An Extension of Proof Graphs for Disjunctive Parameterised Boolean Equation Systems

A parameterised Boolean equation system (PBES) is a set of equations that defines sets as the least and/or greatest fixed-points that satisfy the equations. This system is regarded as a declarative program defining functions that take a datum and returns a Boolean value. The membership problem of PBESs is a problem to decide whether a given element is in the defined set or not, which corresponds to an execution of the program. This paper introduces reduced proof graphs, and studies a technique to solve the membership problem of PBESs, which is undecidable in general, by transforming it into a reduced proof graph. A vertex X(v) in a proof graph represents that the data v is in the set X, if the graph satisfies conditions induced from a given PBES. Proof graphs are, however, infinite in general. Thus we introduce vertices each of which stands for a set of vertices of the original ones, which possibly results in a finite graph. For a subclass of disjunctive PBESs, we clarify some conditions which reduced proof graphs should satisfy. We also show some examples having no finite proof graph except for reduced one. We further propose a reduced dependency space, which contains reduced proof graphs as sub-graphs if a proof graph exists. We provide a procedure to construct finite reduced dependency spaces, and show the soundness and completeness of the procedure

Econometric Analysis of the Factors Contributing to the Fish Price increase in Coastal Turfs in Japan: the Case of the income Pooling Fishery for Coastal Shrimp Sakuraebi (Sergia Lucens)

While right-based managements have often been encouraged as effective management tools, few studies presented an empirical analysis on the effects of those systems. This paper focuses on a special form of Territorial Use Rights Fisheries called an income pooling system, and examines the effects of the system empirically. Income pooling system is a unique Japanese fishery management system where fishermen harvest fish cooperatively, and divide the total income based on a certain rule, in many cases equal distribution. The increase of fish price through control on landing amount and improvement of quality of fish is regarded as the main effect of the system in earlier studies, so we estimated the magnitude of the impact of two factors on the price of fish with econometric method. The results show that the two factors in fact have significant effects for the price changes. Also, the effect of the improvement of quality for the price is not negligible compared to that of control on landing amount. These results suggest that to improve the income of fishermen, the policy encouraging fishermen to improve the quality of fish is effective. This study can be regarded as one of the first attempts to use economic analysis to evaluate the economic performance of fishery management system

In vitro analysis of durability of S-PRG filler-containing composite crowns for primary molar restoration

Objective: To evaluate the reliability, maximum principal stress, shear stress, and crack initiation of a computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite (RC) incorporating surface pre-reacted glass (S-PRG) filler for primary molar teeth. Methods: Mandibular primary molar crowns fabricated by experimental (EB) or commercially available CAD/CAM RCs (HC) were prepared and cemented to a resinous abutment tooth using an adhesive resin cement (Cem) or a conventional glass-ionomer cement (CX). These specimens were subjected to a single compressive test (n = 5/each) and the step-stress accelerated life testing (SSALT) (n = 12/each). Data was evaluated using Weibull analyses and reliability was calculated. Afterwards, the maximum principal stress and crack initiation point of each crown was analyzed by finite element analysis. To evaluate bonding of EB and HC to dentin, microtensile bond strength (μTBS) testing was conducted using primary molar teeth (n = 10/each). Results: There was no significant difference between the fracture loads of EB and HC for either cement (p > 0.05). The fracture loads of EB-CX and HC-CX were significantly lower than EB-Cem and HC-Cem (p 0.05). Significance: The crowns fabricated with the experimental CAD/CAM RC incorporating S-PRG filler yielded greater fracture loads and reliability than the crowns manufactured with commercially available CAD/CAM RC regardless of the luting materials. These findings suggest that the experimental CAD/CAM RC crown may be clinically useful for the restoration of primary molars.Nakase Y., Yamaguchi S., Jalkh E.B.B., et al. In vitro analysis of durability of S-PRG filler-containing composite crowns for primary molar restoration. Dental Materials 39, 640 (2023); https://doi.org/10.1016/j.dental.2023.04.006

Peccei-Quinn invariant extension of the NMSSM

We study a Peccei-Quinn invariant extension of the next-to-minimal supersymmetric Standard Model (NMSSM), which turns out to be free from the tadpole and domain wall problems. Having a non-renormalizable coupling to the axion superfield, the SM singlet added to the Higgs sector can naturally generate an effective Higgs mu term around the weak scale. In the model, the lightest neutralino is dominated by the singlino, which gets a mass only through mixing with the neutral Higgsinos. We explore the phenomenological consequences resulting from the existence of such a relatively light neutralino. The coupling of the SM singlet to the Higgs doublets is constrained by the experimental bound on the invisible Z-boson decay width. Under this constraint, we examine the properties of the SM-like Higgs boson paying attention to its mass and decays. We also demonstrate a UV completion of the model in SU(5) grand unified theory with a missing-partner mechanism.Comment: 22 pages, 3 figures; published versio

Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Abstract: In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M ⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded

Computerized intertemporal choice task in chimpanzees (Pan troglodytes) with/without postreward delay

In intertemporal choice (ITC) tasks, animals are presented with alternative choices between a smaller reward that becomes available sooner and a larger reward that becomes available later. To equate the duration of a trial across the 2 options, postreward delays (PRDs) are inserted after the delivery of the reward. Animals need to incorporate this to increase the long-term reward rate. However, recent studies suggest that they have difficulty understanding the contingency associated with PRDs. Previous research indicates that chimpanzees exhibit particularly great self-control in ITC tasks, but it remains unclear whether chimpanzees do so when considering PRDs. Therefore, we used touchscreen experiments to explore chimpanzee intertemporal preferences when trial duration was equated by a PRD as well as when the PRD was eliminated. The computerized setting was used to try to control delay length flexibly and precisely while reducing the impact of the interaction with human experimenters. Moreover, choice options were presented on touchscreens using symbolic cues. This may reduce the impact of seeing food rewards on making a choice (i.e., the animals’ robust tendency to reach for the larger amount of food). In an ITC task in which the trial duration was equated, 4 chimpanzees preferred larger rewards but chose smaller rewards more often when the ratio of the reward amount was smaller. In an ITC task with no PRDs, 2 of 4 chimpanzees did switch their preference to smaller rewards and enhanced the reward rate although this result should be interpreted in light of some methodological limitations

Three Essays in Environmental and Renewable Resource Economics

The environment and natural resources are fundamental to human life. Clean air is crucial for our health, fossil fuels are the base energy source for the modern economy, and fishery resources are the most important source of protein in many countries. Until the middle of the 20th century, the environment and natural resources were not the main subject of research, as human activities appeared to have negligible effects on them. Since then, however, the consequence of human activities started to manifest themselves. Environmental pollution, climate change, deforestation, and depletion of fishery resources are only a few examples. In effect, we live in an era where the careful management of environment and natural resources has never been more important. A major challenge in environmental and resource management is their lack of property rights. For example, clean air is a public good, which is nonexcludable and nonrival. This means that one's pollution abatement effort benefits everyone in the population, while the cost of the abatement is borne by that individual. Consequently, everyone tries to free-ride on others' abatement efforts, and the resulting abatement effort level and air quality will be less than the socially optimal level. Similarly, many fishery resources are nonexcludable so that anyone can participate in a fishery. Because the cost of fishing increases as the size of the fish stock shrinks, an additional harvest by a new fisherman raises the cost of fishing for other fishermen. Thus, while the profit from harvests is enjoyed by each fisherman, the cost of harvest is shared by everyone in the industry. Consequently, the total harvest will be more than the socially optimal level. In both examples, an action of one individual affects others without market transactions (i.e. agreeing to incur the costs or benefits). This is the concept of externality. A positive externality exists if one's action benefits others---as in the case of abatement---, while a negative externality exists if one's action generates costs to others---as in the case of fishery. In this thesis, I examine the management of fishery resources in Chapter 1 and the management of infectious diseases in Chapters 2 and 3. One may wonder why fishery resources and infectious pathogens are in the same thesis, but a closer look reveals that they share two key features. First, they are both renewable natural resources. Both are a part of the ecosystem, and one reproduces in lakes and oceans while the other reproduces in a host's body. The goal of a fishery resource manager is to maximize the rent from the fishery resource, while the goal of a pathogen resource manager (i.e. public health official) is to minimize the cost from the infectious pathogen. Second, externalities are key in the management of both resources. Infectious diseases transmit from a host to another host without an accompanying market transaction. For many infectious diseases, vaccination exists that reduces the risk of infection. When a person vaccinates, this person bears the cost of vaccination such as money and pain, while everyone in the population benefits via the reduced risk of infection. Thus, everyone tries to free-ride on others’ vaccination decisions, and the vaccination rate will be lower than the social optimal level. This is a classic example of public goods. Therefore, the management of fishery resources and infectious pathogens both center around understanding the nature of externalities and finding the optimal level of resource stocks. My analytical approach to these two types of resource management is also common. I first use reduced form econometrics to examine the overall relationship between key variables. I then use theory to explain the empirical results, and further explore other possible outcomes based on the theory. In the case of fishery resource in Chapter 1, theoretical models already exist in the literature, so I focus primarily on the empirical analysis. Alternatively, I show a new stylized fact about the relationship between income and vaccination rates in Chapter 2. As there is no theory in the literature that is consistent with this result, I construct a new theory in Chapter 3. The combination of theory and empirics is useful in examining the phenomenon of interest and discussing policy implications. In Chapter 1, I investigate the impact of fishery subsidies on resource stocks in 23 OECD countries during 1996-2011. Subsidies are common tools to internalize externalities by aligning private and social costs. They are, however, also used for other political purposes. Thus, whether they have positive or negative consequences is an empirical question. My results show that the effect of subsidies depends on the type of subsidy and the management regime. Within this sample, cost reducing subsidies have no effect on stocks if management is individual quota-based but have negative effects if management uses traditional input/output restrictions. Subsidies for improving fishery management and infrastructure produce beneficial effects on stocks under traditional management, but no effect with individual quota-based management. These results suggest that global efforts to reform fishery subsidies should be carried out in a highly selective manner. In Chapter 2, I present a new stylized fact about the relationship between income and childhood vaccination. It shows vaccination rates first rise but then fall as income increases. This pattern is observed in WHO country-level panel data, and in US county-level panel and individual-level repeated cross-section data. This data pattern suggests that both low and high-income parents are less likely to follow the standard vaccination schedule, and that such behaviour is reflected in the vaccination rate at the population level. I provide several alternative explanations as to why we observe this data pattern, including avoidance measures, medical care, and social segregation. Finally, in Chapter 3, I develops a simple model of vaccination decisions in a population where agents differ in their exogenous income. Agents perceive the risk of infection as independent of their decisions, while it is endogenously determined by the population's vaccination rate. I show that while the monetary cost of vaccination prevents low-income agents from vaccinating, the opportunity cost of illness, interacted with the presence of a substitute for vaccination, can naturally generate non-vaccination at the high-income end. These vaccination decisions at the individual level may in turn generate a rise and fall in the vaccination rate as the population's income rises