bluuebunny/crossref_metadata_2025 huggingface dataset:
Peak energy turnover in lactating European hares: a test of the heat dissipation limitation hypothesis
Authors: Valencak T. G. , Hackländer K. , Ruf T.
Published: July 2010

It has been suggested that maximum sustained metabolic rate (SusMR) in mammals as reached, for instance, during lactation, is due to a limited capacity for heat dissipation. Here, we experimentally tested whether heat dissipation limitation (HDL) also constrains energy turnover in lactating European hares. Experimentally, we made use of the fact that hares nurse their young only once per day, which allowed us to keep females and young either at the same or at different ambient temperatures. During the last lactation week (week 4) females kept at thermoneutrality (22°C), irrespective of the cold load of their young, had significantly lower rates of metabolisable energy intake (MEI) than cold-exposed mothers (5°C), as predicted by the HDL hypothesis. However, in week 2 of lactation females at thermoneutrality rearing cold-exposed young were able to increase MEI to levels indistinguishable from those of cold-exposed females. Thus, even at thermoneutral temperature females reached maximum rates of energy turnover, which was inconsistent with the HDL hypothesis. We conclude that SusMR in lactating European hares typically results not from physiological constraints but from an active restriction of their energy turnover in order to maximise lifetime reproductive success.
Hypercarbic cardiorespiratory reflexes in the facultative air-breathing fish jeju (Hoplerythrinus unitaeniatus): the role of branchial CO2 chemoreceptors
Authors: de Lima Boijink Cheila , Florindo Luiz Henrique , Leite Cleo A. Costa , Kalinin Ana Lúcia , Milsom William K. , Rantin Francisco Tadeu
Published: July 2010

The aim of the present study was to determine the roles that externally versus internally oriented CO2/H+-sensitive chemoreceptors might play in promoting cardiorespiratory responses to environmental hypercarbia in the air-breathing fish, Hoplerythrinus unitaeniatus (jeju). Fish were exposed to graded hypercarbia (1, 2.5, 5, 10 and 20% CO2) and also to graded levels of environmental acidosis (pH ~7.0, 6.0, 5.8, 5.6, 5.3 and 4.7) equal to the pH levels of the hypercarbic water to distinguish the relative roles of CO2versus H+. We also injected boluses of CO2-equilibrated solutions (5, 10 and 20% CO2) and acid solutions equilibrated to the same pH as the CO2 boluses into the caudal vein (internal) and buccal cavity (external) to distinguish between internal and external stimuli. The putative location of the chemoreceptors was determined by bilateral denervation of branches of cranial nerves IX (glossopharyngeal) and X (vagus) to the gills. The data indicate that the chemoreceptors eliciting bradycardia, hypertension and gill ventilatory responses (increased frequency and amplitude) to hypercarbia are exclusively branchial, externally oriented and respond specifically to changes in CO2 and not H+. Those involved in producing the cardiovascular responses appeared to be distributed across all gill arches while those involved in the gill ventilatory responses were located primarily on the first gill arch. Higher levels of aquatic CO2 depressed gill ventilation and stimulated air breathing. The chemoreceptors involved in producing air breathing in response to hypercarbia also appeared to be branchial, distributed across all gill arches and responded specifically to changes in aquatic CO2. This would suggest that chemoreceptor groups with different orientations (blood versus water) are involved in eliciting air-breathing responses to hypercarbia in jeju.
Roles of nitric oxide, nitrite and myoglobin on myocardial efficiency in trout (Oncorhynchus mykiss) and goldfish (Carassius auratus): implications for hypoxia tolerance
Authors: Pedersen Claus Lunde , Faggiano Serena , Helbo Signe , Gesser Hans , Fago Angela
Published: July 2010

The roles of nitric oxide synthase activity (NOS), nitrite and myoglobin (Mb) in the regulation of myocardial function during hypoxia were examined in trout and goldfish, a hypoxia-intolerant and hypoxia-tolerant species, respectively. We measured the effect of NOS inhibition, adrenaline and nitrite on the O2 consumption rate and isometric twitch force development in electrically paced ventricular preparations during hypoxia, and measured O2 affinity and nitrite reductase activity of the purified heart Mbs of both species. Upon hypoxia (9% O2), O2 consumption and developed force decreased in both trout and goldfish myocardium, with trout showing a significant increase in the O2 utilization efficiency, i.e. the ratio of twitch force to O2 consumption, suggesting an increased anaerobic metabolism. NOS inhibition enhanced myocardial O2 consumption and decreased efficiency, indicating that mitochondrial respiration is under a tone of NOS-produced NO. When trout myocardial twitch force and O2 consumption are enhanced by adrenaline, this NO tone disappears. Consistent with its conversion to NO, nitrite reduced O2 consumption and increased myocardial efficiency in trout but not in goldfish. Such a difference correlates with the lower O2 affinity measured for trout Mb that would increase the fraction of deoxygenated heme available to catalyze the reduction of nitrite to NO. Whereas low-affinity trout Mb would favor O2 diffusion within cardiomyocytes at high in vivo O2 tensions, goldfish Mb having higher O2 affinity and higher nitrite reductase activity appears better suited to facilitate O2 diffusion and nitrite reduction in the heart during severe hypoxia, a condition particularly well tolerated by this species.
Phenylhydrazine-induced anemia causes nitric-oxide-mediated upregulation of the angiogenic pathway in Notothenia coriiceps
Authors: Borley Kimberly A. , Beers Jody M. , Sidell Bruce D.
Published: July 2010

Antarctic icefishes possess several cardiovascular characteristics that enable them to deliver oxygen adequately in the absence of hemoglobin (Hb). To gain insight into mechanisms driving development of these cardiovascular characteristics of icefish, we chemically induced severe anemia in a red-blooded notothenioid, Notothenia coriiceps. After 10 days of treatment with phenylhydrazine HCl, the hematocrit and Hb concentration of N. coriiceps decreased by >90% and >70%, respectively. Anemic fish exhibited a significantly higher concentration of nitric oxide (NO) metabolites in their plasma compared with that of control animals, indicating that corporeal levels of NO are higher in anemic animals than in control fish. The activity of nitric oxide synthase (NOS) was measured in brain, retina, pectoral muscle and ventricle of control and anemic animals. With the exception of retina, no significant differences in NOS activities were observed, indicating that the increase in plasma NO metabolites is due to loss of Hb, which normally plays a major role in the degradation of NO, and not due to an overall increase in the capacity for NO production. To determine whether loss of Hb can stimulate remodeling of the cardiovascular system, we measured expression of HIF-1α, PHD2 and VEGF mRNA in retinae of control and anemic fish. Expression of all three genes was higher in anemic animals compared with control N. coriiceps, suggesting a causative relationship between loss of Hb and induction of angiogenesis that probably is mediated through nitric oxide signaling.
Repeated bouts of dehydration deplete nutrient reserves and reduce egg production in the mosquito Culex pipiens
Authors: Benoit Joshua B. , Patrick Kevin R. , Desai Karina , Hardesty Jeffrey J. , Krause Tyler B. , Denlinger David L.
Published: July 2010

In this study of the mosquito, Culex pipiens, we examined the impact of multiple bouts of dehydration and rehydration on survival, depletion of metabolic reserves and egg production in both non-diapausing and diapausing females. Mosquitoes provided with access to sugar during rehydration survived longer than those allowed to rehydrate without sugar, and their survival was similar to that of mosquitoes of the same age that were not dehydrated. Among mosquitoes not provided with sugar, each dehydration bout reduced the mosquito's dry mass – an effect likely to be due to the utilization of carbohydrates and lipid reserves. The toll on glycogen and lipid reserves is likely to be especially costly for diapausing mosquitoes that are dependent on these stored reserves for winter survival. Egg production in both non-diapausing and post-diapausing C. pipiens was also reduced in response to multiple bouts of dehydration. Although egg quality was not compromised, the number of eggs produced was reduced. Both non-diapausing and diapausing females can compensate for the nutrient loss due to dehydration by sugar feeding but the opportunity to feed on sugar is likely to be rarely available in the overwintering habitat of diapausing females, thus the impact of dehydration may be especially pronounced in overwintering populations of C. pipiens.
TrainDy: The New Union Internationale Des Chemins de Fer Software for Freight Train Interoperability
Authors: Cantone L
Published: July 2010

The increasing demand of long and interoperable freight trains requires suitable numerical simulators of train longitudinal dynamics. Focusing attention on the European railway freight transport, such simulators need to properly model the typical Union Internationale des Chemins de Fer (UIC) pneumatic brake, even for more than one active locomotive placed along the train. A pneumatic model, previously developed, has been integrated in a software for longitudinal train dynamics ( TrainDy). This software has been successfully subjected to an international process of validation and certification, undertaken by an ad hoc expert group on behalf of UIC. By using TrainDy, UIC plans to update the actual limits of the UIC leaflet 421. Moreover, UIC has established a consortium dedicated to further improve the code. This article outlines the main features of the simulator along with the most significant results of its validation process.
The benefits and development of windows with improved passenger containment
Authors: Nowell R , Sutton A
Published: July 2010

In the major railway accidents in Great Britain that have occurred in the past 10 years it became increasingly apparent that a significant number of fatalities and serious injuries had arisen as a result of passengers being thrown out through the vehicle windows. This article describes the work that has been carried out to establish the circumstances related to passenger ejection and the performance of existing glazing systems. It then considers the consequences of making passenger vehicle windows more resistant, both in terms of better containment and any detrimental effects on using the windows as potential escape routes or as a means of access by emergency services. The final part of the work was to produce a specification that would give the desired improvement in safety performance and to establish a practical method of performance demonstration by testing.
Active Control of Airspring Secondary Suspension to Improve Ride Quality and Safety against Crosswinds
Authors: Alfi S , Bruni S , Diana G , Facchinetti A , Mazzola L
Published: July 2010

Mechatronic technologies are increasingly adopted on railway vehicles, with particular reference to active secondary suspensions, as a means to improve vehicle performance in terms of ride safety and quality. This article presents the results of a theoretical and experimental research aimed at introducing active control capabilities in the pneumatic secondary suspension of a high-speed railway vehicle. The active airspring suspension is used, together with an active lateral suspension, to reduce passengers’ exposure to lateral acceleration in curves and to improve ride safety with respect to vehicle overturning in the presence of extreme crosswind. In this article, the active airspring concept is developed and suitable open- and closed-loop control strategies are proposed. Then, the results of an experimental characterization of the active suspension are reported, and based on these results a mathematical model of the vehicle with active suspension is defined. Finally, the active suspension performance is demonstrated by means of numerical experiments, showing the potential to bring substantial benefits in terms of both higher service speed for the same cant deficiency sensed by the passengers and increased ride safety.
Assessment of Chronic Wounds by Three-Dimensional Optical Imaging Based on Integrating Geometrical, Chromatic, and Thermal Data
Authors: Barone S , Paoli A , Razionale A V
Published: July 2010

Chronic wounds represent a particular debilitating health care problem, mainly affecting elderly people. A full and correct diagnosis of tissue damage should be carried out considering both dimensional, chromatic, and thermal parameters. A great variety of methods have been proposed with the aim of producing objective assessment of skin lesions, but none of the existing technologies seem to be robust enough to work for all ulcer typologies. This paper describes an innovative and non-invasive system that allows the automatic measurement of non-healing chronic wounds. The methodology involves the integration of a three-dimensional (3D) optical scanner, based on a structured light approach, with a thermal imager. The system enables the acquisition of geometrical data, which are directly related to chromatic and temperature patterns through a mapping procedure. Damaged skin areas are detected by combining visible and thermal imaging. This approach allows for the automatic measurement of extension and depth of ulcers, even in the absence of significant and well-defined chromatic patterns. The proposed technology has been tested in the measurement of ulcers on human legs. Clinical tests have demonstrated the effectiveness of this methodology in supporting medical experts for the assessment of chronic wounds.
Torsional Stability of a Polished, Collarless, Tapered Total Replacement Hip Joint Stem under Vertical Load: An In Vitro Investigation
Authors: Thomson A , Lee A J C
Published: July 2010

The torsional stability of a polished, collarless, tapered total replacement hip joint stem has been investigated. It was believed that such a stem would show increasing torsional stability as the vertical component of load on the stem increased. The aim of the study was to examine this hypothesis by testing a number of specimens (including Exeter stems) with either a matt or polished finish, under increasing vertical load, measuring the torsional resistance of a specimen—cement construct within an outer constrained cement shell. It was concluded that stems with a polished, collarless, tapered shape showed increased torsional stability with increasing vertical load, while stems with a matt finish or a collar did not.
Extensive Risk Analysis of Mechanical Failure for an Epiphyseal Hip Prothesis: A Combined Numerical—Experimental Approach
Authors: Martelli S , Taddei F , Cristofolini L , Gill H S , Viceconti M
Published: July 2010

There has been recent renewed interest in proximal femur epiphyseal replacement as an alternative to conventional total hip replacement. In many branches of engineering, risk analysis has proved to be an efficient tool for avoiding premature failures of innovative devices. An extensive risk analysis procedure has been developed for epiphyseal hip prostheses and the predictions of this method have been compared to the known clinical outcomes of a well-established contemporary design, namely hip resurfacing devices.

Clinical scenarios leading to revision (i.e. loosening, neck fracture and failure of the prosthetic component) were associated with potential failure modes (i.e. overload, fatigue, wear, fibrotic tissue differentiation and bone remodelling). Driving parameters of the corresponding failure mode were identified together with their safe thresholds. For each failure mode, a failure criterion was identified and studied under the most relevant physiological loading conditions. All failure modes were investigated with the most suitable investigation tool, either numerical or experimental.

Results showed a low risk for each failure scenario either in the immediate postoperative period or in the long term. These findings are in agreement with those reported by the majority of clinical studies for correctly implanted devices. Although further work is needed to confirm the predictions of this method, it was concluded that the proposed risk analysis procedure has the potential to increase the efficacy of preclinical validation protocols for new epiphyseal replacement devices.
Computer-Aided Methods in Bespoke Breast Prosthesis Design and Fabrication
Authors: Eggbeer D , Evans P
Published: July 2010

This case study presents a method of utilizing computer-aided design technologies to provide bespoke, external breast prostheses. The technique is illustrated through a case study of a mastectomy patient. Photogrammetry methods were used to capture the breast form when supported by a brassiere and the unsupported breast and defect side. Computer-aided design techniques were used to generate a digital prosthesis based upon the supported breast shape and with a fitting surface that matched the defect side. Furthermore, a two-part mould was designed and fabricated using rapid prototyping methods. A colour-matched prosthesis was then fabricated in a gel-based, platinum-cured silicone.
Sensitivity Analysis of a Validated Subject-Specific Finite Element Model of the Human Craniofacial Skeleton
Authors: Szwedowski T D , Fialkov J , Whyne C M
Published: July 2010

Developing a more complete understanding of the mechanical response of the craniofacial skeleton (CFS) to physiological loads is fundamental to improving treatment for traumatic injuries, reconstruction due to neoplasia, and deformities. Characterization of the biomechanics of the CFS is challenging due to its highly complex structure and heterogeneity, motivating the utilization of experimentally validated computational models. As such, the objective of this study was to develop, experimentally validate, and parametrically analyse a patient-specific finite element (FE) model of the CFS to elucidate a better understanding of the factors that are of intrinsic importance to the skeletal structural behaviour of the human CFS. An FE model of a cadaveric craniofacial skeleton was created from subject-specific computed tomography data. The model was validated based on bone strain measurements taken under simulated physiological-like loading through the masseter and temporalis muscles (which are responsible for the majority of craniofacial physiologic loading due to mastication). The baseline subject-specific model using locally defined cortical bone thicknesses produced the strongest correlation to the experimental data ( r2 = 0.73). Large effects on strain patterns arising from small parametric changes in cortical thickness suggest that the very thin bony structures present in the CFS are crucial to characterizing the local load distribution in the CFS accurately.
Transient Elastohydrodynamic Lubrication Analysis of a Novel Metal-On-Metal Hip Prosthesis with a Non-Spherical Femoral Bearing Surface
Authors: Meng Q E , Liu F , Fisher J , Jin Z M
Published: July 2010

Effective lubrication performance of metal-on-metal hip implants only requires optimum conformity within the main loaded area, while it is advantageous to increase the clearance in the equatorial region. Such a varying clearance can be achieved by using non-spherical bearing surfaces for either acetabular or femoral components. An elastohydrodynamic lubrication model of a novel metal-on-metal hip prosthesis using a non-spherical femoral bearing surface against a spherical cup was solved under loading and motion conditions specified by ISO standard. A full numerical methodology of considering the geometric variation in the rotating non-spherical head in elastohydrodynamic lubrication solution was presented, which is applicable to all non-spherical head designs. The lubrication performance of a hip prosthesis using a specific non-spherical femoral head, Alpharabola, was analysed and compared with those of spherical bearing surfaces and a non-spherical Alpharabola cup investigated in previous studies. The sensitivity of the lubrication performance to the anteversion angle of the Alpharabola head was also investigated. Results showed that the non-spherical head introduced a large squeeze-film action and also led to a large variation in clearance within the loaded area. With the same equatorial clearance, the lubrication performance of the metal-on-metal hip prosthesis using an Alpharabola head was better than that of the conventional spherical bearings but worse than that of the metal-on-metal hip prosthesis using an Alpharabola cup. The reduction in the lubrication performance caused by the initial anteversion angle of the non-spherical head was small, compared with the improvement resulted from the non-spherical geometry.
A New Formulation for the Prediction of Polyethylene Wear in Artificial Hip Joints
Authors: Liu F , Galvin A , Jin Z , Fisher J
Published: July 2010

Artificial joints employing ultra-high molecular weight polyethylene (UHMWPE) are widely used to treat joint diseases and trauma. Wear of the polymer bearing surface largely limits the use of these joints in younger and more active patients. Previous studies have shown the wear factor used in Archard's law for the conventional polyethylene to be highly dependent on contact pressure and this has produced variability in experimental data and has constrained the reliability and applicability of previous computational predictions. A new wear law is proposed, based on wear volume being dependent on, and proportional to, the product of the sliding distance and contact area. The dimensionless proportional constant, wear coefficient, which was independent of contact pressure, was determined from a multi-directional pin on plate study. This was used in computational predictions of the wear of the conventional UHMWPE hip joints. The wear of the polyethylene cup was independently experimentally determined in physiological full hip joint simulator studies. The predicted wear rate from the new computational model was generally increased, with an improved agreement with the experimental measurement compared with the previous computational model. It was shown that wear in the UHMWPE hip joints increased as head size and contact area increased. This resulted in a much larger increase in the wear rate as the head size increased, compared with the previous computational model, and is consistent with clinical observations. This new understanding of the wear mechanism in artificial joints using the UHMWPE bearing surfaces, and the improved ability to predict wear independently and to address previously described discrepancies offer new opportunities to optimize design parameters.
Physico-chemical characterization of functional electrospun scaffolds for bone and cartilage tissue engineering
Authors: Mouthuy P-A , Ye H , Triffitt J , Oommen G , Cui Z
Published: July 2010

Mimicking the zonal organization of the bone–cartilage interface will aid the production of functional osteochondral grafts for regeneration of skeletal joint defects. This study investigates the potential of the electrospinning technique to build a three-dimensional construct recapitulating the zonal matrix of this interface. Poly(lactic- co-glycolic acid) (PLGA) and PLGA–collagen solutions containing different concentrations of hydroxyapatite nanoparticles (nHAp) were electrospun on a thin layer of phosphate buffer saline solution spread on the collector in order to facilitate membrane detachment and recovery. Incorporation of increasing amounts of nHAp in PLGA solutions did not affect significantly the average diameter of the fibres, which was about 700 nm. However, in the presence of collagen, fibres with diameters below 100 nm were generally observed and the number of these fibres was inversely proportional to the ratio PLGA:collagen and proportional to the content of nHAp. PLGA membranes were rather hydrophobic, although the aqueous drop contact angles progressively fell from 125° to 110° when the content of nHAp was increased from 0 per cent to 50 per cent (w/v). PLGA–collagen membranes were more hydrophilic with contact angles between 60° and 110°; the values being proportional to the ratio PLGA:collagen and the content of nHAp. Also, the addition of nHAp from 0 per cent to 50 per cent (w/v) in the absence of collagen resulted in decreasing dramatically both the Young's modulus ( Ym), from 34.3 ± 1.8 MPa to 0.10 ± 0.06 MPa, and the ultimate tensile strain ( εmax), from a value higher than 40 per cent to 5 per cent. However, the presence of collagen together with nHAp allowed the creation of membranes much stiffer, although more brittle, as shown for membranes made with a ratio 8:2 and 10 per cent of nHAp, for which Ym  =  70.0 ± 6.6 MPa and εmax  =  7 per cent.
Doing It Now or Later
Authors: O'Donoghue Ted , Rabin Matthew
Published: July 2010

We examine self-control problems—modeled as time-inconsistent, present-biased preferences—in a model where a person must do an activity exactly once. We emphasize two distinctions: Do activities involve immediate costs or immediate rewards, and are people sophisticated or naive about future self-control problems? Naive people procrastinate immediate-cost activities and preproperate—do too soon—immediate-reward activities. Sophistication mitigates procrastination, but exacerbates preproperation. Moreover, with immediate costs, a small present bias can severely harm only naive people, whereas with immediate rewards it can severely harm only sophisticated people. Lessons for savings, addiction, and elsewhere are discussed. (JEL A12, B49, C70, D11, D60, D74, D91, E21)
The Generalized War of Attrition
Authors: Bulow Jeremy , Klemperer Paul
Published: July 2010

We model a war of attrition with N + K firms competing for N prizes. In a “natural oligopoly” context, the K − 1 lowest-value firms drop out instantaneously, even though each firm's value is private information to itself. In a “standard setting” context, in which every competitor suffers losses until a standard is chosen, even after giving up on its own preferred alternative, each firm's exit time is independent both of K and of other players' actions. Our results explain how long it takes to form a winning coalition in politics. Solving the model is facilitated by the Revenue Equivalence Theorem. (JEL D43, D44, L13, O30)
The Voracity Effect
Authors: Tornell Aaron , Lane Philip R
Published: July 2010

We analyze an economy that lacks a strong legal-political institutional infrastructure and is populated by multiple powerful groups. Powerful groups dynamically interact via a fiscal process that effectively allows open access to the aggregate capital stock. In equilibrium, this leads to slow economic growth and a “voracity effect,” by which a shock, such as a terms of trade windfall, perversely generates a more-than-proportionate increase in fiscal redistribution and reduces growth. We also show that a dilution in the concentration of power leads to faster growth and a less procyclical response to shocks. (JEL F43, O10, O23, O40)
Does Trade Cause Growth?
Authors: Frankel Jeffrey A , Romer David
Published: July 2010

Examining the correlation between trade and income cannot identify the direction of causation between the two. Countries' geographic characteristics, however, have important effects on trade, and are plausibly uncorrelated with other determinants of income. This paper therefore constructs measures of the geographic component of countries' trade, and uses those measures to obtain instrumental variables estimates of the effect of trade on income. The results provide no evidence that ordinary least-squares estimates overstate the effects of trade. Further, they suggest that trade has a quantitatively large and robust, though only moderately statistically significant, positive effect on income. (JEL F43, O40)
Aid, Nontraded Goods, and the Transfer Paradox in Small Countries
Authors: Yano Makoto , Nugent Jeffrey B
Published: July 2010

This paper constructs a model of the transfer paradox for a small open economy with nontraded goods. It demonstrates that increased production of nontraded goods can change their domestic price so as to offset the otherwise beneficial effect of aid and, under certain conditions, to create a transfer paradox even in a small country. The model is estimated with time-series data for 44 aid-dependent countries for the period 1970–1990. The results support the model and show that the nontraded goods expansion effect is more likely to cause immiserization than Johnson's tariff-distorting export-displacement effect. (JEL F0, O1)
The Market for Evaluations
Authors: Avery Christopher , Resnick Paul , Zeckhauser Richard
Published: July 2010

Recent developments in computer networks have driven the cost of distributing information virtually to zero, creating extraordinary opportunities for sharing product evaluations. We present pricing and subsidy mechanisms that operate through a computerized market and induce the efficient provision of evaluations. The mechanisms overcome three major challenges: first, evaluations, which are public goods, are likely to be underprovided; second, an inefficient ordering of evaluators may arise; third, the optimal quantity of evaluations depends on what is learned from the initial evaluations. (JEL D70, D83, H41, L15)
Unequal Treatment of Identical Agents in Cournot Equilibrium
Authors: Salant Stephen W , Shaffer Greg
Published: July 2010

Oligopoly models where prior actions by firms affect subsequent marginal costs have been useful in illuminating policy debates in areas such as antitrust regulation, environmental protection, and international competition. We discuss properties of such models when a Cournot equilibrium occurs at the second stage. Aggregate production costs strictly decline with no change in gross revenue or gross consumer surplus if the prior actions strictly increase the variance of marginal costs without changing the marginal-cost sum. Therefore, unless the cost of inducing second-stage asymmetry more than offsets this reduction in production costs, the private and social optima are asymmetric. (JEL D43, L13, L40)
Do Domestic Firms Benefit from Direct Foreign Investment? Evidence from Venezuela
Authors: Aitken Brian J , Harrison Ann E
Published: July 2010

Governments often promote inward foreign investment to encourage technology “spillovers” from foreign to domestic firms. Using panel data on Venezuelan plants, we find that foreign equity participation is positively correlated with plant productivity (the “own-plant” effect), but this relationship is only robust for small enterprises. We then test for spillovers from joint ventures to plants with no foreign investment. Foreign investment negatively affects the productivity of domestically owned plants. The net impact of foreign investment, taking into account these two offsetting effects, is quite small. The gains from foreign investment appear to be entirely captured by joint ventures. (JEL F2, O1, O3).
Does Where You Stand Depend on Where You Sit? Tithing Donations and Self-Serving Beliefs
Authors: Dahl Gordon B , Ransom Michael R
Published: July 2010

Economists and psychologists argue that individuals skew personal beliefs to accord with their own interests. To test for the presence of self-serving beliefs, we surveyed 1,200 members of the Mormon Church about tithing. A tithe is a voluntary contribution equal to 10 percent of income. Since respondents must decide privately what income items to tithe, we observe how the income definition depends on an individual's religious and financial incentives. We find surprisingly little evidence that an individual's financial situation influences beliefs about what counts as income for the tithe. However, ambiguity increases the role for self-serving biases. (JEL A12, D63)
An Empirical Examination of Information Barriers to Trade in Insurance
Authors: Cawley John , Philipson Tomas
Published: July 2010

This paper uses direct evidence to evaluate whether asymmetric information is a barrier to trade in the largest market for private insurance in the world: life insurance. We report several findings that seem difficult to reconcile with the conventional theory of insurance under asymmetric information. We conjecture that sellers may know their costs of production better than consumers in this market, as in those for most other products. (JEL D8, G1, I1, L0)
Using Field Experiments to Test Equivalence Between Auction Formats: Magic on the Internet
Authors: Lucking-Reiley David
Published: July 2010

William Vickrey's predicted equivalences between first-price sealed-bid and Dutch auctions, and between second-price sealed-bid and English auctions, are tested using field experiments that auctioned off collectible trading cards over the Internet. The results indicate that the Dutch auction produces 30-percent higher revenues than the first-price auction format, a violation of the theoretical prediction and a reversal of previous laboratory results, and that the English and second-price formats produce roughly equivalent revenues. (JEL C93, D44)
Protection for Sale: An Empirical Investigation
Authors: Goldberg Pinelopi Koujianou , Maggi Giovanni
Published: July 2010

The Grossman-Helpman “Protection for Sale” model, concerning the political economy of trade protection, yields clear predictions for the cross-sectional structure of import barriers. Our objective is to check whether the predictions of the Grossman-Helpman model are consistent with the data and, if the model finds support, to estimate its key structural parameters. We find that the pattern of protection in the United States in 1983 is broadly consistent with the predictions of the model. A surprising finding is that the weight of welfare in the government's objective function is many times larger than the weight of contributions. (JEL F1)
On the Size of U.S. Government: Political Economy in the Neoclassical Growth Model
Authors: Krusell Per , Ríos-Rull José-Víctor
Published: July 2010

We study a dynamic version of Meltzer and Richard's median-voter model of the size of government. Taxes are proportional to total income, and they are redistributed as equal lump-sum transfers. Voting takes place periodically over time, and each consumer votes for the tax rate that maximizes his equilibrium utility. We calibrate the model to U.S. data. Key elements in the calibration are the income and wealth distribution and the parameters governing the leisure and consumption choices. The total size of transfers predicted by our political-economy model is quite close to the size of transfers in the data. (JEL E60, H11, P16)
Mobility, Targeting, and Private-School Vouchers
Authors: Nechyba Thomas J
Published: July 2010

This paper uses general-equilibrium simulations to explore the role of residential mobility in shaping the impact of different private-school voucher policies. The simulations are derived from a three-district model of low-, middle-, and high-income school districts (calibrated to New York data) with housing stocks that vary within and across districts. In this model, it is demonstrated that school-district targeted vouchers are similar in their impact to nontargeted vouchers but vastly different from vouchers targeted to low-income households. Furthermore, strong migration effects are shown to significantly improve the likely equity consequences of voucher programs. (JEL I22, I28, H73)
Liberalization, Moral Hazard in Banking, and Prudential Regulation: Are Capital Requirements Enough?
Authors: Hellmann Thomas F , Murdock Kevin C , Stiglitz Joseph E
Published: July 2010

In a dynamic model of moral hazard, competition can undermine prudent bank behavior. While capital-requirement regulation can induce prudent behavior, the policy yields Pareto-inefficient outcomes. Capital requirements reduce gambling incentives by putting bank equity at risk. However, they also have a perverse effect of harming banks' franchise values, thus encouraging gambling. Pareto-efficient outcomes can be achieved by adding deposit-rate controls as a regulatory instrument, since they facilitate prudent investment by increasing franchise values. Even if deposit-rate ceilings are not binding on the equilibrium path, they may be useful in deterring gambling off the equilibrium path. (JEL G2, E4, L5)
ERC: A Theory of Equity, Reciprocity, and Competition
Authors: Bolton Gary E , Ockenfels Axel
Published: July 2010

We demonstrate that a simple model, constructed on the premise that people are motivated by both their pecuniary payoff and their relative payoff standing, organizes a large and seemingly disparate set of laboratory observations as one consistent pattern. The model is incomplete information but nevertheless posed entirely in terms of directly observable variables. The model explains observations from games where equity is thought to be a factor, such as ultimatum and dictator, games where reciprocity is thought to play a role, such as the prisoner's dilemma and gift exchange, and games where competitive behavior is observed, such as Bertrand markets. (JEL C78, C90, D63, D64, H41)
Elephants
Authors: Kremer Michael , Morcom Charles
Published: July 2010

Many open-access resources, such as elephants, are used to produce storable goods. Anticipated future scarcity of these resources will increase current prices and poaching. This implies that, for given initial conditions, there may be rational expectations equilibria leading to both extinction and survival. The cheapest way for governments to eliminate extinction equilibria may be to commit to tough antipoaching measures if the population falls below a threshold. For governments without credibility, the cheapest way to eliminate extinction equilibria may be to accumulate a sufficient stockpile of the storable good and threaten to sell it should the population fall. (JEL Q20)
Collateral Damage: Effects of the Japanese Bank Crisis on Real Activity in the United States
Authors: Peek Joe , Rosengren Eric S
Published: July 2010

The Japanese banking crisis provides a natural experiment to test whether a loan supply shock can affect real economic activity. Because the shock was external to U.S. credit markets, yet connected through the Japanese bank penetration of U.S. markets, this event allows us to identify an exogenous loan supply shock and ultimately link that shock to construction activity in U.S. commercial real estate markets. We exploit the variation across geographically distinct commercial real estate markets to establish conclusively that loan supply shocks emanating from Japan had real effects on economic activity in the United States. (JEL E44, F36)
Unequal Societies: Income Distribution and the Social Contract
Authors: Bénabou Roland
Published: July 2010

This paper develops a theory of inequality and the social contract aiming to explain how countries with similar economic and political “fundamentals” can sustain such different systems of social insurance, fiscal redistribution, and education finance as those of the United States and Western Europe. With imperfect credit and insurance markets some redistributive policies can improve ex ante welfare, and this implies that their political support tends to decrease with inequality. Conversely, with credit constraints, lower redistribution translates into more persistent inequality; hence the potential for multiple steady states, with mutually reinforcing high inequality and low redistribution, or vice versa. (JEL D31, E62, P16, O41, I22)
Saving and Growth with Habit Formation
Authors: Carroll Christopher D , Overland Jody , Weil David N
Published: July 2010

Saving and growth are strongly positively correlated across countries. Recent empirical evidence suggests that this correlation holds largely because high growth leads to high saving, not the other way around. This evidence is difficult to reconcile with standard growth models, since forward-looking consumers with standard utility should save less in a fast-growing economy because they know they will be richer in the future than they are today. We show that if utility depends partly on how consumption compares to a “habit stock” determined by past consumption, an otherwise-standard growth model can imply that increases in growth can cause increased saving. (JEL D91, E21, O40)
Efficiency and Information Aggregation in Auctions
Authors: Pesendorfer Wolfgang , Swinkels Jeroen M
Published: July 2010

The tension between allocative efficiency and information aggregation is explored in the context of an auction: k identical objects of unknown quality are auctioned off to n bidders whose tastes affect their valuation of an object of given quality. Bidders receive a signal about the quality of the objects. The k highest bidders get an object and pay a price equal to the k + 1st highest bid. We find conditions under which, in the limit, objects are allocated efficiently to those with the highest tastes, and price converges in probability to the value of an object to the marginal taste type. (JEL D44, D82)
Ownership Risk, Investment, and the Use of Natural Resources
Authors: Bohn Henning , Deacon Robert T
Published: July 2010

The effect of insecure ownership on ordinary investment and natural resource use is examined. Insecure ownership is postulated to depend on the type of government regime in power and the prevalence of political violence or instability. The political determinants of economywide investment are estimated from cross-country data, and the results are used to form an index of ownership security. When introduced into empirical models of natural resource use, this index has a significant and quantitatively important effect on the use of forests and petroleum. Contrary to conventional wisdom, ownership risk slows resource use in some circumstances. (JEL Q20, Q30, E22)
Asset Pricing with Distorted Beliefs: Are Equity Returns Too Good to Be True?
Authors: Cecchetti Stephen G , Lam Pok-Sang , Mark Nelson C
Published: July 2010

We study a Lucas asset-pricing model that is standard in all respects, except that the representative agent's subjective beliefs about endowment growth are distorted. Using constant relative risk-aversion (CRRA) utility, with a CRRA coefficient below 10; fluctuating beliefs that exhibit, on average, excessive pessimism over expansions; and excessive optimism over contractions (both ending more quickly than the data suggest), our model is able to match the first and second moments of the equity premium and risk-free rate, as well as the persistence and predictability of excess returns found in the data. (JEL E44, G12)
Population, Technology, and Growth: From Malthusian Stagnation to the Demographic Transition and Beyond
Authors: Galor Oded , Weil David N
Published: July 2010

This paper develops a unified growth model that captures the historical evolution of population, technology, and output. It encompasses the endogenous transition between three regimes that have characterized economic development. The economy evolves from a Malthusian regime, where technological progress is slow and population growth prevents any sustained rise in income per capita, into a Post-Malthusian regime, where technological progress rises and population growth absorbs only part of output growth. Ultimately, a demographic transition reverses the positive relationship between income and population growth, and the economy enters a Modern Growth regime with reduced population growth and sustained income growth. (JEL J13, O11, O33, O40)
Endogenous Growth and Cross-Country Income Differences
Authors: Howitt Peter
Published: July 2010

A multicountry Schumpeterian growth model is constructed. Because of technology transfer, R&D-performing countries converge to parallel growth paths; other countries stagnate. A parameter change that would have raised a country's growth rate in standard Schumpeterian theory will permanently raise its productivity and per capita income relative to other countries and raise the world growth rate. Transitional dynamics are analyzed for each country and for the world economy. Steady-state income differences obey the same equation as in neoclassical theory, but since R&D is positively correlated with investment rates, capital accumulation accounts for less than estimated by neoclassical theory. (JEL E10, O40)
Market Contagion: Evidence from the Panics of 1854 and 1857
Authors: Kelly Morgan , Gráda Cormac Ó
Published: July 2010

To test a model of contagion—where individuals hear some bad news and communicate it to their acquaintances, who then pass it on, leading to a market panic—requires a knowledge of the information networks of participants, something hitherto unavailable. For two panics in the 1850's this paper examines the behavior of Irish depositors in a New York bank. As recent immigrants, their social network was determined largely by their place of origin in Ireland, and where they lived in New York. During both panics this social network turns out to be the prime determinant of behavior. (JEL G21, N21)
Endogenous Business Cycles and the Dynamics of Output, Hours, and Consumption
Authors: Schmitt-Grohé Stephanie
Published: July 2010

This paper studies the business-cycle fluctuations predicted by a two-sector endogenous-business-cycle model with sector-specific external increasing returns to scale. It focuses on aspects of actual fluctuations that have been identified both as defining features of business cycles and as ones standard real-business-cycle models cannot explain. For empirically realistic calibrations of the degree of returns to scale, the results suggest that endogenous fluctuations do not provide the dynamic element that is missing in existing real-business-cycle models. (JEL E32)
Diversity and Trade
Authors: Grossman Gene M , Maggi Giovanni
Published: July 2010

We develop a competitive model of trade between countries with similar aggregate factor endowments. The trade pattern reflects differences in the distribution of talent across the labor forces of the two countries. The country with a relatively homogeneous population exports the good produced by a technology with complementarities between tasks. The country with a more diverse workforce exports the good for which individual success is more important. Imperfect observability of talent strengthens the forces of comparative advantage. Finally, we examine the effects of trade on income distribution and the composition of firms in each industry. (JEL F11, D51)
Economic Integration and Political Disintegration
Authors: Alesina Alberto , Spolaore Enrico , Wacziarg Romain
Published: July 2010

In a world of trade restrictions, large countries enjoy economic benefits, because political boundaries determine the size of the market. Under free trade and global markets even relatively small cultural, linguistic or ethnic groups can benefit from forming small, homogeneous political jurisdictions. This paper provides a formal model of the relationship between openness and the equilibrium number and size of countries, and successfully tests two implications of the model. Firstly, the economic benefits of country size are mediated by the degree of openness to trade. Secondly, the history of nation-state creations and secessions is influenced by the trade regime. (JEL F02, O57)
Performance Pay and Productivity
Authors: Lazear Edward P
Published: July 2010

Much of the theory in personnel economics relates to effects of monetary incentives on output, but the theory was untested because appropriate data were unavailable. A new data set for the Safelite Glass Corporation tests the predictions that average productivity will rise, the firm will attract a more able workforce, and variance in output across individuals at the firm will rise when it shifts to piece rates. In Safelite, productivity effects amount to a 44-percent increase in output per worker. This firm apparently had selected a suboptimal compensation system, as profits also increased with the change. (JEL J00, J22, J3)