224 resultados para ROTATIONAL CORE LOSSES


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Title: Boundary-setting as a core activity in complex public systems
Authors: Joanne Murphy & Mary Lee Rhodes

The definition of the boundary of a system is at the core of any systems approach (Midgley 2000; 2003). By defining boundaries we enable – and delimit – the range of outcomes sought and the actions and resources that can be brought to bear. In complex adaptive systems (CAS) analysis, the conceptualisaion and definition of boundaries is particularly challenging as they are constantly undergoing redefinition through agent action, interaction and entry/exit. (Rhodes et al 2011). The concept of ‘boundaries’ appears regularly in a wide range of literature around public management, administration, geopolitics, regeneration and organisational development. Discussions around boundaries focus on many things from concrete physical manifestations and barriers, to virtual interfaces between one organisational unit and another, or even entirely theoretical demarcations between different schools of thought (Kaboolian, 1998, Levi-Faur, 2004, Agranoff & McGuire, 2004).

However, managing ‘beyond’ such boundaries is a routinely recurring aspiration that transcends sectors and local concerns. Unsurprisingly then, there is an increasing understanding of the need to acknowledge and manage such boundaries (whether they be physical, social or organisational) within public management as a discipline (Currie et al 2007, Fitzsimmons and White, 1997, Murtagh, 2002). This paper explores the impact of boundaries on public management strategic decision-making in the sectors of urban regeneration and healthcare. In particular, it focuses on demarcations to physical space, communal identity and within professional relationships in these sectors.

The first section describes the research that gave rise to the paper and the cases examined. Next we briefly define what we mean by boundaries. We explore issues that have emerged from our analysis of urban regeneration and health care singularly, before looking at how the concept of boundaries is a recurrent concern across the sectors. The main contribution of the paper is an exploration of how a CAS lens can bring a new insight into the concept of boundaries and decision-making in the two sets of case studies. This discussion will concentrate on initial conditions, bifurcation and adaptation as key CAS factors in relation to boundaries. We conclude with a brief discussion on the benefits of a CAS lens to an analysis of boundaries in public management decision-making.
References:

Agranoff, R. and McGuire, M. (2003) Collaborative Public Management: Strategies for Local Government. Washington, DC: Georgetown Univ. Press.

Currie, G., Lockett, A. (2007) “A critique of transformational leadership: moral, professional & contingent dimensions of leadership within public services organizations”. Human Relations 60: 341-370.

Fitzsimmons and White, (1997) "Crossing boundaries: communication between professional groups", Journal of Management in Medicine, Vol. 11 Iss: 2, pp.96 – 101

Kaboolian, L. (1998) “The New Public Management: Challenging the Boundaries of the Management vs. Administration Debate” Public Administration Review Vol. 58, No. 3 pp.189-193

Levi-Faur D. and Vigoda-Gadot Eran (eds) (2004) International Public Policy and Management: Policy Learning Beyond Regional, Cultural and Political Boundaries, Marcel Dekker,
Midgley, G. (ed) (2003) Systems Thinking. London: Sage Publications

Midgley, G. (2000) Systemic Intervention: Philosophy, Methodology and Practice. New York, NY: Kluwer.

Murtagh, B. (2002). The Politics of Territory: Policy and Segregation in Northern Ireland. Basingstoke, Palgrave.

Rhodes, ML, Joanne Murphy, Jenny Muir, John Murray (2011) Public Management & Complexity Theory: Richer Decision Making in Irish Public Services, UK: Routledge



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Innate immunity recognizes bacterial molecules bearing pathogen-associated molecular patterns to launch inflammatory responses leading to the activation of adaptive immunity. However, the lipopolysaccharide (LPS) of the gram-negative bacterium Brucella lacks a marked pathogen-associated molecular pattern, and it has been postulated that this delays the development of immunity, creating a gap that is critical for the bacterium to reach the intracellular replicative niche. We found that a B. abortus mutant in the wadC gene displayed a disrupted LPS core while keeping both the LPS O-polysaccharide and lipid A. In mice, the wadC mutant induced proinflammatory responses and was attenuated. In addition, it was sensitive to killing by non-immune serum and bactericidal peptides and did not multiply in dendritic cells being targeted to lysosomal compartments. In contrast to wild type B. abortus, the wadC mutant induced dendritic cell maturation and secretion of pro-inflammatory cytokines. All these properties were reproduced by the wadC mutant purified LPS in a TLR4-dependent manner. Moreover, the core-mutated LPS displayed an increased binding to MD-2, the TLR4 co-receptor leading to subsequent increase in intracellular signaling. Here we show that Brucella escapes recognition in early stages of infection by expressing a shield against recognition by innate immunity in its LPS core and identify a novel virulence mechanism in intracellular pathogenic gram-negative bacteria. These results also encourage for an improvement in the generation of novel bacterial vaccines.

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fA1122 is a T7-related bacteriophage infecting most isolates of Yersinia pestis, the etiologic agent of plague, and used by the CDC in the identification of Y. pestis. fA1122 infects Y. pestis grown both at 20 °C and at 37 °C. Wild-type Yersinia pseudotuberculosis strains are also infected but only when grown at 37 °C. Since Y. pestis expresses rough lipopolysaccharide (LPS) missing the O-polysaccharide (O-PS) and expression of Y. pseudotuberculosis O-PS is largely suppressed at temperatures above 30 °C, it has been assumed that the phage receptor is rough LPS. We present here several lines of evidence to support this. First, a rough derivative of Y. pseudotuberculosis was also fA1122 sensitive when grown at 22 °C. Second, periodate treatment of bacteria, but not proteinase K treatment, inhibited the phage binding. Third, spontaneous fA1122 receptor mutants of Y. pestis and rough Y. pseudotuberculosis could not be isolated, indicating that the receptor was essential for bacterial growth under the applied experimental conditions. Fourth, heterologous expression of the Yersinia enterocolitica O:3 LPS outer core hexasaccharide in both Y. pestis and rough Y. pseudotuberculosis effectively blocked the phage adsorption. Fifth, a gradual truncation of the core oligosaccharide into the Hep/Glc (L-glycero-D-manno-heptose/D-glucopyranose)-Kdo/Ko (3-deoxy-D-manno-oct-2-ulopyranosonic acid/D-glycero-D-talo-oct-2-ulopyranosonic acid) region in a series of LPS mutants was accompanied by a decrease in phage adsorption, and finally, a waaA mutant expressing only lipid A, i.e., also missing the Kdo/Ko region, was fully fA1122 resistant. Our data thus conclusively demonstrated that the fA1122 receptor is the Hep/Glc-Kdo/Ko region of the LPS core, a common structure in Y. pestis and Y. pseudotuberculosis.

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Yersinia enterocolitica (Ye) is a gram-negative bacterium; Ye serotype O:3 expresses lipopolysaccharide (LPS) with a hexasaccharide branch known as the outer core (OC). The OC is important for the resistance of the bacterium to cationic antimicrobial peptides and also functions as a receptor for bacteriophage phiR1-37 and enterocoliticin. The biosynthesis of the OC hexasaccharide is directed by the OC gene cluster that contains nine genes (wzx, wbcKLMNOPQ, and gne). In this study, we inactivated the six OC genes predicted to encode glycosyltransferases (GTase) one by one by nonpolar mutations to assign functions to their gene products. The mutants expressed no OC or truncated OC oligosaccharides of different lengths. The truncated OC oligosaccharides revealed that the minimum structural requirements for the interactions of OC with bacteriophage phiR1-37, enterocoliticin, and OC-specific monoclonal antibody 2B5 were different. Furthermore, using chemical and structural analyses of the mutant LPSs, we could assign specific functions to all six GTases and also revealed the exact order in which the transferases build the hexasaccharide. Comparative modeling of the catalytic sites of glucosyltransferases WbcK and WbcL followed by site-directed mutagenesis allowed us to identify Asp-182 and Glu-181, respectively, as catalytic base residues of these two GTases. In general, conclusive evidence for specific GTase functions have been rare due to difficulties in accessibility of the appropriate donors and acceptors; however, in this work we were able to utilize the structural analysis of LPS to get direct experimental evidence for five different GTase specificities.

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Lipopolysaccharide (LPS) of Yersinia enterocolitica O:3 has an inner core linked to both the O-antigen and to an outer core hexasaccharide that forms a branch. The biological role of the outer core was studied using polar and non-polar mutants of the outer core biosynthetic operon. Analysis of O-antigen- and outer core-deficient strains suggested a critical role for the outer core in outer membrane properties relevant in resistance to antimicrobial peptides and permeability to hydrophobic agents, and indirectly relevant in resistance to killing by normal serum. Wild-type bacteria but not outer core mutants killed intragastrically infected mice, and the intravenous lethal dose was approximately 10(4)-fold higher for outer core mutants. After intragastric infection, outer core mutants colonized Peyer's patches and invaded mesenteric lymph nodes, spleen and liver, and induced protective immunity against wild-type bacteria. In mice co-infected intragastrically with an outer core mutant-wild type mixture, both strains colonized Peyer's patches similarly during the first 2 days, but the mutant was much less efficient in colonizing deeper organs and was cleared faster from Peyer's patches. The results demonstrate that outer core is required for Y. enterocolitica O:3 full virulence, and strongly suggest that it provides resistance against defence mechanisms (most probably those involving bactericidal peptides).

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The use of efficient synchronization mechanisms is crucial for implementing fine grained parallel programs on modern shared cache multi-core architectures. In this paper we study this problem by considering Single-Producer/Single- Consumer (SPSC) coordination using unbounded queues. A novel unbounded SPSC algorithm capable of reducing the row synchronization latency and speeding up Producer-Consumer coordination is presented. The algorithm has been extensively tested on a shared-cache multi-core platform and a sketch proof of correctness is presented. The queues proposed have been used as basic building blocks to implement the FastFlow parallel framework, which has been demonstrated to offer very good performance for fine-grain parallel applications. © 2012 Springer-Verlag.

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Data flow techniques have been around since the early '70s when they were used in compilers for sequential languages. Shortly after their introduction they were also consideredas a possible model for parallel computing, although the impact here was limited. Recently, however, data flow has been identified as a candidate for efficient implementation of various programming models on multi-core architectures. In most cases, however, the burden of determining data flow "macro" instructions is left to the programmer, while the compiler/run time system manages only the efficient scheduling of these instructions. We discuss a structured parallel programming approach supporting automatic compilation of programs to macro data flow and we show experimental results demonstrating the feasibility of the approach and the efficiency of the resulting "object" code on different classes of state-of-the-art multi-core architectures. The experimental results use different base mechanisms to implement the macro data flow run time support, from plain pthreads with condition variables to more modern and effective lock- and fence-free parallel frameworks. Experimental results comparing efficiency of the proposed approach with those achieved using other, more classical, parallel frameworks are also presented. © 2012 IEEE.

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Drawing on data generated via large-scale survey and in-depth interview methods, this article reports findings which show that being a student teacher in early-twenty-first-century England is a demanding personal experience which requires considerable engagement and commitment in the face of built-in challenges and risks, and which engenders, for many, highly charged affective responses. Student teachers are centrally concerned during this time with their (changing) identities, their relationships with others and the relevance of course provision. Findings also indicate that, in some respects, student teachers’ accounts of their experiences are systematically differentiated according to a number of factors, notably the initial teacher preparation route being followed, their age, and their prior conceptions and expectations of teaching and of learning to teach. These findings are situated in the broader literature on teacher development and some implications for teacher educators are discussed. © 2008 Taylor & Francis

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We present observations of the interacting transient SN 2009ip, from the start of the outburst in October 2012 until the end of the 2012 observing season. The transient reached a peak of $M_V$=-17.7 mag before fading rapidly, with a total integrated luminosity of 1.9$\times10^{49}$ erg over the period of August-December 2012. The optical and near infrared spectra are dominated by narrow emission lines, signaling a dense circumstellar environment, together with multiple components of broad emission and absorption in H and He at velocities between 0.5-1.2$\times10^4$ km s$^{-1}$\. We see no evidence for nucleosynthesized material in SN 2009ip, even in late-time pseudo-nebular spectra. We set a limit of $