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We compute the cooperative and the Nash equilibrium solutions for the discounted optimal control problem in a two-player differential game of reclamation of a resource extraction site, where each firm’s planning horizon presents the period that extraction of the resources from their site is economically viable. Hence, the planning horizon is defined by a random duration determined on the infinite time horizon. The comparison of the cooperative and Nash solutions and also the comparative statics are provided numerically. We also define the concept of “normalized value of cooperation” and explain how this concept could help us to better characterize the losses the players will face if they continue to refrain from cooperation.

We first study the optimality of a committed policy mix of tax and subsidy to control pollution when firms are involved in abatement technology R&D that is subject to knowledge spillovers. Then a c...

PurposeWhile the commons problem and the issues related to the negative externalities of harvesting have been studied extensively, there remains a need to bridge these two streams of studies to comprehensively investigate the implications of the strategic interactions among resource harvesters in the presence of such negative externalities. This paper aims to fill this gap.Design/methodology/approachThe authors study a common-pool harvest problem when the extractive activities leave behind negative externalities which affect the resource growth rate and reduce the stock beyond the extracted levels. Markov perfect noncooperative and optimal solutions are presented under different scenarios regarding considerations of negative externalities into harvest decisions.FindingsResults of the study suggest that, in the presence of such externalities, all parties must scale down their extraction in accordance with their externalities. The resource can be preserved by implementation of such harvest rule. However, failure to incorporate the externalities exacerbates the commons problem and can even lead to exhaustion of the biomass even if countries manage to cooperate and coordinate their harvest. Suggesting that if such externalities are large enough – which empirical literature suggests they are – then recognition and consideration of these externalities in the harvest decisions is as crucial as cooperation.Originality/valueThis paper provides a framework that is capable of incorporating the negative externalities of harvest activities into a bioeconomic game theoretic model and thereby providing a more real-world representation of the state of the common-pool resource management. While, the authors extend a well-known simple model, the model of this research study has the capacity to explain the widespread incidences of resource collapses. Therefore, the important policy implication is that agents should rigorously work together to understand the extent of the negative externalities of their harvests on the resources.

Background Traumatic brain injury (TBI) is a critical health problem with various comorbidities and socioeconomic consequences. Tending to increase in recent decades, TBI results in more cases of consciousness disorders including vegetative state (VS)/minimally conscious state (MCS). However, no definite or effective treatment still exists for these conditions. The aim of this article is to study the effects of zolpidem in patients with VS caused by TBI by using brain perfusion single-photon emission computed tomography (SPECT). Materials and methods This was a prospective clinical trial on a cohort of patients with VS. We evaluated the TBI database to find VS/MCS patients, between the ages of 20 and 65 years. We received written consent from their family members prior to enrollment and compared their clinical status and brain perfusion SPECT prior and after 2 weeks of zolpidem therapy. Results Among the 12 patients included in this study, six patients changed to MCS after 2 weeks. Comparison of their motor score, revealed a statistically significant difference (2.08 vs. 3.75, P = 0.007, respectively). None of the quantitative or qualitative brain perfusion parameters showed any differences after zolpidem therapy. However, the perfusion pattern, with focal or multifocal cortical defects, was significantly more prevalent in the responder group (five patients vs. one patient, P = 0.015). Conclusion Zolpidem therapy may improve consciousness levels and motor function in a considerable portion of VS patients with TBI. This study showed that the presence of focal brain perfusion defect can predict response to zolpidem.

Introduction: Ovarian cancer is one of the most prevalent cancers among women. According to several reports micro RNA-499 is involved in the development of ovarian carcinoma. The presence of Single Nucleotide Polymorphisms (SNPs) in miRNA sequences can also affect the risk of cancer. The aim of this study was to investigate the association between SNP mir-499 rs3746444 and the ovarian cancer in the Iranian female population. Materials & Methods: In this case-control study, peripheral blood samples were taken from 35 patients with ovarian cancer referred to Imam Khomeini Hospital and Cancer Institute and 35 healthy individuals. Subsequently, the DNA was extracted, and the polymorphism was investigated using Arms- polymerase chain reaction method. The data was analyzed in SPSS software. Ethics code: IR.PNU.REC.1398.118 Findings: The results of investigating SNP rs3746444 mir-499 between the two groups of patients and control indicated that the genotype frequencies of AA, AG, and GG were % 2.9, % 51.4, and % 45.7 in the patients and %14.3, % 45.7, and % 40 in the controls, respectively. Discussion & Conclusions: According to the results of the study, there was no significant difference between the healthy and patient samples regarding the frequencies of genotypes ([χ2 (1, 70) =0.23, P=0.63]); however, according to odds ratio, the risk of developing ovarian cancer is higher in the GG genotype (Odds Ratio=1.26, 95% CI: 0.49-3.26).

We analyze a transboundary pollution control problem in a heterogeneous two-country differential game setting in which regulators care for the implications of environmental policies on the competitiveness. We characterize the noncooperative and the cooperative solutions, showing that under both scenarios, in the presence of competitiveness considerations, heterogeneous countries will generally set different carbon taxes. This suggests, while implementing a mitigation policy is necessary to combat climate change, a universally homogeneous policy may not be optimal. Moreover, when countries are symmetric, except for their degree of competitiveness concerns, under noncooperation introduction of such concerns lowers the abatement policies in both countries, however, the self-effect is stronger than the cross-effect. Nevertheless, under cooperation, an increase in country j’s competitiveness concerns leads to more stringent policies in country i, while, the self-effect could be either positive or negative. The latter result emphasizes the importance of cooperation to tackle pollution in the presence of competitiveness concerns.

We analyze a transboundary pollution control problem in a heterogeneous two-country differential game in which each country’s regulator cares for the implications of environmental policy on its competitiveness. We characterize and compare the noncooperative and the cooperative solutions, showing that under both scenarios, the heterogeneous countries impose different tax rates despite such competitiveness concerns. This may suggest that, while implementing some kind of mitigation policy is necessary to combat climate change, a universally homogeneous environmental tax may not be either desirable or optimal.

We first study the optimality of a committed policy mix of tax and subsidy to control pollution when firms are involved in abatement technology R&D that is subject to knowledge spillovers. Then a comparison of tax and subsidy is provided when the policy mix is not available and the regulator can use only one single policy. Two different behavioral assumptions for the firms are examined: when firms are myopic, and when they are strategic, i.e., react to the policies strategically. The results suggest that given that policy mix is available a committed regulator can attain optimality if firms are myopic, but that, a strategic reaction from the firms may compromise the efficiency of the policy mix, but the exact impact of that depends on the production technology and the effectiveness of knowledge spillovers. But if the regulator commits to one single policy, then tax policy has advantages over subsidy. Besides, unlike the policy mix, the single policy is more effective in case of strategic firms rather than myopic ones and it is even possible to achieve optimality with a special tax policy.

We introduce learning in a dynamic game of international pollution, with ecological uncertainty. We characterize and compare the feedback non-cooperative emissions strategies of players when the players do not know the distribution of ecological uncertainty but they gain information (learn) about it. We then compare our learning model with the benchmark model of full information, where players know the distribution of ecological uncertainty. We find that uncertainty due to anticipative learning induces a decrease in total emissions, but not necessarily in individual emissions. Further, the effect of structural uncertainty on total and individual emissions depends on the beliefs distribution and bias. Moreover, we obtain that if a player’s beliefs change toward more optimistic views or if she feels that the situation is less risky, then she increases her emissions while others react to this change and decrease their emissions.

We compare the use of price-based policies or taxes, and quantity-based policies or quotas, for controlling emissions in a dynamic setup when the regulator faces two sources of uncertainty: (i) market-related uncertainty; and (ii) ecological uncertainty. We assume that the regulator is a rational Bayesian learner and the regulator and firms have asymmetric information. In our model the structure of Bayesian learning is general. Our results suggest that the expected level of emissions is the same under taxes and quotas. However, the comparison of the total benefits related to these policies suggests that taxes dominate quotas, that is, they provide a higher social welfare. Even though taxes have some benefits over quotas, neither learning nor ecological uncertainty affect the choice of policy, i.e., the only factor having such an impact is uncertainty in the instantaneous net emissions benefits (market-related uncertainty). Besides, the more volatile is this uncertainty, the more benefits of taxes over quotas. Ecological uncertainty leads to a difference between the emissions rule under the informed and the rational learning assumptions. However, the direction of this difference depends on the beliefs bias with regard to ecological uncertainty. We also find that a change in the regulator's beliefs toward more optimistic views will increase the emissions.

Background: Potyviruses are accounted for 40% of viral diseases of various crops including vegetables and legumes. Potyviruses can be transmitted through plant sap, seeds and many aphid species. Due to ease of spread of these viruses detection of such viruses are crucial as to the control of the incited diseases. Objectives: This study compared the efficiencies of two couples of primers in their detection of potyviruses infecting vegetables in North-West of Iran. Materials and Methods: To identify potyviruses infecting vegetables, total RNA preparations from leaves of diseased plants were subjected to reverse transcription (RT) with oligo d(T)15, M4T or a potyvirus-specific primer, followed by polymerase chain reactions (PCR) with two pairs of degenerate primers including Sprimer/M4 or NIb2F/NIb3R that would yield ~ 1700 or 350 bp fragments, respectively. Amplification was achieved from 7 samples when Sprimer and M4 were used, but non- specific fragments were also amplified. However, specific amplifications from 31 samples were achieved with NIb2F2 and NIb3R. PCR products resulting from the use of NIb2F/NIb3R were subjected for cloning and sequencing. Results: BLAST analysis of the sequenced data revealed that the PCR-amplified fragments belonged to Bean common mosaic virus (green bean), Bean yellow mosaic virus (broad bean), Potato virus Y (potato), Watermelon mosaic virus (squash, muskmelon or melon), Zucchini yellow mosaic virus (squash), and Soybean mosaic virus (bean). Conclusions: This study demonstrated the efficiency of NIb2F2/NIb3R in detection of potyviruses and revealed the extent of infections with diverse potyviruses species in the northwest part of Iran.

We study the impact of collective effort in R&D in adaptation technologies, and also spillover effects on formation and size of stable international environmental agreements (IEAs). Our results suggest that it is possible to have more than one size of stable IEA. We can achieve a superior equilibrium, i.e., the grand coalition, if countries manage to keep knowledge spillovers low and arrange a minimum ratification threshold. This threshold is defined endogenously. We also shed light on the effects of two-sided spillover on global welfare and the size of stable IEAs.

Objectives: In this paper, we report the expression and assembly of VLP in cells of E. coli expressing the CMVCP gene. Materials and Methods: In this study, the CMV-CP gene was released from a previously prepared cloning vector. Then, the CMV-CP was ligated into the expression vector. Sequencing was done by Marcrogen, Inc. (South Korea). A recombinant plasmid was transferred to E.coli isolate Rosetta. After inducing by isopropyl thiogalactosides, the molecular weight of the expressed protein was determined by SDS-PAGE. The extraction of proteins was done by NATURE method to see the possible presence of CMV-like particles. Results: CMV-CP was detected by Western blotting by a CMV specific polyclonal antibody and conjugate. The protein extracted from the CP producing clone was studied under a JEOL 100-CXII transmission electron microscope with 100000× magnification at an acceleration voltage of 100 kV. Conclusions: The results showed that the CP gene was expressed in the prokaryotic system successfully and was assembled into the CMVlike particle.