A theory of optimal random crackdowns

An incentives based theory of policing is developed which can explain the phenomenon of random “crackdowns,” i.e., intermittent periods of high interdiction/surveillance. For a variety of police objective functions, random crackdowns can be part of the optimal monitoring strategy. We demonstrate support for implications of the crackdown theory using traffic data gathered by the Belgian Police Department and use the model to estimate the deterrence effectof additional resources spent on speeding interdiction.

A comment on the Nash program and the theory of implementation

The mechanisms in the Nash program for cooperative games are madecompatible with the framework of the theory of implementation. This is donethrough a reinterpretation of the characteristic function that avoids feasibilityproblems, thereby allowing an analysis that focuses exclusively on the payoff space. In this framework, we show that the core is the only majorcooperative solution that is Maskin monotonic. Thus, implementation of mostcooperative solutions must rely on refinements of the Nash equilibrium concept(like most papers in the Nash program do). Finally, the mechanisms in theNash program are adapted into the model.

A theory of international conflict management and sanctioning

In this paper we analyze sanctioning policies in international law. We develop a model of international military conflict where the conflicting countries can be a target of international sanctions. These sanctions constitute an equilibrium outcome of an international political market for sanctions, where different countries trade political influence. We show that the level of sanctions in equilibrium is strictly positive but limited, in the sense that higher sanctions would exacerbate the military conflict, not reduce it. We then propose an alternative interpretation to the perceived lack of effectiveness of international sanctions, by showing that the problem might not be one of undersanctioning but of oversanctioning.

On the robust effects of technology shocks on hours worked and output

We analyze the effects of neutral and investment-specific technology shockson hours and output. Long cycles in hours are captured in a variety of ways.Hours robustly fall in response to neutral shocks and robustly increase inresponse to investment specific shocks. The percentage of the variance ofhours (output) explained by neutral shocks is small (large); the opposite istrue for investment specific shocks. News shocks are uncorrelated with theestimated technology shocks.

A leverage theory of reputation building with co-branding: Complementarity in reputation building

We present a leverage theory of reputation building with co-branding. We showthat under certain conditions, co-branding that links unknown firms in a new sectorwith established firms in a mature sector allows the unknown firms to signal a highproduct quality and establish their own reputation. We compare this situationwith a benchmark in which both sectors are new and firms signal their qualityonly with prices. We investigate how this comparison is affected by the nature ofthe technology linking the two sectors and a cross-sector inference problem thatconsumers might face in identifying the true cause of product failure. We find thatco-branding facilitates the process in which a Þrm in the new sector to signal itsproduct quality only if the co-branding sectors produce complementary inputs andconsumers face a cross-sector inference problem. We apply our insight to economicsof superstars, multinational firms and co-authorship.

Development and use of a high-fidelity simulator for fetal endotracheal balloon occlusion (FETO) insertion and removal.

Objectives The objective of this article is to describe the development of an anatomically accurate simulator in order to aid the training of a perinatal team in the insertion and removal of a fetal endoscopic tracheal occlusion (FETO) balloon in the management of prenatally diagnosed congenital diaphragmatic hernia. Methods An experienced perinatal team collaborated with a medical sculptor to design a fetal model for the FETO procedure. Measurements derived from 28-week fetal magnetic resonance imaging were used in the development of an anatomically precise simulated airway within a silicone rubber preterm fetal model. Clinician feedback was then used to guide multiple iterations of the model with serial improvements in the anatomic accuracy of the simulator airway. Results An appropriately sized preterm fetal mannequin with a high-fidelity airway was developed. The team used this model to develop surgical skills with balloon insertion, and removal, and to prepare the team for an integrated response to unanticipated delivery with the FETO balloon still in situ. Conclusions This fetal mannequin aided in the ability of a fetal therapy unit to offer the FETO procedure at their center for the first time. This model may be of benefit to other perinatal centers planning to offer this procedure.

Growth accounting in items of turbulence and death: efficiency, technology, capital accumulation and human capital 1929-1950

We employ a non-parametrical approach to growth accounting (Data Envelopment Analysis,DEA) to disentangle the proximate sources of labour productivity growth in 41 nationsbetween 1929 and 1950 by decomposing productivity growth into four components:technological change; efficiency catch-up (movements towards the production frontier),capital accumulation and human capital accumulation. We show that efficiency catch-upgenerally explains productivity growth, whereas technological change and factoraccumulation were limited and distorted by the effects of war. War clearly hamperedefficiency. Moreover, an unbalanced ratio of human capital to physical capital (a gap to thetechnological leader) was crucial for efficiency catching-up.

A search theory of money and commerce with Neoclassical production

This paper advances a highly tractable model with search theoretic foundations for money and neoclassical growth. In the model, manufacturingand commerce are distinct and separate activities. In manufacturing,goods are efficiently produced combining capital and labor. In commerce,goods are exchanged in bilateral meetings. The model is applied to studythe effects of inßation on capital accumulation and welfare. With realisticparameters, inflation has large negative effects on welfare even though itraises capital and output. In contrast, with cash-in-advance, a deviceinformally motivated with bilateral trading, inflation depresses capitaland output and has a negligible effect on welfare.

Nesting and use of pollen resources by Tetrapedia diversipes Klug (Apidae) in Atlantic Forest areas (Rio de Janeiro, Brazil) in different stages of regeneration

Nesting and use of pollen resources by Tetrapedia diversipes Klug (Apidae) in Atlantic Forest areas (Rio de Janeiro, Brazil) in different stages of regeneration. The nesting in trap-nests and use of pollen sources in larval food by Tetrapedia diversipes Klug, 1810 (Apidae) was compared between regenerating areas of Atlantic Forest. The study was conducted between April 2008 and October 2009 at União Biological Reserve, Rio de Janeiro, Brazil. T. diversipes nested in 66 trap-nests and showed a peak of nesting during the months of highest rainfall. The most frequent pollen type in brood cells during the wet season was Dalechampia sp. 1. During the dry season, the type Ludwigia sp. was the most frequent, followed by Dalechampia sp. 2. The high frequency of Dalechampia and Ludwigia species in the larval food, observed in both habitats and in the two seasons could be considered relevant for T. diversipes, suggesting highly selective diet based primarily on two plant species unrelated, but similar in size of pollen grains.

Trends in hours, balanced growth and the role of technology in the business cycle

The present paper revisits a property embedded in most dynamic macroeconomic models: the stationarity of hours worked. First, I argue that, contrary to what is often believed, there are many reasons why hours could be nonstationary in those models, while preserving the property of balanced growth. Second, I show that the postwar evidence for most industrialized economies is clearly at odds with the assumption of stationary hours per capita. Third, I examine the implications of that evidence for the role of technology as a source of economic fluctuations in the G7 countries.

Metabolic labeling and protein linearization technology allow the study of proteins secreted by cultured cells in serum-containing media.

Supernatants from cell cultures (also called conditioned media, CMs) are commonly analyzed to study the pool of secreted proteins (secretome). To reduce the exogenous protein background, serum-free media are often used to obtain CMs. Serum deprivation, however, can severely affect cell viability and phenotype, including protein secretion. We present a strategy to analyze the proteins secreted by cells in fetal bovine serum-containing CMs, which combines the advantage of metabolic labeling and protein concentration linearization techniques. Incubation of CMs with a hexapeptide ligand library was used to reduce the dynamic range of the samples and led to the identification of 3 times more proteins than in untreated CM samples. Labeling with a deuterated amino acid was used to distinguish between cellular proteins and homologous bovine proteins contained in the medium. Application of the strategy to two breast cancer cell lines led to the identification of proteins secreted in different amounts and which could correlate with their varying degree of aggressiveness. Selected reaction monitoring (SRM)-based quantitation of three proteins of interest in the crude samples yielded data in good agreement with the results from concentration-equalized samples.

A positive theory of geographic mobility and social insurance

This paper presents a tractable dynamic general equilibrium model thatcan explain cross-country empirical regularities in geographical mobility,unemployment and labor market institutions. Rational agents vote overunemployment insurance (UI), taking the dynamic distortionary effects ofinsurance on the performance of the labor market into consideration.Agents with higher cost of moving, i.e., more attached to their currentlocation, prefer more generous UI. The key assumption is that an agent'sattachment to a location increases the longer she has resided there. UIreduces the incentive for labor mobility and increases, therefore, thefraction of attached agents and the political support for UI. The mainresult is that this self-reinforcing mechanism can give rise to multiplesteady-states-one 'European' steady-state featuring high unemployment,low geographical mobility and high unemployment insurance, and one'American' steady-state featuring low unemployment, high mobility andlow unemployment insurance.

Changes over time in risk factors for cardiovascular disease and use of lipid-lowering drugs in HIV-infected individuals and impact on myocardial infarction.

BACKGROUND: Because of the known relationship between exposure to combination antiretroviral therapy and cardiovascular disease (CVD), it has become increasingly important to intervene against risk of CVD in human immunodeficiency virus (HIV)-infected patients. We evaluated changes in risk factors for CVD and the use of lipid-lowering therapy in HIV-infected individuals and assessed the impact of any changes on the incidence of myocardial infarction. METHODS: The Data Collection on Adverse Events of Anti-HIV Drugs Study is a collaboration of 11 cohorts of HIV-infected patients that included follow-up for 33,389 HIV-infected patients from December 1999 through February 2006. RESULTS: The proportion of patients at high risk of CVD increased from 35.3% during 1999-2000 to 41.3% during 2005-2006. Of 28,985 patients, 2801 (9.7%) initiated lipid-lowering therapy; initiation of lipid-lowering therapy was more common for those with abnormal lipid values and those with traditional risk factors for CVD (male sex, older age, higher body mass index [calculated as the weight in kilograms divided by the square of the height in meters], family and personal history of CVD, and diabetes mellitus). After controlling for these, use of lipid-lowering drugs became relatively less common over time. The incidence of myocardial infarction (0.32 cases per 100 person-years [PY]; 95% confidence interval [CI], 0.29-0.35 cases per 100 PY) appeared to remain stable. However, after controlling for changes in risk factors for CVD, the rate decreased over time (relative rate in 2003 [compared with 1999-2000], 0.73 cases per 100 PY [95% CI, 0.50-1.05 cases per 100 PY]; in 2004, 0.64 cases per 100 PY [95% CI, 0.44-0.94 cases per 100 PY]; in 2005-2006, 0.36 cases per 100 PY [95% CI, 0.24-0.56 cases per 100 PY]). Further adjustment for lipid levels attenuated the relative rates towards unity (relative rate in 2003 [compared with 1999-2000], 1.06 cases per 100 PY [95% CI, 0.63-1.77 cases per 100 PY]; in 2004, 1.02 cases per 100 PY [95% CI, 0.61-1.71 cases per 100 PY]; in 2005-2006, 0.63 cases per 100 PY [95% CI, 0.36-1.09 cases per 100 PY]). CONCLUSIONS: Although the CVD risk profile among patients in the Data Collection on Adverse Events of Anti-HIV Drugs Study has decreased since 1999, rates have remained relatively stable, possibly as a result of a more aggressive approach towards managing the risk of CVD.