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Basic Studies on the Development of a Microbial Pesticide Bacillus thuringiensis (Bacillus thuringiensis을 이용한 미생물 살충제에 관한 연구)

  • 이형환;김기상
    • Microbiology and Biotechnology Letters
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    • v.11 no.3
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    • pp.223-231
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    • 1983
  • The productions of beta-exotoxin from sixteen Bacillus thuringiensis strains were examined by Micrococus flava primarily, and then measured by spectrophotometer during culturing in Conner and Hansen mineral salts medium at 28$^{\circ}C$. Also the toxic effects of the toxin to mice were checked. The growth of Bacillus thuringiensis K2 and BTK2-T1, -T13, -T33 and -T40 got into stationary phase at 6 hour culture and then maintained it up to 48 hours without severe fluctuation. The production of beta-exotoxin from the strains, BTK2, BTK2-T1, -T13, -T17 and -T33 appeared at 6 hour culture and the amounts of the toxin were about 40 $\mu\textrm{g}$/$m\ell$ at 6 hour culture, approximately 70 $\mu\textrm{g}$/$m\ell$ at 12 hours, approximately 85$\mu\textrm{g}$/$m\ell$ from 24 hours to 48 hours. At 48 hour-culture, BTK2 produced 80 $\mu\textrm{g}$/$m\ell$ of beta-exotoxin (5.5$\times$10$^{8}$ cells/$m\ell$, BTK2-T13 produced 84 $\mu\textrm{g}$/$m\ell$ (4.3$\times$10$^{8}$ cells/$m\ell$), BTK2-T17 produced 87$\mu\textrm{g}$/$m\ell$ (1.4$\times$10$^{8}$ cells/$m\ell$), and BTK2-T33 produced 84 $\mu\textrm{g}$/$m\ell$ (4.9$\times$10$^{8}$ cells/$m\ell$). All other serotypes also produced beta-exotoxin. At 48 hour culture, BTK-37 produced 88$\mu\textrm{g}$/$m\ell$ (6.1$\times$10$^{8}$ cells/$m\ell$), BTK-35 produced 81 $\mu\textrm{g}$/$m\ell$), and the rest of them produced less than 70 $\mu\textrm{g}$/$m\ell$. To check the toxicity of beta-exotoxin and B. thuringiensis, the cultured media with microorganisms were inoculated to mice by per os, intraperiloneal, subcutaneous and intracerebral injection, and nasal cavity inoculation for 30 days. However, the toxin did not kill all of the treated mice.

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Continuous Removal of Organic Matters of Eutrophic Lake Using Freshwater Bivalves: Inter-specific and Intra-specific Differences (CROM를 이용한 부영양 저수지의 유기물 제어: 이매패의 종 특이성에 대하여)

  • Lee, Ju-Hwan;Hwang, Soon-Jin;Park, Sen-Gu;Hwang, Su-Ok;Yu, Chun-Man;Kim, Baik-Ho
    • Korean Journal of Ecology and Environment
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    • v.42 no.3
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    • pp.350-363
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    • 2009
  • Inter- and intra-specific differences in removal activities, filtering rates (FR) and production of feces-and pseudo-feces (PF) between a native freshwater bivalve in Korea, Anodonta woodiana Lea and Unio douglasiae Griffith et Pidgeon, were compared using a continuous removal of organic matters (CROM) system. The CROM system comprised five steps; input of polluted water, control of water flow, mussel treatment, analysis of water quality and discharge of clean water. The study was designed to compare the removal activity of organic matters between A. woodiana and U. douglasiae, and the intra-specific differences between density and length in A. woordiana. Results clearly indicate that two kinds of mussels had obvious removal activities of seston in the eutrophic reservoir. First, if both are similar in shell length, there were no significant inter-specific differences in removal activity between A. woordiana and U. douglasiae (P>0.5), but FRs of U. douglasiae was relatively high due to low ash-fee dry weight. Second, if both are same in animal density, the smaller mussels (1$\sim$2 years old) showed a higher filtering rate and production of feces- and pseudo-feces and less release of ammonium than the larger mussels. Third, if both are same in biomass, FRs and PF of mussels were higher in the low-density tank than the high-density tank, While the Concentration of $NH_4$-N and $PO_4$-P released WRS similar to each other (P>0.5). Therefore, these results suggest that CROM system using a young bivalve A. woordiana can be applied to control the nuisance seston in eutrophic lake system, if a relevant species and density were selected. Additional pilot tests to optimize the age and density of domestic bivalves were needed for the generalization of CROM operation.

Effect of Chlorine Dioxide Treatment on Microbial Safety and Quality of Saury during Storage (이산화염소 처리가 꽁치의 저장 기간 중 미생물학적 안전성 및 품질변화에 미치는 영향)

  • Kim, Sunkyoung;Ma, Yuhyun;Gu, Kyoungju;Lee, Yunjung;Kim, Eunjung;Song, Kyung-Bin
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.34 no.8
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    • pp.1258-1264
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    • 2005
  • We determined the effect of chlorine dioxide ($ClO_{2}$) treatment on microbial growth and quality of saury. Saury samples were treated with aqueous $ClO_{2}$ at 3, 10, and 50 ppm. After the treatment, saury samples were stored at -20$^{\circ}C$ and 4$ ^{\circ}C$, respectively. Saury samples treated with $ClO_{2}$ had significantly lower total bacterial counts during storage. In particular, treatment of 50 rpm $ClO_{2}$ decreased total bacterial count most significantly among the $ClO_{2}$ treated saury samples. After 4 days, populations of total bacteria for the control reached 6.43 log CFU/g, while the sample treated with 50 ppm of $ClO_{2}$ had 5.47 log CFU/g at the 9th day of storage. $ClO_{2}$ treatment also delayed increase in the population of psychrotrophic bacteria on saury. The pH of saury samples decreased with increase of $ClO_{2}$ concentration. Volatile basic nitrogen (VBN) and thiobarbituric acid reactive substance (TBARS ) values of saury samples increased during storage, regardless of $ClO_{2}$ concentration. Sen-sory evaluation of saury samples showed that treatment with $ClO_{2}$ could improve the quality of saury. These results indicate that $ClO_{2}$ treatment could be useful in improving microbial safety and quality of saury.

Die Korrelation zwischen der DG und GB-Theorie (의존문법과 생성문법 간의 상호관계)

  • Rhie Jum-Chool
    • Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
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    • v.5
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    • pp.143-166
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    • 2002
  • Das Ziel dieses Aufsatzes liegt darin, auf Grund der Theorien von einigen Grammatikern die Korrelation zwischen der Dependenzgrammatik (=DG) und GB­Theorie(=GB) zu beschreiben. Nach Eroms(2000) sind VPn in eine engere Phrase, die die $Erg\"{a}nzungen$ in obliquen Kasus bindet, und eine $\"{a}u{\ss}ere$, die Subjektsvalenz abbindet, zu trennen. Dem INFL-Phrasenkopf der GB entspricht das Finitheitsmorphem in der DG. In der $herk\"{o}mmlichen$ DG steht das Verb an der Spitze des Satzes, aber Eroms(2000) stellt S an die Satzspitze. Die S(mit S., S?, S!) sind $n\"{a}mlich$ oberstes Element des Satzes, von dem alle anderen $W\"{o}rter\;abh\"{a}ngig$ sind. Die Konjunktionen regieren ihren Satz, bzw. der Satz wird durch sie gesteuert. Damit ist die Analogie zur X-bar-Syntax $vollst\"{a}ndig$. Nach Vater(l996) lasst sich die Struktur der deutschen VP systernatisch nach dem X-bar-Schema darstellen, wobei die Zuordnung der Objekte mehrere $M\"{o}glichkeiten\;zul\"{a}sst$. X-bar-Regeln allein $k\"{o}nnen$ nicht die Vielfalt $m\"{o}glicher$ VP-Strukturen erzeugen. Hier greifen V-bar-Regeln und Valenz ineinander. Vater(l996) $schl\"{a}gt$ vor, den von $\'{A}gel(1993)$ vorgeschlagenen Unterschied zwischen Valenzpotenz und Valenzrealisierung zu $ber\"{u}cksichtigen$, um die verschiedenen syntaktischen und morphologischen Realisierungen zwischen verschiedenen Sprachen in den Griff zu bekommen. $\'{A}gel(1993, 2000)$ nimmt in Anlehnung an $L\'{a}szlo(l988)$ zwei Realisierungsebenen der Valenz, die Mikroebene(=die der morphologischen Aktanten) und die Makroebene(=die der syntaktischen Aktanten) an. Der $Tr\"{a}ger$ auf Mikroebene ist der Mikroaktant, also der Teil des Verbflexivs, der $Tr\"{a}ger$ auf Makroebene ist der Makroaktant, also das syntaktische Subjekt. Die Begriffe 'Mikroebene' und 'Makroebene' werden sowohl statisch und als auch dynamisch interpretiert. Auf Grund dieser Begriffe versucht $\'{A}gel(1993, 2000)$, nach Parallelen der Valenzrealisierung in S und NP zu suchen. Aber die Untersuchung der $Valenzrealisierungsverh\"{a}ltnisse$ in der NP wird zu einem scheinbaren typologischen Gegensatz zwischen S und NP $f\"{u}hren$. Um diesen Gegensatz $aufzul\"{o}sen$, wird das Konzept 'finites Substantiv' $eingef\"{u}hrt$, das analog zum Konzept 'finites Verb' ist. Dabei wird die sog. starke Adjektivflexion in einen Teil der Substantivflexion uminterpretiert. Die GB-Theorie definiert sich als eine Theorie der sog. mentalen Grammatik, des $Sprachverm\"{o}gens$. Da als der Gegenstand der DG die sog. objektive Grammatik angesehen werden kann, scheint der grundlegende Unterschied zwischen den $Gegenst\"{a}nden$ beider Theorien in der Opposition 'intem(=mental vs. extern (=objektiv)' zu liegen. Da die GB eine 'naturwissenschaftlicher' organisierte Theorie ist als die empirische Richtung der DG, ware eine Vergleichsgrundlage in der Tat nicht einfach zu etablieren. Obwohl die beiden Theorien von $v\"{o}llig$ anderen Voraussetzungen und Zielsetzungen ausgehen, gibt es zwischen der DG und der GB $\"{U}berlappungen$ und zunehmende $Ann\"{a}herungen$. Generell ist es notwendig, dass Teileinsichten aus einer Theorie in eine andere Theorie $\"{u}bernommen$ werden. In diesem Aufsatz konnten wir durch die Untersuchung der Korrelation von beiden Theorien partielle Konvergenzen erkennen. Nach Engel(l994) gibt es keine Grammatik 'an sich', sie wird von Grammatikern gemacht. Grammatiken sind Menschenwerk und Linguistenwerk. Wir sind auf der Suche nach 'einer besseren Grammatik.'

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A Study of The planting Arrangement of Ornamental Trees And Shrubs in Intermane Buddhist Temples. (산지형 사찰에 있어 조경식물 배치형식에 관한 연구)

  • Shim, Jai-Sung;Bae, Jeong-Kwan;Seo, Byung-Key
    • The Journal of Natural Sciences
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    • v.14 no.1
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    • pp.63-81
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    • 2004
  • It is the purpose of this study to arrange in ornamental trees and shrubs the planting that leads to an appropriate type of templescape. The study was designed primarily as an examples for each Buddhist temple which desires further decoration with several ornamental plants, doubles the effectiveness of the Sen-Buddhist meditation, and boosts tourists' attraction. To investigate the planting status and type of trees and shrubs in the precincts of Buddhism temples, We close three temples : They are Nagsansa, Boolgoogsa and Booseugsa, which are intermonatane area temples all together. The results investigated were summarized as follows :1. Planting status and pattern in temples Open spaces of the Daewoogjeon in all temples, a main Sanctuaries in temple buildings, where Buddha is enshrined in, we could not find any kind of trees of shrubs to be planted.Muryangsujeon, a symbol of "Future", which can be also found at Boosugsa temple, is living in Western Elysium world and takes mercy on mankind of this life. Taxus cuspidata was planted at this Muryangsujeon, known as an immeasurable bliss building, where an Amitabha is enshrined in.Total 25 species of trees and shrubs were planted around Birozani building of Buddhist temples, Birozani is enshrined at the Birojion of Boollgoogsa temple.The buddhist Goddess of Mercy which is a buddhist saint for pursuit of fortune and blessing to relieve the mankind is enshrined at Wonchonjeon, Daebijeon and Kwaneumjeon which are able to observe at both Boolgoogsa and Nagsnsa temples, where Euonymus japonicus trees including other 26 species could be found in common at both temples.2. Correlation between trees/shrubs and temple buildingsTrees and flowers symbolizing Buddha are often planted as material sources of gardening to decorate : They are Logerstroemia indica as Buddha's flower, Viburmum opulus var. calvescens resembling Buddha's head, Tilia mandshurica producing the beads of rosary, Gardenia jaminoides Ellis with white flower blade and flower of bliss, not flower to this day and Lotus flowering clearly in the pond filling with dirty water which is able to clarifies the world full of crime, infidelity and injustification. Among these Buddhist' plants, however, Logerstroemia indica could be found in all three temples, and Viburmum opulus var. calvescens at both Nagsansa and Boosugsa. Also, Lager stroemia indica was planted at all three temples and Viburmum opulus var. calvescens at both temples of Nagsansa and Boosugsa. Tilia mandshurica and Gardenia jasminoides Ellis were not found in any temples which might become the subject of investigation.In relation of the buildings of each temples as a sanctified space, the planting of trees and shrubs was not considered for the arrangement, templescape architecture or species. And, also, we could not find in the study any special relationship of trees/ shrubs with the characteristics of temples.With the results obtained through precise studies we presented here in this paper newly designed model of templescape in intermane buddhist temple which can be applied for planting and arrangement of trees or/and shrubs. Basic principles of model in mind are:To consider the correlation of the dominant between plants and temple buildings.To plant trees/shrubs for special functions as well as conditions of temple location.To make tree arrangement correlating to Buddhism spirit.To induce environment friendly plants to be planted, suitable to regional conditions.This redecorated model of templescape might be used as a canon of the tree planting and arrangement in the precincts of Buddhism temples.

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A Study of the Degree of Obesity in Elementary School Students according to Grade and Gender (초등학생의 학년별 성별 비만실태)

  • Cho, In-sook;Park, In-hyae;Ryu, Hyun-sook;Park, Yo-sup;Hwang, Sen-lye;Ahan, hyun-hee
    • Journal of agricultural medicine and community health
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    • v.31 no.2
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    • pp.177-185
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    • 2006
  • Objectives: This study was carried out with 31, 519(16,653 boys, 14,857 girls) of elementary school students to investigate the prevalence of obesity at a district in Gwangju City. It can be applied to develope an educational program of the obesity control as basic data in this local area Methods: The data collected from May, 2004 to July, 2004 were analyzed by SAS PC+ 8.0 program. Children were selected depending on criteria from obesity index (%) by using physical index (height, body weight), and then subjects were classified into one of three groups according to the degree of obesity: mild(20~29.9%), moderate(30~49.9%), and severe($?50%{\cdot}$) obesity. Results: It showed that male elementary school students were higher and heavier than female elementary school students(p< .001) in every grade except the 4th grade(height) and the 6th grade ( body weight). The obesity rates of male students(11.6%) showed higher(p< .001) than those of female students(8.8%). Specially the 4th grade elementary school boys were higher than any other groups in obesity(13.7%). As a whole, the prevalence of obestiy showed mild(5.9%), moderate(3.8%), and severe(0.6%). Male students showed higher rate of obesity than those of female students. The obesity of male students showed higher rate than that of female students except 2-3rd grade elementary school students(p< .001). The obesity of 4~6th grade elementary school students showed higher rate than those of 1~3rd grade students(p< .001). Conclusions: The obesity rates of male students are higher than that of female students, and the obesity rates of 4~6th grade students are higher than those of 1-3rd grade students in the elementary school. Additionally, these results suggest that the program may be needed to prevent obesity of children.

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F. H. Jacobi und Spinoza-Streit (야코비와 스피노자 논쟁)

  • Choi, Shin-Hann
    • Journal of Korean Philosophical Society
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    • v.129
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    • pp.315-339
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    • 2014
  • Diese Abhandlung untersucht Jacobis ${\ddot{U}}ber$ die Lehre Spinoza und den von diesem veranlassten Spinoza-Streit. Damit sie $enth{\ddot{u}}llt$ zuerst Jacobischen Zusammenhang zwischen transzent und immanent und folgt auf seine Wirkungsgeschichte in der Moderne. Ich rekonstruiere den Streit zwischen Jacobi und Lessing und danach interpretiere dessen Rezeption durch Hegel und Schleiermacher. Lessing stellt anstatt der traditionellen Begriffe der Gottheit ἑν ${\kappa}{\alpha}{\iota}$ ${\pi}{\alpha}{\nu}$ auf. $Demgegen{\ddot{u}}ber$ behauptet Jacobi Salto mortale um ihn ${\ddot{u}}berschreiten$ zu $k{\ddot{o}}nnen$, indem er Lessing als Pantheist und Atheist bestimmt. Salto mortale bei Jacobi ist der Sprung zu dem ${\ddot{U}}bernat{\ddot{u}}rlichen$ und dem Glaube. Der Streit zwischen Jacobi und Lessing ist der zwischen dem Naturalismus und ${\ddot{U}}bernaturalismus$ und $dar{\ddot{u}}berhinaus$ der zwischen dem Athismus und Theismus. $W{\ddot{a}}hrend$ die Natur der Inbegriff der Bedingten ist, ist Gott der absolute Anfang der Natur $au{\ss}erhalb$ des Naturzusammenhangs. $W{\ddot{a}}hrend$ Spinoza Gott im $nat{\ddot{u}}rlichen$ Zusammenhang begreift, $fa{\ss}t$ Jacobi den im ${\ddot{u}}bernat{\ddot{u}}rlichen$ auf. Deus sive natura bei Spinoza $ver{\ddot{a}}ndert$ sich Gott im Menschen bei Jacobi. Gott im Menschen ist nichts anders als das Prinzip des Lebens und das aller Vernuft. In diesem Zusammenhang $fa{\ss}t$ Hegel Gott als Geist denn Subjekt des Lebens auf und $h{\ddot{a}}lt$ das Wesen des Geistes $f{\ddot{u}}r$ die sich selbst vermittelnde Bewegung. Dies zeigt sich als die Spinoza ${\ddot{u}}berbietende$ Immanenzphilosophie. $Demgegen{\ddot{u}}ber$ behauptet Schleiermacher die Einheit des Endlichen und Unendlichen in der $religi{\ddot{o}}sen$ Anschuung. Die Verbindung von Mensch und Gott ist die im Endlichen immanent bleibende Anschauung der $g{\ddot{o}}ttlichen$ Eigenschaft. Dies zeigt das transzendente im immanenten.

Die dialektische Aporetik bei Aristoteles und ihre methodologische Funktion (아리스토텔레스에게서 아포리아의 변증적 탐구술과 그 방법론적 기능)

  • Lee, Jae-hyun
    • Journal of Korean Philosophical Society
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    • v.126
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    • pp.263-293
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    • 2013
  • Die vorliegende Abhandlung beachtet die methodologische $N{\ddot{u}}tzlichkeit$ der Dialektik $f{\ddot{u}}r$ die philosophische $Wissenschaftst{\ddot{a}}tigkeit$ des Aristoteles in einer besonderen Aufmerksamkeit auf den Begriff "${\delta}{\iota}{\alpha}{\pi}o{\rho}{\varepsilon}{\iota}{\nu}$". Bei Aristoteles bedeutet "${\delta}{\iota}{\alpha}{\pi}o{\rho}{\varepsilon}{\iota}{\nu}$" 'das durchaus $gr{\ddot{u}}ndliche$ Untersuchen einer Aporie', und eine solche Untersuchungsweise folgt der Dialektik. Deshalb beabsichtige ich zuerst, durch eine Begriffsanalyse und - interpretation von "${\delta}{\iota}{\alpha}{\pi}o{\rho}{\varepsilon}{\iota}{\nu}$" die dialektische Aporetik zu bestimmen als eine Argumentationsmethode nicht nur in einer dialogischen, sondern auch in einer nicht-dialogischen Situation. Besonders will ich einen methodologischen Grund $daf{\ddot{u}}r$ suchen, dass ein allein Forschender in der nicht-dialogischen Situation die dialektische Aporetik verwendet, indem ich einen Text von "De caelo" II 13, 294b 6~13 interpretiere. $N{\ddot{a}}mlich$ betont Aristoteles in Bezug auf den Durchgang der $Wissenschaftst{\ddot{a}}tigkeit$ eine Forderung der selbstkritischen Haltung, die der allein Forschende sich selbst seine Untersuchung in $R{\ddot{u}}cksicht$ auf die anderen Untersuchungen und auch auf die vorhersehbaren Hypothesen ${\ddot{u}}berpr{\ddot{u}}fen$ und verifizieren, um die aus seiner Untersuchung zu entdeckenden Aporien auf die dialektische Weise zu $l{\ddot{o}}sen$. Und diese Position von Aristoteles kann der wichtige Grund $daf{\ddot{u}}r$ sein, den fachsprachlichen Sinn von "${\delta}{\iota}{\alpha}{\pi}o{\rho}{\varepsilon}{\iota}{\nu}$" als auch den wissenschaftlichen Sinn der dialektischen Untersuchung der Aporie richtig verstehen und $erkl{\ddot{a}}ren$ zu $k{\ddot{o}}nnen$. Zuletzt bin ich in der Absicht, die dialektische Aporetik und ihre Funktion in drei Modeln zu formulieren und einige Beispiele $f{\ddot{u}}r$ jedes Model vorzustellen, um zu zeigen, auf welche Art und Weise Aristoteles die dialektische Aporetik $f{\ddot{u}}r$ den Lauf seiner Theoriebildung in der Tat anwendet. Durch solchen Versuch $w{\ddot{u}}nsche$ ich, dass meine Untersuchung ${\ddot{u}}ber$ die dialektische Aporetik etwas besseres $Verst{\ddot{a}}ndnis$ $f{\ddot{u}}r$ die wissenschaftliche Bedeutung der aristotelischen Dialektik anbieten $k{\ddot{o}}nnte$, und auch dass diese Studie als bedeutsame Basisdaten zu einer noch tieferen Forschung und $Verst{\ddot{a}}ndigung$ ${\ddot{u}}ber$ die philosophische Haltung und Methode des Aristoteles betrachtet werden $k{\ddot{o}}nnte$.

Heavy concrete shielding properties for carbon therapy

  • Jin-Long Wang;Jiade J Lu;Da-Jun Ding;Wen-Hua Jiang;Ya-Dong Li;Rui Qiu;Hui Zhang;Xiao-Zhong Wang;Huo-Sheng Ruan;Yan-Bing Teng;Xiao-Guang Wu;Yun Zheng;Zi-Hao Zhao;Kai-Zhong Liao;Huan-Cheng Mai;Xiao-Dong Wang;Ke Peng;Wei Wang;Zhan Tang;Zhao-Yan Yu;Zhen Wu;Hong-Hu Song;Shuo-Yang Wei;Sen-Lin Mao;Jun Xu;Jing Tao;Min-Qiang Zhang;Xi-Qiang Xue;Ming Wang
    • Nuclear Engineering and Technology
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    • v.55 no.6
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    • pp.2335-2347
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    • 2023
  • As medical facilities are usually built at urban areas, special concrete aggregates and evaluation methods are needed to optimize the design of concrete walls by balancing density, thickness, material composition, cost, and other factors. Carbon treatment rooms require a high radiation shielding requirement, as the neutron yield from carbon therapy is much higher than the neutron yield of protons. In this case study, the maximum carbon energy is 430 MeV/u and the maximum current is 0.27 nA from a hybrid particle therapy system. Hospital or facility construction should consider this requirement to design a special heavy concrete. In this work, magnetite is adopted as the major aggregate. Density is determined mainly by the major aggregate content of magnetite, and a heavy concrete test block was constructed for structural tests. The compressive strength is 35.7 MPa. The density ranges from 3.65 g/cm3 to 4.14 g/cm3, and the iron mass content ranges from 53.78% to 60.38% from the 12 cored sample measurements. It was found that there is a linear relationship between density and iron content, and mixing impurities should be the major reason leading to the nonuniform element and density distribution. The effect of this nonuniformity on radiation shielding properties for a carbon treatment room is investigated by three groups of Monte Carlo simulations. Higher density dominates to reduce shielding thickness. However, a higher content of high-Z elements will weaken the shielding strength, especially at a lower dose rate threshold and vice versa. The weakened side effect of a high iron content on the shielding property is obvious at 2.5 µSv=h. Therefore, we should not blindly pursue high Z content in engineering. If the thickness is constrained to 2 m, then the density can be reduced to 3.3 g/cm3, which will save cost by reducing the magnetite composition with 50.44% iron content. If a higher density of 3.9 g/cm3 with 57.65% iron content is selected for construction, then the thickness of the wall can be reduced to 174.2 cm, which will save space for equipment installation.

Exploring the Role of Preference Heterogeneity and Causal Attribution in Online Ratings Dynamics

  • Chu, Wujin;Roh, Minjung
    • Asia Marketing Journal
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    • v.15 no.4
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    • pp.61-101
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    • 2014
  • This study investigates when and how disagreements in online customer ratings prompt more favorable product evaluations. Among the three metrics of volume, valence, and variance that feature in the research on online customer ratings, volume and valence have exhibited consistently positive patterns in their effects on product sales or evaluations (e.g., Dellarocas, Zhang, and Awad 2007; Liu 2006). Ratings variance, or the degree of disagreement among reviewers, however, has shown rather mixed results, with some studies reporting positive effects on product sales (e.g., Clement, Proppe, and Rott 2007) while others finding negative effects on product evaluations (e.g., Zhu and Zhang 2010). This study aims to resolve these contradictory findings by introducing preference heterogeneity as a possible moderator and causal attribution as a mediator to account for the moderating effect. The main proposition of this study is that when preference heterogeneity is perceived as high, a disagreement in ratings is attributed more to reviewers' different preferences than to unreliable product quality, which in turn prompts better quality evaluations of a product. Because disagreements mostly result from differences in reviewers' tastes or the low reliability of a product's quality (Mizerski 1982; Sen and Lerman 2007), a greater level of attribution to reviewer tastes can mitigate the negative effect of disagreement on product evaluations. Specifically, if consumers infer that reviewers' heterogeneous preferences result in subjectively different experiences and thereby highly diverse ratings, they would not disregard the overall quality of a product. However, if consumers infer that reviewers' preferences are quite homogeneous and thus the low reliability of the product quality contributes to such disagreements, they would discount the overall product quality. Therefore, consumers would respond more favorably to disagreements in ratings when preference heterogeneity is perceived as high rather than low. This study furthermore extends this prediction to the various levels of average ratings. The heuristicsystematic processing model so far indicates that the engagement in effortful systematic processing occurs only when sufficient motivation is present (Hann et al. 2007; Maheswaran and Chaiken 1991; Martin and Davies 1998). One of the key factors affecting this motivation is the aspiration level of the decision maker. Only under conditions that meet or exceed his aspiration level does he tend to engage in systematic processing (Patzelt and Shepherd 2008; Stephanous and Sage 1987). Therefore, systematic causal attribution processing regarding ratings variance is likely more activated when the average rating is high enough to meet the aspiration level than when it is too low to meet it. Considering that the interaction between ratings variance and preference heterogeneity occurs through the mediation of causal attribution, this greater activation of causal attribution in high versus low average ratings would lead to more pronounced interaction between ratings variance and preference heterogeneity in high versus low average ratings. Overall, this study proposes that the interaction between ratings variance and preference heterogeneity is more pronounced when the average rating is high as compared to when it is low. Two laboratory studies lend support to these predictions. Study 1 reveals that participants exposed to a high-preference heterogeneity book title (i.e., a novel) attributed disagreement in ratings more to reviewers' tastes, and thereby more favorably evaluated books with such ratings, compared to those exposed to a low-preference heterogeneity title (i.e., an English listening practice book). Study 2 then extended these findings to the various levels of average ratings and found that this greater preference for disagreement options under high preference heterogeneity is more pronounced when the average rating is high compared to when it is low. This study makes an important theoretical contribution to the online customer ratings literature by showing that preference heterogeneity serves as a key moderator of the effect of ratings variance on product evaluations and that causal attribution acts as a mediator of this moderation effect. A more comprehensive picture of the interplay among ratings variance, preference heterogeneity, and average ratings is also provided by revealing that the interaction between ratings variance and preference heterogeneity varies as a function of the average rating. In addition, this work provides some significant managerial implications for marketers in terms of how they manage word of mouth. Because a lack of consensus creates some uncertainty and anxiety over the given information, consumers experience a psychological burden regarding their choice of a product when ratings show disagreement. The results of this study offer a way to address this problem. By explicitly clarifying that there are many more differences in tastes among reviewers than expected, marketers can allow consumers to speculate that differing tastes of reviewers rather than an uncertain or poor product quality contribute to such conflicts in ratings. Thus, when fierce disagreements are observed in the WOM arena, marketers are advised to communicate to consumers that diverse, rather than uniform, tastes govern reviews and evaluations of products.

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