The Cluster Wind from Local Massive Star Clusters

Results of a study of the theoretically predicted and observed X-ray properties of local massive star clusters are presented, with a focus on understanding the mass and energy flow from these clusters into the ISM via a cluster wind. A simple theoretical model, based on the work of Chevalier & Clegg (1985), is used to predict the theoretical cluster properties, and these are compared to those obtained from recent Chandra observations. The model includes the effect of lower energy transfer efficiency and mass-loading. In spite of limited statistics, some general trends are indicated; the observed temperature of the diffuse X-ray emission is lower than that predicted from the stellar mass and energy input rates, but the predicted scaling of X-ray luminosity with cluster parameters is seen. The implications of these results are discussed.Comment: 9 pages, 6 figues, accepted for publication in MNRA

Chandra and XMM-Newton Observations of NGC 4214: The Hot Interstellar Medium and the Luminosity Function of Dwarf Starbursts

We present results from Chandra and XMM-Newton X-ray observations of NGC 4214, a nearby dwarf starburst galaxy containing several young regions of very active star-formation. Starburst regions are known to be associated with diffuse X-ray emission, and in this case the X-ray emission from the galaxy shows an interesting morphological structure within the galaxy, clearly associated with the central regions of active star-formation. Of the two main regions of star-formation in this galaxy, X-ray emission associated with the older is identified whereas little is detected from the younger, providing an insight into the evolutionary process of the formation of superbubbles around young stellar clusters. The spectra of the diffuse emission from the galaxy can be fitted with a two temperature component thermal model with kT=0.14keV and 0.52keV, and analysis of this emission suggests that NGC 4214 will suffer a blow-out in the future. The point source population of the galaxy has an X-ray luminosity function with a slope of -0.76. This result, together with those for other dwarf starburst galaxies (NGC 4449 and NGC 5253), was added to a sample of luminosity functions for spiral and starburst galaxies. The slope of the luminosity function of dwarf starbursts is seen to be similar to that of their larger counterparts and clearly flatter than those seen in spirals. Further comparisons between the luminosity functions of starbursts and spiral galaxies are also made.Comment: 16 pages, 12 figures. Accepted for publication in MNRA

If You’re Going Through Hell, Keep Going: Nonlinear Effects of Financial Liberalization in Transition Economies

Copyright © Taylor & Francis Group, LLC. Did increasing the level and pace of financial liberalization during transition expose countries to crises? And if a crisis did strike, did liberalization do more harm or good? Using a database of 28 transition economies over 22 years, this article examines these questions across a host of economic outcomes, including savings and the size of the private sector. The results provide evidence that, while liberalization may initially increase the probability of a crisis, the prospect of a crisis drops dramatically at higher levels of financial openness. Moreover, the benefits of liberalization across several metrics outweigh the risks of these intermediate stages

Identifying dynamical modules from genetic regulatory systems: applications to the segment polarity network

BACKGROUND It is widely accepted that genetic regulatory systems are 'modular', in that the whole system is made up of smaller 'subsystems' corresponding to specific biological functions. Most attempts to identify modules in genetic regulatory systems have relied on the topology of the underlying network. However, it is the temporal activity (dynamics) of genes and proteins that corresponds to biological functions, and hence it is dynamics that we focus on here for identifying subsystems. RESULTS Using Boolean network models as an exemplar, we present a new technique to identify subsystems, based on their dynamical properties. The main part of the method depends only on the stable dynamics (attractors) of the system, thus requiring no prior knowledge of the underlying network. However, knowledge of the logical relationships between the network components can be used to describe how each subsystem is regulated. To demonstrate its applicability to genetic regulatory systems, we apply the method to a model of the Drosophila segment polarity network, providing a detailed breakdown of the system. CONCLUSION We have designed a technique for decomposing any set of discrete-state, discrete-time attractors into subsystems. Having a suitable mathematical model also allows us to describe how each subsystem is regulated and how robust each subsystem is against perturbations. However, since the subsystems are found directly from the attractors, a mathematical model or underlying network topology is not necessarily required to identify them, potentially allowing the method to be applied directly to experimental expression data

Overcoming challenges in delivering integrated motivational interviewing and cognitive behavioural therapy for bipolar disorder with co-morbid alcohol use:Therapist perspectives

Background: Alcohol misuse is common in bipolar disorder and is associated with worse outcomes. A recent study evaluated integrated motivational interviewing and cognitive behavioural therapy for bipolar disorder and alcohol misuse with promising results in terms of the feasibility of delivering the therapy and the acceptability to participants. Aims: Here we present the experiences of the therapists and supervisors from the trial to identify the key challenges in working with this client group and how these might be overcome. Method: Four therapists and two supervisors participated in a focus group. Topic guides for the group were informed by a summary of challenges and obstacles that each therapist had completed at the end of therapy for each individual client. The audio recording of the focus group was transcribed and data were analysed using thematic analysis.Results:We identified five themes: addressing alcohol use versus other problems; impact of bipolar disorder on therapy; importance of avoidance and overcoming it; fine balance in relation to shame and normalising use; and 'talking the talk' versus 'walking the walk'. Conclusions: Findings suggest that clients may be willing to explore motivations for using alcohol even if they are not ready to change their drinking, and they may want help with a range of mental health problems. Emotional and behavioural avoidance may be a key factor in maintaining alcohol use in this client group and therapists should be aware of a possible discrepancy between clients' intentions to reduce misuse and their actual behaviour

Cycle-centrality in complex networks

Networks are versatile representations of the interactions between entities in complex systems. Cycles on such networks represent feedback processes which play a central role in system dynamics. In this work, we introduce a measure of the importance of any individual cycle, as the fraction of the total information flow of the network passing through the cycle. This measure is computationally cheap, numerically well-conditioned, induces a centrality measure on arbitrary subgraphs and reduces to the eigenvector centrality on vertices. We demonstrate that this measure accurately reflects the impact of events on strategic ensembles of economic sectors, notably in the US economy. As a second example, we show that in the protein-interaction network of the plant Arabidopsis thaliana, a model based on cycle-centrality better accounts for pathogen activity than the state-of-art one. This translates into pathogen-targeted-proteins being concentrated in a small number of triads with high cycle-centrality. Algorithms for computing the centrality of cycles and subgraphs are available for download

Error and attack tolerance of complex networks

Many complex systems, such as communication networks, display a surprising degree of robustness: while key components regularly malfunction, local failures rarely lead to the loss of the global information-carrying ability of the network. The stability of these complex systems is often attributed to the redundant wiring of the functional web defined by the systems' components. In this paper we demonstrate that error tolerance is not shared by all redundant systems, but it is displayed only by a class of inhomogeneously wired networks, called scale-free networks. We find that scale-free networks, describing a number of systems, such as the World Wide Web, Internet, social networks or a cell, display an unexpected degree of robustness, the ability of their nodes to communicate being unaffected by even unrealistically high failure rates. However, error tolerance comes at a high price: these networks are extremely vulnerable to attacks, i.e. to the selection and removal of a few nodes that play the most important role in assuring the network's connectivity.Comment: 14 pages, 4 figures, Late