Differences In Rates Of Return Research Articles

Is shifting from Li-ion NMC to LFP in EVs beneficial for second-life storages in electricity markets?

While electric vehicles are promising to reduce carbon emissions on the road, from a holistic life-cycle view, further environmental considerations in the production and end-of-life management of their batteries are required. Recently, circular end-of-life thinking has been promoted with strategies to increase retired batteries' lifetime through second-life as lifetime extension is typically favoured in life cycle assessment. However, standardization of these strategies toward recycling or repurposing paths is recommended for different Li-ion chemistries. This categorization mainly concerns the cobalt-containing cathode Li-ion batteries i.e., NMC which is the dominant technology for transportation, and the alternative technology i.e., LFPs with a more recent attention toward them in automobile sector due the cobalt scarcity in the supply chain. This technology shift will impact their end-of-life management at the retirement. In this arrangement, the economic priority of repurposing such battery chemistries needs quantification. This study evaluated the financial return of repurposing retired Li-ion NMC and LFP batteries for energy arbitrage applications in power systems. The feasibility of repurposing is examined in the Irish and Queensland's markets. Results show that retired Li-ion LFPs respond to price fluctuations more frequently with a higher financial return compared to NMCs; thus, they have higher potential for repurposing as such their greater integration in new vehicles is promising from a circular economy perspective. Different rates of return have been observed for various sizes of systems and battery durations. The financial benefits are more prominent for a one-hour battery in a medium system compared to half and two-hour durations and a smaller system. A sensitivity analysis shows that even spending the same capital cost as a new system for a repurposed system results in a marginal financial return in a competitive electricity market like Queensland's, whereas further incentives toward circular-enabling business models from local authorities will effectively make such investments feasible.

Study within a trial of electronic versus paper-based Patient-Reported oUtcomes CollEction (SPRUCE): study protocol for a partially randomised patient preference study

IntroductionPatient-reported outcomes (PRO) are currently collected from trial participants using paper questionnaires by the Clinical Trials and Statistics Unit at The Institute of Cancer Research (ICR-CTSU). Streamlining PRO collection using...

The effectiveness of the contrarian and momentum strategies on the US REIT market

When making investment decisions in financial markets, investors use various investment strategies. The traditional ones include the contrarian strategy and the moment strategy. In recent years, one of the dynamically developing segments of the global financial market has been the American REIT market. The literature on the subject lacks research on the effectiveness of investment strategies in this market. The aim of the article is therefore to compare the effectiveness of the contrarian strategy and momentum strategy on the US REIT market in different ranking periods. Based on the data on the rates of return of individual REITs listed on public capital markets in the US, the rates of return resulting from the application of the contrarian and momentum strategies were estimated. The results of the conducted analyses showed that for the three-year ranking period, the rates of return of the portfolio composed of loser REITs significantly exceeded the rates of return of the portfolio of winner REITs. This means that during this period the use of the contrarian strategy was more effective than the use of the momentum strategy. For other analysed ranking periods, the differences in rates of return were not statistically significant. The results of the conducted analyses may help investors in choosing the most effective investment strategy on the REIT market. This research also answers the question whether the REIT market should use investment strategies that, according to research, are effective on the broad stock market, or strategies that work well on the investment fund market.

Enclosing a pen in a postal questionnaire follow-up to increase response rate: a study within a trial.

Poor response rates to follow-up questionnaires can adversely affect the progress of a randomised controlled trial and the validity of its results. This embedded 'study within a trial' aimed to investigate the impact of including a pen with the postal 3-month questionnaire completed by the trial participants on the response rates to this questionnaire. This study was a two-armed randomised controlled trial nested in the Gentle Years Yoga (GYY) trial. Participants in the intervention group of the GYY trial were allocated 1:1 using simple randomisation to either receive a pen (intervention) or no pen with their 3-month questionnaire (control). The primary outcome was the proportion of participants sent a 3-month questionnaire who returned it. Secondary outcomes were time taken to return the questionnaire, proportion of participants sent a reminder to return the questionnaire, and completeness of the questionnaire. Binary outcomes were analysed using logistic regression, time to return by Cox Proportional Hazards regression and number of items completed by linear regression. There were 111 participants randomised to the pen group and 118 to the no pen group who were sent a 3-month questionnaire. There was no evidence of a difference in return rates between the two groups (pen 107 (96.4%), no pen 117 (99.2%); OR 0.23, 95% CI 0.02 to 2.19, p=0.20). Furthermore, there was no evidence of a difference between the two groups in terms of time to return the questionnaire (HR 0.90, 95% CI 0.69 to 1.18, p=0.47), the proportion of participants sent a reminder (OR 0.85, 95% CI 0.48 to 1.53, p=0.60) nor the number of items completed (mean difference 0.51, 95% CI -0.04 to 1.06, p=0.07). The inclusion of a pen with the postal 3-month follow-up questionnaire did not have a statistically significant effect on response rate.

Sector rotation multi-factor stock selection strategy based on six boards

This paper proposes an investment strategy based on a regression linear model to predict sector rotation and a multi-factor scoring model to select stocks to achieve excess returns. The strategy uses January 2006 December 2020 as the model construction period and January 2021 June 2021 as the model validation and backtesting period. Using Shenyin & wanguo’s industry classification as a standard, the cyclicality of industries is classified by β value and the existence of sector rotation is verified using the difference in rate of return between cyclical and non-cyclical industry. The factors associated with the annualized rate of return are selected and the fitted formula for the annualized rate of return is obtained by regressing linear equation and neural network multidimensional correlation to select the dominant board. Valid factors for each board were selected for fitting, and the factors were assigned weights for scoring, resulting in 32 stocks. The backtest results significantly outperformed the CSI 300 Index, and the model performance is stable and can achieve better returns.

Does Point-of-care Ultrasound Improve Survival when Used During Cardiac Arrest? A Systematic Review and Meta-analysis

Aim of the review: This review aimed to evaluate the impact of Point-of-care Ultrasound during cardio- pulmonary resuscitation for adult non-traumatic CA on clinical outcomes and survival. Data sources: This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The PubMed and Embase databases were searched on 14 November 2022. The eligibility criteria were studies including: adults with non-traumatic cardiac arrest and Point-of-care Ultrasound utilisation, a control group, and an analysis of short- and long-term outcomes and neurological outcomes. The risk of bias and certainty of evidence were assessed using the Grading of Recommendations Assessment, Development and Evaluation form. Data are reported as risk of ratios for each outcome. Results: From the two databases, 7658 studies were identified, of which 3 met the predefined eligibility criteria. The main findings showed no difference in rate of return of spontaneous circulation (RR 0.83, 95% CI 0.24–1.66, p=0.60) (very low certainty of evidence) and a significant decrease in rate of survival to hospital discharge (RR 0.44, 95% CI 0.22–0.88, p=0.02) (very low quality of evidence). No study reported data regarding neurological status at hospital discharge, 30-day survival rate, or neurological outcome. Conclusion: The impact of Point-of-care Ultrasound during cardiopulmonary resuscitation on clinical outcomes during cardiac arrest is hampered by the very low certainty of evidence, heterogeneity, and high risk of bias. Studies have shown no difference in return of spontaneous circulation but a significant decrease in survival to hospital discharge when Point-of-care Ultrasound was performed.

Enclosing a pen in a postal questionnaire follow-up to increase response rate: a study within a trial

Poor response rates to follow-up questionnaires can adversely affect the progress of a randomised controlled trial and the validity of its results. This embedded 'study within a trial' aimed to investigate the impact of including a pen with the postal 3-month questionnaire completed by the trial participants on the response rates to this questionnaire. This study was a two-armed randomised controlled trial nested in the Gentle Years Yoga (GYY) trial. Participants in the intervention group of the GYY trial were allocated 1:1 using simple randomisation to either receive a pen (intervention) or no pen with their 3-month questionnaire (control). The primary outcome was the proportion of participants sent a 3-month questionnaire who returned it. Secondary outcomes were time taken to return the questionnaire, proportion of participants sent a reminder to return the questionnaire, and completeness of the questionnaire. Binary outcomes were analysed using logistic regression, time to return by Cox Proportional hazards regression and number of items completed by linear regression. There were 111 participants randomised to the pen group and 118 to the no pen group who were sent a 3-month questionnaire. There was no evidence of a difference in return rates between the two groups (pen 107 (96.4%), no pen 117 (99.2%); OR 0.23, 95% CI 0.02 to 2.19, p=0.20). Furthermore, there was no evidence of a difference between the two groups in terms of time to return the questionnaire (HR 0.90, 95% CI 0.69 to 1.18, p=0.47), the proportion of participants sent a reminder (OR 0.85, 95% CI 0.48 to 1.53, p=0.60) nor the number of items completed (mean difference 0.51, 95% CI-0.04 to 1.06, p=0.07). The inclusion of a pen with the postal 3-month follow-up questionnaire did not have a statistically significant effect on response rate.

Recruitment of diverse community health center patients in a pragmatic weight gain prevention trial.

Pragmatic trials are needed to establish evidence-based obesity treatment in primary care settings, particularly in community health centers (CHCs) that serve populations at heightened risk of obesity. Recruiting a representative trial sample is a critical first step to informing care for diverse communities. We described recruitment strategies utilized in a pragmatic obesity trial and assessed the sociodemographic characteristics and odds of enrollment by recruitment strategy. We analyzed data from Balance, a pragmatic trial implemented within a network of CHCs. We recruited participants via health center-based and electronic health record (EHR)-informed mail recruitment. We analyzed associations between sociodemographic characteristics and the return rate of patient authorization forms (required for participation) from EHR-informed mail recruitment. We also compared sociodemographic characteristics and randomization odds by recruitment strategy after returning authorization forms. Of the individuals recruited through EHR-informed mail recruitment, females were more likely than males to return authorization forms; however, there were no differences in rates of return by preferred language (English/Spanish) or age. Females; underrepresented racial and ethnic groups; Spanish speakers; younger adults; and those with lower education levels were recruited more successfully in the health center. In contrast, their counterparts were more responsive to mail recruitment. Once authorization forms were returned, the odds of being randomized did not significantly differ by recruitment method. Health center-based recruitment was essential to meeting recruitment targets in a pragmatic weight gain prevention trial, specifically for Hispanic and Spanish-speaking communities. Future pragmatic trials should consider leveraging in-person recruitment for underrepresented groups in research.

Fast-Track Nonelective Laparoscopic Cholecystectomy is Safe and Feasible

IntroductionAmple evidence exists to support the safety of fast-track discharge after elective laparoscopic cholecystectomy (LC), but there is currently no data available to support the safety of fast-tracking patients undergoing nonelective LC. We sought to determine whether fast-tracking patients undergoing nonelective LC is safe and feasible. MethodsWe performed a retrospective cohort review of 661 consecutive patients undergoing LC at a single teaching institution from April 2018 to January 2020. Subjects were divided into two groups: elective LC (ELC) and fast-track nonelective LC (FTLC). FTLC was defined as nonelective LC with total length of stay <36 h. Patients undergoing nonelective LC with length of stay exceeding 36 h were excluded. The primary outcome of interest was readmission within 30 d. The secondary outcomes included incidences of return to emergency department within 30 d, retained stone, bile leak, and wound infection. ResultsOf 661 LC, 185 (27%) were ELC and 476 (72%) were nonelective. FTLC included 121 (25%) of the nonelective LC. Preoperative characteristics were similar among the groups. On final pathology, chronic cholecystitis was predominant in both groups, but FTLC exhibited higher rates of acute cholecystitis (P < 0.0001). There was no significant difference in the primary outcome among groups: readmission within 30 d occurred in 6 (3%) ELC patients and 4 (3%) FTLC patients (P = 1.0). There were no significant differences in rates of return to emergency department within 30 d, retained stone, bile leak, or wound infection. ConclusionsWith comparable postoperative complication rates to ELC, FTLC can be safely used in select patients. Additional studies are needed to determine preoperative predictors of FTLC suitability to prospectively identify appropriate patients.

Service Decisions in a Two-Echelon Retailing System with Customer Returns

Many manufacturers and retailers have already opened online stores to sell their products. Thus, manufacturers are competing as sellers, and retailers are transforming into dual-channel retailers (DCRs). Such an expansion in business scope and the wide spread of lenient return policies trigger tremendous return volume that requires great deal of logistical efforts. The service levels offered within online stores greatly affect channels’ demand. However, they also influence the channel choice of return for online customers, if applicable, when their purchases are unsatisfactory. Therefore, this paper studies the optimal service level for a centralized DCR. In addition, it examines the optimal levels for a decentralized two-echelon system through the implementation of Nash and Stackelberg theoretical frameworks. Important properties of optimal solutions and vital managerial insights have been devised through analytical and sensitivity analysis. It is found that a DCR may have the following tradeoff: decrease service level to increase the reward from the physical store or increase service level to enhance competitiveness of the online store. The optimal decision depends greatly on how sensitive the customers’ return behavior is to service level. In addition, as the exogenous price increases, the change in the retailer’s offered level depends significantly on the different rates of return.

Calculation of the transition coefficient and moderate level of China's pension system unification

In this paper, the transition coefficient of replacement rate is taken as the breakthrough point for studying the pension system unification of China's government and public institutions. We present the basic principles and mathematical model of the transition coefficient for the pension replacement rate based on horizontal unification and vertical transition characteristics using time smoothing methods. We construct a general measurement model for calculating the pension unification transition coefficient and further transform it based on the current policy and the moderate replacement rate. On this basis, we introduce the pension account rate of return in order to simulate the realisation of the transition coefficient and determine the characteristics of the transition coefficient under the different rates of return, thus providing an important reference for the coordinated development of pension unification transition and the individual and occupational pension accounts. Based on this, we put forward relevant countermeasures and suggestions.

Conventional and downside CAPM: The case of London stock exchange

Many studies on asset pricing have highlighted the importance of downside risk, in line with the actual losses of investors. In addition, the capital asset pricing model (CAPM), although presented as a universal theory, may provide significantly different rates of return in bull and bear markets. Using the CAPM under different conditions could be regarded as an alternative measurement and valuation approach to downside risk. This paper investigates conventional and downside approaches to risk taking into account different measures of downside beta coefficients. A further contribution of this research is the development of an alternative approach to testing the CAPM relationship. For this purpose, conditional relationships of the CAPM are proposed in which risk premiums are set separately in bull and bear periods. Using equity data and portfolios from the United Kingdom, we obtained positive and statistically significant downside risk premiums. We observed a slight advantage of downside measures over conventional beta measures. Conditional models provide evidence of a positive risk premium in rising markets and a negative risk premium in falling markets. The robustness analysis in subperiods indicates that these findings are largely unchanged for downside beta coefficients, which is not fulfilled by the model in a variance approach.

Increasing Fecal Immunochemical Test Return Rates by Implementing Effective "Reminder to Complete Kit" Communication With Participants: A Quality Improvement Study.

BackgroundThe incidence of colorectal cancer (CRC) in the United States is increasing. It remains the second leading cause of cancer death in the United States for men and women combined, mainly due to underutilization of screening methods. The American Cancer Society now recommends that adults aged 45 years and older with an average risk of CRC undergo regular screening with either a high-sensitivity stool-based test or structural (visual) examination, depending on patient preference and test availability. The primary objective of this quality improvement project was to determine if reminder methods, such as telephone or letter reminders, increased the return rate of fecal immunochemical tests (FIT) for CRC screening.MethodologyAt public outreach events and daily clinics in the West Texas Panhandle area, participants in the GET FIT program were provided with FIT kits after completing the education on CRC. Participants who fit the inclusion criteria and had received a FIT kit from the program were included. They were instructed on how to perform the test and mail it back. Participants who did not return the completed kits within two weeks were reminded either through (1) a reminder letter, (2) telephone, or (3) a combination of letter reminder and telephone call every two weeks (±three days) for 60 days or five attempts to contact. We de-identified and analyzed the FIT kit return data from April-September 2019 before analyzing these reminder methods. We then calculated the change in return rates from October 2019 to March 2020. Our goal was to increase the FIT return rates by 25% compared to the baseline return rate.ResultsThe pre-intervention return rate of kits for April-September 2019 was 61.52%, and the post-intervention return rate for October 2019-March 2020 was 71.85%. This rate was equal to an approximately 16.79% increase in return rates that was statistically significant (p < 0.01). There was a significant difference in the method of reminder between the two groups, but no significant differences in gender and race/ethnicity between the two groups. There was a significant difference in return rates between race/ethnicities in the October-March cohort with black and Hispanic participants having the highest return rates of 82.3% and 77.25%, respectively.ConclusionsFIT remains one of the primary options for CRC screening. Due to its lower cost and noninvasiveness, FIT was offered to patients at average risk. We demonstrated an increase in return rates, although we did not meet our target return rate goal for this project. This study was limited due to a gradual increase in coronavirus disease 2019 (COVID-19) cases and a subsequent shift and conversation of ongoing research into COVID-19.

How Do Inheritances Shape Wealth Inequality? Theory and Evidence from Sweden

Abstract This article aims to measure and understand the role of inheritances in shaping wealth inequality. We use a quasi-experimental design and Swedish administrative data to document that the average heir depletes her inheritance within a decade while the inheritances of wealthy heirs remain intact. These different depletion rates are not due to different consumption or labour supply responses but due to different rates of return on inherited wealth. Upon their receipt, inheritances reduce relative measures of wealth inequality, such as top shares or percentile ratios. Theoretically, this reduction in inequality could be due to either a compressed inheritance distribution or similar chances of having wealthy parents (high intergenerational mobility). Empirically, the first force is more significant in Sweden. Within a decade, however, the effect is reversed: inheritances increase wealth inequality since the different depletion rates widen the inequality in inherited wealth over time. This implies that inheritance taxation can reduce long run wealth inequality only through the taxation of wealthy heirs.

Can I Ski Doc?: Return to Skiing Following Total Joint Arthroplasty.

Currently, there are little data on performance, safety, or return to downhill skiing after total joint arthroplasty (TJA). This leaves surgeons with little information for patient counseling regarding skiing. An online survey was sent to 4360 patients who had undergone at least 1 primary TJA at a single academic center over the past 10 years (4 surgeons). The survey asked patients about their prior and current skiing activity including ability level, limitations, and reoperations. Demographics, patient-reported outcomes, and reoperations were also captured through chart review. Chi-squared, analysis of variance, and t-tests were used to compare demographics and outcomes. Paired t-tests were used to compare preoperative and postoperative skiing levels. Of the 763 survey respondents, the average follow-up was 4.4 years (range 0.5-10.3). In total, 35.6% had never skied, 26.5% had not skied in the 5 years prior to surgery (remote), and 37.9% had skied in the 5 years prior to surgery (recent). Seventy percent of recent skiers returned to skiing after surgery, compared to 11.9% of remote skiers. The majority of skiers, mostly advanced, returned to their prior level. There was no difference in return rates in those with a single total hip arthroplasty vs total knee arthroplasty vs multiple TJAs. Rates of reoperation were not significantly different between patients who did and did not return to skiing. The majority of recent skiers were able to return to skiing after TJA at their same level without an increase in reoperation rate. Further studies are needed to determine long-term consequences of skiing after TJA.

An embedded randomised controlled retention trial of personalised text messages compared to non-personalised text messages in an orthopaedic setting

Background: Several studies have investigated whether personalising trial documentation can aid recruitment and retention. We did a 'study within a trial' (SWAT) evaluating the effectiveness of a personalised text message compared to a non-personalised text message, on the retention rate in a large orthopaedic trial. Methods: The SWAT was embedded in the Knee Replacement Bandaging Study (KReBS) trial. The primary outcome was the proportion of 12-month questionnaires returned. Secondary outcomes were the proportion of questionnaires completed and time to questionnaire return. Binary data were analysed using logistic regression and time to return using Cox proportional hazards regression. Odds ratios (OR) and hazard ratios (HR) are presented, with associated 95% confidence intervals (CI) and p-values. Results: In total, 1465 participants were included in the SWAT. In the personalised group, 644/723 (89.1%) of participants returned a questionnaire, compared to 654/742 (88.1%) in the non-personalised group. The absolute difference in return rate was 0.9% (95% CI: -2.3% to 4.2%; p=0.57). There was no evidence of a difference between the groups in the likelihood of returning a questionnaire (OR 1.09; 95% CI: 0.79 to 1.51; p=0.61), the likelihood of returning a complete questionnaire (OR 1.11; 95% CI: 0.82 to 1.51; p=0.50) nor in time to return (HR 1.05; 95% CI: 0.94 to 1.17; p=0.40). Conclusion: This SWAT adds to the growing evidence base for whether personalised text messages are effective. Registration: ISRCTN87127065 (20/02/2017); SWAT 35 (01/12/2015).

An embedded randomised controlled retention trial of personalised text messages compared to non-personalised text messages in an orthopaedic setting

Background: Several studies have investigated whether personalising trial documentation can aid recruitment and retention. We did a ‘study within a trial’ (SWAT) evaluating the effectiveness of a personalised text message compared to a non-personalised text message, on the retention rate in a large orthopaedic trial. Methods: The SWAT was embedded in the Knee Replacement Bandaging Study (KReBS) trial. The primary outcome was the proportion of 12-month questionnaires returned. Secondary outcomes were the proportion of questionnaires completed and time to questionnaire return. Binary data were analysed using logistic regression and time to return using Cox proportional hazards regression. Odds ratios (OR) and hazard ratios (HR) are presented, with associated 95% confidence intervals (CI) and p-values. Results: In total, 1465 participants were included in the SWAT. In the personalised group, 644/723 (89.1%) of participants returned a questionnaire, compared to 654/742 (88.1%) in the non-personalised group. The absolute difference in return rate was 0.9% (95% CI: -2.3% to 4.2%; p=0.57). There was no evidence of a difference between the groups in the likelihood of returning a questionnaire (OR 1.09; 95% CI: 0.79 to 1.51; p=0.61), the likelihood of returning a complete questionnaire (OR 1.11; 95% CI: 0.82 to 1.51; p=0.50) nor in time to return (HR 1.05; 95% CI: 0.94 to 1.17; p=0.40). Conclusion: This SWAT adds to the growing evidence base for whether personalised text messages are effective. Registration: ISRCTN87127065 (20/02/2017); SWAT 35 (01/12/2015)

A comprehensive multidisciplinary care pathway for hip fractures better outcome than usual care?

IntroductionHip fracture surgery is among the most performed surgical procedures in elderly patients. Mortality rates are high, however, and patients often fail to live independently following a hip fracture. To improve outcome, multidisciplinary care pathways have been initiated, but longer-term results are lacking. Aim of this study was to compare functional outcome and living situation six months after hip fracture treatment with and without a care pathway. Patients and methodsA multicentre prospective controlled trial was conducted with three hospitals: in one hospital patients were treated with a care pathway, in the other hospitals patients received usual care. All patients aged ≥ 60 years with a hip fracture were asked to participate. Besides basic characteristics, health-related quality of life (EQ-5D) and performance scores of activities of daily living (Katz Index and Lawton IADL) were assessed. Differences in scores were analysed using linear regression. Propensity score adjustment was used to correct for differences between the care pathway and the usual care group. Missing data were imputed. ResultsNo differences in rate of return to prefracture ADL level were found between patients in the care pathway group and the usual care group. The percentage of participants in the same situation as before the fracture was the same in both treatment groups (81%). There were no significant differences in quality of life, activities of daily living or mortality (15% vs 10%, p = 0.17), but hospital stay in the care pathway group was significantly shorter (median 7 vs 10 days). DiscussionTreatment of elderly patients with a hip fracture is commonly organised in care pathways. Although short-term advantages are reported, positive effects on longer-term functional results could not be proven in our study. This study confirmed a shorter hospital stay in the care pathway group, which potentially may lead to a reduction in costs. ConclusionsFunctional outcome and living situation six months after a hip fracture is the same for patients treated with or without a care pathway.

Return to Work After Primary Rotator Cuff Repair: A Systematic Review and Meta-analysis

Background: Rotator cuff tears are a prevalent pathology in injured workers, causing significant economic ramifications and time away from work. To date, published articles on work outcomes after rotator cuff repair have not been cumulatively assessed and analyzed. Purpose: To systematically review reports on return to work after rotator cuff repair and perform a meta-analysis on factors associated with improved work outcomes. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: A systematic review of return-to-work investigations was performed using PubMed, Embase, and the Cochrane Database of Systematic Reviews in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Individual studies reporting rates of return to previous work with level of evidence 1 to 4 were independently screened by 2 authors for inclusion, and study quality was assessed using the Methodologic Index for Non-randomized Studies and Newcastle-Ottawa Scale. Work outcome data were synthesized and analyzed using random effects modeling to identify differences in rates of return to previous work as a function of operative technique, work intensity, and workers’ compensation status. Results: Thirteen retrospective investigations comprising 1224 patients who underwent rotator cuff repair met inclusion criteria for this investigation. Across all investigations, a weighted average of 62.3% of patients returned to previous level of work at 8.15 ± 2.7 months (mean ± SD) after surgery. Based on random effects modeling, higher rates of return to previous work were identified with decreasing work intensity (P < .001), while rates were similar between open and arthroscopic repair technique (P = .418) and between workers’ compensation and non–workers’ compensation cohorts (P = .089). All shoulder pain and functional outcome assessments demonstrated significant improvements at final follow-up when compared with baseline across all investigations. Conclusion: The majority of injured workers undergoing rotator cuff repair return to previous work at approximately 8 months after surgery. Despite this, >35% of patients are unable to return to their previous work level after their repair procedure. Similar rates of return to work can be anticipated regardless of workers’ compensation status and operative technique, while patients in occupations with higher physical intensity experience inferior work outcomes.

On the Coexistence of Cryptocurrency and Fiat Money

Cryptocurrency is private money and is costly to produce. In this paper, I ask whether cryptocurrency can serve as a medium of exchange, and whether it can coexist with fiat money as a widely accepted medium of exchange. To answer these questions, I develop two search-theoretic models: a model of monetary exchange in an economy with cryptocurrency only and a model of currency competition between cryptocurrency and fiat money. In my models, profit-maximizing miners produce cryptocurrency. In the economy with cryptocurrency only, unlike fiat money models, there is no equilibrium in which the stock of cryptocurrency grows at a constant rate. In a stationary equilibrium in which cryptocurrency is valued, the stock of cryptocurrency must be constant. In the two-currency economy, cryptocurrency and fiat money differ in terms of issuers, production costs, supply rules, and degrees of acceptability in decentralized markets. Different from the traditional two-fiat money models in which currencies have the same rate of return in equilibrium, cryptocurrency and fiat money can circulate in equilibrium with different rates of return. Further, Gresham’s Law does not hold in the sense that, even if cryptocurrency is costly to produce and less acceptable, cryptocurrency can coexist with fiat money, a widely accepted asset that is costless to produce.