Composable consistency for large-scale peer replication

technical reportThe lack of a flexible consistency management solution hinders P2P implementation of applications involving updates, such as directory services, online auctions and collaboration. Managing shared data in a P2P setting requires a consistency solution that can operate in a heterogenous network, support pervasive replication for scaling, and give peers autonomy to tune consistency to their sharing needs and resource constraints. Existing solutions lack one or more of these features. In this paper, we propose a new way to structure consistency management for P2P sharing of mutable data called composable consistency. It lets applications compose a rich variety of consistency solutions appropriate for their sharing needs, out of a small set of primitive options. Our approach splits consistency management into design choices along five orthogonal aspects, namely, concurrency, consistency, availability, update visibility and isolation. Various combinations of these choices can be employed to yield numerous consistency semantics and to fine-tune resource use at each replica. Our experience with a prototype implementation suggests that composable consistency can effectively support diverse P2P applications

Flexible consistency for wide area peer replication

technical reportThe lack of a flexible consistency management solution hinders P2P implementation of applications involving updates, such as read-write file sharing, directory services, online auctions and wide area collaboration. Managing mutable shared data in a P2P setting requires a consistency solution that can operate efficiently over variable-quality failure-prone networks, support pervasive replication for scaling, and give peers autonomy to tune consistency to their sharing needs and resource constraints. Existing solutions lack one or more of these features. In this paper, we describe a new consistency model for P2P sharing of mutable data called composable consistency, and outline its implementation in a wide area middleware file service called Swarm1. Composable consistency lets applications compose consistency semantics appropriate for their sharing needs by combining a small set of primitive options. Swarm implements these options efficiently to support scalable, pervasive, failure-resilient, wide-area replication behind a simple yet flexible interface. We present two applications to demonstrate the expressive power and effectiveness of composable consistency: a wide area file system that outperforms Coda in providing close-to-open consistency overWANs, and a replicated BerkeleyDB database that reaps order-of-magnitude performance gains by relaxing consistency for queries and updates

Khazana: a flexible wide area data store

technical reportKhazana is a peer-to-peer data service that supports efficient sharing and aggressive caching of mutable data across the wide area while giving clients significant control over replica divergence. Previous work on wide-area replicated services focussed on at most two of the following three properties: aggressive replication, customizable consistency, and generality. In contrast, Khazana provides scalable support for large numbers of replicas while giving applications considerable flexibility in trading off consistency for availability and performance. Its flexibility enables applications to effectively exploit inherent data locality while meeting consistency needs. Khazana exports a file system-like interface with a small set of consistency controls which can be combined to yield a broad spectrum of consistency flavors ranging from strong consistency to best-effort eventual consistency. Khazana servers form failure-resilient dynamic replica hierarchies to manage replicas across variable quality network links. In this report, we outline Khazana?s design and show how its flexibility enables three diverse network services built on top of it to meet their individual consistency and performance needs: (i) a wide-area replicated file system that supports serializable writes as well as traditional file sharing across wide area, (ii) an enterprise data service that exploits locality by caching enterprise data closer to end-users while ensuring strong consistency for data integrity, and (iii) a replicated database that reaps order of magnitude gains in throughput by relaxing consistency

Mechanisms of disturbed emotion processing and social interaction in borderline personality disorder: state of knowledge and research agenda of the German Clinical Research Unit

The last two decades have seen a strong rise in empirical research in the mechanisms of emotion dysregulation in borderline personality disorder. Major findings comprise structural as well as functional alterations of brain regions involved in emotion processing, such as amygdala, insula, and prefrontal regions. In addition, more specific mechanisms of disturbed emotion regulation, e.g. related to pain and dissociation, have been identified. Most recently, social interaction problems and their underlying neurobiological mechanisms, e.g. disturbed trust or hypersensitivity to social rejection, have become a major focus of BPD research. This article covers the current state of knowledge and related relevant research goals. The first part presents a review of the literature. The second part delineates important open questions to be addressed in future studies. The third part describes the research agenda for a large German center grant focusing on mechanisms of emotion dysregulation in BPD

An Examination of Aggressive Behavior in Indo-Pacific Bottlenose Dolphins (\u3ci\u3eTursiops Aduncus\u3c/i\u3e)

Agonistic behavior is often observed in animal groups in which individuals have long-term relationships. Although bottlenose dolphins (Tursiops sp.) are known to behave aggressively, relatively little is known about such behavior among wild animals. Much of the data on delphiilid aggression comes from captive studies, and is likely biased by the limited space available to the animals. In this study, video data collected from 1997 to 2007 were analyzed to examine aggressive behaviors in a wild population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) off the coast ofMikura Island, Japan. The purpose of the study was to determine if age class, sex, approach angle, and body posture influenced aggression within this population. The area of the recipient\u27s body towards which aggression was directed was also examined to determine which body parts were most commonly attacked, if any. Neither age class nor sex predicted t11e type of aggressive behavior nor influenced the duration of the aggressive bout. However, adult initiators aggressed more toward females than males. Additionally, bouts involving females were more likely to consist of a more severe type of aggression, regardless of whether the involved female was the initiator or the receiver of the aggressive act. Headto- head approaches were directed most often toward the rostrum, while perpendicular approaches were most often directed toward the sides. Additional research on other wild populations is needed in order to clarify the generality of these findings and the overall significance of behavioral context on aggressive behavior in dolphins

Post-impressionism : universal, British, global

Starting from the possibility of a ‘global’ account of a style, this essay examines the consequences of the idea of post-impressionism. Around 1910, Roger Fry drew on histories of world art and international art historiography to cast post-impressionism as putatively universal, a style that was not just a new development, but was a rediscovery of a natural form of artistic creation. Seen this way, post-impressionism also had the potential to go global: to have a causal role in the development of multiple international modernisms following its spatial circulation across the globe. The essay goes on to explore first how even within Britain local variations and divisions quickly came to undercut this specifically British articulation of a universal style. It then turns to aspects of post-impressionism's subsequent circulations in India, Nigeria, Japan, and China to examine further how its putative universalism was transformed in a variety of locally specific ways.Publisher PDFPeer reviewe

Process Design in an Information-Intensive Service Delivery System: an Empirical Study

The objective of this thesis is to explore the design of operational processes in information-intensive service delivery systems. Empirical data is presented which builds upon existing literature within the Business Process Management (BPM) and Service Operations Management (SOM) disciplines. Adopting a theory building mode, the thesis concludes with the formulation of several research propositions which specify the design characteristics of the processes that provide the service concept to the customer. The research addresses a number of gaps in the literature. First, there is little empirical evidence concerning the relationship between the service concept, customer inputs, and process design. Second, service classification schemes promote homogeneous thinking in the design of service systems delivering diverse service concepts. Third, the BPM literature provides generic process design principles which offer limited theoretical insights into the design requirements of operational processes. Finally, there is a need for process design research in information-intensive service organisations. A research framework that integrates theoretical models addressing service process design is investigated using a single case study approach. Fieldwork was carried out over a sixteen-month period in a large electricity supplier in the UK. In contrast to the macro-orientation found within the literature, this study employs a more granular level of analysis to address the unique requirements of ‘service concept – processes’ pairs. This approach results in a number of important findings which, in several instances, are in contradiction to current thinking. First, the results empirically validate the theoretical relationship between service concept, customer inputs, and process design. Different service concepts lead to different process designs, and the more customised the service concept, the more the process is uniquely designed. Significant differences in the design of the individual processes that collectively provide the service concept to the customer are highlighted. The results also provide some new insights into the design of front office – back office activities as well as into the design characteristics of processes characterised by low customer contact. In addition, the study refutes the view that generic process design principles are universally applicable irrespective of the context in which the processes operate. Finally, the research findings show that a process-based view of service systems allows for heterogeneity; that is differences in the design of service delivery processes within the same organisation