For trade involving perfect complements and fragmented ownership, lower bounds on the deficit cost of supporting efficiency is provided by first providing informative estimates for the generalized ...VCG mechanism, then doing so for all incentive-feasible direct mechanisms, and finally for all voluntary trading mechanisms.
•Trade involving perfect complements with fragmented ownership is plagued by the holdout problem.•Lower bound on the deficit cost of supporting efficiency in second-best mechanisms is provided.•The generalized VCG mechanism plays a crucial role in the estimates.
Mechanical ventilation (MV) is associated with adverse effects on the diaphragm, but the cellular basis for this phenomenon, referred to as ventilator-induced diaphragmatic dysfunction (VIDD), is ...poorly understood.
To determine whether mitochondrial function and cellular energy status are disrupted in human diaphragms after MV, and the role of mitochondria-derived oxidative stress in the development of VIDD.
Diaphragm and biceps specimens obtained from brain-dead organ donors who underwent MV (15-176 h) and age-matched control subjects were compared regarding mitochondrial enzymatic function, mitochondrial DNA integrity, lipid content, and metabolic gene and protein expression. In addition, diaphragmatic force and oxidative stress after exposure to MV for 6 hours were evaluated in mice under different conditions.
In human MV diaphragms, mitochondrial biogenesis and content were down-regulated, with a more specific defect of respiratory chain cytochrome-c oxidase. Laser capture microdissection of cytochrome-c oxidase-deficient fibers revealed mitochondrial DNA deletions, consistent with damage from oxidative stress. Diaphragmatic lipid accumulation and responses of master cellular metabolic sensors (AMP-activated protein kinase and sirtuins) were consistent with energy substrate excess as a possible stimulus for these changes. In mice, induction of hyperlipidemia worsened diaphragmatic oxidative stress during MV, whereas transgenic overexpression of a mitochondria-localized antioxidant (peroxiredoxin-3) was protective against VIDD.
Our data suggest that mitochondrial dysfunction lies at the nexus between oxidative stress and the impaired diaphragmatic contractility that develops during MV. Energy substrate oversupply relative to demand, resulting from diaphragmatic inactivity during MV, could play an important role in this process.
A holdout problem arises in a land assembly environment in which one buyer is interested in a large landmass characterized by fragmented ownership among many landowners. A simple holdout-resolving ...mechanism is obtained that asymptotically (as the number of landowners increase) solves a mechanism design problem with two novel criteria. One, a partial coercion constraint that respects property rights only in an ‘aggregate’ sense; and two, a fairness constraint that requires the terms of trade (per unit area) to be the same for every landowner. The mechanism is budget-balanced, semi-anonymous, weakly strategy-proof and non-coercive for the buyer while also being strategy-proof in the large for landowners.
A prospective study of survival, functional outcome, living arrangements, daily activities and leisure engagements among octogenarians up to 5 years after cardiac surgery was performed.
The study ...consisted of a cohort of 300 consecutive octogenarians with three interviews made at 6-month intervals for a total of 593 postoperative interviews. Functional outcomes were measured using the Barthel index and Karnofsky performance scores and divided into autonomous, semiautonomous, or dependent. Living arrangements and leisure activities within the social, physical, cognitive, and creative domains were recorded in an open-ended questionnaire.
There were 150 men and 150 women with a mean age 82.6 years. The 30-day survival was 84.3%. Actuarial survival at 1, 3, and 5 years was 76.6%, 66.6%, and 57.8%, respectively. Among the survivors at the first interview, 2.2 years postoperatively, there were 63.9% autonomous, 31.7% semiautonomous, and 4.3% dependent patients versus at the last interview, 3.6 years postoperatively, in which there were 64.9% autonomous, 28.1% semiautonomous, and 9.2% dependent. At the first interview, 76.4% were at home, 19.2 % in a residence, and 4.3% in a supervised setting. At the third interview, 71.8% were at home, 21.2% in a residence, and 6.9% in a supervised setting. Nearly all patients were involved in leisure activities in the social (98.9%), cognitive (98.4%), and physical (93.1%) domains. At the end of the last interview, activities within the social and cognitive domains were maintained with a small decrease in the physical domain.
Surviving octogenarians remain at home, function independently, and engage in regular leisure activities years after cardiac surgery. This information might help physicians and surgeons regarding long-term outcome of open cardiac surgery in octogenarians.
Raiffa's solution to the bargaining problem, outlined in Luce and Raiffa (1957), is the point where the negotiation curve - a sequence of points that constitute step-by-step improvements from the ...status quo in the feasible payoff space - meets (possibly in the limit) the efficient boundary of the feasible region. A bargaining model with interim agreements yields a negotiation curve in equilibrium (in the spirit of Raiffa), and as the bargaining frictions disappear, the Raiffa path of payoffs converges to the Nash solution.
Management of severe ischemic mitral regurgitation remains difficult with disappointing early and intermediate-term surgical results of valve repair.
Forty-four patients with severe (4+) Carpentier ...type IIIb ischemic mitral regurgitation underwent mitral valve repair, with or without surgical revascularization, by posterior leaflet extension with a patch of bovine pericardium and a remodeling annuloplasty. Serial echocardiography was performed preoperatively, intraoperatively, and postoperatively to assess mitral valve competence. The postoperative functional status of patients was assessed. The average Parsonnet score was 38+/-13. Thirty-day mortality was 11%, and late mortality was 14%. Mean follow-up was 38 months. The actuarial freedom from moderate or severe recurrent mitral regurgitation was 90% at 2 years, whereas 90% of patients were in New York Heart Association class I at 2 years.
Posterior leaflet extension with annuloplasty of the mitral valve for severe type IIIb ischemic regurgitation is a safe, effective method that provides good early and intermediate-term competence of the mitral valve and therefore good functional status.
•A multilateral bargaining mechanism is studied that relaxes the institutional feature of ‘every responder has veto power’.•The mechanism has good efficiency properties in the setting of strictly ...supermodular games.•Provided bargaining frictions are not too high, efficient equilibria in pure stationary strategies exist.•All such equilibria are payoff equivalent in the limit as bargaining frictions vanish.•The limiting payoff is the core-constrained Nash Bargaining Solution.
A new feature pertaining to proposer's ability to implement offers is introduced in the extensive form bargaining mechanism studied in Okada (1996). This mechanism is used to analyze the coalitional setting of strictly supermodular games. The new feature in the mechanism is that the proposer has a choice to implement his proposal with any subset of responders who have accepted it. Thus the institutional feature of ‘every responder has veto power’ is relaxed here. It is shown that for all sufficiently high discount factors δ, there exists an efficient subgame perfect equilibrium in pure stationary strategies (SSPE) whose limiting outcome is the core-constrained Nash Bargaining Solution. Moreover, all efficient SSPE are payoff-equivalent in the limit as δ→1.
•A new mechanism is proposed to mitigate the holdout problem in land assembly.•A 2X2 treatment structure is used to experimentally investigate the effects of two parameters that define the ...mechanism.•The efficiency performance of the mechanism is found to be better than a baseline market mechanism.•The incentive compatibility and individual rationality performance of the treatments are also studied.
Market mechanisms for land assembly problems suffer from a holdout problem and coercive legal solutions like eminent domain introduce new inefficiencies. A new mechanism that is not fully market-based but attempts price discovery is proposed, experimentally studied and is shown to improve efficiency. The mechanism is fully specified by two parameters - a percentile value of the empirical distribution of ask-prices that serves as a trading threshold for the buyer and a quantum of penalty to be applied to landowners who bid relatively very high. In a 2 × 2 treatment, it is found that reducing the trading threshold and increasing the penalty improves the efficiency performance.
For a trading problem where a buyer is interested in an aggregate resource with fragmented ownership, the individually owned resources are perfect complements in trade. A double auction, chosen in ...accordance with a value alignment principle which we formulate, is shown to be strategy proof for owners. Since it also values the aggregate resource correctly, it mitigates the holdout problem by changing the source of inefficiency from complementarity on owners' side to lack of competition on buyer side. The value alignment principle implies that this double auction has a majority trading rule. With multiple buyers, a suitable modification makes the double auction strategy proof even for the buyers, thus mitigating the holdout problem by achieving approximate ex post efficiency when the number of owners is large.
Background and Aim
With the advancement of percutaneous coronary interventions (PCIs), more patients with diffuse coronary artery disease are referred for coronary artery bypass graft (CABG) surgery. ...The use of coronary endarterectomy may be useful in such cases. We reviewed our experience with left anterior descending artery endarterectomy as an adjunct to conventional CABG.
Methods
Between June 2005 and 2011, 58 consecutive patients underwent left anterior descending artery endarterectomy as an adjunct to CABG. These were matched to 58 cases based on age, gender, and Parsonnet score. All data were collected prospectively in a departmental database. Postoperative complications and in‐hospital mortality were analyzed. Survival curves were produced.
Results
There was one death in the endarterectomy group (1.7%) from liver failure. There was no significant difference in postoperative complications (especially perioperative myocardial infarction) between the two groups with similar hospital mortality. Computed tomography (CT) angiography was performed in 24 patients with endarterectomy (41%), which showed 100% patency of the left internal mammary artery graft to the left anterior descending artery. Survival and freedom from intervention at a mean follow‐up of 4.2 years were similar.
Conclusions
In patients with diffuse disease, the use of endarterectomy is a safe technique with no increase in short‐term morbidity or mortality. Mid‐term results are similar to nonendarterectomized patients. This technique is useful in patients with diffuse coronary artery disease. doi: 10.1111/jocs.12230 (J Card Surg 2014;29:1‐7)
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