Is altruism bad for cooperation?

Some philosophers and social scientists have stressed the importance for good government of an altruistic citizenry that values the well being of one another. Others have emphasized the need for incentives that induce even the self interested to contribute to the public good. Implicitly most have assumed that these two approaches are complementary or at worst additive. But this need not be the case. Behavioral experiments find that if reciprocity-minded subjects feel hostility towards free riders and enjoy inflicting harm on them, near efficient levels of contributions to a public good may be supported when group members have opportunities to punish low contributors. Cooperation may also be supported if individuals are sufficiently altruistic that they internalize the group benefits that their contributions produce. Using a utility function embodying both reciprocity and altruism we show that unconditional altruism towards other members attenuates the punishment motive and thus may reduce the level of punishment inflicted on defectors, resulting in lower rather than higher levels of contributions. Increases in altruism may also reduce the level of benefits from the public project net of contribution costs and punishment costs. The negative effect of altruism on cooperation and material payoffs is greater the stronger is the reciprocity motive among the members. JEL Categories: D64 (altruism); H41 (public goods)public goods, altruism, spite, reciprocity, punishment, cooperation

Social Preferences and Public Economics: Mechanism design when social preferences depend on incentives

Social preferences such as altruism, reciprocity, intrinsic motivation and a desire to uphold ethical norms are essential to good government, often facilitating socially desirable allocations that would be unattainable by incentives that appeal solely to self-interest. But experimental and other evidence indicates that conventional economic incentives and social preferences may be either complements or substitutes, explicit incentives crowding in or crowding out social preferences. We investigate the design of optimal incentives to contribute to a public good under these conditions. We identify cases in which a sophisticated planner cognizant of these non-additive effects would make either more or less use of explicit incentives, by comparison to a naive planner who assumes they are absent. JEL Categories: D52, D64, H21. H41Social preferences, implementation theory, incentive contracts, incomplete contracts, framing, motivational crowding out, ethical norms, constitutions

Production and characterization of MutS for use in error correction

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 20-21).The availability of inexpensive synthetic DNA (oligonucleotides) has allowed for the synthesis of longer, gene-length constructs of DNA. However, a critical barrier to making this technology a low-cost and high-throughput process has been due to the rate at which errors pervade the final product. The current state of the error reduction technology includes three different categories: error filtration, error correction, and error prevention. My research is a joint project as well as an addendum to the work done by Research Scientist Dr. Peter Carr and current MIT Department of Biological Engineering Masters Student Jason Park (MIT '05) who have been working on research in gene synthesis error correction over the past several years. I have been working very closely with both Dr. Carr and Jason Park on this research for the past two years. We have a publication we're about to submit in regards to optimizations of gene synthesis and a significant portion of my thesis deals with work done for the upcoming publication. My work includes optimizing the synthesis of large gene constructs, the synthesis of new hyper-thermophilic MutS proteins, characterizing these proteins using instruments such as the circular dichroism spectrophotometer and the Evotec MF20, as well as perfecting old error correction protocols while designing several new ones.by Samuel James Hwang.S.B

Towards photostatistics from photon-number discriminating detectors

We study the properties of a photodetector that has a number-resolving capability. In the absence of dark counts, due to its finite quantum efficiency, photodetection with such a detector can only eliminate the possibility that the incident field corresponds to a number of photons less than the detected photon number. We show that such a {\em non-photon} number-discriminating detector, however, provides a useful tool in the reconstruction of the photon number distribution of the incident field even in the presence of dark counts.Comment: 7 pages, 4 figure

Effective SAR sea ice image segmentation and touch floe separation using a combined multi-stage approach

Accurate sea-ice segmentation from satellite synthetic aperture radar (SAR) images plays an important role for understanding the interactions between sea-ice, ocean and atmosphere in the Arctic. Processing sea-ice SAR images are challenging due to poor spatial resolution and severe speckle noise. In this paper, we present a multi-stage method for the sea-ice SAR image segmentation, which includes edge-preserved filtering for pre-processing, k-means clustering for segmentation and conditional morphology filtering for post-processing. As such, the effect of noise has been suppressed and the under-segmented regions are successfully corrected

A comprehensive meta-analysis of stem cell therapy for chronic angina

Background: A substantial proportion of patients with coronary artery disease do not achieve complete revascularization and continue to experience refractory angina despite optimal medical therapy. Recently, stem cell therapy has emerged as a potential therapeutic option for these patients. However, findings of individual trials have been scrutinized because of their small sample sizes and lack of statistical power. Therefore, we conducted an updated comprehensive meta-analysis of available randomized controlled trials (RCTs) with the largest sample size ever reported on this subject.Hypothesis: In patients with chronic angina stem cell therapy improves clinical outcomes.Methods: Scientific databases and websites were searched for RCTs. Data were independently collected by 2 investigators, and disagreements were resolved by consensus. Data from 10 trials including 658 patients were analyzed.Results: Stem cell therapy improved Canadian Cardiovascular Society angina class (risk ratio: 1.53, 95% CI: 1.09 to 2.15, P = 0.013), exercise capacity (standardized mean difference [SMD]: 0.56, 95% CI: 0.23 to 0.88, P = 0.001), and left ventricular ejection fraction (SMD: 0.63, 95% CI: 0.27 to 1.00, P = 0.001) compared with placebo. It also decreased anginal episodes (SMD: -1.21, 95% CI: -2.40 to -0.02, P = 0.045) and myocardial perfusion defects (SMD: -0.70, 95% CI: -1.11 to -0.29, P = 0.001). However, no improvements in all-cause mortality were observed after a relatively short follow-up.Conclusions: In patients with chronic angina on optimal medical therapy, stem cell therapy improves symptoms, exercise capacity, and left ventricular ejection fraction. These findings warrant confirmation using larger trials

2D Visualization of the Psoriasis Transcriptome Fails to Support the Existence of Dual-Secreting IL-17A/IL-22 Th17 T Cells.

The present paradigm of psoriasis pathogenesis revolves around the IL-23/IL-17A axis. Dual-secreting Th17 T cells presumably are the predominant sources of the psoriasis phenotype-driving cytokines, IL-17A and IL-22. We thus conducted a meta-analysis of independently acquired RNA-seq psoriasis datasets to explore the relationship between the expression of IL17A and IL22. This analysis failed to support the existence of dual secreting IL-17A/IL-22 Th17 cells as a major source of these cytokines. However, variable relationships amongst the expression of psoriasis susceptibility genes and of IL17A, IL22, and IL23A were identified. Additionally, to shed light on gene expression relationships in psoriasis, we applied a machine learning nonlinear dimensionality reduction strategy (t-SNE) to display the entire psoriasis transcriptome as a 2-dimensonal image. This analysis revealed a variety of gene clusters, relevant to psoriasis pathophysiology but failed to support a relationship between IL17A and IL22. These results support existing theories on alternative sources of IL-17A and IL-22 in psoriasis such as a Th22 cells and non-T cell populations