A companion modeling approach applied to fishery management

Don Hoi Lord, a coastal wetland in the upper gulf of Thailand, is famous for the razor clam (Solen regularis), which is a source of food and income for local fishermen. However, the razor clam population is significantly decreasing so the aim of this study was to analyze the razor clam fishery and develop a management plan engaging the different stakeholders in collective discussions. A participatory modelling approach was used, including (a) agent-based modelling (ABM) and (b) role-playing games (RPG). First, an individual-state distribution model of the razor clam population was designed and calibrated to synthesise knowledge. Two RPG sessions supported by this biological model were organised to initiate collective learning and promote discussion among stakeholders. After playing with the baseline scenario showing the actual harvesting situation, discussions led to the definition of alternative scenarios for clam management such as establishment and rotation of zones closed for harvesting, and quota systems. These scenarios developed during the RPG sessions were more deeply investigated with an agent-based model that included fishermen agents and the individual-state distribution model of the razor clam population. Simulations of different scenarios (reserve, quota and combination of reserve and quota) were produced to enable better informed discussion between different stakeholders. Stakeholders have acknowledged that management through rotating reserves is not efficient if the duration of reserves is too short. They have realised that the efficiency of reserves is hard to assess without better data on clam recruitment. They have also explored another management option which is the quota system. In the final stage, the local participatory process was endorsed by the incumbent regional policy-making actor. Unfortunately, because of rapid administrative rotation the project abruptly lost support. This unexpected event emphasises the need for continuous monitoring of all actors entering and/or leaving the system, which can radically change the interactions among them and, therefore, the whole management context.     

Promoting robust black-box solvers through competitions

This paper presents the experiences of the organizers of the four constraint solver competitions which were held in conjunction with CP in the previous years. The paper mainly focuses on the competitions which were held in 2008 and 2009, outlines the reasons for organizing the competitions, describes how the solvers were evaluated, and presents lessons, observations, and general trends.     

A survey of the algorithmic aspects of modular decomposition

Modular decomposition is a technique that applies to (but is not restricted to) graphs. The notion of a module naturally appears in the proofs of many graph theoretical theorems. Computing the modular decomposition tree is an important preprocessing step to solve a large number of combinatorial optimization problems. Since the first polynomial time algorithm in the early 1970’s, the algorithmic of the modular decomposition has known an important development. This paper survey the ideas and techniques that arose from this line of research.     

Psychophysical reverse correlation with multiple response alternatives.

Psychophysical reverse-correlation methods such as the “classification image” technique provide a unique tool to uncover the internal representations and decision strategies of individual participants in perceptual tasks. Over the past 30 years, these techniques have gained increasing popularity among both visual and auditory psychophysicists. However, thus far, principled applications of the psychophysical reverse-correlation approach have been almost exclusively limited to two-alternative decision (detection or discrimination) tasks. Whether and how reverse-correlation methods can be applied to uncover perceptual templates and decision strategies in situations involving more than just two response alternatives remain largely unclear. Here, the authors consider the problem of estimating perceptual templates and decision strategies in stimulus identification tasks with multiple response alternatives. They describe a modified correlational approach, which can be used to solve this problem. The approach is evaluated under a variety of simulated conditions, including different ratios of internal-to-external noise, different degrees of correlations between the sensory observations, and various statistical distributions of stimulus perturbations. The results indicate that the proposed approach is reasonably robust, suggesting that it could be used in future empirical studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aggregation behavior of a polystyrene–b-poly(phenylsilsesquioxane) H-type copolymer at the air/water interface

A comprehensive Langmuir film balance/atomic force microscope study of the surface aggregation behavior of an H-type block copolymer having four branches of polystyrene (PS) blocks (number average molar mass (M_n) = 5000 Da per each branch) and poly(phenylsilsesquioxane) (PPSQ) (M_n = 40,000 Da) has been performed. Temperature dependent surface pressure isotherms and hysteresis experiments were combined with molecules aggregation number per surface micelle, leading to a self-consistent picture of the surface morphology and aggregation phenomena. In spite of the ladder structure of the PPSQ segment, the micelles mostly exist as spherical aggregates because of strong interaction between PS blocks.     

Amorphous Ge‐Sb‐Se thin films fabricated by co‐sputtering: Properties and photosensitivity

Amorphous Ge–Sb–Se thin films were fabricated by a rf‐magnetron co‐sputtering technique employing the following cathodes: GeSe₂, Sb₂Se₃, and Ge₂₈Sb₁₂Se₆₀. The influence of the composition, determined by energy‐dispersive X‐ray spectroscopy, on the optical properties was studied. Optical properties were analyzed based on variable angle spectroscopic ellipsometry and UV‐Vis‐NIR spectrophotometry. The results show that the optical bandgap range 1.35‐2.08 eV with corresponding refractive index ranging from 3.33 to 2.36 can be reliably covered. Furthermore, morphological and topographical properties of selenide‐sputtered films studied by scanning electron microscopy and atomic force microscopy showed a good quality of fabricated films. In addition, structure of the films was controlled using Raman scattering spectroscopy. Finally, irreversible photoinduced changes by means of change in optical bandgap energy and refractive index of co‐sputtered films were studied revealing the photobleaching effect in Ge‐rich films when irradiated by near‐bandgap light under Ar atmosphere. The photobleaching effect tends to decrease with increasing antimony content.     

Flash synthesis of Magnéli phase (TinO2n-1) nanoparticles by thermal plasma treatment of H2TiO3

A flash synthesis method of titanium suboxides (TSO) Ti_nO_2n-1 nanoparticles with Magnéli phases by thermal plasma using rutile-phase metatitanic acid (H₂TiO₃) as the raw material was proposed and investigated, comparing with common sintering hydrogenation process of H₂TiO₃. TSO powders with diverse colors were prepared and characterized by means of XRD, SEM and TEM. The results showed Magnéli phase nanoparticles with perfect spherical shape and particle size of 20–100 nm were rapidly synthesized by thermal plasma treatment under Ar and Ar/H₂ atmospheres. Typical Magnéli phases of Ti₅O₉ and Ti₄O₇ with peacock blue color were formed under argon atmosphere. An increase of hydrogen content in the atmosphere made nano-H₂TiO₃ efficiently reduced to form a different TSO phases with diverse colors of dark blue to blue black. Notably, parts of nanoparticles were of carbon shell/Magnéli phase core structure. The UV–visible absorptivity and electric conductivity of samples were tested and the results indicate that thermal plasma is an efficient way to improve the optical and conductive properties of materials. But the electric resistivity of nano Magnéli phase powders still keep 10⁵–10⁶ Ω^.cm.     

Polymer electrolyte membranes prepared by EB‐crosslinking of sulfonated poly(ether ether ketone) with 1,4‐butanediol

Crosslinked sulfonated poly(ether ether ketone) (SPEEK) membranes were prepared through the electron beam (EB)‐irradiation crosslinking of SPEEK/1,4‐butanediol under various irradiation conditions and used as a proton exchange membrane (PEM) for fuel cell applications. The crosslinked membranes were characterized by gel fraction, a universal testing machine (UTM), dynamic mechanical analysis (DMA), and small‐angle X‐ray scattering (SAXS). The gel fraction of the crosslinked membranes was used to estimate the degree of crosslinking, and the gel fraction was found to be increased with an increase of the crosslinker content and EB‐absorbed dose. The UTM results indicate that a brittle EB‐crosslinked membrane becomes more flexible with an increase in the crosslinker content. The DMA results show that the EB‐crosslinked membranes have well‐developed ionic aggregation regions and the cluster T_g of membranes decrease with an increase in the 1,4‐butanediol crosslinker content. The SAXS results show that the Bragg and persistence distance of crosslinked membranes increase with an increase in the crosslinker content. The proton conductivities of the EB‐crosslinked membranes were more than 9 × 10^?2 S/cm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41760.     

Synthetic Ni‐talc as filler for producing polyurethane nanocomposites

New synthetic Ni‐talc was used as filler in the synthesis of polyurethane (PU) nanocomposites by in situ polymerization and to emphasize the contribution of the new material compared with natural talc. Good dispersion of Ni‐talc was supported by homogeneous green coloration observed in the polymer matrix. X‐ray diffraction (XRD) analyses indicate the intercalation of polymeric matrix into the filler layers by the increase in d₀₀₁‐spacing value of the Ni‐talc for the nanocomposites when compared to the pristine filler. The nanocomposites obtained with synthetic talc showed an improvement in the crystallization temperature and in thermal stability when compared to pure PU and the composite obtained with natural talc. The young modulus of PU/talc materials containing both Ni‐talc and natural talc were slight higher than pure PU. As shown by scanning electron microscope (SEM), Ni‐talc fillers were well dispersed into the polymeric matrix probably due to the good compatibility of both phases filler/polymer mainly achieved by the filler OH interaction with the urethane group of the polymeric chain. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41854.