• Title/Summary/Keyword: Kim's model

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Removal Properties of Methylene Blue using Biochar Prepared from Street Tree Pruning Branches and Household Wood Waste (가로수 전정가지 및 생활계 폐목재를 이용하여 제조한 바이오차의 Methylene Blue 흡착특성)

  • Do, Ji-Young;Kim, Dong-Su;Park, Kyung-Chul;Park, Sam-Bae;Chang, Yoon-Young;Yang, Jae-Kyu
    • Journal of the Korea Organic Resources Recycling Association
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    • v.30 no.3
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    • pp.13-22
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    • 2022
  • In order to improve water quality of the water system contaminated with dyes, biochars prepared using discarded waste resources were applied in this study. Biochars with a large specific surface area were manufactured using street tree pruning products or waste wood, and were applied to remove an organic dye in synthetic water. Biochars were made by pyrolysis of typical street tree porch products (Platanas, Ginkgo, Aak) and waste wood under air-controlled conditions. Methylene blue (MB), which is widely used in phosphofibers, paper, leather, and cotton media, was selected in this study. The adsorption capacity of Platanas for MB was the highest and the qmax value obtained using the Langmuir model equation was 78.47 mg/g. In addition, the adsorption energy (E) (kJ/mol) of MB using the Dubinin-Radushkevich (D-R) model equation was 4.891 kJ/mol which was less than 8 kJ/mol (a criteria distinguishing physical adsorption from chemical adsorption). This result suggests a physical adsorption with weak interactions such as van der Waals force between the biochar and MB. In addition, the physical adsorption may resulted from that Platanas-based biohar has the largest specific surface area and pore volume. The ∆G value obtained through the adsorption experiment according to temperature variation was -3.67 to -7.68, which also suggests a physical adsorption. Considering these adsorption results, the adsorption of MB onto Platanas-based biochar seems to occur through physical adsorption. Overall, it was possible to suggest that adsorption capacity of the biochr prepared from this study was equal to or greater than that of commercial activated carbon reported in other studies.

Optimization of the Indole-3-Acetic Acid Production Medium of Pantoea agglomerans SRCM 119864 using Response Surface Methodology (반응표면분석법을 활용한 Pantoea agglomerans SRCM 119864의 Indole-3-acetic acid 생산 배지 최적화)

  • Ho Jin, Jeong;Gwangsu, Ha;Su Ji, Jeong;Myeong Seon, Ryu;JinWon, Kim;Do-Youn, Jeong;Hee-Jong, Yang
    • Journal of Life Science
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    • v.32 no.11
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    • pp.872-881
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    • 2022
  • In this study, we optimized the composition of the indole-3-acetic acid (IAA) production medium using response surface methodology on Pantoea agglomerans SRCM 119864 isolated from soil. IAA-producing P. aglomerans SRCM 119864 was identified by 16S rRNA gene sequencing. There are 11 intermediate components known to affect IAA production, hence the effect of each component on IAA production was investigated using a Plackett-Burman design (PBD). Based on the PBD, sucrose, tryptone, and sodium chloride were selected as the main factors that enhanced the IAA production at optimal L-tryptophan concentration. The predicted maximum IAA production (64.34 mg/l) was obtained for a concentration of sucrose of 13.38 g/l, of tryptone of 18.34 g/l, of sodium chloride of 9.71 g/l, and of L-tryptophan of 6.25 g/l using a the hybrid design experimental model. In the experiment, the nutrient broth medium supplemented with 0.1% L-tryptophan as the basal medium produced 45.24 mg/l of IAA, whereas the optimized medium produced 65.40 mg/l of IAA, resulting in a 44.56% increase in efficiency. It was confirmed that the IAA production of the designed optimal composition medium was very similar to the predicted IAA production. The statistical significance and suitability of the experimental model were verified through analysis of variance (ANOVA). Therefore, in this study, we determined the optimal growth medium concentration for the maximum production of IAA, which can contribute to sustainable agriculture and increase crop yield.

Research on the Ethical Characteristics of 'Mutual Beneficence' Shown in the Principle of 'Guarding against Self-deception' in Daesoon Thought: in Comparison to Kantian and Utilitarian Ethical Views (대순사상의 무자기(無自欺)에 나타난 상생윤리 - 칸트와 밀의 윤리관과의 대비를 중심으로 -)

  • Kim, Tae-soo
    • Journal of the Daesoon Academy of Sciences
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    • v.27
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    • pp.283-317
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    • 2016
  • This research is an attempt to detail the multi-layered ethical characteristics of 'mutual beneficence', shown in the principle of 'guarding against self-deception' in Daesoon Thought while focusing on its major differences as well as the similarities with Kantian and Utilitarian ethical views. In these Western ethical perspectives, the concept of self-deception has received a considerable amount of attention, centering on the context of natural rights and contract theory. Meanwhile, in Daesoon Thought, 'guarding against self-deception' is presented as one of the principal objectives as well as the method or deontological ground for practice. It further encompasses the features of virtue ethics oriented toward the perfection of Dao. Here, the deontological aspect is interlinked with the concept of cultivation and the pursuit of ethics and morals. Hence this makes it a necessary condition for achieving the perfection of Dao, and likewise renders the practice of 'guarding against self-deception' more active through facilitating mutual relations based on the expansion model wherein human nature is characterized as possessing innate goodness. With regard to the tenet of 'resolution of grievances for mutual beneficence,' this concept is presented as a positive ground for practicing virtues toward others without forming grudges. Furthermore, as long as it reveals the great principle of humanity built on conscience, it will come to harmonize practitioners with others and spirits in an expression of beneficence. Moreover, originating in the Dao of Deities, guarding against self-deception is expressed as a form of life ethics and can be suggested as a new alternative for the model of virtue ethics proposed by Nussbaum. All in all, there is a natural causal relationship by which 'guarding against self-deception' in accord one's own conscience and the principle of humanity as a pursuit of perfect virtues in Dao result in the fulfillment of mutual beneficence. This readily akin to how gravity causes water to flow from high ground to low ground. Consequently, these relational features of mutual beneficence can serve an effective alternative to the Western ethical views which also address the need to overcome the egoistic mind which is liable to self-interest and alienation.

Development of Seasonal Habitat Suitability Indices for the Todarodes Pacificus around South Korea Based on GOCI Data (GOCI 자료를 활용한 한국 연근해 살오징어의 계절별 서식적합지수 모델 개발)

  • Seonju Lee;Jong-Kuk Choi;Myung-Sook Park;Sang Woo Kim
    • Korean Journal of Remote Sensing
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    • v.39 no.6_2
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    • pp.1635-1650
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    • 2023
  • Under global warming, the steadily increasing sea surface temperature (SST) severely impacts marine ecosystems,such as the productivity decrease and change in marine species distribution. Recently, the catch of Todarodes Pacificus, one of South Korea's primary marine resources, has dramatically decreased. In this study, we analyze the marine environment that affects the formation of fishing grounds of Todarodes Pacificus and develop seasonal habitat suitability index (HSI) models based on various satellite data including Geostationary Ocean Color Imager (GOCI) data to continuously manage fisheries resources over Korean exclusive economic zone. About 83% of catches are found within the range of SST of 14.11-26.16℃,sea level height of 0.56-0.82 m, chlorophyll-a concentration of 0.31-1.52 mg m-3, and primary production of 580.96-1574.13 mg C m-2 day-1. The seasonal HSI models are developed using the Arithmetic Mean Model, which showed the best performance. Comparing the developed HSI value with the 2019 catch data, it is confirmed that the HSI model is valid because the fishing grounds are formed in different sea regions by season (East Sea in winter and Yellow Sea in summer) and the high HSI (> 0.6) concurrences to areas with the high catch. In addition, we identified the significant increasing trend in SST over study regions, which is highly related to the formation of fishing grounds of Todarodes Pacificus. We can expect the fishing grounds will be changed by accelerating ocean warming in the future. Continuous HSI monitoring is necessary to manage fisheries' spatial and temporal distribution.

Assessment of water supply reliability in the Geum River Basin using univariate climate response functions: a case study for changing instreamflow managements (단변량 기후반응함수를 이용한 금강수계 이수안전도 평가: 하천유지유량 관리 변화를 고려한 사례연구)

  • Kim, Daeha;Choi, Si Jung;Jang, Su Hyung;Kang, Dae Hu
    • Journal of Korea Water Resources Association
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    • v.56 no.12
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    • pp.993-1003
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    • 2023
  • Due to the increasing greenhouse gas emissions, the global mean temperature has risen by 1.1℃ compared to pre-industrial levels, and significant changes are expected in functioning of water supply systems. In this study, we assessed impacts of climate change and instreamflow management on water supply reliability in the Geum River basin, Korea. We proposed univariate climate response functions, where mean precipitation and potential evaporation were coupled as an explanatory variable, to assess impacts of climate stress on multiple water supply reliabilities. To this end, natural streamflows were generated in the 19 sub-basins with the conceptual GR6J model. Then, the simulated streamflows were input into the Water Evaluation And Planning (WEAP) model. The dynamic optimization by WEAP allowed us to assess water supply reliability against the 2020 water demand projections. Results showed that when minimizing the water shortage of the entire river basin under the 1991-2020 climate, water supply reliability was lowest in the Bocheongcheon among the sub-basins. In a scenario where the priority of instreamflow maintenance is adjusted to be the same as municipal and industrial water use, water supply reliability in the Bocheongcheon, Chogang, and Nonsancheon sub-basins significantly decreased. The stress tests with 325 sets of climate perturbations showed that water supply reliability in the three sub-basins considerably decreased under all the climate stresses, while the sub-basins connected to large infrastructures did not change significantly. When using the 2021-2050 climate projections with the stress test results, water supply reliability in the Geum River basin was expected to generally improve, but if the priority of instreamflow maintenance is increased, water shortage is expected to worsen in geographically isolated sub-basins. Here, we suggest that the climate response function can be established by a single explanatory variable to assess climate change impacts of many sub-basin's performance simultaneously.

Cognitive Improvement Effects of Krill Oil in a Scopolamine-induced Mice Model (Scopolamine 유도 인지 저하 마우스 모델에서 크릴 오일의 인지 개선 효과)

  • Hye-Min Seol;Jeong-Ah Lee;Mi-Sun Hwang;Sang-Hoon Park;Hyeong-Soo Kim
    • Journal of Life Science
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    • v.34 no.7
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    • pp.509-519
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    • 2024
  • A previous study showed that krill oil improved recognition and memory through anti-oxidative effects in an amyloid β model, but the authors noted that further investigations are necessary of alterations to neurotransmitters' states and of serum lipid profile improvements related to serum lipid peroxidation. Accordingly, in this study, ICR mice were pre-treated intraperitoneally with scopolamine prior to induced neurotransmission impairment, and the effects of krill oil provision on their capabilities of cognition were tested by performing a passive avoidance test (PAT), water maze test (WMT), and novel object recognition test. Then, parameters including the acetylcholine (ACh) concentration, acetylcholinesterase activity (AChE), lipid peroxidation, serum lipid levels, and nerve cell proliferation were investigated. The results showed that krill oil improved the mice's abilities in recognition and memory as the times taken to complete the PAT and WMT were reduced compared to the mice in a comparison scopolamine-treated group. Krill oil produced an increased concentration of Ach, and this was accompanied by a decrease in AChE. As shown in a scopolamine-treated SH-SY5Y cell line, krill oil reduced the activity of AChE. Moreover, the suppression of lipid peroxidation-reflected in the finding that malondialdehyde was decreased with krill oil provision-is speculated to affect the recorded serum triglyceride and cholesterol decreases and LDL cholesterol increase. The intake of krill oil was also found to produce an improvement in brain-derived neurotrophic factor expression by stimulating the activation of cyclic AMP response element binding protein in the brain tissue. Overall, the current results imply that the provision of krill oil raises the cognition and memory by elevating neurotransmitters and by improving the serum lipid profile and nerve cell proliferation, which occur as lipid peroxidation is suppressed in the brain tissue.

Precipitation Characteristics in Mountainous Regions During Changma Period in 2023 (2023년 장마기간 동안 산악지역의 강우 특성)

  • Inhye Kim;Keunchang Jang;Byung Oh Yoo
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.26 no.3
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    • pp.161-173
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    • 2024
  • In South Korea, 50-65% of the annual precipitation is concentrated during the summer monsoon season, which is called Changma. In 2023, extreme precipitation was observed during Changma period, and was recorded the highest amount in southern part of Korea. Extreme precipitation in forest region is one of significant factors related to the landslide. Therefore, accurate monitoring and understanding of precipitation patterns are crucial for preventing the landslide disasters in Changma period. This study investigated the precipitation patterns including precipitation intensity, duration, and total amount in mountainous and non-mountainous regions during the Changma period using dataset observed from the Korea Forest Service's Automatic Mountain Meteorology Observation Station (AMOS) and the Korea Meteorological Administration (KMA). Precipitation map produced from the Modified Korean-Parameter elevation Regressions an Independent Slopes Model (MK-PRISM) was also used to verify precipitation patterns in areas affected by landslides in Gyeongsangbuk-do province. The results used from precipitation observations revealed that the total amount of precipitation was greater at elevations such as mountainous regions. In particular, extreme precipitation events such as precipitation duration exceeding 50 hours with amount of over 300 mm and heavy rainfalls of over 30 mm/hr occurred at landslide areas including Mungyeong, Bonghwa, and Yeongju in Gyeongsangbuk-do province. Total amount of precipitation produced by MK-PRISM in these areas during Changma period were more than double compared with 30 years mean values obtained from KMA. The results conducted in this study indicate that it is essential to establish the thresolds considering recent precipitation patterns to effectively prepare and prevent for landslide disasters.

The Effects of the Perceived Motivation Type toward Corporate Social Responsibility Activities on Customer Loyalty (기업사회책임활동적인지인지동기류형대고객충성도적영향(企业社会责任活动的认知认知动机类型对顾客忠诚度的影响))

  • Kim, Kyung-Jin;Park, Jong-Chul
    • Journal of Global Scholars of Marketing Science
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    • v.19 no.3
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    • pp.5-16
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    • 2009
  • Corporate social responsibility (CSR) activities have been shown to be potential factors that can improve corporate image and increase the ability of corporations to compete. However, most previous studies related to CSR activities investigated how these activities influence product and corporate evaluation, as well as corporate image. In addition, some researchers treated consumers' perceptions of corporate motives as moderator variables in evaluating the relationship between corporate social responsibilities and consumer response. However, motive-based theories have some weaknesses. Corporate social responsibility activities cause two motives(egoistic vs. altruistic) for consumers, but recently, Vlachos et al. (2008) argued that these motives should be segmented. Thus, it is possible to transform the original theory into a modified theory model (persuasion knowledge model, PKM). Vlachos et al. (2008) segmented corporate social responsibility motives into four types and compared the effects of these motives on customer loyalty. Prior studies have proved that CSR activities with positive motives have positive influences on customer loyalty. However, the psychological reasons underlying this finding have not been determined empirically. Thus, the objectives of this research are twofold. First, we attempt to determine why most customers favor companies that they feel have positive motives for their corporate social responsibility activities. Second, we attempt to measure the effects of consumers' reciprocity when society benefits from corporate social responsibility activities. The following research hypotheses are constructed. H1: Values-driven motives for corporate social responsibility activities have a positive influence on the perceived reciprocity. H2: Stakeholder-driven motives for corporate social responsibility activities have a negative influence on the perceived reciprocity. H3: Egoistic-driven motives for corporate social responsibility activities have a negative influence on perceived reciprocity. H4: Strategic-driven motives for corporate social responsibility activities have a negative influence on perceived reciprocity. H5: Perceived reciprocity for corporate social responsibility activities has a positive influence on consumer loyalty. A single company is selected as a research subject to understand how the motives behind corporate social responsibility influence consumers' perceived reciprocity and customer loyalty. A total sample of 200 respondents was selected for a pilot test. In addition, to ensure a consistent response, we ensured that the respondents were older than 20 years of age. The surveys of 172 respondents (males-82, females-90) were analyzed after 28 invalid questionnaires were excluded. Based on our cutoff criteria, the model fit the data reasonably well. Values-driven motives for corporate social responsibility activities had a positive effect on perceived reciprocity (t = 6.75, p < .001), supporting H1. Morales (2005) also found that consumers appreciate a company's social responsibility efforts and the benefits provided by these efforts to society. Stakeholder-driven motives for corporate social responsibility activities did not affect perceived reciprocity (t = -.049, p > .05). Thus, H2 was rejected. Egoistic-driven motives (t = .3.11, p < .05) and strategic-driven (t = -4.65, p < .05) motives had a negative influence on perceived reciprocity, supporting H3 and H4, respectively. Furthermore, perceived reciprocity had a positive influence on consumer loyalty (t = 4.24, p < .05), supporting H5. Thus, compared with the general public, undergraduate students appear to be more influenced by egoistic-driven motives. We draw the following conclusions from our research findings. First, value-driven attributions have a positive influence on perceived reciprocity. However, stakeholder-driven attributions have no significant effects on perceived reciprocity. Moreover, both egoistic-driven attributions and strategic-driven attributions have a negative influence on perceived reciprocity. Second, when corporate social responsibility activities align with consumers' reciprocity, the efforts directed towards social responsibility activities have a positive influence on customer loyalty. In this study, we examine whether the type of motivation affects consumer responses to CSR, and in particular, we evaluate how CSR motives can influence a key internal factor (perceived reciprocity) and behavioral consumer outcome (customer loyalty). We demonstrate that perceived reciprocity plays a mediating role in the relationship between CSR motivation and customer loyalty. Our study extends the research on consumer CSR-inferred motivations, positing them as a direct indicator of consumer responses. Furthermore, we convincingly identify perceived reciprocity as a sub-process mediating the effect of CSR attributions on customer loyalty. Future research investigating the ultimate behavior and financial impact of CSR should consider that the impacts of CSR also stem from perceived reciprocity. The results of this study also have important managerial implications. First, the central role that reciprocity plays indicates that managers should routinely measure how much their socially responsible actions create perceived reciprocity. Second, understanding how consumers' perceptions of CSR corporate motives relate to perceived reciprocity and customer loyalty can help managers to monitor and enhance these consumer outcomes through marketing initiatives and management of CSR-induced attribution processes. The results of this study will help corporations to understand the relative importance of the four different motivations types in influencing perceived reciprocity.

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The Effect of Nonspecific Endothelin-1 Receptor Blocker ($Bosentan^{(R)}$) on Paraquat Induced Pulmonary Fibrosis in Rat (Paraquat에 의한 백서의 폐섬유화증에서 비선택적 Endothelin-1 receptor blocker($Bosentan^{(R)}$)의 치료효과)

  • Jeong, Hye-Cheol;Jung, Ki-Hwan;Kim, Byung-Gyu;Lee, Seung-Heon;Kim, Min-Kyung;Kim, Chung-Yeul;Park, Sang-Myun;Lee, Sin-Hyung;Shin, Chol;Cho, Jae-Youn;Shim, Jae-Jeong;In, Kwang-Ho;Kim, Han-Gyum;Yoo, Se-Hwa;Kang, Kyung-Ho
    • Tuberculosis and Respiratory Diseases
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    • v.50 no.2
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    • pp.182-195
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    • 2001
  • Background : Idiopathic pulmonary fibrosis(IPF) is a devastating illness for which there is little effective treatment. The key cytokines currently implicated in the fibrotic process are the transforming growth factor-${\beta}_1$(TGF-${\beta}_1$), tumor necrosis factor-$\alpha$(TNF-$\alpha$), endothelin-1(ET-1) and interferon-$\gamma$(IFN-$\gamma$). The rat model for paraquat-induced pulmonary fibrosis was chosen to investigate the role of ET-1 in this disease. Both ET-1 and TGF-${\beta}_1$ expression in lung lesions were examined using immunohistochemical staining. After $Bosentan^{(R)}$ administration, an orally active ET-$l_A$ and ET-$1_B$ receptor antagonist, the degree of pulmonary fibrosis and ET-1 and TGF-${\beta}_1$ expression were analyzed. Method : Sprague-Dawley rats were divided into three groups, the control group, the fibrosis group, and the fibrosis-$Bosentan^{(R)}$-treated group. The animals were sacrificed periodically at 1, 3, 5, 7, 10, 14 days after administering saline or paraquat. The effects between groups were compared with the results of light microscopy and immunohistochemical staining for ET-1 and TGF-${\beta}_1$. The degree of fibrosis was evaluated by H&E and Masson's trichrome staining, which were graded by a computerized image analyzer. The degree of immunohistochemical staining was categorized by a semi-quantitative analysis method. Results : The lung collagen content had increased in the paraquat instillated animals by day 3, and continued to increase up to day 14. A daily treatment by gavage with $Bosentan^{(R)}$ (100mg/kg) did not prevent the increase in collagen deposition on the lung that was induced by paraquat instillation. There were increased immunohistochemical stains of ET-1 on the exudate, macrophages, vascular endothelial cells and pneumocytes in the paraquat instillated group. Furthermore, TGF-${\beta}_1$ expression was higher on the exudate, macrophages, some inflammatory cells, pneumocytes( type I, and II), vascular endothelium and the respiratory epithelial cells around the fibrotic area. After Bosentan treatment, there were no definite changes in ET-1 and TGF-${\beta}_1$ expression. Conclusion : Fibrosis of the Paraquat instillated group was more advanced when compared with the control group. In addition, there was increased ET-1 and TGF-${\beta}_1$ expression around the fibrotic area. ET-1 is associated with lung fibrosis but there was little effect of the ET-1 receptor blocker($Bosentan^{(R)}$) on antifibrosis.Background : Idiopathic pulmonary fibrosis(IPF) is a devastating illness for which there is little effective treatment. The key cytokines currently implicated in the fibrotic process are the transforming growth factor-${\beta}_1$(TGF-${\beta}_1$), tumor necrosis factor-$\alpha$(TNF-$\alpha$), endothelin-1(ET-1) and interferon-$\gamma$(IFN-$\gamma$). The rat model for paraquat-induced pulmonary fibrosis was chosen to investigate the role of ET-1 in this disease. Both ET-1 and TGF-${\beta}_1$ expression in lung lesions were examined using immunohistochemical staining. After $Bosentan^{(R)}$ administration, an orally active ET-$1_A$ and ET-$1_B$ receptor antagonist, the degree of pulmonary fibrosis and ET-1 and TGF-${\beta}_1$ expression were analyzed. Method : Sprague-Dawley rats were divided into three groups, the control group, the fibrosis group, and the fibrosis-$Bosentan^{(R)}$-treated group. The animals were sacrificed periodically at 1, 3, 5, 7, 10, 14 days after administering saline or paraquat. The effects between groups were compared with the results of light microscopy and immunohistochemical staining for ET-1 and TGF-${\beta}_1$. The degree of fibrosis was evaluated by H&E and Masson's trichrome staining, which were graded by a computerized image analyzer. The degree of immunohistochemical staining was categorized by a semi-quantitative analysis method. Results : The lung collagen content had increased in the paraquat instillated animals by day 3, and continued to increase up to day 14. A daily treatment by gavage with $Bosentan^{(R)}$ (100mg/kg) did not prevent the increase in collagen deposition on the lung that was induced by paraquat instillation. There were increased immunohistochemical stains of ET-1 on the exudate, macrophages, vascular endothelial cells and pneumocytes in the paraquat instillated group. Furthermore, TGF-${\beta}_1$ expression was higher on the exudate, macrophages, some inflammatory cells, pneumocytes( type I, and II), vascular endothelium and the respiratory epithelial cells around the fibrotic area. After Bosentan treatment, there were no definite changes in ET-1 and TGF-${\beta}_1$ expression. Conclusion : Fibrosis of the Paraquat instillated group was more advanced when compared with the control group. In addition, there was increased ET-1 and TGF-${\beta}_1$ expression around the fibrotic area. ET-1 is associated with lung fibrosis but there was little effect of the ET-1 receptor blocker($Bosentan^{(R)}$) on antifibrosis.

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A Study on Industries's Leading at the Stock Market in Korea - Gradual Diffusion of Information and Cross-Asset Return Predictability- (산업의 주식시장 선행성에 관한 실증분석 - 자산간 수익률 예측 가능성 -)

  • Kim Jong-Kwon
    • Proceedings of the Safety Management and Science Conference
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    • 2004.11a
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    • pp.355-380
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    • 2004
  • I test the hypothesis that the gradual diffusion of information across asset markets leads to cross-asset return predictability in Korea. Using thirty-six industry portfolios and the broad market index as our test assets, I establish several key results. First, a number of industries such as semiconductor, electronics, metal, and petroleum lead the stock market by up to one month. In contrast, the market, which is widely followed, only leads a few industries. Importantly, an industry's ability to lead the market is correlated with its propensity to forecast various indicators of economic activity such as industrial production growth. Consistent with our hypothesis, these findings indicate that the market reacts with a delay to information in industry returns about its fundamentals because information diffuses only gradually across asset markets. Traditional theories of asset pricing assume that investors have unlimited information-processing capacity. However, this assumption does not hold for many traders, even the most sophisticated ones. Many economists recognize that investors are better characterized as being only boundedly rational(see Shiller(2000), Sims(2201)). Even from casual observation, few traders can pay attention to all sources of information much less understand their impact on the prices of assets that they trade. Indeed, a large literature in psychology documents the extent to which even attention is a precious cognitive resource(see, eg., Kahneman(1973), Nisbett and Ross(1980), Fiske and Taylor(1991)). A number of papers have explored the implications of limited information- processing capacity for asset prices. I will review this literature in Section II. For instance, Merton(1987) develops a static model of multiple stocks in which investors only have information about a limited number of stocks and only trade those that they have information about. Related models of limited market participation include brennan(1975) and Allen and Gale(1994). As a result, stocks that are less recognized by investors have a smaller investor base(neglected stocks) and trade at a greater discount because of limited risk sharing. More recently, Hong and Stein(1999) develop a dynamic model of a single asset in which information gradually diffuses across the investment public and investors are unable to perform the rational expectations trick of extracting information from prices. Hong and Stein(1999). My hypothesis is that the gradual diffusion of information across asset markets leads to cross-asset return predictability. This hypothesis relies on two key assumptions. The first is that valuable information that originates in one asset reaches investors in other markets only with a lag, i.e. news travels slowly across markets. The second assumption is that because of limited information-processing capacity, many (though not necessarily all) investors may not pay attention or be able to extract the information from the asset prices of markets that they do not participate in. These two assumptions taken together leads to cross-asset return predictability. My hypothesis would appear to be a very plausible one for a few reasons. To begin with, as pointed out by Merton(1987) and the subsequent literature on segmented markets and limited market participation, few investors trade all assets. Put another way, limited participation is a pervasive feature of financial markets. Indeed, even among equity money managers, there is specialization along industries such as sector or market timing funds. Some reasons for this limited market participation include tax, regulatory or liquidity constraints. More plausibly, investors have to specialize because they have their hands full trying to understand the markets that they do participate in

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