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Objective This study explores the fiduciary advantage of a Vascular Surgery program to an academic, tertiary care hospital. Methods This is a retrospective review of hospital (HealthQuest) and physician (IDX) billing databases from April 2009 to September 2010. We identified all patients interacting with Vascular Surgery (VS) to provide an overview of global finances. Patients introduced solely by VS were identified to minimize confounding of the downstream effect. Outcome measures obtained were revenue, average and total gross margin, relative value unit production, and service utilization. Results A total of 552 cases were identified demonstrating $13 million in revenue. This translated into a gross margin of $5 million. Examined per surgeon, VS was the most profitable, producing $1.6 million. Lower extremity amputation had the highest average gross margin at $34,000. Notably, $8 million in direct cost is among the highest in the health system. A total of 137 cases unique to VS generated $5 million in total revenue. This patient subset made use of up to 29 physician specialty services. General Medicine and Radiology were the most frequently utilized. Conclusion The overall profitability of a comprehensive vascular program is tremendously positive. This study verifies that new vascular-specific referrals are a significant catalyst for revenue.

Objectives The purpose of this study was to identify predictors of decreased survival after open abdominal aortic aneurysm (AAA) repair at a single university hospital. Methods Patients undergoing open AAA repair from June 2003 to June 2009 were identified. Primary outcomes were 30-day and 5-year survival. Preoperative, intraoperative, and postoperative variables were assessed for their influence on outcomes using univariate and multivariate analysis, as appropriate. One- and 5-year survival were determined by Kaplan-Meier analysis. Results Four hundred eight patients (289 men; 70.8%) with a mean age of 72.4 ± 8.3 years underwent open AAA repair. Sixty-seven patients (16.4%) underwent nonelective repair. The clamp site was infrarenal in 137 patients (33.6%), suprarenal in 97 patients (23.8%), and supraceliac in 174 patients (42.6%). Thirty-day survival was 95.6%. One- and 5-year survival were 90.0% ± 1.5% and 65.1% ± 3.0%, respectively. Seventy-nine patients (19.4%) had decreased renal function postoperatively compared to preoperatively, 71 patients (17.4%) sustained cardiac complications, and 45 patients (11.0%) sustained pulmonary complications. Patients with chronic obstructive pulmonary disease (91.9% vs 97.2%; P = .004) and chronic renal insufficiency (92.0% vs 98.3%; P = .009) had decreased 30-day survival. Patients with chronic obstructive pulmonary disease (55.8% ± 5.8% vs 67.3% ± 3.6%; P = .013), chronic renal insufficiency (51.2% ± 5.2% vs 72.8% ± 3.7%; P = .043), and cerebrovascular disease (46.8% ± 7.4% vs 67.4% ± 3.4%; P = .003) had decreased 5-year survival. Patients who had decreased postoperative renal function (41.0% ± 7.4% vs 72.2% ± 3.4%; P = .004), and patients who sustained pulmonary complications (45.6% ± 8.8% vs 66.3% ± 3.3%; P = .042) had worse 5-year survival. Conclusions Open AAA repair can be done with low morbidity and mortality in the era of endovascular aneurysm repair. Careful consideration should be given to preoperative optimization and perioperative care in patients with chronic obstructive pulmonary disease, chronic renal insufficiency, and cerebrovascular disease. Postoperative decrease in renal function and pulmonary complication portend decreased 5-year survival; strategies to ameliorate these factors should be sought.

Despite its popularity as a fundraiser for charities, very little research has been done on the bidding and revenue properties of the silent auction. This paper examines the consequences of two behaviors common in silent auctions, jump-bidding and sniping, in laboratory experiments with endogenous participation. Our results suggest that deliberative jumping, the result of impatient bidders attempting to telescope time, tends to increase revenue, while deliberative sniping by experienced bidders tends to decrease it. We also show that when charities can encourage jumping and discourage sniping, silent auctions can perform as well as their sometimes more entertaining but more expensive alternative, the English auction.

Outside of economics, researchers have recently identified genetic predictors of “sensation-seeking” that have been linked to risky and impulsive behaviors. We examine the implications of these genetic polymorphisms for economic behavior. Our analysis indicates that the 7-repeat allele of the DRD4 gene that regulates dopamine uptake in the brain predicts risk-taking and time preferences in economic experiments that allow for ambiguity, losses and discounting. These genetic polymorphisms can also be used to directly predict financial choice patterns that are consistent with previous findings in the behavioral genetics literature.

I. INTRODUCTION Laboratory experiments in economics have provided overwhelming evidence that many student participants exhibit social preferences: they care about the outcomes achieved by reference agents in addition to their own outcomes. These preferences include conditional cooperation (Fischbacher, Gaechter, and Fehr 2001) and the propensity to punish free riders (Fehr and Gaechter 2000) and have been shown to transform various social dilemmas like team production into coordination problems in which participants often achieve Pareto efficient outcomes. However, the laboratory data suffer two shortcomings. One problem that has resulted in many recent field experiments, is that it is hard to know how well student responses in the lab generalize to other important populations--the representativeness problem. A second related problem is that experimentalists have provided little reason for other economists to care about social preferences--the external validity problem. (1) That is, showing that non-students exhibit social preferences is not the same as showing that social preferences have an impact on economic outcomes. (2) Until experiments establish direct links in relevant populations between experimental measures of social preference and economic outcomes, these ideas will continue to have limited impact. Although there are a growing number of field experiments to examine how well the results of student lab experiments generalize to different populations, there are very few experiments that (convincingly) link behavioral measures from experiments to economic outcomes, and, to the best of our knowledge, none that accomplish both goals. Harrison and List (2004) review the recent literature on economic field experiments but are mostly silent on the topic of social preferences. In other specific experiments, Henrich (2000) showed that one would have to travel to Amazonia to find participants who look remotely like the self-interested agent that much of traditional economic theory is built around and Cardenas, Stranlund, and Willis (2000) demonstrated how institutions can crowd out social preferences for cooperation among rural farmers in Colombia. More recently, Henrich et al. (2001) extend the earlier experiments to 15 different cultures; Carpenter, Burks, and Verhoogen (2005) show important differences exist between blue collar workers and students in distribution experiments; and List (2004) finds similar differences using the voluntary contribution mechanism. With respect to the link between social preferences and economic outcomes, Karlan (2005) has shown that those participants who were more trustworthy in an experiment were more likely to repay their loans 1 yr later. Carter and Castillo (2002) conduct trust and distribution games in South Africa and find that their experimental measures of altruism and trust are positively associated with household expenditures. Cardenas and Carpenter (2005) conduct a similar analysis of the links between experimental measures of cooperation from public goods games played by urban slum dwellers in Vietnam and Thailand and household expenditures and find that more cooperative players were better off in Thailand but not Vietnam. Lastly, and more relevant for our purposes, Barr and Serneels (2009) find that individual experimental measures of trustworthiness are positively associated with the wages of Ghanaian manufacturing workers; however, any link to productivity is only inferential. The experiment that we report on in this paper is unique because it addresses both shortcomings simultaneously and therefore is the first research to directly link standard social preferences that have been identified in hundreds of lab experiments with topics that are at the core of economic theory. To accomplish this goal, we conducted a series of experiments in Toyama Prefecture, Japan. Our participants belonged to one of two groups; they were either local college students or fishermen who catch shrimp in the bay. …

We design a real-time, intercultural common pool resource experiment using participants from cultures that derive different benefits from a global public good (extraction vs. conservation of biodiversity resources) to analyze the effect of group affiliation on cooperative behavior. We also collect survey attitudes toward conservation to augment our experimental results. We find that when participants interact interculturally, extraction choices change significantly and that these changes can be attributed to an amplification of the relationship between attitudes and choices cued by the intercultural treatment.

Objective The purpose of this study was to determine the feasibility of open abdominal aortic aneurysm (AAA) repair in octogenarians during a time period of multiple commercially available endografts, in which only proximal aneurysms or the most challenging anatomy are not stented. Methods A retrospective review was performed of all patients aged ≥80 years undergoing open AAA repair over a 7-year period (2003-2009) at a single academic medical center. Demographic data, aneurysm characteristics, comorbidities, operative results, perioperative complications, length of stay, and late outcomes were analyzed. Results Sixty-five patients were identified (men, n=27) with a median age of 82 years (80-89 years old). Mean aneurysm size was 6.7 cm. Morphology consisted of type IV thoracoabdominal (n = 19), suprarenal (n = 14), pararenal (n = 19), and infrarenal (n = 13). Eighty-five percent of cases were performed electively. A tube graft was used in 58 patients, and the left renal artery was bypassed in 33 patients. Fifty-two patients required a suprarenal or supraceliac clamp, with a mean proximal clamp time of 22 minutes. Mean estimated blood loss was 1800 mL. Mortality was 6% at 30 days. Overall morbidity was 42%, most commonly an arrhythmia (25%). Major complication rate was 18%. Median intensive care unit (ICU) and hospital length of stay was 3 and 9 days, respectively. Sixty-one percent of patients were discharged directly home. Six patients developed acute renal failure, although none progressed to dialysis. Mean serum creatinine was 1.3 mg/dL preoperatively and 1.5 mg/dL at discharge. One patient developed bowel necrosis (sigmoid colon) requiring resection. Follow-up ranged from 1 to 81 months (mean, 24 months). Three-year survival was 79%. Conclusion With an increasing population of elderly patients, vascular surgeons are continually confronted with patients over 80 years of age. Our patients consisted of those not anatomically suitable for endovascular aortic aneurysm repair. Despite a predominance of proximal aneurysms, our results demonstrate excellent rates of morbidity and mortality. Thus, open AAA repair can be done safely and effectively in octogenarians, and age alone should not exclude this form of repair.

Objective The primary purpose of this study was to examine outcomes following open repair of extent IV thoracoabdominal aortic aneurysms (TAAAs) at a single university hospital. As a secondary aim, comparison was made to patients who underwent open abdominal aortic aneurysm (AAA) repair with supraceliac clamping but without left renal artery bypass to assess the effect of left renal artery bypass on outcomes. Methods Patients undergoing open extent IV TAAA repair from 1998 to 2008 were identified (n = 108). Primary outcomes were 30-day and long-term survival. Secondary outcomes were major complication, renal failure, and postoperative change in renal function. A second analysis was performed, comparing patients undergoing extent IV TAAA repair with patients undergoing AAA repair with supraceliac clamping but without left renal artery bypass (n = 50). Results Eighty-three men (76.9%) and 25 women (23.1%), with a mean age of 72.9 years, underwent open extent IV TAAA repair. Nine patients (8.3%) were ruptured. Mean aneurysm maximal diameter was 6.5 ± 1.3 cm. Supraceliac and left renal ischemic times were 22.9 ± 9.3 and 40.6 ± 16.2 minutes, respectively. Six patients (5.6%) died at 30 days. The only predictor of 30-day mortality was decreased preoperative estimated glomerular filtration rate (eGFR) (P = .044 by multivariate analysis; and P = .011 by univariate analysis). One-year and 5-year survival rates were 87% and 50%, respectively. Patients with a history of cerebrovascular disease (P = .001) and postoperative renal insufficiency (P = .034) had increased long-term mortality by log-rank test. Twenty-five (25.3%) patients sustained a postoperative decrease in renal function, while 19 (19.2%) patients had an improvement in renal function. There was no difference in 30-day mortality (5.6% vs 6.0%; P = 1.000), 5-year survival (50% vs 48%; P = .886), major complications (37.0% vs 38.0%; P = 1.000), renal failure (6.1% vs 0%; P = .215), or postoperative change in renal function, in patients undergoing extent IV TAAA repair vs AAA repair with supraceliac clamping but without left renal artery bypass. Conclusions Open extent IV TAAA repair can be performed with low morbidity and mortality rates. The performance of left renal artery bypass does not appear to contribute to the morbidity and mortality of extent IV TAAA repair. While decreased preoperative eGFR appears to increase the risk of 30-day mortality, a history of cerebrovascular disease and postoperative renal insufficiency appear to increase the risk of long-term mortality. Finally, open extent IV TAAA repair not uncommonly improves renal function.

Data from a recent field experiment suggests that differences in participation rates are responsible for much of the variations in charity auction revenues across formats. We provide a theoretical framework for the analysis of this and other related results. The model illustrates the limits of previous results that assume full participation and introduces some new considerations to the choice of auction mechanism. It also implies, however, that the data cannot be explained in terms of participation costs alone: there must exist mechanism-specific obstacles to participation.

We examine motivations for prosocial behavior using new data on volunteer firefighters that contain a dictator game based measure of altruism, surveyed measures of other behavioral factors, and call records that provide an objective measure of time spent volunteering. Controlling for a variety of other explanations, we find that the decision to volunteer is positively correlated with altruism as well as with concern for social reputation or “image.” Moreover, by utilizing variation in the presence and level of small stipends paid to the firefighters, we find that the positive effect of monetary incentives declines with image concerns, supporting a prediction that extrinsic incentives can crowd out image motivation for prosocial behavior.

Objectives We describe initial human experience with a novel cerebral embolic protection device. Background Cerebral emboli are the major cause of procedural stroke during percutaneous aortic valve interventions. Methods With right radial artery access, the embolic protection device is advanced into the aortic arch. Once deployed a porous membrane shields the brachiocephalic trunk and the left carotid artery deflecting emboli away from the cerebral circulation. Embolic material is not contained or removed by the device. The device was used in 4 patients (mean age 90 years) with severe aortic stenosis undergoing aortic balloon valvuloplasty (n = 1) or transcatheter aortic valve implantation (n = 3). Results Correct placement of the embolic protection device was achieved without difficulty in all patients. Continuous brachiocephalic and aortic pressure monitoring documented equal pressures without evidence of obstruction to cerebral perfusion. Additional procedural time due to the use of the device was 13 min (interquartile range: 12 to 16 min). There were no procedural complications. Pre-discharge cerebral magnetic resonance imaging found no new defects in any of 3 patients undergoing transcatheter aortic valve implantation and a new 5-mm acute cortical infarct in 1 asymptomatic patient after balloon valvuloplasty alone. No patient developed new neurological symptoms or clinical findings of stroke. Conclusions Embolic protection during transcatheter aortic valve intervention seems feasible and might have the potential to reduce the risk of cerebral embolism and stroke.

Objective Current long-term surveillance after endovascular abdominal aortic aneurysm repair (EVAR) is based on high-resolution contrast-enhanced computed tomography (CT) scans at scheduled, lifelong intervals. The cancer and nephrotoxicity risks of interval CT scanning and prolonged radiation exposure are concerning. We sought to determine if surveillance CT angiography (CTA) can be safely reduced. Methods From July 2000 to November 2007, 345 patients were enrolled in U.S. Food and Drug Administration trials of the Powerlink System (Endologix, Irvine, Calif). An independent core laboratory analyzed 1519 post-EVAR CT scans (N = 1519) to 5 years to evaluate aneurysm size, migration, presence of endoleak, and evidence of graft obstruction. Analyses were conducted to determine the value of the initial CTA scan in predicting future secondary procedures in enrolled patients. Results At any time during follow-up, CTA identified endoleak in 123 patients (36%), with 95% of endoleaks being type II. In addition, 49 patients underwent 72 secondary procedures at a mean of 22 ± 21 months (range, 2-2007 days) after initial EVAR. These were based on clinical identification of limb ischemia in 13 interventions (18%) or core laboratory identification of abnormal CT finding in 58 interventions (81%). Of the 58 core laboratory identified findings, the inciting abnormality was present on the initial postoperative scan in 49 (84%). Of the remaining nine CT-driven procedures, three (5.2%) were due to late sac expansion attributed to type II endoleak (n = 2) or endotension (n = 1); two (3.4%) were for prophylactic reasons in the absence of endoleak; and four (6.8%) were in patients with type II endoleak not observed by the core laboratory and without sac expansion. The negative predictive value of the initial postoperative CTA for the need for a secondary procedure is therefore 96.4%, which can be improved to 97.6% with duplex ultrasound surveillance to detect sac expansion. Thus, a negative initial postoperative CTA is highly predictive of long-term freedom from secondary intervention. Conclusions Among enrolled patients with suitable anatomy for EVAR, most abnormalities that result in a secondary procedure are detected on the initial postoperative CTA or present with clinical symptoms. Long-term surveillance CTA may therefore be replaced by duplex ultrasound imaging if the initial postoperative CTA shows no abnormalities.

Purpose To evaluate the success of endoleak repair using translumbar (TL) endoleak embolization compared with a transarterial (TA) technique that involves embolization of the endoleak cavity itself in addition to the feeding artery. Materials and Methods Eighty-four patients (mean age, 78.2 years; age range, 58–94 years) with type 2 endoleaks were included in this retrospective study. Patients underwent either TL endoleak embolization or TA embolization between January 2002 and December 2007. TA embolization involved entering the endoleak cavity through the inferior mesenteric or lumbar artery. Both the endoleak cavity and the feeding artery were then embolized by using coils through a microcatheter. TL embolizations were performed by using standard technique with coils and n-butyl cyanoacrylate as the embolization agents. Clinical success was defined as the absence of an endoleak and/or aneurysm enlargement at follow-up CT angiography. Statistical comparison was performed with the Fisher exact test. Results Endoleak repair was successful in 72% (45/62) of the TL embolizations and 78% (18/23) of the TA embolizations, with a mean follow-up of 18.7 months (range, 1–84 months). There was no significant difference in clinical success between the two groups ( P = .41). There were two (3.2%) complications in the TL group and no complications in the TA group. Conclusions The effectiveness of the TA endoleak embolization technique, which involves embolizion of the endoleak cavity and the feeding artery, is similar to that of TL embolization for treatment of type 2 endoleaks.

An 84-year-old patient presented with an endoleak after endovascular repair of a ruptured thoracic aortic aneurysm. The endoleak was thought to be a type II endoleak on computed tomographic (CT) angiography and was not visualized on angiography. The endoleak was accessed via direct puncture of the endoleak sac through the pleura and lung parenchyma with use of fluoroscopic and C-arm CT guidance. The endoleak was embolized with platinum coils and n-butyl cyanoacrylate with no complications. Follow-up imaging with CT angiography at 43 days revealed no recurrent endoleak.

Punishment of shirkers is often an effective means of attenuating incentive problems and sustaining coordination in work teams. Explanations of the motivation to punish generally rely either on small group size or on a Folk theorem that requires coordinated punishment and, hence, highly accurate information concerning the behavior of each player. We pro- vide a model of team production in which the punishment of shirkers depends on strong reciprocity: the willingness of some team members to contribute altruistically to a joint project and also to bear costs in order to discipline fellow members who do not con- tribute. This alternative does not require small group size, complex coordinated punishing activities, or implausible informational assumptions. An experimental public goods game provides evidence for the behavioral relevance of strong reciprocity and how it differs from unconditional altruism. © 2009 Elsevier B.V. All rights reserved.

We report the results of an artefactual field experiment with bicycle messengers in Switzerland and the United States. Messenger work is individualized enough that firms can choose to condition pay on it, but significant externalities in messenger behavior nonetheless give their on-the-job interactions the character of a social dilemma. Second-mover behavior in our sequential prisoner's dilemma allows us to characterize the cooperativeness of our participants. Among messengers, we find that employees at firms that pay for performance are significantly less cooperative than those at firms that pay hourly wages or who are members of cooperatives. To examine whether the difference is the result of treatment or selection we exploit the fact that firm type is location-specific in Switzerland and that entering messengers must work in performance pay firms in the U.S.

Many experiments have demonstrated the power of norm enforcement—peer monitoring and punishment—to maintain, or even increase, contributions in social dilemma settings, but little is known about the underlying norms that monitors use to make punishment decisions, either within or across groups. Using a large sample of experimental data, we empirically recover the set of norms used most often by monitors and show first that the decision to punish should be modeled separately from the decision of how much to punish. Second, we show that absolute norms often fit the data better than the group average norm often assumed in related work. Third, we find that different norms seem to influence the decisions about punishing violators inside and outside one’s own group.

Objective: To determine whether there is a difference in outcome between endovascular repair of abdominal aortic aneurysm (EVAR) of small versus large aneurysms. Methods: A total of 192 patients from the Power-link trial were subdivided into small abdominal aortic aneurysms (AAA; ≤5 cm) and large AAA (>5 cm) groups. Demographics, perioperative morbidity, mortality, overall survival, and freedom from major adverse events, endoleak, aneurysm-related death, migration, and secondary procedures were assessed. Aneurysmal involvement of the iliacs as well as neck length and angulation was compared between groups. Results: Perioperative morbidity (P = 1.000), mortality (P = .4603), and extent of iliac involvement did not differ between groups (P = .2260). The necks in small AAA were longer (P = .0028) and less angulated (P < .0001). There was no difference in overall survival (P = .6066), freedom from major adverse events (P = .7842), endoleak, (P = .1832), migration (P = .5765), aneurysm-related death (P = .4728), or need for secondary procedures (P = .2323). Conclusion: Under controlled conditions of patient and device selection, there is no significant difference in outcome for EVAR of small versus large AAA.

Objective This study was conducted to determine the results of left subclavian artery (LSA) coverage during thoracic endovascular aortic repair (TEVAR). Methods We retrospectively reviewed the results of 308 patients who underwent TEVAR from 1999 to 2007. The LSA was completely covered in 70 patients (53 men, 13 women), with a mean age of 67 years (range 41-89). Elective revascularization of the LSA was performed in 42 cases, consisting of transposition (n = 5), bypass and ligation (n = 3), or bypass and coil embolization (n = 34). Mean follow-up was 11 months (range, 1-48 months). The χ 2 test was used for statistical analysis. Results Indications for treatment included aneurysm in 47, dissection in 16, transection in 4, pseudoaneurysm in 2, and right subclavian aneurysm in 1, with 47 elective and 23 emergency operations. Aortic coverage extended from the left common carotid artery (LCCA) to the distal arch (n = 29), middle thoracic aorta (n = 9), or celiac artery (n = 32). Operative success was 99%. The 30-day mortality was 4% (intraoperative myocardial infarction, 1; traumatic injuries, 1; visceral infarction, 1). No paraplegia developed. The stroke rate was 8.6%; no strokes were related to LSA coverage because there were no posterior strokes. Stroke rates between the revascularization (7%) and non-revascularization (11%) groups were not significantly different ( P = .6). All but one patient fully recovered by 6 months. No left arm symptoms developed in patients with LSA revascularization. All bypasses remained patent throughout follow-up. One complication (2%) resulted in an asymptomatic persistently elevated left hemidiaphragm, likely related to phrenic nerve traction. Left upper extremity symptoms developed in five (18%) patients without LSA revascularization. Two required LSA revascularization, one of which was for acute limb-threatening ischemia. No permanent left upper extremity dysfunction or ischemia developed in any patient. Conclusion Zone 2 TEVAR with LSA coverage can be accomplished safely in both elective and emergency settings and with and without revascularization (with the exception of a patent LIMA-LAD bypass). Nevertheless, overall stroke rates are higher compared with all-zone TEVAR. Staged LSA revascularization and even urgent revascularization may be necessary but can be performed without long-term detriment to the left arm.

Explanations of poverty, growth and development depend on the assumptions made about individual preferences and the willingness to engage in strategic behaviour. Economic experiments, especially those conducted in the field, have begun to paint a picture of economic agents in developing communities that is at variance with the traditional portrait. We review this growing literature with an eye towards preference-related experiments conducted in the field. We also offer lessons on what development economists might learn from experiments. We conclude by sharing our thoughts on how to conduct experiments in the field and then offer a few ideas for future research.

We conduct a representative dictator game in which students and random members of the community choose both what charity to support and how much to donate to the charity. We find systematic differences between the choices of students and community members. Community members are much more likely to write in their own charity, community members donate significantly more ($17), on average, and community members are much more likely (32%) to donate the entire $100 endowment. Based on this evidence, it does not appear that student behavior is very representative in the context of the charitable donations and the dictator game.

Fixed-wage workers comprise the bulk of the labor force and yet little is known about how they respond to changes in their wage. Given recent interest in theories of reciprocity and intrinsic motivation and their implications for effort provision, the neoclassical prediction seems less obvious today. To better understand the motivation of these workers, I estimate their labor supply using a real effort experiment. Two results stand out. First, no one theory seems to fit the pooled data. On average, people work considerably harder than the minimum but they do not respond to changes in the wage. Second, pooling the data is deceptive because there seem to be distinct types with differing responses to the wage. Most workers can be classified as reciprocal or intrinsically motivated and, indeed, these types respond as theory would predict: reciprocators return wage gifts with increased effort and extrinsic incentives crowd out motivation for intrinsic workers.

Despite the “1/N problem” associated with profit sharing, the empirical literature finds that sharing profits with workers has a positive impact on work team and firm performance. We examine one possible resolution to this puzzle by observing that, although the incentive to work harder under profit sharing is weak, it might be sufficient to motivate workers to report each other for shirking, especially if the workers are reciprocally minded. Our model provides the rationale for this conjecture, and we discuss the results of an experiment finding that workers who share in firm profits are more willing to provide accurate information about their peers to management and that profit sharing is most effective when peer reporting is possible. The online appendix is available at https://doi.org/10.1287/mnsc.2017.2831 . This paper was accepted by Uri Gneezy, behavioral economics.

Auctions are a popular way to raise money for charities, but relatively little is known, either theoretically or empirically, about the properties of charity auctions. We conduct field experiments to see which sealed bid format, first price, second price or all-pay, raises the most money. Our experiment suggests that both the all-pay and second price formats are dominated by the first price auction. Our design also allows us to identify differential participation as the source of the difference between existing theory and the field.

Backgound Stroke has emerged as an important complication of thoracic endovascular aortic repair (TEVAR). Identifying risk factors for stroke is important to define the risks of this procedure. Methods All neurologic complications were analyzed in a prospective database of patients in thoracic aortic stent graft trials from 1999 to 2006. Serial neurological examination was performed. Stroke was defined as any new onset focal neurologic deficit. Results The TEVAR was performed on 171 patients; 52 had lesions requiring coverage of the proximal descending thoracic aorta (extent A), 50 requiring coverage of the distal descending aorta (extent B), and 69 requiring coverage of the entire descending thoracic aorta (extent C). The incidence of stroke was 5.8%. Eighty-nine percent (8 of 9) of strokes occurred within 24 hours of operation. Stroke was associated with a 33% in-hospital mortality rate. Risk factors identified for stroke included prior stroke (odds ratio [OR] 9.4, confidence interval [CI] 2.3 to 38.1, p = 0.002) and extent A or C coverage (OR 5.5, CI 1.7–12.5, p = 0.001). The stroke rate in patients with both prior stroke and extent A or C coverage was 27.7%. Severe atheromatous disease involving the aortic arch by computed tomographic scan was strongly associated with perioperative stroke (OR = 14.8, CI 1.7 to 675.6, p = 0.0016). Transesophageal echocardiography demonstrated mobile atheroma in two patients with stroke. Conclusions Stroke after TEVAR was associated with a high mortality. The TEVAR of the proximal descending aorta (extent A or C) in patients with a history of stroke had the highest perioperative stroke rate. These risk factors, together with high grade aortic atheroma of the aortic arch, predicted a high probability for cerebral embolization and can be used to identify patients at high risk for stroke as a consequence of TEVAR.

The authors draw on an internal attitude survey conducted yearly from 1996 to 2000 in the freight-handling terminals of a unionized trucking firm to investigate the effect of local labor market conditions on employee wage-fairness perceptions. Their research design exploits the fact that local managers had no discretion to vary wage rates in response to local labor market conditions; local economic shocks thus generated exogenous variation in the attractiveness of the wage paid by the firm relative to employees' options in the outside labor market. The authors find robust associations between the wage-fairness perceptions of employees in the firm and two indicators of local conditions—the rate of unemployment and the wages of similar workers in the outside market. They argue that these correlations reflect a causal relationship: an increase in unemployment or a decrease in outside wages led workers to perceive their wage to be more fair.

While many experiments demonstrate that behavior differs from the predictions of traditional economic theory, they have not shown that economic reasoning is necessarily incorrect. Instead, these experiments illustrate that the preferences of homo economicus have been mis-specified. Modeled with social preferences, it may be rational for agents to forego material gains. Social dilemmas are examples in which punishment is not credible and yet people often pay to reprimand other participants. At the same time, we show that these people also react to changes in the price of punishing and income as if punishment was an ordinary and inferior good.

Objective The Nellix EndoVascular Aneurysm Sealing system (Endologix, Inc, Irvine, Calif) is a novel approach to abdominal aortic aneurysm (AAA) endovascular repair whereby biocompatible polymer is employed to exclude and to seal the AAA sac. We report 30-day results of the U.S. pivotal trial. Methods Consecutive, eligible, consenting patients were enrolled at 29 sites in the United States and Europe. Inclusion criteria required an asymptomatic infrarenal AAA, with aortic neck length ≥10 mm and angle to the sac ≤60 degrees, aortic neck diameter of 18 to 32 mm, aneurysm blood lumen diameter ≤6 cm, common iliac artery lumen diameter of 9 to 35 mm, access artery diameter ≥6 mm, and serum creatinine level ≤2 mg/dL. Follow-up at 30 days included clinical assessment and computed tomography angiography evaluation of endoleaks and device integrity as assessed by a core laboratory. The primary safety end point is the incidence of independently adjudicated 30-day major adverse events (MAEs), with success defined as superiority with reference to the Society for Vascular Surgery open repair control group (56%). Results Between January and November 2014, 150 trial patients having a mean AAA diameter of 5.8 cm were enrolled and treated with the Nellix system with 100% procedural success. One early death (0.7%) occurred secondary to multisystem organ failure. All 149 surviving patients completed 30-day follow-up. There were no aneurysm ruptures, conversions, limb thromboses, stent fractures, or stent kinking. Five early MAEs occurred in four patients (2.7%) and included one death, bowel ischemia (1), renal failure (2), and respiratory failure (1). One (0.7%) secondary intervention to treat inadvertent coverage of a renal artery was performed. The core laboratory identified nine (6%) endoleaks (one type I, eight type II) on 30-day computed tomography angiography. Freedom from MAE was 97.3% (95% confidence interval, 93.3%-99.0%). Conclusions In selected patients, perioperative outcomes with the Nellix system for endovascular aneurysm sealing are encouraging, with very low 30-day morbidity and mortality and high procedural success. The primary safety end point has been achieved. Longer term follow-up is in progress.

PURPOSE This study was performed to determine whether endoleaks could be detected after endovascular aneurysm repair (EVAR) with use of technetium-99m sulfur colloid and 99m Tc-labeled red blood cell (RBC) nuclear medicine scans. MATERIALS AND METHODS There were 13 patients enrolled in this study: nine with endoleaks seen on computed tomographic (CT) angiography and four with no endoleak on CT angiography. All patients underwent regularly scheduled surveillance CT angiography examination after EVAR to evaluate for endoleak. Endoleak detection was then attempted in each patient with two nuclear medicine scans: a 99m Tc sulfur colloid scan and a 99m Tc-labeled RBC scan. Flow images (5 seconds per frame) were obtained for 1 minute after intravenous administration of 555 MBq (15 mCi) 99m Tc sulfur colloid. Sequential dynamic images were then obtained every minute for 30 minutes. Next, a 99m Tc-labeled RBC study was performed after the intravenous administration of 370–1,073 MBq (10–29 mCi) in vitro labeled 99m Tc RBCs. Flow images were obtained, followed by sequential dynamic images obtained every minute for 30 minutes. Single photon emission CT images of the abdomen were then acquired. The nuclear medicine scans were evaluated for the presence or absence of endoleak independent of the CT angiography findings. RESULTS Of the nine patients with endoleaks on CT angiography, seven (78%) had them detected by nuclear medicine examinations. Two of the nine endoleaks seen on CT angiography (22%) were not seen on either scintigraphic examination. All patients with no endoleak on CT angiography had their nuclear medicine scans correctly interpreted as showing no endoleak present ( n = 4; 100%). No complications occurred as a result of the nuclear medicine scans. CONCLUSIONS Endoleaks can be detected with 99m Tc sulfur colloid and 99m Tc-labeled RBC nuclear medicine scans. This initial work suggests that the sensitivities of these scintigraphic scanning methods for endoleak detection are lower than that of CT angiography.

This paper examines the spatial dimensions of trust in two Southeast Asian cities using data from both household surveys and field experiments conducted in low-income communities. The results suggest that space and location are important to understanding communal action and trust in developing countries. Not surprisingly, space matters in different ways depending on culture, history and the political-economy of a particular country or city.

Thoracic endografting offers many advantages over open repair. However, delivery of the device can be difficult and may necessitate adjunctive procedures. We describe our techniques for preserving perfusion to the left subclavian artery despite endograft coverage to obtain a proximal seal zone. We reviewed our experience with the Talent thoracic stent graft (Medtronic, Santa Rosa, CA). From 1999 to 2003, 49 patients received this device (29 men, 20 women). Seventeen patients required adjunctive procedures to facilitate proximal graft placement. We performed left subclavian-to-left common carotid artery transposition (6), left common carotid-to-left subclavian artery bypass with ligation proximal to the vertebral artery (7), and left common carotid-to-left subclavian artery bypass with proximal coil embolization (4). Patients who had anatomy unfavorable to transposition or bypass with proximal ligation (large aneurysms or proximal vertebral artery origin) were treated with coil embolization of the proximal left subclavian artery in order to prevent subsequent type II endoleaks. Technical success rate of the carotid subclavian bypass was 100%. Patient follow-up ranged from 3 to 48 months with a mean of 12 months. Six patients had follow-up

Objective Endovascular aneurysm repair (EVAR) is rapidly becoming the predominant technique for repair of abdominal aortic aneurysms. Results from current studies, however, are conflicting on the effect of EVAR on renal function compared with standard open repair. Furthermore, data for open repair in patients with baseline renal insufficiency suggests worse outcomes, including renal function. This analysis compared the effects of open repair vs EVAR on renal function in patients with baseline renal insufficiency. Methods We reviewed our records for patients with preoperative chronic renal insufficiency (serum creatinine, 1.5 mg/dL) who underwent open repair or EVAR between 1999 and 2004. The same group of vascular surgeons at a single institution performed aneurysm repair on 98 patients: 46 open (37 men, 9 women) and 52 EVAR (50 men, 2 women). Preoperative, postoperative, and follow-up serum creatinine and creatinine clearance were compared, as was the development of postoperative renal impairment (increase in serum creatinine >30%). Results Serum creatinine and creatinine clearance were not statistically different between the open and EVAR groups during any time period studied. Likewise when comparing the magnitude of change in serum creatinine in patients between the postoperative and follow-up times with preoperative values, no significant differences existed between the open and EVAR groups. When the change in serum creatinine over time within each group was compared, however, the open group had a significant increase in serum creatinine postoperatively (2.43 ± 1.20 vs 2.04 ± 0.64, P = .012), which returned to baseline during follow-up (1.96 ± 0.94, P = .504). Although serum creatinine in the EVAR group increased compared with preoperative values of 2.04 ± 0.55 (postoperative, 2.27 ± 1.04; follow-up, 2.40 ± 1.37), this failed to reach statistical significance for the postoperative ( P = .092) or follow-up ( P = .081) periods. A similar pattern was noted in creatinine clearance. Postoperative renal impairment was noted in 13 open (28%) and 15 EVAR patients (29%) and was not statistically different between groups. Overall, two patients (4.3%) from the open group and four (7.7%) from the EVAR group required hemodialysis; one in the EVAR group required permanent hemodialysis. This difference was not statistically significant ( P = .681). Conclusions Open and endovascular repair of abdominal aortic aneurysms in patients with pre-existent renal insufficiency can be performed safely with preservation of renal function. In contrast to previous reports, no significant differences existed between open repair and EVAR in postoperative alterations in renal function. Although a significant increase in serum creatinine develops in patients with renal insufficiency postoperatively with open repair, this appears to be transient, and preoperative renal dysfunction alone should not exclude either approach. After EVAR, patients with pre-existing renal insufficiency continue to be at risk for progressive renal dysfunction, and protective measures should be taken to preserve renal function in this patient population.

Despite improvements in operative technique and perioperative management, conventional open repair of descending thoracic aortic aneurysms (DTAs) continues to be associated with significant morbidity and a perioperative mortality between 4.8% and 20%, which may be even more pronounced in the acute setting. Since the first description of the endovascular repair of a thoracic aortic aneurysm by Dake et al, several studies have shown the safety of this approach, as well as possible decreases in perioperative mortality and complications, most notably paraplegia. Because of the less invasive nature and likely improved perioperative outcomes of endovascular repair of DTA, this is rapidly becoming the favored approach for management in these patients. Many patients, however, continue to be ineligible because of suboptimal vascular access, aortic arch angulation, and landing zone inadequacies. Although industry has been working to solve the last two issues, vascular access continues to be of major concern because delivery systems remain excessively large. In the United States, the currently available endografts for thoracic aorta aneurysms require delivery sheaths ranging from 20F to 25F, depending on the size of the graft and the manufacturer (Table). Despite these challenges, with the recent approval by the US Food and Drug Administration of the Gore Thoracic Aortic Graft endoprosthesis (W.L. Gore and Associates, Inc, Flagstaff, Ariz) and the ongoing evaluation of the Talent (Medtronic, Santa Rosa, Calif) and Zenith TX1 and TX2 (Cook Inc, Bloomington, Ind) endografts, it is clear that this technology is moving forward. With more widespread use and continued innovation, industry should be able to overcome the difficulties currently encountered with vascular access for the introduction of thoracic aortic endografts. Until that time, however, one should be knowledgeable of and comfortable with the implementation of several adjunctive maneuvers that may allow graft placement in otherwise ineligible patients. Furthermore, a thorough knowl

The purpose of this study was to determine the safety and efficacy of angioplasty and stenting for symptomatic innominate-subclavian lesions by review of records of symptomatic patients undergoing angioplasty and stenting of high-grade lesions (>80%) of the innominate and subclavian arteries. Follow-up consisted of history (symptoms) and physical examination (pulses and blood pressures) at 1, 3, 6, and then every 12 months plus an annual duplex ultrasound examination. Between 1998 to 2003, 25 patients (27 lesions) were treated. Ages ranged from 48 to 89 years. Symptoms included vertebrobasilar/steal (15), claudication (6), ischemia (4), and coronary artery bypass grafting/left internal mammary artery (2). There were 7 occlusions and 20 high-grade stenoses. Access was attempted via brachial cutdown (19) or percutaneous puncture of the brachial (2) or femoral arteries (10). Twenty-two lesions were stented with either self-expanding (13) or balloon-expandable (9) stents. Technical success was 89%; 3 occluded lesions could not be crossed owing to complete occlusion. The remaining 4 occlusions were all crossed via a retrograde approach. The mean difference in systolic blood pressure between upper limbs decreased from 36 mm Hg (preprocedure) to 10 mm Hg (postprocedure). There were no procedure-related complications. Mean follow-up was 18 months (range 1–62 months). One patient died 4 months after the procedure secondary to complications from pulmonary surgery unrelated to the percutaneous transluminal angioplasty/stent. Of the 4 successfully treated occlusions, 2 were followed up to 3 years with continued patency. Three patients developed recurrent stenoses documented by duplex examination. However, these patients remained asymptomatic and were not treated. Endovascular management of high-grade lesions of the subclavian or innominate arteries is safe and efficacious and may be considered as a first line of therapy. Continued follow-up is needed to assess long-term patency.

Aspiration-based evolutionary dynamics have recently been used to model the evolution of fair play in the ultimatum game showing that incredible threats to reject low offers persist in equilibrium. We focus on two extensions of this analysis: we experimentally test whether assumptions about agent motivations (aspiration levels) and the structure of the game (binary strategy space) reflect actual play, and we examine the problematic assumption embedded in the standard replicator dynamic that unhappy agents who switch strategies may return to a rejected strategy without exploring other options. We find that the resulting “no switchback” dynamic predicts the evolution of play better than the standard dynamic and that aspirations are a significant motivator for our participants. In the process, we also construct and analyze a variant of the ultimatum game in which players can adopt conditional (on their induced aspirations) strategies.

A long-standing discussion in economics asks whether institutions affect people’s social predispositions. The current experiment tests whether different aspects of markets affect people’s social preferences. The results are that people are less socially minded in more anonymous settings. Additionally, market competition erodes social preferences through two mechanisms. First, market competition encourages opportunistic behavior, and second, the market institution itself decreases the other-regardingness of the participants. JEL classification: C72; C92; D64

We replicate previous results showing that stakes do not affect offers in the ultimatum game (UG) and show that stakes also have no effect on allocations in the dictator game (DG). Both results are robust to the inclusion of demographic factors.

We conduct experiments in urban slums to measure trust and cooperation and to see how behavior varies with demographic factors and associational measures of social capital. Overall, we find high contribution rates among Thai and Vietnamese participants in a voluntary contribution game, and we see that many participants are willing to signal their disapproval of free riding despite it being costly to do so. At the individual level, we find that behavior varies with many demographic factors and with many associational factors. However, these correlations often differ significantly between our two locations, indicating the role of culture, defined broadly.

ObjectiveThis study was undertaken to determine whether a complicated aortic neck is associated with unfavorable outcome after abdominal aortic aneurysm (AAA) endografting.MethodsIn a prospective pivotal clinical trial, 237 consecutive patients underwent implantation of the bifurcated Talent Low Profile System. Patients were divided into 2 groups, those with complicated aortic necks (short, 28 mm; angulated, >45 degrees; calcified; and thrombus-lined) versus those with uncomplicated neck anatomy. Major outcome parameters included procedure time, operative blood loss, transfusion requirements, volume of contrast medium used during the implant procedure, endoleaks, migration, limb patency, AAA regression, conversion to open repair, morbidity, and mortality. Mean follow-up was 620.5 days.ResultsOverall, 32% of aortic necks were short, 19% were very short, 20% were dilated, 18% were calcified, 8.5% were thrombus-lined, and 19.9% were angulated. Thirty percent and 70% of patients, respectively, were stratified to the uncomplicated and complicated groups (P < .01. Procedure time, operative blood loss, transfusions, volume of contrast medium used in the implant procedure, migration, endograft patency, AAA sac regression, conversion to open repair, and mortality were not significantly different in necks with complicated versus uncomplicated anatomy. At 21 months, sacs were regressing or stable in 98% (complicated) versus 96% (uncomplicated). Primary graft limb patency was 100% in both groups. The endoleak rate was 4.3% (complicated) versus 17% (uncomplicated) at 18 months, but this difference was not statistically significant. Adverse renal events, however, occurred in 27.5% (complicated) versus 13.6% (uncomplicated; P = .04).ConclusionsComplicated aortic neck is not associated with unfavorable outcome at midterm follow-up after AAA endografting. However, statistically more adverse renal events occur in patients with complicated neck anatomy.

We assessed the results of abdominal aortic aneurysm (AAA) repair with the Powerlink bifurcated endovascular graft compared with open AAA repair.A prospective controlled multicenter trial of the Powerlink system for endovascular aneurysm repair was conducted at 15 sites as part of a pivotal US Food and Drug Administration trial. Between July 2000 and March 2003, 258 patients (192 test patients, 66 control patients) were enrolled. Stent grafts were oversized by 10% to 20% relative to computed tomography scan (CT)-based diameter measurements. All repairs were performed in the operating room through 1 surgically exposed femoral artery and a contralateral 9F sheath percutaneously placed. Results were assessed with contrast material-enhanced CT scans and plain abdominal x-ray studies at 1, 6, and 12 months, and annually postoperatively.Patients were followed up for a mean of 22 months (median, 24 months). Technical success was achieved in 97.9% of patients, with 4 failed insertions (3 early conversions because of deployment issues, 1 access failure). There were no significant differences in mortality between the Powerlink and control groups, and only 1 death was procedure-related. Blood loss (341 mL vs 1583 mL; P.0001), operative time (136 minutes vs 222 minutes; P.0001), intensive care unit stay (0.78 days vs 4.1 days; P.0001), and hospital length of stay (3.3 days vs 9.5 days; P.0001) were significantly less in the Powerlink cohort compared with the control group. There were significantly fewer adverse events (myocardial infarction, P = .0131; renal failure, P = .0042; gastrointestinal complications, P = .0125) in the perioperative period in the Powerlink cohort compared with the control group, but in the longer follow-up interval adverse event-free survival was equivalent between groups (P = .456, log-rank test). At the time of the first-month CT scan, endoleaks were noted in 25 patients, yielding a 30-day endoleak rate of 22.7%. Type II endoleaks predominated, and there were no type III or IV endoleaks. Secondary procedures were performed in 19 patients (10%), for treatment of endoleak (n = 10), limb obstruction (n = 7), and other causes (n = 2). There were 3 graft migrations (2.2%), 1 of which resulted in an endoleak. There were no ruptures, graft fabric defects, or wire fractures. Significant reduction in mean AAA diameter and volume was noted at every follow-up interval. Increase in AAA diameter was noted in only 1.5% of patients at 24 months.The Powerlink system appears safe, and effectively protects patients from AAA rupture over the intermediate term. The graft and stent materials have thus far been free from failure and fatigue. Percutaneous contralateral limb access facilitates graft placement in patients with disadvantaged access routes. Endovascular aneurysm repair with the Powerlink system produces significantly fewer early adverse events compared with open AAA repair, but mortality is equivalent with both procedures. Careful follow-up over the longer term is necessary to ensure the durability of these results.

Recently economists have become interested in why people who face social dilemmas in the experimental lab use the seemingly incredible threat of punishment to deter free riding. Three theories with evolvutionary microfoundations have been developed to explain punishment. We survey these theories and use behavioral data from surveys and experiments to show that the theory called social reciprocity in which people punish norm violators indiscriminately explains punishment best.

We ask whether conformity, copying the most observed behavior in a population, affects free riding. Our model suggests that, if sufficiently frequent at the start of a public goods game, conformity will increase the growth rate of free riding. We confirm this prediction in an experiment by showing that free riding grows faster when players have the information necessary to conform. As a stricter test, we econometrically estimate the dynamic on which the model is based and find that, controlling for the payoff incentive to free ride, players react significantly to the number of free riders in their groups.

Objective The purpose of this study was to determine the impact of using computerized software-assisted centerline measurements for extensions and graft junctions during the selection of endograft components for modular aortic endografts in endovascular repair of abdominal aortic aneurysms. Methods From April 1998 to December 2002, 289 modular aortic endografts were implanted at our institution. These included 248 grafts (prior to 2002, group 1) with components selected on the basis of manual caliper measurements from combined contrast computed tomography (CT) and marker-catheter arteriography data, and 41 grafts (2002, group 2) with components selected with the use of computerized software that allowed for centerline measurements on 3-dimensional reconstructions based on CT data. These 2 groups were compared for the number and type of extensions required per case. Seventeen other relevant variables were analyzed for their potential influence on selection of endograft components. These variables included age, gender, maximum aneurysm size, level of distal fixation, length and diameter at the fixation points, endograft manufacturer (make), and configuration. The significance of the observed differences was analyzed with a multivariate regression model, adjusting for potentially confounding preoperative measures. Results Multivariate analysis demonstrated that the number of right iliac extensions, left iliac extensions, total extensions, and total graft junctions was significantly reduced by the use of computerized software-assisted centerline measurements (group 2) compared with caliper measurements (group 1), independent of all other 17 preoperative variables. Notably, the mean number of required right iliac extensions was double in group 1 versus group 2. Conclusions Centerline software-assisted measurements can significantly reduce the need for iliac extensions and, concomitantly, the number of required endograft junctions. On average, twice as many extensions were required for right iliac fixation when the manual caliper measurements were used compared with software-assisted measurements. These findings are highly relevant to issues of total endograft cost and long-term endograft integrity and focus attention on the tools that may need to be considered standards of care rather than optional for selection of endograft components.

MRA and MRI have become increasingly important diagnostic modalities in vascular surgery. The ability to obtain cross-sectional and angiographic images by these noninvasive and non-nephrotoxic modalities represents one of the most significant advances in vascular surgery over the past decade. We review the current status of MRI and MRA in vascular surgical practice.

This paper conducts a comparative analysis of social capital and environmental management in two rapidly growing regions in south-east Asia, Bangkok and Ho Chi Minh City. Theoretical and empirical triangulation are used to clarify the nature of social capital and the ways that gender, in particular, affects trust and co-operation. Theoretical triangulation is accomplished by drawing on conceptual arguments made in economics, geography and urban planning to develop a theoretical framework explaining social capital and environmental management in south-east Asia. Empirical triangulation is accomplished through a multimethod analytical approach, including survey methods and experimental games conducted with the same populations. The results of the comparative analysis among squatter residents in Bangkok and Ho Chi Minh City are presented with a focus on gender differences in trust and co-operation and the paper concludes with a summary of the results and recommendations for policy and future research.