and information flowing through networked media. They address issues of information overload by making sense of distributed and unstructured data, finding a single concept such as news in what Sankaranarayanan et al., say is “akin to finding needles in stacks of tweets’ (43). danah boyd eloquently captured the potential for such as system, writing that “those who are most enamoured with services like Twitter talk passionately about feeling as though they are living and breathing with the world around them, peripherally aware and in tune, adding content to the stream and grabbing it when appropriate.” Conclusion While this paper has focused on Twitter in its discussion of ambient journalism, it is possible that the service may be overtaken by another or several similar digital technologies. This has happened, for example, in the social networking space, with Friendster been supplanted by MySpace and more recently by Facebook. However, underlying services like Twitter are a set of characteristics often referred to by the catchall phrase, the real-time Web. As often with emerging and rapidly developing Internet trends, it can be challenging to define what the real-time Web means. Entrepreneur Ken Fromm has identified a set of characteristics that offer a good starting point to understand the real-time Web. He describes it as a new form of loosely organised communication that is creating a new body of public content in real-time, with a related social graph. In the context of our discussion of the term ‘ambient’, the characteristics of the real-time Web do not only extend the pervasiveness of ambient news. They also enable the former audience to become part of the news environment as it has the means to gather, select, produce and distribute news and information. Writing about changing news habits in the US, Purcell et al. conclude that “people’s relationship to news is becoming portable, personalized, and participatory” (2). Ambient news has evolved into ambient journalism, as people contribute to the creation, dissemination and discussion of news via social media services such as Twitter. To adapt Ian Hargreaves' description of ambient news in his book, Journalism: Truth or Dare?, we can say that journalism, which was once difficult and expensive to produce, today surrounds us like the air we breathe. Much of it is, literally, ambient, and being produced by professionals and citizens. The challenge going forward is helping the public negotiate and regulate this flow of awareness information, facilitating the collection, transmission and understanding of news. References Ang, Ien. Desperately Seeking the Audience. London: Routledge, 1991. Boczkowski, Pablo. J. Digitizing the News: Innovation in Online Newspapers. Cambridge: MIT Press, 2004. boyd, danah. “Streams of Content, Limited Attention.” UX Magazine 25 Feb. 2010. 27 Feb. 2010 ‹http://uxmag.com/features/streams-of-content-limited-attention›. Bowman, Shayne, and Chris Willis. We Media: How Audiences Are Shaping the Future of News and Information. The Media Center, 2003. 10 Jan. 2010 ‹http://www.hypergene.net/wemedia/weblog.php›. Bruns, Axel. Blogs, Wikipedia, Second Life, and Beyond: From Production to Produsage. New York: Peter Lang, 2008. Cashmore, Pete. “Michael Jackson Dies: Twitter Tributes Now 30% of Tweets.” Mashable 25 June 2009. 26 June 2010 ‹http://mashable.com/2009/06/25/michael-jackson-twitter/›. Department of the Interior. “U.S. Geological Survey: Twitter Earthquake Detector (TED).” 13 Jan. 2010. 12 Feb. 2010 ‹http://recovery.doi.gov/press/us-geological-survey-twitter-earthquake-detector-ted/›. Deuze, Mark. “The Web and Its Journalisms: Considering the Consequences of Different Types of Newsmedia Online.” New Media and Society 5 (2003): 203-230. Dickinson, Elizabeth. “Chile's Twitter Response.” Foreign Policy 1 March 2010. 2 March 2010 ‹http://blog.foreignpolicy.com/posts/2010/03/01/chiles_twitter_response›. Domingo, David, Thorsten Quandt, Ari Heinonen, Steve Paulussen, Jane B. Singer and Marina Vujnovic. “Participatory Journalism Practices in the Media and Beyond.” Journalism Practice 2.3 (2008): 326-342. Fromm, Ken. “The Real-Time Web: A Primer, Part 1.” ReadWriteWeb 29 Aug. 2009. 7 Dec. 2009 ‹http://www.readwriteweb.com/archives/the_real-time_web_a_primer_part_1.php›. Hargreaves, Ian. Journalism: Truth or Dare? Oxford: Oxford University Press, 2003. Hargreaves, Ian, and Thomas, James. “New News, Old News.” ITC/BSC, Oct. 2002. 5 Dec. 2009 ‹http://legacy.caerdydd.ac.uk/jomec/resources/news.pdf›. Hermida, Alfred. “Twittering the News: The Emergence of Ambient Journalism.” Journalism Practice. First published on 11 March 2010 (iFirst). 12 March 2010 ‹http://www.informaworld.com/smpp/content~content=a919807525›. Jenkins, Henry. Convergence Culture: Where Old and New Media Collide. New York: New York University Press, 2006. Lenhard, Amanda, and Susannah Fox. “Twitter and Status Updating.” Pew Internet and American Life Project, 12 Feb. 2009. 13 Feb. 2010 ‹http://www.pewinternet.org/Reports/2009/Twitter-and-status-updating.aspx›. Lugmayr, Artur. “The Future Is ‘Ambient.’” Proceedings of SPIE Vol. 6074, 607403 Multimedia on Mobile Devices II. Vol. 6074. Eds. Reiner Creutzburg, Jarmo H. Takala, and Chang Wen Chen. San Jose: SPIE, 2006. Markopoulos, Panos, Boris De Ruyter and Wendy MacKay. Awareness Systems: Advances in Theory, Methodology and Design. Dordrecht: Springer, 2009. McCarthy, Anna. Ambient Television: Visual Culture and Public Space. Durham: Duke University Press, 2001. McQuail, Denis. McQuail’s Mass Communication Theory. London: Sage, 2000. Parr, Ben. “Mindblowing #IranElection Stats: 221,744 Tweets per Hour at Peak.” Mashable 17 June 2009. 10 August 2009 ‹http://mashable.com/2009/06/17/iranelection-crisis-numbers/›. Purcell, Kristen, Lee Rainie, Amy Mitchell, Tom Rosenstiel, and Kenny Olmstead, “Understanding the Participatory News Consumer.” Pew Internet and American Life Project, 1 March 2010. 2 March 2010 ‹http://www.pewinternet.org/Reports/2010/Online-News.aspx?r=1›. Rosen Jay. “The People Formerly Known as the Audience.” Pressthink 27 June 2006. 8 August 2009 ‹http://journalism.nyu.edu/pubzone/weblogs/pressthink/2006/06/27/ppl_frmr.html›. Sankaranarayanan, Jagan, Hanan Samet, Benjamin E. Teitler, Michael D. Lieberman, and Jon Sperling. “TwitterStand: News in Tweets. Proceedings of the 17th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems (GIS '09). New York: ACM, 2009. 42-51. Shirky, Clay. “How Social Media Can Make History.” TED Talks June 2009. 2 March 2010 ‹http://www.ted.com/talks/clay_shirky_how_cellphones_twitter_facebook_can_make_history.html›. Shoemaker, Pamela J., Tim P. Vos, and Stephen D. Reese. “Journalists as Gatekeepers.” Eds. Karin Wahl-Jorgensen and Thomas Hanitzsch, Handbook of Journalism Studies. New York: Routledge, 2008. 73-87. Silverman, Matt. “Chile Earthquake Pictures: Twitter Photos Tell the Story.” Mashable 27 Feb. 2010. 2 March 2010 ‹http://mashable.com/2010/02/27/chile-earthquake-twitpics/›. Singer, Jane. “Strange Bedfellows: The Diffusion of Convergence in Four News Organisations.” Journalism Studies 5 (2004): 3-18. Twitter. “Measuring Tweets.” Twitter blog, 22 Feb. 2010. 23 Feb. 2010 ‹http://blog.twitter.com/2010/02/measuring-tweets.html›. Weinberger, David. Small Pieces, Loosely Joined. Cambridge, MA: Perseus Publishing, 2002.