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Too many problems at home to help you: Domestic disincentives for military coalition participation
Atsushi Tago 한국외국어대학교 국제지역연구센터 2014 International Area Studies Review Vol.17 No.3
Scholars have begun to examine the determinants of military coalition participation. Most studies pay closer attention to international (both systemic/dyadic) rather than domestic factors. While admitting the predominance of such international factors, this study claims that the domestic conditions of potential participants also determine if a state actually joins in a coalition. Specifically, domestic conditions work as suppressing factors for coalition participation. First, riots and violent domestic protests lead to a significant reduction in the probability of sending military troops for a coalition operation, because military resources cannot be deployed when they might be needed to maintain domestic order. Second, a state that is experiencing an economic recession cannot easily send its troops to a coalition operation because the domestic audience would prefer to prioritize resource allocations for domestic economic recovery.
Tracing a high redshift cosmic web with quasar systems
Einasto, Maret,Tago, Erik,Lietzen, Heidi,Park, Changbom,Heinä,mä,ki, Pekka,Saar, Enn,Song, Hyunmi,Liivamä,gi, Lauri Juhan,Einasto, Jaan EDP Sciences 2014 Astronomy and astrophysics Vol.568 No.1
<P>Context. To understand the formation, evolution, and present-day properties of the cosmic web we need to study it at low and high redshifts. Aims. We trace the cosmic web at redshifts that range from 1.0 ≤ z ≤1.8 by using the quasar (QSO) data from the SDSSDR7QSO catalogue. Methods. We apply a friend-of-friend algorithm to the quasar and random catalogues to determine systems at a series of linking length and analyse richness and sizes of these systems. Results. At the linking lengths l ≤ 30 h<SUP>−1</SUP> Mpc, the number of quasar systems is larger than the number of systems detected in random catalogues, and the systems themselves have smaller diameters than random systems. The diameters of quasar systems are comparable to the sizes of poor galaxy superclusters in the local Universe. The richest quasar systems have four members. The mean space density of quasar systems, ≈10<SUP>−7</SUP> (h<SUP>−1</SUP> Mpc)<SUP>−3</SUP>, is close to the mean space density of local rich superclusters. At intermediate linking lengths (40 ≤ l ≤70 h<SUP>−1</SUP> Mpc), the richness and length of quasar systems are similar to those derived from random catalogues. Quasar system diameters are similar to the sizes of rich superclusters and supercluster chains in the local Universe. The percolating system, which penetrate the whole sample volume appears in a quasar sample at a smaller linking length than in random samples (85 h<SUP>−1</SUP> Mpc). At the linking length 70 h<SUP>−1</SUP> Mpc, the richest systems of quasars have diameters exceeding 500 h<SUP>−1</SUP> Mpc. Quasar luminosities in systems are not correlated with the system richness. Conclusions. Quasar system catalogues in our web pages and at the Strasbourg Astronomical Data Center (CDS) serve as a database for searching superclusters of galaxies and for tracing the cosmic web at high redshifts.</P>
( Hiroyasu Fujitsuka ),( Teruoki Tago ) 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
Hydrogen is one of the important materials not only as energy resources for fuel cells but as a chemical feedstock for biomass conversion into valuable chemicals via hydrodeoxygenation. Noble metal catalysts, such as Pt, Ni, and Pd, are reported to exhibit high activity for hydrogen production. Carbon is one of promising catalyst support because they have no acid/base sites, which causes undesired reactions such as cracking and isomerization. On the other hand, the metal fine particles on carbon support are easily aggregated during the catalyst preparation and the reaction, leading to the deactivation of the catalyst. To maintain the metal particle size small, we developed a novel preparation method for carbon-supported Pt and Ni fine particles by using a cation-exchange resin and corresponding metal ammine complexes as initial materials of carbon support and metals, respectively. This preparation method consists of ion exchange at room temperature and carbonization of the metal-loaded resin at 500°C to convert the resin into carbon support. We succeeded in the preparation of Pt-Ni bimetal catalysts with the predetermined metal composition by using this method. The metal loading of the prepared catalysts was 25-49 wt% and the metal particle size was 2-4 nm. We applied the prepared catalysts to hydrogen production from formic acid. The obtained catalysts showed higher hydrogen production rates based on the reactor volume (44,100-2,020 Nm3-H<sub>2</sub>/(m3-reactor·h)) than the industrially required level (1,000 Nm3-H2/(m3-reactor·h)) due to the high metal loading and small metal particle size of the active metal. The bimetal catalyst exhibited higher turnover frequency than the single metal catalyst, suggesting that alloy formation enhanced the catalytic activity. Besides, metal catalysts, such as Cu and Ru, are considered to show high activity for hydrodeoxygenation of polyols derived from biomass to valuable diols. To inhibit side reactions such as C-C cleavage and dimerization of polyols over acid sites on catalyst support at temperatures above 200°C, the carbon-supported metal catalyst prepared from the ion-exchange resin was believed to be useful. We prepared a carbon-supported Cu catalyst in the same manner as the Pt and Ni loaded carbon catalyst. The prepared carbon-supported Cu catalyst possessed 67 wt% of metal loading and 15 nm of Cu metal particle size. This catalyst showed high selectivity of the conversion of erythritol (C4H<sub>6</sub>(OH)<sub>4</sub>) into butanediols. It was worthwhile to point out that the vicinal diols, that is 1,2-butanediol and 2,3-butanediol, were mainly obtained. This result implies that the vicinal OH groups are adsorbed on Cu particle in the prepared catalyst and the OH groups which were not involved in the adsorption was reacted with hydrogen. In conclusion, carbon-supported metal nanoparticle catalysts were successfully prepared by using ion-exchange resin. The prepared catalyst showed high activity for hydrogen production and selective hydrodeoxygenation of polyols because of high metal loading and small metal particle size.
Impact of Planning Target Volume Margins in Stereotactic Radiosurgery for Brain Metastasis: A Review
Fiagbedzi Emmanuel,Hasford Francis,Tagoe Samuel Nii 한국의학물리학회 2024 의학물리 Vol.35 No.1
Margin inclusion or exclusion remains the most critical and controversial aspect of stereotactic radiosurgery (SRS) for metastatic brain tumors. This review aimed to examine the available literature on the impact of margins in SRS of brain metastasis and to assess the response of some medical physicists on the use of these margins. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses method was used to review articles published in PubMed, Embase, and Science Direct databases from January 2012 to December 2022 using the following keywords: planning target volume, brain metastasis, margin, and stereotactic radiosurgery. A simple survey consisting of five questions was completed by ten medical physicists with experience in SRS treatment planning. The results were analyzed using IBM SPSS Statistics version 26.0. Of the 1,445 articles identified, only 38 articles were chosen. Of these, eight papers were deemed relevant to the focus of this review. These papers showed an increase in the risk of radionecrosis, whereas differences in local control were variable as the margin increased. In the survey, the response rate to whether or not to use margins in SRS, a critical question, was 50%. Margin addition increases the risk of radio necrosis. The local control rate varies among treatment modalities and cannot be generalized. From the survey, no consensus was reached regarding the use of these margins. This calls for further deliberations among professionals directly involved in SRS.