Peer punishment with third-party approval in a social dilemma game

This paper investigates how punishment promotes cooperation when the punishment enforcer is a third party independent of the implicated parties who propose the punishment. In a prisoner's dilemma experiment, we find an independent third party vetoes not only punishment to the cooperators but punishment to the defectors as well. Compared with the case when the implicated parties are allowed to punish each other, both the cooperation rate and the earnings are lower when the enforcement of punishment requires approval from an independent third party.Social dilemmas; third party; punishment; cooperation; experiment

Determining layer number of two dimensional flakes of transition-metal dichalcogenides by the Raman intensity from substrate

Transition-metal dichalcogenide (TMD) semiconductors have been widely studied due to their distinctive electronic and optical properties. The property of TMD flakes is a function of its thickness, or layer number (N). How to determine N of ultrathin TMDs materials is of primary importance for fundamental study and practical applications. Raman mode intensity from substrates has been used to identify N of intrinsic and defective multilayer graphenes up to N=100. However, such analysis is not applicable for ultrathin TMD flakes due to the lack of a unified complex refractive index ($\tilde{n}$) from monolayer to bulk TMDs. Here, we discuss the N identification of TMD flakes on the SiO$_2$/Si substrate by the intensity ratio between the Si peak from 100-nm (or 89-nm) SiO$_2$/Si substrates underneath TMD flakes and that from bare SiO$_2$/Si substrates. We assume the real part of $\tilde{n}$ of TMD flakes as that of monolayer TMD and treat the imaginary part of $\tilde{n}$ as a fitting parameter to fit the experimental intensity ratio. An empirical $\tilde{n}$, namely, $\tilde{n}_{eff}$, of ultrathin MoS$_{2}$, WS$_{2}$ and WSe$_{2}$ flakes from monolayer to multilayer is obtained for typical laser excitations (2.54 eV, 2.34 eV, or 2.09 eV). The fitted $\tilde{n}_{eff}$ of MoS$_{2}$ has been used to identify N of MoS$_{2}$ flakes deposited on 302-nm SiO$_2$/Si substrate, which agrees well with that determined from their shear and layer-breathing modes. This technique by measuring Raman intensity from the substrate can be extended to identify N of ultrathin 2D flakes with N-dependent $\tilde{n}$ . For the application purpose, the intensity ratio excited by specific laser excitations has been provided for MoS$_{2}$, WS$_{2}$ and WSe$_{2}$ flakes and multilayer graphene flakes deposited on Si substrates covered by 80-110 nm or 280-310 nm SiO$_2$ layer.Comment: 10 pages, 4 figures. Accepted by Nanotechnolog

Unit Root Tests with Markov-Switching

Diba and Grossman (1988) and Hamilton and Whiteman (1985) recommended unit root tests for rational bubbles. They argued that if stock prices are not more explosive than dividends, then it can be concluded that rational bubbles are not present. Evans (1991) demonstrated that these tests will fail to detect the class of rational bubbles which collapse periodically. When such bubbles are present, stock prices will not appear to be more explosive than the dividends on the basis of these tests, even though the bubbles are substantial in magnitude and volatility. Hall et al. (1999) show that the power of unit root test can be improved substantially when the underlying process of the sample observations is allowed to follow a first-order Markov process. Our paper applies unit root tests to the property prices of Hong Kong and Seoul, allowing for the data generating process to follow a three states Markov chain. The null hypothesis of unit root is tested against the explosive bubble or stable alternative. Simulation studies are used to generate the critical values for the one-sided test. The time series used in the tests are the monthly price and rent indices of Seoul's housing (1986:1 to 2003:6) and Hong Kong's retail premise (1980:12 to 2003:1). The investigations show that only one state appears to be highly likely in both cases. The switching unit root tests failed to find explosive bubbles in the price series, which might be due to the fact that the power of test is weak in the presence of heteroscedasticityunit root, three states markov switching, explosive rational bubbles

Signal Extraction with Kalman Filter: A Study of the Hong Kong Property Price Bubbles

Since Flood and Garber (1980), the debate surrounding speculative bubbles has never subsided. A key obstacle to resolve this issue is the identification problem. A bubble is usually inferred from some assumed fundamental determinants of a price. These assumptions could be over-simplified. Furthermore, there might be data measurement errors. In this paper, we attempt to capture such errors with a latent state variable. This variable is extracted with Kalman filter. Based on our empirical comparisons, we find that it is possible to attribute the observed large price swings in the property market of Hong Kong during the 1980s and 1990s to a periodically collapsing rational speculative bubble.rational speculative bubble, misspecification or measurement error, Kalman filter

Unit Root Tests With Markov-Switching

Diba and Grossman (1988) and Hamilton and Whiteman (1985) recommended unit root tests for rational bubbles. They argued that if stock prices are not more explosive than dividends, then it can be concluded that rational bubbles are not present. Evans (1991) demonstrated that these tests will fail to detect the class of rational bubbles which collapse periodically. When such bubbles are present, stock prices will not appear to be more explosive than the dividends on the basis of these tests, even though the bubbles are substantial in magnitude and volatility. Hall et al. (1999) show that the power of unit root test can be improved substantially when the underlying process of the sample observations is allowed to follow a first-order Markov process. Our paper applies unit root tests to the property prices of Hong Kong and Seoul, allowing for the data generating process to follow a three states Markov chain. The null hypothesis of unit root is tested against the explosive bubble or stable alternative. Simulation studies are used to generate the critical values for the one-sided test. The time series used in the tests are the monthly price and rent indices of Seoul’s housing (1986:1 to 2003:6) and Hong Kong’s retail premise (1980:12 to 2003:1). The investigations show that only one state appears to be highly likely in all series under investigation and the switching unit root procedure failed to find explosive bubbles in both prices.unit root, bootstrap, Markov-Switching

Markov-switching Unit Root Test: A study of the Property Price Bubbles in Hong Kong and Seoul

Evans (1991) demonstrates that the unit root tests recommended by Hamilton and Whiteman (1985) and Diba and Grossman (1988) will fail to detect periodically collapsing rational bubbles. Hall et al. (1999) however show that the power of this test procedure can be improved by incorporating a Markov-switching state variable. In this paper, we apply both procedures to selected data from Hong Kong and Seoul. Both point to the possible existence of a periodically-collapsing bubble in each price series investigated, with the second procedure more precise on timing the bubble. Our Markovswitching model is validated using a symmetry test and a Wald test.Markov-switching, unit root test, periodically-collapsing bubble, real-estate

DISCOVERY OF SELECTIVE PROBES TARGETING RNA POLYMERASE I

RNR Polymerase I (RNA Pol I) is a “factory” that orchestrate the transcription of ribosomal rRNA for constructing ribosomes as a primary workshop for protein translation to sustain cell growth. Misregulation of RNA Pol I can cause uncontrolled cell proliferation, which leads to the development of cancer. Yeast (Saccharomyces cerevisiae) is a valuable model system to study RNA Pol I. Recently, the X-ray crystal structure of the yeast homologue of RNA Pol I was elucidated, offering the structural basis to selectively target this transcriptional machinery. The approach to selective RNA Pol I targeting was to disrupt the interaction between a specific transcription factor, RRN3 that bind distinct regions of RNA Pol I. For this purpose, a recombined plasmid was designed to carry human rDNA plus its promoter as target together with a selection marker gene. Therefore, this plasmid could not only introduce the target gene into the yeast (host), but also facilitate the passage of this target gene into a stable yeast strain. In this project, one uracil deficient yeast strain of YBR140C was transformed with the recombined yeast integrative plasmid of pHmrDNA-YIPlac211-TG1. This is a recombined plasmid containing not only the human rDNA but also the URA3 gene as a selection marker. PCR amplification of the human ribosomal DNA was indicative of successful integration of the human ribosomal DNA into the genome of the two yeast strains. Virtual screening using a library of 700 FDA-approved compounds was docked into the RRN3-RNA Pol I complex to identify small molecule disruptors of the RRN3-RNA Pol I as a selective strategy. Using growth assays, gel electrophoresis and transcriptional assays, we identified cerivastatin sodium as a lead virtual hit. The result implicates cerivastatin sodium as a selective RNA Pol I inhibitor worthy of further development with potential as targeted anticancer therapeutic