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Background Major surgery accounts for a substantial proportion of health service activity and resource consumption, due not only to the primary procedure, but also the short and long-term implications of perioperative complications. It is likely that both compliance with best practice processes and outcomes from major surgery vary substantially between hospitals and therefore could be targets for quality improvement. Methods The Perioperative Quality Improvement Programme (PQIP) patient study is a multi-centre prospective cohort study which recruits participants undergoing major inpatient non-cardiac surgery with three main aims: to measure and improve processes of care and outcome from major surgery; to implement and evaluate a complex intervention aiming to enhance the use of data for improvement by clinical teams; and to create a national database to support collaborative research and efficient study design. The prospective dataset combines variables for risk adjustment, process measures and both objective and patient reported outcome data. Longer-term outcomes are collected through linkage to national administrative datasets (mortality and readmissions). PQIP deploys a theoretically underpinned improvement methodology to support the use of data for improvement by perioperative clinicians, incorporating action research principles to enable changes to be made in response to user feedback. Dissemination of interim findings (non-inferential) form a part of the improvement methodology and are provided to participating centres at regular intervals, including near-real-time feedback of key process measures. Inferential analyses will be published in the peer-reviewed literature, supported by a multi-modal communications strategy to patients, public, policy makers and academic audiences as well as clinicians. Discussion PQIP is the first national effort in the UK to measure and report risk-adjusted complications, patient-reported outcome and mortality rates for patients undergoing major surgery across multiple surgical specialties in the UK. Its main limitation is the risk of sampling bias due to the requirement for patient consent, and because local resource constraints may lead hospitals to recruit a convenience sample, rather than a truly random sample. We will evaluate this risk by using Hospital Episode Statistics (HES) to identify all patients undergoing PQIP eligible procedures, and undertaking sensitivity analyses comparing common data points in the PQIP sample and the HES population. As the purpose of PQIP is to support quality improvement and research as opposed to quality assurance or institutional comparisons, even if they exist, such sampling biases are unlikely to materially affect the ability of the programme to achieve its aims.

Introduction Major surgery accounts for a substantial proportion of health service activity, due not only to the primary procedure, but the longer-term health implications of poor short-term outcome. Data from small studies or from outside the UK indicate that rates of complications and failure to rescue vary between hospitals, as does compliance with best practice processes. Within the UK, there is currently no system for monitoring postoperative complications (other than short-term mortality) in major non-cardiac surgery. Further, there is variation between national audit programmes, in the emphasis placed on quality assurance versus quality improvement, and therefore the principles of measurement and reporting which are used to design such programmes. Methods and analysis The PQIP patient study is a multi-centre prospective cohort study which recruits patients undergoing major surgery. Patient provide informed consent and contribute baseline and outcome data from their perspective using a suite of patient-reported outcome tools. Research and clinical staff complete data on patient risk factors and outcomes in-hospital, including two measures of complications. Longer-term outcome data are collected through patient feedback and linkage to national administrative datasets (mortality and readmissions). As well as providing a uniquely granular dataset for research, PQIP provides feedback to participating sites on their compliance with evidence-based processes and their patients’ outcomes, with the aim of supporting local quality improvement. Ethics and dissemination Ethical approval has been granted by the Health Research Authority in the UK. Dissemination of interim findings (non-inferential) will form a part of the improvement methodology and will be provided to participating centres at regular intervals, including near-real time feedback of key process measures. Inferential analyses will be published in the peer-reviewed literature, supported by a comprehensive multi-modal communications strategy including to patients, policy makers and academic audiences as well as clinicians.

Background Among patients undergoing emergency laparotomy, 30-day postoperative mortality is around 10–15%. The risk of death among these patients, however, varies greatly because of their clinical characteristics. We developed a risk prediction model for 30-day postoperative mortality to enable better comparison of outcomes between hospitals. Methods We analysed data from the National Emergency Laparotomy Audit (NELA) on patients having an emergency laparotomy between December 2013 and November 2015. A prediction model was developed using multivariable logistic regression, with potential risk factors identified from existing prediction models, national guidelines, and clinical experts. Continuous risk factors were transformed if necessary to reflect their non-linear relationship with 30-day mortality. The performance of the model was assessed in terms of its calibration and discrimination. Interval validation was conducted using bootstrap resampling. Results There were 4458 (11.5%) deaths within 30-days among the 38 830 patients undergoing emergency laparotomy. Variables associated with death included (among others): age, blood pressure, heart rate, physiological variables, malignancy, and ASA physical status classification. The predicted risk of death among patients ranged from 1% to 50%. The model demonstrated excellent calibration and discrimination, with a C-statistic of 0.863 (95% confidence interval, 0.858–0.867). The model retained its high discrimination during internal validation, with a bootstrap derived C-statistic of 0.861. Conclusions The NELA risk prediction model for emergency laparotomies discriminates well between low- and high-risk patients and is suitable for producing risk-adjusted provider mortality statistics.

BACKGROUND: Safety and cellular immunogenicity of rising doses and varying regimens of a poly-epitope vaccine were evaluated in advanced metastatic melanoma. The vaccine comprised plasmid DNA and recombinant modified vaccinia virus Ankara (MVA) both expressing a string (Mel3) of seven HLA.A2/A1 epitopes from five melanoma antigens. METHODS: Forty-one HLA-A2 positive patients with stage III/IV melanoma were enrolled. Patient groups received one or two doses of DNA.Mel3 followed by escalating doses of MVA.Mel3. Immunisations then continued eight weekly in the absence of disease progression. Epitope-specific CD8+ T cell responses were evaluated using ex-vivo tetramer and IFN-gamma ELISPOT assays. Safety and clinical responses were monitored. RESULTS: Prime-boost DNA/MVA induced Melan-A-specific CD8+ T cell responses in 22/31 (71%) patients detected by tetramer assay. ELISPOT detected a response to at least one epitope in 10/31 (32%) patients. T cell responder rates were

We consider large double auctions with private values. Values need be neither symmetric nor independent. Multiple units may be owned or desired. Participation may be stochastic. We introduce a very mild notion of "a little independence." We prove that all nontrivial equilibria of auctions that satisfy this notion are asymptotically efficient. For any alpha > 0, inefficiency disappears at rate 1/n(2-alpha).

We analyze reputation effects in two-player repeated games of strictly conflicting interests. In such games player 1 has a commitment action such that a best reply to it gives player 1 the highest individually rational payoff and player 2 the minmax payoff. Players have equal discount factors. With positive probability player 1 is a type who chooses the commitment action after every history. We show that player 1’s payoff converges to the maximally feasible payoff when the discount factor converges to one. This contrasts with failures of reputation effects for equal discount factors that have been demonstrated in the literature. Journal of Economic Literature Classification Number: C71.

We study the long-run sustainability of reputations in games with imperfect public monitoring. It is impossible to maintain a permanent reputation for playing a strategy that does not play an equilibrium of the game without uncertainty about types. Thus, a player cannot indefinitely sustain a reputation for non-credible behavior in the presence of imperfect monitoring.

The paper analyzes the Nash equilibria of two-person discounted repeated games with one-sided incomplete information and known own payoffs. If the informed player is arbitrarily patient, relative to the uninformed player, then the characterization for the informed player's payoffs is essentially the same as that in the undiscounted case. This implies that even small amounts of incomplete information can lead to a discontinuous change in the equilibrium payoff set. For the case of equal discount factors, however, and under an assumption that strictly individually rational payoffs exist, a result akin to the Folk Theorem holds when a complete information game is perturbed by a small amount of incomplete information.

This paper considers the situation where two products are sold by the same seller, but to disjoint sets of potential buyers. Externalities may arise from each market outcome to the other. The paper examines the nature of the seller's optimal mechanism, and, for example in the case of positive externalities, it is shown that the allocation decision in either market depends on the highest types in both markets. The optimal mechanism can be implemented by an indirect mechanism that essentially charges winning bidders for the value of their externalities. The analysis is applied to the sale of public sector franchises including exploration and development rights for oil and gas tracts.

I consider an alternating offer bargaining game which is played by a risk neutral buyer and seller, where the value of the good to be traded follows a Markov process. For these games the existence of a perfect equilibrium is proved and the set of equilibrium payoffs and strategies are characterised. The main results are (a) if the buyer is less patient than the seller, then there will be delays in the players reaching an agreement, the buyer is forced into a suboptimal consumption policy and the equilibrium is ex-ante inefficient, and (b) if the buyer is more patient than the seller, then there is a unique and efficient equilibrium where agreement is immediate.

The paper analyzes reputation effects in general perturbed repeated games with discounting. If there is some positive prior probability that one of the players is committed to play the same (pure or mixed) action in every period, then this provides a lower bound for her equilibrium payoff in all Nash equilibria. This bound is tight and independent of what other types have positive probability. It is generally lower than Fudenberg and Levine's (1989, 1992) bound for games with a long-run player facing a sequence of short-run opponents. The bound cannot be improved by considering types playing history dependent commitment strategies.

Consider two agents who learn the value of an unknown parameter by observing a sequence of private signals. Will the agents commonly learn the value of the parameter, i.e., will the true value of the parameter become approximate common-knowledge? If the signals are independent and identically distributed across time (but not necessarily across agents), the answer is yes (Cripps et al., Econometrica, 76(4):909–933, 2008). This paper explores the implications of allowing the signals to be dependent over time. We present a counterexample showing that even extremely simple time dependence can preclude common learning, and present sufficient conditions for common learning.

Consider two agents who learn the value of an unknown parameter by observing a sequence of private signals. Will the agents commonly learn the value of the parameter, i.e., will the true value of the parameter become approximate common-knowledge? If the signals are independent and identically distributed across time (but not necessarily across agents), the answer is yes (Cripps, Ely, Mailath, and Samuelson, 2008). This paper explores the implications of allowing the signals to be dependent over time. We present a counterexample showing that even extremely simple time dependence can preclude common learning, and present sufficient conditions for common learning.

There has been significant interest recently both in the empirical investigation of the determinants of trade union membership, in the U.K. and elsewhere, and in the theoretical analysis of the economic effects of the closed shop trade union. However, there is little rigorous microeconomic explanation of union membership which is relevant for much of the U.K. and similar labour markets where the ‘open shop’ union is prevalent. This paper attempts to overcome the free-rider problem of explaining union membership in the open shop. We argue that both private pecuniary gains and social influences affect the individuals' union membership decisions, citing evidence in support of these basic assumptions. We show that stable intermediate union density is a possible equilibrium outcome in a generalised social custom model. We also analyse the simultaneous determination of wages and union membership, deriving a number of comparative static results. In particular, we find that both wages and union density depend upon, inter alia, the level of strike pay, the net cost of union membership and the individual's sensitivity to social custom and associated solidarity effects. We argue that the approach is consistent with various stylised facts concerning both wage bargaining and union membership and is able to explain a number of otherwise puzzling features of union membership.

The author solves for the reputational equilibrium in a class of linear quadratic Gaussian dynamic games with noisy control. This equilibrium is particularly simple to describe and tractable. There is imperfect monitoring but a sequential equilibrium is found where the uninformed agents always smoothly learn the type of the informed agent. Reputation effects are temporary in the infinite horizon case for positive discount rates; as the discount factor tends to unity there is a permanent reputation. Copyright 1993 by Royal Economic Society.

The widespread use of parallel machines has been hampered by the difficulty of mapping applications onto them effectively. The difficulty arises because current programming languages require the programmer to specify a problem to be solved at a low level of abstraction in an imperative form. Thus the programmer must immediately encode an architecture-specific algorithm detailing every communication and calculation. This process is prone to error and complicates the reuse of software. An alternative approach is to specify the problem to be solved at a high-level in a functional language. Meaning-preserving program transformations can then be used to derive a parallel algorithm. Such algorithms can be run on parallel graph-reduction or dataflow machines which automatically exploit the implicit parallelism in a functional language program. Such automatic decomposition techniques, however, are not yet capable of fully yielding the extra performance offered by the parallel hardware. We show how, by including an architecture specification with the problem specification, and extending the amount of transformation performed, it is possible to produce functional language code that explicity expresses the calculations and communications to be performed by the processors. This simplifies compilation, yields faster programs and enables parallel software to be developed for a wide variety of parallel computer architectures. A goal-seeking transformation methodology has been developed which enables a high-level functional specification of the problem and a high-level functional abstraction of the target computer architecture to be systematically manipulated to produce an efficient parallel algorithm tailored to the target architecture. As the transformations start from very high-level specifications, the discovery of new algorithms is facilitated. A case study is used to demonstrate the effectiveness of the technique. We show how a high level specification for sort can be transformed with a pipeline architecture specification to give a mergesort and how the same specification with a dynamic-message-passing architecture specification can be transformed to a novel parallel quicksort.

There is a considerable body of work which shows that the set of outcomes from rational play in a game is identical to a set of correlated equilibria. We show that the set of outcomes from evolutionary stable behavior, where nature serves as a correlating device, is identical to the set of strict correlated equilibria. This extends the result that ESS corresponds to strict Nash equilibrium, provided by R. Selten (Math. Social Sci. 5, 1983, 269–363), by allowing for correlation.

For games of public reputation with uncertainty over types and imperfect public monitoring, Cripps, Mailath, and Samuelson (2004) showed that an informed player facing short-lived uninformed opponents cannot maintain a permanent reputation for playing a strategy that is not part of an equilibrium of the game without uncertainty over types. This paper extends that result to games in which the uninformed player is long-lived and has private beliefs, so that the informed player's reputation is private.

This Paper studies a game of strategic experimentation with two-armed bandits whose risky arm might yield a pay-off only after some exponentially distributed random time. Because of free-riding, there is an inefficiently low level of experimentation in any equilibrium where the players use stationary Markovian strategies with posterior beliefs as the state variable. After characterizing the unique symmetric Markovian equilibrium of the game, which is in mixed strategies, we construct a variety of pure-strategy equilibria. There is no equilibrium where all players use simple cut-off strategies. Equilibria where players switch finitely often between the roles of experimenter and free-rider all lead to the same pattern of information acquisition; the efficiency of these equilibria depends on the way players share the burden of experimentation among them. In equilibria where players switch roles infinitely often, they can acquire an approximately efficient amount of information, but the rate at which it is acquired still remains inefficient; moreover, the expected pay-off of an experimenter exhibits the novel feature that it rises as players become more pessimistic. Finally, over the range of beliefs where players use both arms a positive fraction of the time, the symmetric equilibrium is dominated by any asymmetric one in terms of aggregate pay-offs.

We study the long-run sustainability of reputations in games with imperfect public monitoring. It is impossible to maintain a permanent reputation for playing a strategy that does not play an equilibrium of the game without uncertainty about types. Thus, a player cannot indefinitely sustain a reputation for non-credible behavior in the presence of imperfect monitoring.

This paper studies a game of strategic experimentation in which the players have access to two-armed bandits where the risky arm distributes lumpsum payoffs according to a Poisson process with unknown intensity. Because of free-riding, there is an inefficiently low level of experimentation in any equilibrium where the players use stationary Markovian strategies. We characterize the unique symmetric Markovian equilibrium of the game, which is in mixed strategies. A variety of asymmetric pure-strategy equilibria is then constructed for the special case where there are two players and the arrival of the first lump-sum fully reveals the quality of the risky arm. Equilibria where players switch finitely often between the roles of experimenter and free-rider all lead to the same pattern of information acquisition; the efficiency of these equilibria depends on the way players share the burden of experimentation among them. We show that at least for relatively pessimistic beliefs, even the worst asymmetric equilibrium is more efficient than the symmetric one. In equilibria where players switch roles infinitely often, they can acquire an approximately efficient amount of information, but the rate at which it is acquired still remains inefficient.

We study the long-run sustainability of reputations in games with imperfect public monitoring. It is impossible to maintain a permanent reputation for playing a strategy that does not eventually play an equilibrium of the game without uncertainty about types. Thus, a player cannot indefinitely sustain a reputation for non-credible behavior in the presence of imperfect monitoring.

This paper studies a game of strategic experimentation in which the players learn from the experiments of others as well as their own. We first establish the efficient benchmark where the players co-ordinate in order to maximise joint expected payoffs, and then show that, because of free-riding, the strategic problem leads to inefficiently low levels of experimentation in any equilibrium when the players use stationary Markovian strategies. Efficiency can be approximately retrieved provided that the players adopt strategies which slow down the rate at which information is acquired; this is achieved by their taking periodic breaks from experimenting, which get progressively longer. In the public information case (actions and experimental outcomes are both observable), we exhibit a class of non-stationary equilibria in which the $\varepsilon$-efficient amount of experimentation is performed, but only in infinite time. In the private information case (only actions are observable, not outcomes), the breaks have two additional effects: not only do they enable the players to finesse the inference problem, but also they serve to signal their experimental outcome to the other player. We describe an equilibrium with similar non-stationary strategies in which the $\varepsilon$-efficient amount of experimentation is again performed in infinite time, but with a faster rate of information acquisition. The equilibrium rate of information acquisition is slower in the former case because the short-run temptation to free-ride on information acquisition is greater when information is public.

The paper analyzes the Nash equilibria of two-person discounted repeated games with one-sided incomplete information and known own payoffs. If the informed player is arbitrarily patient relative to the uninformed player, then the characterization for the informed player's payoffs is essentially the same as that in the undiscounted case. This implies that even small amounts of incomplete information can lead to a discontinuous change in the equilibrium payoff set. For the case of equal discount factors, however, and under an assumption that strictly individually rational payoffs exist, a result akin to the Folk Theorem holds when a complete information game is perturbed by a small amount of incomplete information.

This paper introduces a dynamic model of the wealth distribution with aggregate risk in the capital market; the model combines credit rationing and portfolio selection decisions. In a closed economy the long-run behaviour of wealth is independent of the initial income distribution when there is aggregate uncertainty, although further restrictions are necessary when there is no aggregate uncertainty. There can be credit rationing at the long-run equilibrium. In poor economies aggregate risk in the capital market slows growth, whereas in richer economies a risky capital market is good for income growth.

Hepatitis B virus (HBV)-specific T cell responses play an important role in the clearance of HBV infection. Heterologous Hi-8™ PrimeBoost vaccination using HBV surface antigen (HBsAg) is a promising approach for inducing T cell responses in chronic hepatitis B patients and results in viral suppression and liver function normalisation. Cellular immune responses against HBV antigens were determined in PBMC isolated from patients treated with Hi-8™ HBV therapy. Samples were tested by ex vivo IFN-γ ELISPOT assay and after 14 days of culture in the presence of overlapping peptides spanning the HBsAg and HBV core antigen (HBcAg) sequences. Ex vivo HBsAg-specific T cell responses were of very low frequency and transient. However, higher frequency T cell responses that could be correlated with clinical outcome were measured after culture. Notably, HBsAg but not HBcAg-specific responses increased after treatment, indicating that responses were driven by vaccination. Further experiments are being conducted to determine the relative contribution of CD4 and CD8 T cells to the immune response. In conclusion, HBsAg specific IFN-γ producing T cells were detected in PBMC from chronically infected patients and increased in those receiving Hi-8™ HBV therapy. Since the T cell immune responses could only be detected following in vitro culture, they are either of very low frequency in the peripheral blood or of a memory phenotype.

The joint determination of the timing of investment and wage bargaining is modelled. Two cases are considered: (a) There is an alternating-offer bargaining game over binding wage contracts and production is possible only when agreement is reached. (b) There are no binding contracts so revenue is divided in period-by- period bargaining post-investment. Investment can occur earlier in case (b) than in case (a) and the equilibrium in case (b) can Pareto dominate the equilibrium with binding contracts. These conclusions depend on players' discount factors.

Two-person repeated games with no discounting are considered where there is uncertainty about the type of the players. If there is a possibility that a player is an automaton committed to a particular pure or mixed stage -game action, then this provides a lower bound on the Nash equilibrium payoffs to a normal type of this player. The lower bound is the best available and is robust to the existence of other types. The results are extended to the case of two-sided uncertainty. This work extends Schmidt (1993) who analysed the restricted class of conflicting interest games.

Much work has been carried out within the last few years to link together "islands of automation" on a factory floor using local area networks. This has led to the development of standards in communication systems, such as the Manufacturing Automation Protocol sponsored by the General Motors Corporation. At present a standard, low-cost approach to implementing manufacturing systems, ensuring compatability with the higher-cost MAP-based systems, is not available. If such a standard were available then small firms could install distributed automation control systems incrementally. This paper describes the application of multi-level, hierarchical control to a simple assembly flow line for the consumer electronics industry. There are four basic levels in the system, the lowest being an assembly operation carried out by human or robotic operators. A number of separate assembly operations, each controlled by work station controllers, are formed into a flow line with a number of flow lines forming the complete manufacturing facility controlled by a Computer Aided Manufacture (CAM) host. It is only at the level of the flow line controller and above that the MAP protocols can be applied cost-effectively in a small manufacturing environment. Adoption of the hierarchical approach throughout the system ensures that it is flexible, reliable, easily maintained and can be installed incrementally. The standardisation of low-cost local area networks (LANs) to interconnect the programmable logic controllers (PLCs) is crucial to this task because the lower level communication can then be implemented at much reduced cost as the performance required is minimised. An analysis of the requirements and implementations of LANs for this purpose is provided. To ensure correct operation of the workstation controllers and the associated communication to their flow line controller, a complete and novel Petri-net based logic controller design (PNLC) has been tested. This allows emulation and simulation of algorithms in the stations, to prove both the algorithms and their intercommunication are correct, prior to direct transfer to running on the factory floor.