bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling intermetallic phase formation in dissimilar metal ultrasonic welding of aluminium and magnesium alloys
Authors: Robson J , Panteli A , Prangnell P B
Published: May 2012

Intermetallic compound (IMC) formation at the joint line usually has strongly detrimental effect on the performance of dissimilar metal welds. To understand the formation of IMC interlayers, and explore strategies to control their growth, a model has been developed and applied to the case of dissimilar joining of aluminium and magnesium alloys using ultrasonic welding. The model accounts for microbond formation during welding, diffusion across the joint line, as well as nucleation, spreading and thickening of the first IMC layer (Mg17Al12 phase) and the formation and simultaneous thickening of the second (Al3Mg2) layer. The model predictions match measurements reasonably well and the model has been used to predict the sensitivity of IMC layer thickness to weld temperature and time.
Effect of processing routes on evolution of texture heterogeneity in 2014 aluminium alloy deformed by equal channel angular pressing (ECAP)
Authors: Venkatachalam P , Roy Shibayan , Ravisankar B , Paul V Thamos , Vijayalakshmi M , Suwas S
Published: May 2012

In the present study, the effect of the processing routes (A, BA, BC and C) of equal channel angular pressing (ECAP) on texture evolution has been investigated for different initial microstructural conditions of the 2014 Al alloy. The present study also features the issue of heterogeneity in texture evolution along the thickness of the ECAP processed sample as a function of the processing routes. A stronger texture evolution was observed in the solution treated (ST) conditions for most of the processing routes (A, BA and BC except for C) due to the increased contribution from solid solution hardening during ECAP. A comparatively weak texture evolution is observed for as extruded+annealed and solutionised+aged conditions because of the strain scattering due to the fragmentation and dissolution of precipitates. The texture evolution along the thickness direction for ST samples suggests that the inherent heterogeneity of the ECAP process is minimised when processed via route C.
High cycle rotating bending fatigue property in high strength casting steel with carbide free bainite
Authors: Carmo D J , Dias J F , Santos D B
Published: May 2012

The present work shows a steel structure with bainitic ferrite dispersed on a matrix of carbon enriched retained austenite. The steel was produced using an air melting technique, and it was austempered at 200°C for 240 h. The steel presents tensile strength of ∼2 GPa. The authors report the new results of resistance to high cycle rotating fatigue in high strength bending life limit 107 cycles. A fatigue strength of 593 MPa was obtained, a result that is higher than that presented by important engineering materials such as forged steel and austempered ductile iron, even with the presence of fracture type ‘fish eye’, which nucleates mainly on shrinkage defects.
TEM observation of recrystallisation in rapidly solidified hypercooled Co80Pd20 alloy
Authors: Xu X L , Chen Y Z , Liu F
Published: May 2012

Applying the fluxing method, hypercooling was achieved in Co80Pd20 alloys. After recalescence, the rapidly solidified microstructures of hypercooled Co80Pd20 alloys were subjected to rapid quenching. Applying transmission electron microscopy, high densities of substructures, e.g. dislocations and subgrains, and migration of high angle grain boundaries suggest the occurrence of partial recrystallisation in the hypercooled Co80Pd20 alloys.
Sol–gel derived hydroxyapatite coating on TiB2/TiB/Ti substrate
Authors: Esfahani H , Dabir F , Taheri M , Sohrabi N , Toroghinejad M R
Published: May 2012

The low erosion resistance of titanium and its alloys has prevented their widespread application as joint implants. In addition, one essential requirement for the implants to bond with the living bone is the formation of a bone-like apatite on their surfaces in the host body. To enhance the erosion resistance of the surface, a diffused layer of TiB2 was formed at 1000°C on the commercial pure titanium. Hydroxyapatite was then coated on the boronised titanium by means of dip coating in a sol–gel solution. In order to confirm the biocompatibility of the specimens, they were soaked in a simulated body fluid for several days. The surface morphology of the specimens after exposure was studied by scanning electron microscopy, whereas X-ray diffraction patterns clearly revealed the growth of a calcium phosphate phase on top of the surface. Results showed that both wear resistance and biocompatibility of the hydroxyapatite coated samples on boronised films were improved.
Surface modification of pure Ti with TiB2/Si3N4 reinforced coating
Authors: Liu P , Zhang Y B , Luo H
Published: May 2012

In this study, Al–Ti–Co was first used to improve the surface performance of pure Ti. The synthesis of hard composite coating on pure Ti by laser cladding of Al–Ti–Co+TiB2/Si3N4 preplaced powders was investigated in detail. The SEM result indicated that a composite coating with metallurgical joint to the substrate was formed, and the coating can also have major dilution from the substrate. X-ray diffraction result indicated that this composite coating mainly consisted of Ti3Al, TiB2, TiB, TiN, Ti5Si3 and Co–Ti intermetallics. Compared with pure Ti, the improvement of the microhardness and wear resistance was observed for this composite coating.
A maximum likelihood QTL analysis reveals common genome regions controlling resistance to Salmonella colonization and carrier-state
Authors: Thanh-Son Tran , Catherine Beaumont , Nigel Salmon , Mark Fife , Pete Kaiser , Elisabeth Le Bihan-Duval , Alain Vignal , Philippe Velge , Fanny Calenge
Published: May 2012

Background

The serovars Enteritidis and Typhimurium of the Gram-negative bacterium Salmonella enterica are significant causes of human food poisoning. Fowl carrying these bacteria often show no clinical disease, with detection only established post-mortem. Increased resistance to the carrier state in commercial poultry could be a way to improve food safety by reducing the spread of these bacteria in poultry flocks. Previous studies identified QTLs for both resistance to carrier state and resistance to Salmonella colonization in the same White Leghorn inbred lines. Until now, none of the QTLs identified was common to the two types of resistance. All these analyses were performed using the F2 inbred or backcross option of the QTLExpress software based on linear regression. In the present study, QTL analysis was achieved using Maximum Likelihood with QTLMap software, in order to test the effect of the QTL analysis method on QTL detection. We analyzed the same phenotypic and genotypic data as those used in previous studies, which were collected on 378 animals genotyped with 480 genome-wide SNP markers. To enrich these data, we added eleven SNP markers located within QTLs controlling resistance to colonization and we looked for potential candidate genes co-localizing with QTLs.

Results

In our case the QTL analysis method had an important impact on QTL detection. We were able to identify new genomic regions controlling resistance to carrier-state, in particular by testing the existence of two segregating QTLs. But some of the previously identified QTLs were not confirmed. Interestingly, two QTLs were detected on chromosomes 2 and 3, close to the locations of the major QTLs controlling resistance to colonization and to candidate genes involved in the immune response identified in other, independent studies.

Conclusions

Due to the lack of stability of the QTLs detected, we suggest that interesting regions for further studies are those that were identified in several independent studies, which is the case of the QTL regions on chromosomes 2 and 3, involved in resistance to both Salmonella colonization and carrier state. These observations provide evidence of common genes controlling S. Typhimurium colonization and S. Enteritidis carrier-state in chickens.
Effects of temperature on mortality in Chiang Mai city, Thailand: a time series study
Authors: Guo Yuming , Punnasiri Kornwipa , Tong Shilu
Published: May 2012

Background

The association between temperature and mortality has been examined mainly in North America and Europe. However, less evidence is available in developing countries, especially in Thailand. In this study, we examined the relationship between temperature and mortality in Chiang Mai city, Thailand, during 1999–2008.

Method

A time series model was used to examine the effects of temperature on cause-specific mortality (non-external, cardiopulmonary, cardiovascular, and respiratory) and age-specific non-external mortality (<=64, 65–74, 75–84, and > =85 years), while controlling for relative humidity, air pollution, day of the week, season and long-term trend. We used a distributed lag non-linear model to examine the delayed effects of temperature on mortality up to 21 days.

Results

We found non-linear effects of temperature on all mortality types and age groups. Both hot and cold temperatures resulted in immediate increase in all mortality types and age groups. Generally, the hot effects on all mortality types and age groups were short-term, while the cold effects lasted longer. The relative risk of non-external mortality associated with cold temperature (19.35°C, 1st percentile of temperature) relative to 24.7°C (25th percentile of temperature) was 1.29 (95% confidence interval (CI): 1.16, 1.44) for lags 0–21. The relative risk of non-external mortality associated with high temperature (31.7°C, 99th percentile of temperature) relative to 28°C (75th percentile of temperature) was 1.11 (95% CI: 1.00, 1.24) for lags 0–21.

Conclusion

This study indicates that exposure to both hot and cold temperatures were related to increased mortality. Both cold and hot effects occurred immediately but cold effects lasted longer than hot effects. This study provides useful data for policy makers to better prepare local responses to manage the impact of hot and cold temperatures on population health.
Ocular melanoma in a patient successfully treated for diffuse malignant peritoneal mesothelioma: a case report
Authors: Langlais Sara , Velazquez-Martin Juan Pablo , Dubé Pierre , Simpson Ernest Rand , Leblanc Guy , Sideris Lucas
Published: May 2012

Background

Diffuse malignant peritoneal mesothelioma and ocular melanoma are both rare tumors. To the best of our knowledge there is only one previous report of three cases in a family with known susceptibility to malignancies associating diffuse malignant peritoneal mesothelioma and ocular melanoma, with no sporadic cases previously reported.

Case presentation

We describe the case of a 59-year-old man with a history of diffuse malignant peritoneal mesothelioma, who presented with ocular melanoma 41 months after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. We also briefly review the literature.

Conclusions

Diffuse malignant peritoneal mesothelioma is an uncommon but aggressive disease. As diffuse malignant peritoneal mesothelioma characteristically remains confined to the abdominal cavity, any new extra-abdominal symptom should eventually raise suspicion of another primary tumor. Few cases of diffuse malignant peritoneal mesothelioma associated with other primary tumors have been reported. As ocular melanoma is also infrequent, we suspect a genetic predisposition to these tumors. There is emerging evidence supporting the role of BAP1 mutations in the pathogenesis of these two neoplasias.
Enhanced antitumoral efficacy and immune response following conditionally replicative adenovirus containing constitutive HSF1 delivery to rodent tumors
Authors: Fan Rong , Wang Cheng , Wang Yang , Ren Ping , Gan Pingping , Ji Hui , Xia Zian , Hu Suiyu , Zeng Qiongyao , Huang Wei , Jiang Yebin , Huang Xi
Published: May 2012

Background

Oncolytic adenoviruses are promising as anticancer agents but have limited clinical responses. Our previous study showed that heat shock transcription factor 1 (HSF1) overexpression could increase the anti-tumor efficacy of E1B55kD deleted oncolytic adenovirus through increasing the viral burst. Due to the important roles of heat shock proteins (HSPs) in eliciting innate and adaptive immunity, we reasoned that besides increasing the viral burst, HSF1 may also play a role in increasing tumor specific immune response.

Methods

In the present study, intra-dermal murine models of melanoma (B16) and colorectal carcinoma (CT26) were treated with E1B55kD deleted oncolytic adenovirus Adel55 or Adel55 incorporated with cHSF1, HSF1i, HSP70, or HSP90 by intra-tumoral injection. Tumors were surgically excised 72 h post injection and animals were analyzed for tumor resistance and survival rate.

Results

Approximately 95% of animals in the Adel55-cHSF1 treated group showed sustained resistance upon re-challenge with autologous tumor cells, but not in PBS, Adel55, or Adel55-HSF1i treated groups. Only 50–65% animals in the Adel55-HSP70 and Adel55-HSP90 treated group showed tumor resistance. Tumor resistance was associated with development of tumor type specific cellular immune responses. Adel55-cHSF1 treatment also showed higher efficacy in diminishing progression of the secondary tumor focus than Adel55-HSP70 or Adel55-HSP90 treatment.

Conclusions

Besides by increasing its burst in tumor cells, cHSF1 could also augment the potential of E1B55kD deleted oncolytic adenovirus by increasing the tumor-specific immune response, which is beneficial to prevent tumor recurrence. cHSF1 is a better gene for neoadjuvant immunotherapy than other heat shock protein genes.
Novel classes of non-coding RNAs and cancer
Authors: Sana Jiri , Faltejskova Petra , Svoboda Marek , Slaby Ondrej
Published: May 2012

For the many years, the central dogma of molecular biology has been that RNA functions mainly as an informational intermediate between a DNA sequence and its encoded protein. But one of the great surprises of modern biology was the discovery that protein-coding genes represent less than 2% of the total genome sequence, and subsequently the fact that at least 90% of the human genome is actively transcribed. Thus, the human transcriptome was found to be more complex than a collection of protein-coding genes and their splice variants. Although initially argued to be spurious transcriptional noise or accumulated evolutionary debris arising from the early assembly of genes and/or the insertion of mobile genetic elements, recent evidence suggests that the non-coding RNAs (ncRNAs) may play major biological roles in cellular development, physiology and pathologies. NcRNAs could be grouped into two major classes based on the transcript size; small ncRNAs and long ncRNAs. Each of these classes can be further divided, whereas novel subclasses are still being discovered and characterized. Although, in the last years, small ncRNAs called microRNAs were studied most frequently with more than ten thousand hits at PubMed database, recently, evidence has begun to accumulate describing the molecular mechanisms by which a wide range of novel RNA species function, providing insight into their functional roles in cellular biology and in human disease. In this review, we summarize newly discovered classes of ncRNAs, and highlight their functioning in cancer biology and potential usage as biomarkers or therapeutic targets.
A taxonomy of cross layer routing metrics for wireless mesh networks
Authors: Bin Ngadi Md Asri , Ali Saqib , Abdullah Abdul Hanan , Khokhar Rashid Hafeez
Published: May 2012

Multi-hop, multi-channel, and multi-radio wireless mesh networks (WMNs) are emerging as promising field of wireless technology with self-organizing and self-healing features for internet and real time applications, i.e., VoIP and Video over IP. Interoperability feature of WMNs have made them to integrate easily with other network technologies like wired networks, WiFi, WiMax, MANETs, and cellular networks. WMNs are gaining popularity due to their high network throughput which highly depends on the routing procedures. Routing algorithms like optimized link state routing protocol and dynamic source routing make efficient routing decisions on the basis of routing metrics which actually predict the cost of link quality. Most of the routing protocols and routing metrics implemented in WMNs are actually designed for mobile ad hoc networks (MANETs). Since WMNs have different characteristics and limitations as compared to MANETs, so the routing metrics design for MANETs do not perform well in WMNs. Furthermore, quality of service (QoS) and throughput of the network in WMNs can be enhanced by using cross layer routing approach and by deploying multi-channel multi-radio (MCMR) scenarios in each relay node. This article discusses a design taxonomy, limitations and qualitative comparison of existing routing metrics for QoS in MCMR WMNs with respect to routing parameters, i.e., transmission rate, inter-flow interference, intra-flow interference, congestion, and channel diversity. Moreover, our taxonomy also opens the door up for new research areas in the design of cross layer routing metrics for MCMR radio WMNs for high throughput IP connectivity.
Molecular characterization of immunoinhibitory factors PD-1/PD-L1 in chickens infected with Marek’s disease virus
Authors: Matsuyama-Kato Ayumi , Murata Shiro , Isezaki Masayoshi , Kano Rika , Takasaki Sara , Ichii Osamu , Konnai Satoru , Ohashi Kazuhiko
Published: May 2012

Background

An immunoinhibitory receptor, programmed death-1 (PD-1), and its ligand, programmed death-ligand 1 (PD-L1), are involved in immune evasion mechanisms for several pathogens causing chronic infections and for neoplastic diseases. However, little has been reported for the functions of these molecules in chickens. Thus, in this study, their expressions and roles were analyzed in chickens infected with Marek’s disease virus (MDV), which induces immunosuppression in infected chickens.

Results

A chicken T cell line, Lee1, which constitutively produces IFN-γ was co-cultured with DF-1 cells, which is a spontaneously immortalized chicken fibroblast cell line, transiently expressing PD-L1, and the IFN-γ expression level was analyzed in the cell line by real-time RT-PCR. The IFN-γ expression was significantly decreased in Lee1 cells co-cultured with DF-1 cells expressing PD-L1. The expression level of PD-1 was increased in chickens at the early cytolytic phase of the MDV infection, while the PD-L1 expression level was increased at the latent phase. In addition, the expression levels of PD-1 and PD-L1 were increased at tumor lesions found in MDV-challenged chickens. The expressions levels of PD-1 and PD-L1 were also increased in the spleens and tumors derived from MDV-infected chickens in the field.

Conclusions

We demonstrated that the chicken PD-1/PD-L1 pathway has immunoinhibitory functions, and PD-1 may be involved in MD pathogenesis at the early cytolytic phase of the MDV infection, whereas PD-L1 could contribute to the establishment and maintenance of MDV latency. We also observed the increased expressions of PD-1 and PD-L1 in tumors from MDV-infected chickens, suggesting that tumor cells transformed by MDV highly express PD-1 and PD-L1 and thereby could evade from immune responses of the host.
Comparison of linear mixed model analysis and genealogy-based haplotype clustering with a Bayesian approach for association mapping in a pedigreed population
Authors: Dashab Golam R , Kadri Naveen K , Shariati Mohammad M , Sahana Goutam
Published: May 2012

Background

Despite many success stories of genome wide association studies (GWAS), challenges exist in QTL detection especially in datasets with many levels of relatedness. In this study we compared four methods of GWA on a dataset simulated for the 15th QTL-MAS workshop. The four methods were 1) Mixed model analysis (MMA), 2) Random haplotype model (RHM), 3) Genealogy-based mixed model (GENMIX), and 4) Bayesian variable selection (BVS). The data consisted of phenotypes of 2000 animals from 20 sire families and were genotyped with 9990 SNPs on five chromosomes.

Results

Out of the eight simulated QTL, these four methods MMA, RHM, GENMIX and BVS identified 6, 6, 8 and 7 QTL respectively and 4 QTL were common across the methods. GENMIX had the highest power to detect QTL however it also produced 4 false positives. BVS was the second best method in terms of power, detecting all QTL except the one on chromosome 5 with epistatic interaction. Two spurious associations were obtained across methods. Though all the methods considered the full pedigree in the analyses, it was not sufficient to avoid all the spurious associations arising due to family structure.

Conclusions

Using several methods with divergent approaches for GWAS can be useful in gaining confidence on the QTL identified. In our comparison, GENMIX was found to be the best method in terms of power but it needs appropriate correction for multiple testing to avoid the false positives. This study shows that the issues of multiple testing and the relatedness among study samples need special attention in GWAS.
Attenuation of visceral nociception by α-bisabolol in mice: investigation of mechanisms
Authors: Leite Gerlânia de Oliveira , Fernandes Cícera Norma , de Menezes Irwin Rose Alencar , da Costa José Galberto Martins , Campos Adriana Rolim
Published: May 2012

Background

We previously described the visceral antinociceptive property of α-bisabolol (BISA) in mouse models of visceral nociception induced by cyclophosphamide and mustard oil (MO). This study examined the effect of BISA in mouse models of visceral nociception induced by acetic acid, capsaicin, formalin, and the contribution of the nitric oxide system, α2, KATP, 5-HT3 and TRPV1 receptors to the effect of BISA on MO-evoked nociceptive behaviors. Mice were pretreated orally with BISA (50, 100 and 200 mg/kg) or vehicle, and the pain-related behavioral responses to intraperitoneal administration of acetic acid or intracolonic injection of MO were analyzed.

Results

BISA significantly suppressed the nociceptive behaviors in a dose-unrelated manner. The antinociceptive effect of BISA (50 mg/kg) was show to be glibenclamide resistant, but it was not blocked by pretreatment with the other antagonists tested. In the open-field test that detects sedative or motor abnormality, mice received 50 mg/kg BISA did not show any per se influence in ambulation frequency.

Conclusions

However, their precise antinociceptive mechanisms of action have not been determined.
Risk Assessment Tool for Distant Recurrence After Platinum-Based Concurrent Chemoradiation in Patients With Locally Advanced Cervical Cancer: A Korean Gynecologic Oncology Group Study
Authors: Kang Sokbom , Nam Byung-Ho , Park Jeong-Yeol , Seo Sang-Soo , Ryu Sang-Young , Kim Jae Weon , Kim Seung-Cheol , Park Sang-Yoon , Nam Joo-Hyun
Published: May 2012

Purpose

Our study aimed to develop a model to predict distant recurrence in locally advanced cervical cancer, which can be used to select high-risk patients in enriched clinical trials.

Patients and Methods

Our study was a retrospective analysis of a multi-institutional cohort of patients treated between 2001 and 2009. According to the order of data submission, data from three institutions were allocated to a model development cohort (n = 434), and data from the remaining two institutions were allocated to an external validation cohort (n = 115). Patient information including [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) data and clinical outcome was modeled using competing risk regression analysis to predict 5-year cumulative incidence of distant recurrence.

Results

The competing risk analysis revealed that the following four parameters were significantly associated with distant recurrence: pelvic and para-aortic nodal positivity on FDG-PET, nonsquamous cell histology, and pretreatment serum squamous cell carcinoma antigen levels. This four-parameter model showed good discrimination and calibration, with a bootstrap-adjusted concordance index of 0.70. Also, the validation set showed good discrimination with a bootstrap-adjusted concordance index of 0.73. A user-friendly Web-based nomogram predicting 5-year probability of distant recurrence was developed.

Conclusion

We have developed a robust model to predict the risk of distant recurrence in patients with locally advanced cervical cancer. Further, we discussed how the selective enrichment of the patient population could facilitate clinical trials of systemic chemotherapy in locally advanced cervical cancer.
Limited-Purpose Banking—Moving from “Trust Me” to “Show Me” Banking
Authors: Chamley Christophe , Kotlikoff Laurence J , Polemarchakis Herakles
Published: May 2012

There are many alleged culprits for the bank runs of 2008 and their devastating economic fallout. But proprietary information and leverage top our list. Claims of proprietary information forced financial markets to operate on trust, while providing the perfect breeding ground for fraud. And leverage permitted creditors to run at the first whiff of fraud, leveling one financial giant after another. Limited Purpose Banking (LPB), presented here, is a financial reform that sharply curtails proprietary information and eliminates leverage and, thus, the possibility of financial collapse. LPB's adoption is supported by our simple model showing how fraud can destroy finance.
Within-City Variation in Urban Decline: The Case of Detroit
Authors: Guerrieri Veronica , Hartley Daniel , Hurst Erik
Published: May 2012

When a city experiences a decline in income or population, do all neighborhoods within the city decline equally? Or, do some neighborhoods decline more than others? What are the characteristics of the neighborhoods that decline the most? We answer these questions by looking at what happened to neighborhoods within Detroit as Detroit experienced a sharp decline in income and population from the 1980s to the late 2000s. We find patterns of changes in income and population that are consistent with the model and empirical patterns of gentrification presented in Guerrieri, Hartley, and Hurst (2011), only playing out in reverse.
Heterogeneity in Neighborhood-Level Price Growth in the United States, 1993–2009
Authors: Ferreira Fernando , Gyourko Joseph
Published: May 2012

Examination of detailed geographical information on U.S. housing transactions from 1993 to 2009 find much heterogeneity at the neighborhood level in when the recent boom began, how big the initial jumps in price growth were, how long the booms lasted, and what types of neighborhoods boomed first. There is less neighborhood-level heterogeneity in when the bust began and in aggregate price appreciation during the boom. This heterogeneity suggests that there was no one dominant cause of the boom. We also comment on how very local data may help understand the role of contagion, among other housing market phenomena.
Market Prices of Risk with Diverse Beliefs, Learning, and Catastrophes
Authors: Cogley Timothy , Sargent Thomas J , Tsyrennikov Viktor
Published: May 2012

We compare market prices of risk in economies with identical patterns of endowments, priors, and information flows, but two different market structures, one with complete markets, another in which consumers can trade only a single risk-free bond. We study how opportunities to speculate, uncommon priors, and learning affect market prices of risk. Two types of consumers have diverse beliefs about the law of motion for a random exogenous endowment. One type knows the true law of motion while the other type learns about it via Bayes' theorem. Less-well-informed consumers are pessimistic, initially overestimating the probability of a catastrophic state. Learning dynamics and the wealth dynamics that they drive contribute to differences in evolutions of market prices of risk across market structures.
International Robust Disagreement
Authors: Colacito Riccardo , Croce Mariano M
Published: May 2012

We characterize the equilibrium of a two-country, two-good economy in which agents have opposite preference bias toward one of the two consumption goods and fear model misspecification. We document that disagreement about endowments' growth prospects is a persistent endogenous outcome of this class of economies.
Heterogeneous Beliefs, Wealth Distribution, and Asset Markets with Risk of Default
Authors: Tsyrennikov Viktor
Published: May 2012

We study asset markets and wealth dynamics in the economy with heterogeneous beliefs and risk of default. Agents can trade a full set of Arrow securities but are allowed to default on their delivery promises. Financial markets rationally subject agents to the endogenous “no-default” borrowing limits. Because of the rich menu of financial assets traded in the market speculation opportunities are plentiful. Financial wealth is volatile and the endogenous borrowing limits are always active. Variance of the asset returns is amplified. The asset trading volume is substantial and volatile.
Evolving Monetary/Fiscal Policy Mix in the United States
Authors: Bianchi Francesco
Published: May 2012

A micro-founded model that allows for changes in the monetary/fiscal policy mix and in the volatility of structural shocks is fit to US post-WWII data. Agents are aware of the possibility of regime changes and their beliefs have an impact on the law of motion of the macroeconomy. The results show that the '60s and the '70s were characterized by a prolonged period of active fiscal policy and passive monetary policy. The appointment of Volcker marked a change in the conduct of monetary policy, but it took almost ten years for the fiscal authority to start accommodating this regime change.
Fiscal Consolidation in an Open Economy
Authors: Erceg Christopher J , Lindé Jesper
Published: May 2012

his paper uses a New Keynesian DSGE model of a small open economy to compare how the effects of fiscal consolidation differ depending on whether monetary policy is constrained by currency union membership or by the zero lower bound on policy rates. We show that there are important differences in the impact of fiscal shocks across these monetary regimes that depend both on the duration of the zero lower bound and on features that determine the responsiveness of inflation.
Can Asia Overcome the IMF Stigma?
Authors: Ito Takatoshi
Published: May 2012

Asian countries still have the IMF stigma, which originates from the experiences of the Asian crisis of 1997-98. The feeling of being unfairly treated grew even stronger afterward. The Asian countries built large foreign reserves, carried out structural reforms, and became even stronger than pre- crisis period. Asians are confident in not repeating the same mistake of falling into a crisis with too much external borrowing. Whether IMF can entice Asia to new precautionary liquidities facilities remains uncertain. Asia may choose either to focus on completing a regional safety net or to engage in IMF, demanding for a greater voice and votes.
Capital Flow Management
Authors: Jeanne Olivier
Published: May 2012

There is a wide variety in the capital account policies of emerging markets and developing economies. Some countries, such as Brazil, have recently experimented with prudential controls on capital inflows, whereas others, such as China, have continued to maintain tight controls. This paper reviews the recent theoretical literature explaining the motivations behind capital account policies, and whether there is a case for international coordination in this area.
International Shock Transmission after the Lehman Brothers Collapse: Evidence from Syndicated Lending
Authors: Haas Ralph De , Horen Neeltje Van
Published: May 2012

After Lehman Brothers filed for bankruptcy in September 2008, cross-border bank lending contracted sharply. To explain the severity and variation in this contraction, we analyze detailed data on cross-border syndicated lending by 75 banks to 59 countries. We find that banks which had to write down sub-prime assets, refinance large amounts of long-term debt, and which experienced sharp declines in their market-to-book ratio, transmitted these shocks across borders by curtailing their lending abroad. While shocked banks differentiated between countries in much the same way as less constrained banks, they restricted their lending more to small borrowers.
Adaptation to Climate Change in Preindustrial Iceland
Authors: Turner Matthew A , Rosenthal Jeffrey S , Chen Jian , Hao Chunyan
Published: May 2012

We investigate the effect of climate change on population growth in 18th and 19th century Iceland. We find that annual temperature changes help determine the population growth rate in pre-industrial Iceland: a year 1 degree Celsius cooler than average drives down population growth rates by 1.14%. We also find that 18th and 19th century Icelanders adapt to prolonged changes in climate after 20 years. These adaptations reduce the short run effect of annual change in temperature by about 60%. Finally, a 1 degree Celsius sustained decrease in temperature decreases the steady state population by 10% to 26%.
War and Stature: Growing Up during the Nigerian Civil War
Authors: Akresh Richard , Bhalotra Sonia , Leone Marinella , Osili Una Okonkwo
Published: May 2012

The Nigerian civil war of 1967-70 was precipitated by secession of the Igbo-dominated south-eastern region to create the state of Biafra. It was the first civil war in Africa, the predecessor of many. We investigate the legacies of this war four decades later. Using variation across ethnicity and cohort, we identify significant long-run impacts on human health capital. Individuals exposed to the war at all ages between birth and adolescence exhibit reduced adult stature and these impacts are largest in adolescence. Adult stature is portentous of reduced life expectancy and lower earnings.
Nation Building and Economic Growth
Authors: Creasey Ellyn , Rahman Ahmed S , Smith Katherine A
Published: May 2012

Over the past half-century there have been over three hundred instances of nation building initiatives, episodes where countries jointly give military and economic aid to a country embroiled in conflict. Despite the prevalence and expense of this foreign policy, little research has explored the potential growth effects from these operations. This project uses a standard growth regression framework to quantify the effects of nation building on GDP per capita growth of the recipient nation. The research considers how the characteristics of conflict zones and the interaction of diverse types of both military and economic aid impact the development process.
The Determinants and Consequences of School Choice Errors in Kenya
Authors: Lucas Adrienne M , Mbiti Isaac M
Published: May 2012

School choice systems designed to help disadvantaged groups might be hindered by information asymmetries. Kenyan elite secondary schools admit students from the entire country based on a national test score, district quotas, and stated school choices. We find even the highest ability students make school choice errors. Girls, students with lower test scores, and students from public and low quality schools are more likely to make such errors. Net of observable demographic characteristics, these errors are associated with a decrease in the probability that a student is admitted to an elite secondary school, relegating them to schools of lower quality.
Child Health and Conflict in Côte d'Ivoire
Authors: Minoiu Camelia , Shemyakina Olga
Published: May 2012

We examine the impact of the 2002-07 civil conflict in Cote d'Ivoire on children's health status measured by height-for-age. We use pre- and post-war survey data coupled with information on the location of violent incidents to capture exposure to the conflict of children born during 1997-2007. Our results indicate that children from regions more affected by the conflict suffered significant health setbacks compared with children from less affected regions. Further, household-level victimization -- such as war-related economic stress, health stress, and displacement -- has a large and negative effect on child health in conflict-affected regions.
Robustly Ranking Mechanisms
Authors: Börgers Tilman , Smith Doug
Published: May 2012

For a mechanism designer with an objective such as welfare we propose a method for robustly ranking mechanisms. The method is based on eliminating weakly dominated strategies only, and thus does not require any assumptions about agents' beliefs about each other except full support. We illustrate the usefulness of this method in two examples: bilateral trading and voting. In both examples we show that there are mechanisms that are ranked by our method above dominant strategy mechanisms. These examples question the literature's focus on dominant strategy mechanisms in cases when such mechanisms yield undesirable outcomes.
Copyright Research in the Digital Age: Moving from Piracy to the Supply of New Products
Authors: Waldfogel Joel
Published: May 2012

Twelve years into the Napster era, economists have devoted substantial attention to revenue consequences of unpaid file sharing. Yet, this is only one of a host of questions whose answers are needed to inform evidence-based copyright policy in the digital era. Digitization's effect on travel agents suggests fruitful research questions, which include the impact of digitization on the supply of new works, methods for consumer discovery of new products, and new business models available with digital distribution.
Is Wikipedia Biased?
Authors: Greenstein Shane , Zhu Feng
Published: May 2012

This study empirically examines whether Wikipedia has a neutral point of view. It develops a method for measuring the slant of 28 thousand articles about US politics. In its earliest years, Wikipedia's political entries lean Democrat on average. The slant diminishes during Wikipedia's decade of experience. This change does not arise primarily from revision of existing articles. Most articles arrive with a slant, and most articles change only mildly from their initial slant. The overall slant changes due to the entry of articles with opposite slants, leading toward neutrality for many topics, not necessarily within specific articles.
Information Choice Technologies
Authors: Hellwig Christian , Kohls Sebastian , Veldkamp Laura
Published: May 2012

Theories based on information costs or frictions have become increasing popular in macroeconomics and macro-finance. The literature has used various types of information choices, such as rational inattention, inattentiveness, information markets and costly precision. Using a unified framework, we compare these different information choice technologies and explain why some generate increasing returns and others, particularly those where agents choose how much public information to observe, generate multiple equilibria. The results can help applied theorists to choose the appropriate information choice technology for their application and to understand the consequences of that modeling choice.
New Challenges in Multihospital Kidney Exchange
Authors: Ashlagi Itai , Roth Alvin E
Published: May 2012

The growth of kidney exchange presents new challenges for the design of kidney exchange clearinghouses. The players now include directors of transplant centers, who see sets of patient-donor pairs, and can choose to reveal only difficult-to-match pairs to the clearinghouse, while withholding easy-to-match pairs to transplant locally. This reduces the number of transplants. We discuss how the incentives for hospitals to enroll all pairs in kidney exchange can be achieved, and how the concentration of hard to match pairs increases the importance of long, non-simultaneous nondirected donor chains.
Dynamic Pricing of Electricity
Authors: Joskow Paul L , Wolfram Catherine D
Published: May 2012

As both a regulator and an academic, Fred Kahn argued that end-use electricity consumers should face prices that reflect the time-varying marginal costs of generating electricity. This has been very slow to happen in the US, even in light of recent technological advances that have lowered costs and improved functionality for meters and automated demand response technologies. We describe these recent developments and discuss the remaining barriers to the proliferation of time-varying electricity pricing.
Government Policy for a Partially Deregulated Industry: Deregulate it Fully
Authors: Winston Clifford
Published: May 2012

Alfred Kahn was a major force behind regulatory reform that initially benefited air travelers and subsequently consumers in other industries by placing greater reliance on markets than on regulators to allocate resources. Kahn also believed that effective governance was important for deregulation's success. In this paper, I argue that such governance has not occurred in practice and that problems that persist in partially deregulated industries are more likely to be solved by full deregulation and, if necessary, privatization than by government intervention.
Global Supply Chains and Wage Inequality
Authors: Costinot Arnaud , Vogel Jonathan , Wang Su
Published: May 2012

A salient feature of globalization in recent decades is the emergence of “global supply chains” in which different countries specialize in different stages of a sequential production process. In Costinot, Vogel and Wang (2011) (CVW hereafter), we have developed a simple theory of trade with sequential production to shed light on how global supply chains affect the interdependence of nations. In this paper we develop a multi-factor extension of CVW to explore how the emergence of global supply chains may affect wage inequality within countries.
Proximity and Production Fragmentation
Authors: Johnson Robert C , Noguera Guillermo
Published: May 2012

Cross-border production chains tend to include geographically proximate countries. This suggests that increases in fragmentation should be largest among nearby trading partners, and thus may serve to localize gross trade. Using data on gross and value added trade from 1970-2009, we present three results supporting this conjecture. First, value added to export ratios are lower and falling more rapidly within geographic regions than between them. Second, gross trade travels shorter distances from source to destination than value added trade, and this gap is growing over time. Third, bilateral value added to export ratios have fallen most among nearby trading partners.
Liberalized Trade and Worker-Firm Matching
Authors: Davidson Carl , Heyman Fredrik , Matusz Steven , Sjöholm Fredrik , Zhu Susan Chun
Published: May 2012

Recent theoretical analysis suggests that a reduction in the cost of exporting increases the degree of assortative matching between workers and firms in export-oriented industries. Changes that reduce the cost of imports have an ambiguous impact on matching. We combine detailed Swedish matched worker-firm data from 1995-2005 with tariff data to test these hypotheses. The data cover 94 sectors subject to international competition and include all firms with at least 20 employees. Our findings strongly support the theoretical predictions.
Village Economic Accounts: Real and Financial Intertwined
Authors: Paweenawat Archawa , Townsend Robert M
Published: May 2012

We propose a framework to create village economic and balance of payments accounts from a micro-level household survey. Using the Townsend Thai data, we create the accounts for villages in rural and semi-urban areas of Thailand. We then study these village economies as small open countries, exploring in particular the relationship between the real and financial variables. We examine cross-village risk-sharing and the Feldstein-Horioka puzzle. Our results suggest that within-village risk-sharing is better than across-village and, while there is smoothing in both, the mechanisms are different. We also find that, unlike countries, the cross-village capital markets are highly integrated.
Ricardo's Theory of Comparative Advantage: Old Idea, New Evidence
Authors: Costinot Arnaud , Donaldson Dave
Published: May 2012

When asked to name one proposition in the social sciences that is both true and non-trivial, Paul Samuelson famously replied: ‘Ricardo's theory of comparative advantage’. Truth, however, in Samuelson's reply refers to the fact that Ricardo's theory of comparative advantage is mathematically correct, not that it is empirically valid. In this paper we develop and implement an empirical test of Ricardo's ideas. We use novel agricultural data that describe the productivity in 17 crops of 1.6 million parcels of land in 55 countries around the world. We find that a regression of log observed output on log predicted output has a (precisely estimated) slope of 0.84 and an R-squared of 0.93. In our view, these findings offer considerable support for Ricardo's ideas.
Profits in the “New Trade” Approach to Trade Negotiations
Authors: Ossa Ralph
Published: May 2012

I highlight two advantages of adopting a “new trade” approach to trade negotiations. First, it allows for a view of trade negotiations in which producer interests play a prominent role. And second, it lends itself naturally to quantitative analyses of non-cooperative and cooperative trade policy. My specific focus is on profit shifting effects through which countries can gain at the expense of one another.
On the Use of Holdout Samples for Model Selection
Authors: Schorfheide Frank , Wolpin Kenneth I
Published: May 2012

Researchers often hold out data from the estimation of econometric models to use for external validation. However, the use of holdout samples is suboptimal from a Bayesian perspective, which prescribes using the entire sample to form posterior model weights. This paper examines a possible rationale for the use of holdout samples: data-inspired modifications of structural models are likely to lead to an exaggeration of model fit. The use of holdout samples can, in principle, set an incentive for the modeler not to exaggerate model fit.
Prediction with Misspecified Models
Authors: Geweke John , Amisano Gianni
Published: May 2012

The assumption that one of a set of prediction models is a literal description of reality formally underlies many formal econometric methods, including Bayesian model averaging and most approaches to model selection. Prediction pooling does not invoke this assumption and leads to predictions that improve on those based on Bayesian model averaging, as assessed by the log predictive score. The paper shows that the improvement is substantial using a pool consisting of a dynamic stochastic general equilibrium model, a vector autoregression, and a dynamic factor model, in conjunction with standard US postwar quarterly macroeconomic time series.
Assumptions Matter: Model Uncertainty and the Deterrent Effect of Capital Punishment
Authors: Durlauf Steven N , Fu Chao , Navarro Salvador
Published: May 2012

This paper examines how estimates of the deterrent effect of capital punishment depend on alternate choices of assumptions concerning the homicide process. Specific models of the homicide process represent bundles of these assumptions, which involve the unobserved heterogeneity, the relevant penalty probabilities for homicide choices, possible cross-polity parameter variation, and exchangeability between polity-time pairs that do and do not experience positive numbers of murders. We demonstrate how various assumptions have driven the conflicting findings from studies on capital punishment, and isolate a particular set of assumptions that are required to find a positive deterrent effect.
Heuristics and Heterogeneity in Health Insurance Exchanges: Evidence from the Massachusetts Connector
Authors: Ericson Keith Marzilli , Starc Amanda
Published: May 2012

We examine heuristic decision rules in consumer choice on health insurance exchanges using data from the Massachusetts Connector. Consumers may have difficulty making optimal choices in a complex environment. The heuristic “choose the cheapest plan” is suggested by the decision context, previous research, and the data: about 20% of enrollees choose the cheapest plan possible. We find evidence of this heuristic in many models, but while heuristics may play a role, preference heterogeneity is also important. Our most flexible models find an insignificant heuristic effect. In part because holding context fixed, this heuristic is observationally equivalent to extreme price sensitivity.