Cooperation in anonymous dynamic social networks

Abstract We study the extent to which cooperative behavior can be sustained in large, anonymous, evolving social networks. Individuals strategically form relationships under a social matching protocol and engage in prisoner's dilemma interactions with their partners. We characterize a class of equilibria that support cooperation as a stationary outcome. When cooperation is possible, its level is uniquely determined. While neither community enforcement nor contagion mechanisms have force in our setting, the endogenous dynamics of the social network imply that cooperation allows an individual to gradually accumulate a large network of profitable interactions, while defection results in social marginalization. Even as players become perfectly patient, equilibrium allows for full cooperation, only autarky, or the coexistence of cooperation and defection, depending on payoffs. Smaller levels of cooperation can be sustained by a form of exclusivity among cooperators. * We than

Effect on treatment adherence of distributing essential medicines at no charge : the CLEAN Meds randomized clinical trial

This work is supported by grant 381409 from the Canadian Institutes for Health Research, the Ontario SPOR Support Unit that is supported by the Canadian Institutes of Health Research and the Province of Ontario, the Canada Research Chairs program, and the St Michael’s Hospital Foundation.Importance: Nonadherence to treatment with medicines is common globally, even for life-saving treatments. Cost is one important barrier to access, and only some jurisdictions provide medicines at no charge to patients. Objective: To determine whether providing essential medicines at no charge to outpatients who reported not being able to afford medicines improves adherence. Design, Setting, and Participants: A multicenter, unblinded, parallel, 2-group, superiority, outcomes assessor-blinded, individually randomized clinical trial conducted at 9 primary care sites in Ontario, Canada, enrolled 786 patients between June 1, 2016, and April 28, 2017, who reported cost-related nonadherence. Follow-up occurred at 12 months. The primary analysis was performed using an intention-to-treat principle. Interventions: Patients were randomly allocated to receive free medicines on a list of essential medicines in addition to otherwise usual care (n = 395) or usual medicine access and usual care (n = 391). Main Outcomes and Measures: The primary outcome was adherence to treatment with all medicines that were appropriately prescribed for 1 year. Secondary outcomes were hemoglobin A1c level, blood pressure, and low-density lipoprotein cholesterol levels 1 year after randomization in participants taking corresponding medicines. Results: Among the 786 participants analyzed (439 women and 347 men; mean [SD] age, 51.7 [14.3] years), 764 completed the trial. Adherence to treatment with all medicines was higher in those randomized to receive free distribution (151 of 395 [38.2%]) compared with usual access (104 of 391 [26.6%]; difference, 11.6%; 95% CI, 4.9%-18.4%). Control of type 1 and 2 diabetes was not significantly improved by free distribution (hemoglobin A1c, -0.38%; 95% CI, -0.76% to 0.00%), systolic blood pressure was reduced (-7.2 mm Hg; 95% CI, -11.7 to -2.8 mm Hg), and low-density lipoprotein cholesterol levels were not affected (-2.3 mg/dL; 95% CI, -14.7 to 10.0 mg/dL). Conclusions and Relevance: The distribution of essential medicines at no charge for 1 year increased adherence to treatment with medicines and improved some, but not other, disease-specific surrogate health outcomes. These findings could help inform changes to medicine access policies such as publicly funding essential medicines. Trial Registration: ClinicalTrials.gov identifier: NCT02744963.Publisher PDFPeer reviewe

The Effect of Sea Ice on Tidal Propagation in the Kitikmeot Sea, Canadian Arctic Archipelago

The tides in the Kitikmeot Sea, in the southern Canadian Arctic Archipelago, are found to be heavily influenced by seasonal sea-ice formation and blocking in a strait. Data from a moored current profiler in Dease Strait exhibit strong tidal damping during wintertime seasonal sea-ice cover, with 50%– 60% reduction in tidal elevation and 65% reduction in tidal velocities. We used a 3D unstratified barotropic numerical tidal model of the region to show that the observed wintertime tidal damping likely requires both high sea-ice friction and a partial sea-ice blockage in Victoria Strait (VS), the eastern gateway of the Kitikmeot Sea, where tidal-induced ridging causes thick, rough ice to accumulate over its shallow sill. Our analysis of the model shows different dynamics for the M2 and K1 tides. Both tidal constituents are dominated by the Atlantic tides entering through VS. Overall, ∼90% of the M2 tidal energy entering VS does not reach Dease Strait because, in addition to dissipation in VS (∼25%), it is significantly diverted into adjoining bays and around an amphidrome in eastern Queen Maud Gulf (∼65%). In contrast, the smaller K1 tide is less diverted into the subsidiary channels, after ∼20% dissipation in VS and only ∼25% in adjoining bays, it propagates far into the region and is amplified due to resonance in Dease Strait and Coronation Gulf, resulting in larger tidal height than the M2 tide in Coronation Gulf

A patient-centered deprescribing intervention for hospitalized older patients with polypharmacy: rationale and design of the Shed-MEDS randomized controlled trial

Abstract Background Polypharmacy is prevalent among hospitalized older adults, particularly those being discharged to a post-care care facility (PAC). The aim of this randomized controlled trial is to determine if a patient-centered deprescribing intervention initiated in the hospital and continued in the PAC setting reduces the total number of medications among older patients. Methods The Shed-MEDS study is a 5-year, randomized controlled clinical intervention trial comparing a patient-centered describing intervention with usual care among older (≥50 years) hospitalized patients discharged to PAC, either a skilled nursing facility (SNF) or an inpatient rehabilitation facility (IPR). Patient measurements occur at hospital enrollment, hospital discharge, within 7 days of PAC discharge, and at 60 and 90 days following PAC discharge. Patients are randomized in a permuted block fashion, with block sizes of two to four. The overall effectiveness of the intervention will be evaluated using total medication count as the primary outcome measure. We estimate that 576 patients will enroll in the study. Following attrition due to death or loss to follow-up, 420 patients will contribute measurements at 90 days, which provides 90% power to detect a 30% versus 25% reduction in total medications with an alpha error of 0.05. Secondary outcomes include the number of medications associated with geriatric syndromes, drug burden index, medication adherence, the prevalence and severity of geriatric syndromes and functional health status. Discussion The Shed-MEDS trial aims to test the hypothesis that a patient-centered deprescribing intervention initiated in the hospital and continuing through the PAC stay will reduce the total number of medications 90 days following PAC discharge and result in improvements in geriatric syndromes and functional health status. The results of this trial will quantify the health outcomes associated with reducing medications for hospitalized older adults with polypharmacy who are discharged to post-acute care facilities. Trial registration This trial was prospectively registered at clinicaltrials.gov (NCT02979353). The trial was first registered on 12/1/2016, with an update on 09/28/17 and 10/12/2018