Quantum Computation by Communication

We present a new approach to scalable quantum computing--a ``qubus computer''--which realises qubit measurement and quantum gates through interacting qubits with a quantum communication bus mode. The qubits could be ``static'' matter qubits or ``flying'' optical qubits, but the scheme we focus on here is particularly suited to matter qubits. There is no requirement for direct interaction between the qubits. Universal two-qubit quantum gates may be effected by schemes which involve measurement of the bus mode, or by schemes where the bus disentangles automatically and no measurement is needed. In effect, the approach integrates together qubit degrees of freedom for computation with quantum continuous variables for communication and interaction.Comment: final published versio

Homelessness and the meaning of home: rooflessness or rootlessness?

This paper has several objectives. These are: (1) to analyse the meaning of homelessness in the light of recent contributions on the meaning of home: (2) to criticize some current perspectives on homelessness as a social problem; (3) to identify and explore a number of different dimensions of the meaning of home and homelessness; (4) to reassess the evidence on the context of home and homelessness, and re-examine the meaning of homelessness in the light of that reassessed evidence; and (5) to explain the political meaning of homelessness as expressed in official definitions, legislation and state provision (or lack of it)

The New ‘Hidden Abode’: Reflections on Value and Labour in the New Economy

In a pivotal section of Capital, volume 1, Marx (1976: 279) notes that, in order to understand the capitalist production of value, we must descend into the ‘hidden abode of production’: the site of the labour process conducted within an employment relationship. In this paper we argue that by remaining wedded to an analysis of labour that is confined to the employment relationship, Labour Process Theory (LPT) has missed a fundamental shift in the location of value production in contemporary capitalism. We examine this shift through the work of Autonomist Marxists like Hardt and Negri, Lazaratto and Arvidsson, who offer theoretical leverage to prize open a new ‘hidden abode’ outside employment, for example in the ‘production of organization’ and in consumption. Although they can open up this new ‘hidden abode’, without LPT's fine-grained analysis of control/resistance, indeterminacy and structured antagonism, these theorists risk succumbing to empirically naive claims about the ‘new economy’. Through developing an expanded conception of a ‘new hidden abode’ of production, the paper demarcates an analytical space in which both LPT and Autonomist Marxism can expand and develop their understanding of labour and value production in today's economy. </jats:p

The antifungal protein PAF interferes with PKC/MPK and cAMP/PKA signalling of Aspergillus nidulans

The Penicillium chrysogenum antifungal protein PAF inhibits polar growth and induces apoptosis in Aspergillus nidulans. We report here that two signalling cascades are implicated in its antifungal activity. PAF activates the cAMP/protein kinase A (Pka) signalling cascade. A pkaA deletion mutant exhibited reduced sensitivity towards PAF. This was substantiated by the use of pharmacological modulators: PAF aggravated the effect of the activator 8-Br-cAMP and partially relieved the repressive activity of caffeine. Furthermore, the Pkc/mitogen-activated protein kinase (Mpk) signalling cascade mediated basal resistance to PAF, which was independent of the small GTPase RhoA. Non-functional mutations of both genes resulted in hypersensitivity towards PAF. PAF did not increase MpkA phosphorylation or induce enzymes involved in the remodelling of the cell wall, which normally occurs in response to activators of the cell wall integrity pathway. Notably, PAF exposure resulted in actin gene repression and a deregulation of the chitin deposition at hyphal tips of A. nidulans, which offers an explanation for the morphological effects evoked by PAF and which could be attributed to the interconnection of the two signalling pathways. Thus, PAF represents an excellent tool to study signalling pathways in this model organism and to define potential fungal targets to develop new antifungals

Ryanodine receptor dispersion disrupts Ca2+ release in failing cardiac myocytes

Reduced cardiac contractility during heart failure (HF) is linked to impaired Ca2+ release from Ryanodine Receptors (RyRs). We investigated whether this deficit can be traced to nanoscale RyR reorganization. Using super-resolution imaging, we observed dispersion of RyR clusters in cardiomyocytes from post-infarction HF rats, resulting in more numerous, smaller clusters. Functional groupings of RyR clusters which produce Ca2+ sparks (Ca2+ release units, CRUs) also became less solid. An increased fraction of small CRUs in HF was linked to augmented ‘silent’ Ca2+ leak, not visible as sparks. Larger multi-cluster CRUs common in HF also exhibited low fidelity spark generation. When successfully triggered, sparks in failing cells displayed slow kinetics as Ca2+ spread across dispersed CRUs. During the action potential, these slow sparks protracted and desynchronized the overall Ca2+ transient. Thus, nanoscale RyR reorganization during HF augments Ca2+ leak and slows Ca2+ release kinetics, leading to weakened contraction in this disease

Dyadic plasticity in cardiomyocytes

Contraction of cardiomyocytes is dependent on sub-cellular structures called dyads, where invaginations of the surface membrane (t-tubules) form functional junctions with the sarcoplasmic reticulum (SR). Within each dyad, Ca2+ entry through t-tubular L-type Ca2+ channels (LTCCs) elicits Ca2+ release from closely apposed Ryanodine Receptors (RyRs) in the SR membrane. The efficiency of this process is dependent on the density and macroscale arrangement of dyads, but also on the nanoscale organization of LTCCs and RyRs within them. We presently review accumulating data demonstrating the remarkable plasticity of these structures. Dyads are known to form gradually during development, with progressive assembly of both t-tubules and junctional SR terminals, and precise trafficking of LTCCs and RyRs. While dyads can exhibit compensatory remodeling when required, dyadic degradation is believed to promote impaired contractility and arrythmogenesis in cardiac disease. Recent data indicate that this plasticity of dyadic structure/function is dependent on the regulatory proteins junctophilin-2, amphiphysin-2 (BIN1), and caveolin-3, which critically arrange dyadic membranes while stabilizing the position and activity of LTCCs and RyRs. Indeed, emerging evidence indicates that clustering of both channels enables “coupled gating”, implying that nanoscale localization and function are intimately linked, and may allow fine-tuning of LTCC-RyR crosstalk. We anticipate that improved understanding of dyadic plasticity will provide greater insight into the processes of cardiac compensation and decompensation, and new opportunities to target the basic mechanisms underlying heart disease

Ryanodine receptors are part of the myospryn complex in cardiac muscle

The Cardiomyopathy–associated gene 5 (Cmya5) encodes myospryn, a large tripartite motif (TRIM)-related protein found predominantly in cardiac and skeletal muscle. Cmya5 is an expression biomarker for a number of diseases affecting striated muscle and may also be a schizophrenia risk gene. To further understand the function of myospryn in striated muscle, we searched for additional myospryn paralogs. Here we identify a novel muscle-expressed TRIM-related protein minispryn, encoded by Fsd2, that has extensive sequence similarity with the C-terminus of myospryn. Cmya5 and Fsd2 appear to have originated by a chromosomal duplication and are found within evolutionarily-conserved gene clusters on different chromosomes. Using immunoaffinity purification and mass spectrometry we show that minispryn co-purifies with myospryn and the major cardiac ryanodine receptor (RyR2) from heart. Accordingly, myospryn, minispryn and RyR2 co-localise at the junctional sarcoplasmic reticulum of isolated cardiomyocytes. Myospryn redistributes RyR2 into clusters when co-expressed in heterologous cells whereas minispryn lacks this activity. Together these data suggest a novel role for the myospryn complex in the assembly of ryanodine receptor clusters in striated muscle

Nursing considerations to complement the Surviving Sepsis Campaign guidelines

Objectives: To provide a series of recommendations based on the best available evidence to guide clinicians providing nursing care to patients with severe sepsis. Design: Modified Delphi method involving international experts and key individuals in subgroup work and electronic-based discussion among the entire group to achieve consensus. Methods: We used the Surviving Sepsis Campaign guidelines as a framework to inform the structure and content of these guidelines. We used the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) system to rate the quality of evidence from high (A) to very low (D) and to determine the strength of recommendations, with grade 1 indicating clear benefit in the septic population and grade 2 indicating less confidence in the benefits in the septic population. In areas without complete agreement between all authors, a process of electronic discussion of all evidence was undertaken until consensus was reached. This process was conducted independently of any funding. Results: Sixty-three recommendations relating to the nursing care of severe sepsis patients are made. Prevention recommendations relate to education, accountability, surveillance of nosocomial infections, hand hygiene, and prevention of respiratory, central line-related, surgical site, and urinary tract infections, whereas infection management recommendations related to both control of the infection source and transmission-based precautions. Recommendations related to initial resuscitation include improved recognition of the deteriorating patient, diagnosis of severe sepsis, seeking further assistance, and initiating early resuscitation measures. Important elements of hemodynamic support relate to improving both tissue oxygenation and macrocirculation. Recommendations related to supportive nursing care incorporate aspects of nutrition, mouth and eye care, and pressure ulcer prevention and management. Pediatric recommendations relate to the use of antibiotics, steroids, vasopressors and inotropes, fluid resuscitation, sedation and analgesia, and the role of therapeutic end points. Conclusion: Consensus was reached regarding many aspects of nursing care of the severe sepsis patient. Despite this, there is an urgent need for further evidence to better inform this area of critical care

Business ethics as practice

In this article we develop a conceptualization of business ethics as practice. Starting from the view that the ethics that organizations display in practice will have been forged through an ongoing process of debate and contestation over moral choices, we examine ethics in relation to the ambiguous, unpredictable, and subjective contexts of managerial action. Furthermore, we examine how discursively constituted practice relates to managerial subjectivity and the possibilities of managers being moral agents. The article concludes by discussing how the 'ethics as practice' approach that we expound provides theoretical resources for studying the different ways that ethics manifest themselves in organizations as well as providing a practical application of ethics in organizations that goes beyond moralistic and legalistic approaches. © 2006 British Academy of Management