Social support, network heterogeneity, and smoking behavior in women: The 10-town study

Purpose. Examine the associations among social support, network heterogeneity, and smoking behavior in a large sample of Finnish female municipal employees.

Prominent Effect of Soil Network Heterogeneity on Microbial Invasion

Using a network representation for real soil samples and mathematical models for microbial spread, we show that the structural heterogeneity of the soil habitat may have a very significant influence on the size of microbial invasions of the soil pore space. In particular, neglecting the soil structural heterogeneity may lead to a substantial underestimation of microbial invasion. Such effects are explained in terms of a crucial interplay between heterogeneity in microbial spread and heterogeneity in the topology of soil networks. The main influence of network topology on invasion is linked to the existence of long channels in soil networks that may act as bridges for transmission of microorganisms between distant parts of soil.

The challenge of real-time automatic mapping for environmental monitoring network management

The automatic interpolation of environmental monitoring network data such as air quality or radiation levels in real-time setting poses a number of practical and theoretical questions. Among the problems found are (i) dealing and communicating uncertainty of predictions, (ii) automatic (hyper)parameter estimation, (iii) monitoring network heterogeneity, (iv) dealing with outlying extremes, and (v) quality control. In this paper we discuss these issues, in light of the spatial interpolation comparison exercise held in 2004.

IP Mobility in Wireless Operator Networks

Wireless network access is gaining increased heterogeneity in terms of the types of IP capable access technologies. The access network heterogeneity is an outcome of incremental and evolutionary approach of building new infrastructure. The recent success of multi-radio terminals drives both building a new infrastructure and implicit deployment of heterogeneous access networks. Typically there is no economical reason to replace the existing infrastructure when building a new one. The gradual migration phase usually takes several years. IP-based mobility across different access networks may involve both horizontal and vertical handovers. Depending on the networking environment, the mobile terminal may be attached to the network through multiple access technologies. Consequently, the terminal may send and receive packets through multiple networks simultaneously. This dissertation addresses the introduction of IP Mobility paradigm into the existing mobile operator network infrastructure that have not originally been designed for multi-access and IP Mobility. We propose a model for the future wireless networking and roaming architecture that does not require revolutionary technology changes and can be deployed without unnecessary complexity. The model proposes a clear separation of operator roles: (i) access operator, (ii) service operator, and (iii) inter-connection and roaming provider. The separation allows each type of an operator to have their own development path and business models without artificial bindings with each other. We also propose minimum requirements for the new model. We present the state of the art of IP Mobility. We also present results of standardization efforts in IP-based wireless architectures. Finally, we present experimentation results of IP-level mobility in various wireless operator deployments.

BitTorrent based transmission of real-time scalable video over P2P networks

The number of software applications available on the Internet for distributing video streams in real time over P2P networks has grown quickly in the last two years. Typical this kind of distribution is made by television channel broadcasters which try to make their content globally available, using viewer's resources to support a large scale distribution of video without incurring in incremental costs. However, the lack of adaptation in video quality, combined with the lack of a standard protocol for this kind of multimedia distribution has driven content providers to basically ignore it as a solution for video delivery over the Internet. While the scalable extension of the H. 264 encoding (H.264/SVC) can be used to support terminal and network heterogeneity, it is not clear how it can be integrated in a P2P overlay to form a large scale and real time distribution. In this paper, we start by defining a solution that combines the most popular P2P file-sharing protocol, the BitTorrent, with the H. 264/SVC encoding for a real-time video content delivery. Using this solution we then evaluate the effect of several parameters in the quality received by peers.

Supporting ad hoc collaborations in peer-to-peer networks

Traditionally, applications and tools supporting collaborative computing have been designed only with personal computers in mind and support a limited range of computing and network platforms. These applications are therefore not well equipped to deal with network heterogeneity and, in particular, do not cope well with dynamic network topologies. Progress in this area must be made if we are to fulfil the needs of users and support the diversity, mobility, and portability that are likely to characterise group work in future. This paper describes a groupware platform called Coco that is designed to support collaboration in a heterogeneous network environment. The work demonstrates that progress in the p development of a generic supporting groupware is achievable, even in the context of heterogeneous and dynamic networks. The work demonstrates the progress made in the development of an underlying communications infrastructure, building on peer-to-peer concept and topologies to improve scalability and robustness.

HETEROGENEIDADE EM REDE: PRESENÇA E PRÁTICAS DE USO ENTRE ESTUDANTES DA UNIVERSIDADE METODISTA DE SÃO PAULO NAS REDES SOCIAIS

As redes sociais pela internet ganham destaque nos processos comunicacionais atuais ao permitirem uma maior interação entre os conectados. Entretanto, o conceito de rede, ao contrário do senso comum e do que se convencionou no meio acadêmico, de fato não propõe uma organização simétrica, estática e homogênea. A rede é, por natureza, dinâmica e heterogênea, assim como a sociedade é. As redes sociais e as redes digitais demonstram isso. Elas aumentam e diminuem seus nós e possuem diferentes graus de conexões, e mesmo nestes graus de conexões são diversas. O presente estudo está dividido em duas partes fundamentais. A primeira visa compreender o conceito de rede, e para isso baseia-se em Milton Santos, Pierre Musso e Albert-Lásló Barabási. Na segunda parte, a partir de uma pesquisa com estudantes universitários, há a preocupação de identificar as heterogeneidades existentes nas suas presenças nas redes e suas práticas de uso, a partir de seis categorias de análise e atividades relacionadas: relações pessoais, estudo, trabalho, ativismo, entretenimento e lazer, e informações e notícias. A questão de fundo, a respeito das possibilidades das redes, é sobre os diferentes níveis de participação, ou seja, a heterogeneidade em rede. O resultado do estudo constata a heterogeneidade, na qual os estudantes, por mais que possuam semelhanças em função da idade aproximada, da condição social e pelo fato de estudarem em uma universidade particular, são diferentes entre si, em especial, se comparados pelas áreas de formação. Não só a presença nas redes sociais se dá em níveis diferentes, quanto suas práticas também são. Portanto, o conceito de redes heterogêneas contido no pensamento de Milton Santos, Pierre Musso e Albert-Lásló Barabási, é confirmado com a pesquisa aplicada aos estudantes universitários dos cursos de graduação presencial da Universidade Metodista de São Paulo, a partir da análise de suas presenças e práticas de uso.  

Creating heterogeneity: Evolving use of groupware in a network of freelancers

This contribution is a long-term study of the evolving use of the organization-wide groupware in a service network. We are describing the practices related to organization-wide groupware in conjunction with local groupware-related practices and how they have proceeded since the organization was established. In the discussion of these practices we are focussing on issues such as: 1. tendencies for proliferation and integration, 2. local appropriations of a variety of systems, 3. creative appropriations, including the creation of a unique heterogeneous groupware fabric, 4. the design strategy of multiple parallel experimental use an; 5. the relation between disparate local meanings and successful computer supported cooperative practice. As an overarching theme we are exploring the explanatory value of the concepts of objectification and appropriation as compared to the concepts of design vs. use.

Modelling heterogeneity of concrete using 2D lattice network for concrete fracture and comparison with AE study

In this paper, numerical modelling of fracture in concrete using two-dimensional lattice model is presented and also a few issues related to lattice modelling technique applicable to concrete fracture are reviewed. A comparison is made with acoustic emission (AE) events with the number of fractured elements. To implement the heterogeneity of the plain concrete, two methods namely, by generating grain structure of the concrete using Fuller's distribution and the concrete material properties are randomly distributed following Gaussian distribution are used. In the first method, the modelling of the concrete at meso level is carried out following the existing methods available in literature. The shape of the aggregates present in the concrete are assumed as perfect spheres and shape of the same in two-dimensional lattice network is circular. A three-point bend (TPB) specimen is tested in the experiment under crack mouth opening displacement (CMOD) control at a rate of 0.0004 mm/sec and the fracture process in the same TPB specimen is modelled using regular triangular 2D lattice network. Load versus crack mouth opening isplacement (CMOD) plots thus obtained by using both the methods are compared with experimental results. It was observed that the number of fractured elements increases near the peak load and beyond the peak load. That is once the crack starts to propagate. AE hits also increase rapidly beyond the peak load. It is compulsory here to mention that although the lattice modelling of concrete fracture used in this present study is very similar to those already available in literature, the present work brings out certain finer details which are not available explicitly in the earlier works.

Efficient Network in Player and Partner Heterogeneity Models

This paper characterizes efficient networks in player and partner heterogeneity models for both the one-way flow and the two-way flow models. Player (partner) dependent network formation allows benefits and costs to be player (partner) heterogeneous which is an important extension for modeling social networks in the real world. Employing widely used assumptions, I show that efficient networks in the two way flow model are minimally connected and have star or derivative of star type architectures, whereas efficient networks in the one way flow model have wheel architectures.

Molecular network analysis using reverse phase protein microarrays for patient tailored therapy.

The practice of medicine has always aimed at individualized treatment of disease. The relationship between patient and physician has always been a personal one, and the physician's choice of treatment has been intended to be the best fit for the patient's needs. The necessary pooling/grouping of disease families and their assignment to a number of drugs or treatment methods has, consequently, led to an increase in the number of effective therapies. However, given the heterogeneity of most human diseases, and cancer specifically, it is currently impossible for the treating clinician to effectively predict a patient's response and outcome based on current technologies, much less the idiosyncratic resistances and adverse effects associated with the limited therapeutic options.

Co-movements in commodity prices : a note based on network analysis

This article analyses co-movements in a wide group of commodity prices during the time period 1992–2010. Our methodological approach is based on the correlation matrix and the networks inside. Through this approach we are able to summarize global interaction and interdependence, capturing the existing heterogeneity in the degrees of synchronization between commodity prices. Our results produce two main findings: (a) we do not observe a persistent increase in the degree of co-movement of the commodity prices in our time sample, however from mid-2008 to the end of 2009 co-movements almost doubled when compared with the average correlation; (b) we observe three groups of commodities which have exhibited similar price dynamics (metals, oil and grains, and oilseeds) and which have increased their degree of co-movement during the sampled period.

An Empirical Analysis of Heterogeneity in IEEE 802.11 MAC Protocol Implementations and its Implications

Wireless LAN (WLAN) market consists of IEEE 802.11 MAC standard conformant devices (e.g., access points (APs), client adapters) from multiple vendors. Certain third party certifications such as those specified by the Wi-Fi alliance have been widely used by vendors to ensure basic conformance to the 802.11 standard, thus leading to the expectation that the available devices exhibit identical MAC level behavior. In this paper, however, we present what we believe to be the first ever set of experimental results that highlight the fact that WLAN devices from different vendors in the market can have heterogeneous MAC level behavior. Specifically, we demonstrate with examples and data that in certain cases, devices may not be conformant with the 802.11 standard while in other cases, they may differ in significant details that are not a part of mandatory specifications of the standard. We argue that heterogeneous MAC implementations can adversely impact WLAN operations leading to unfair bandwidth allocation, potential break-down of related MAC functionality and difficulties in provisioning the capacity of a WLAN. However, on the positive side, MAC level heterogeneity can be useful in applications such as vendor/model level device fingerprinting.

Prosocial norms and degree heterogeneity in social networks

We provide empirical evidence to support the claims that social diversity promotes prosocial behavior. We elicit a real-life social network and its members’ adherence to a social norm, namely inequity aversion. The data reveal a positive relationship between subjects’ prosociality and several measures of centrality. This result is in line with the theoretical literature that relates the evolution of social norms to the structure of social interactions and argues that central individuals are crucial for the emergence of prosocial behavior.

Learning in Network Games

We report the findings of an experiment designed to study how people learn and make decisions in network games. Network games offer new opportunities to identify learning rules, since on networks (compared to e.g. random matching) more rules differ in terms of their information requirements. Our experimental design enables us to observe both which actions participants choose and which information they consult before making their choices. We use this information to estimate learning types using maximum likelihood methods. There is substantial heterogeneity in learning types. However, the vast majority of our participants' decisions are best characterized by reinforcement learning or (myopic) best-response learning. The distribution of learning types seems fairly stable across contexts. Neither network topology nor the position of a player in the network seem to substantially affect the estimated distribution of learning types.