Naoru Koizumi
George Mason University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Naoru Koizumi.
Administration and Policy in Mental Health | 2009
Naoru Koizumi; Aileen B. Rothbard; Eri Kuno
The purpose of this study is to examine the influence of race, geographic distance and quality on the choice of community mental health programs. The study population was comprised of adult Medicaid recipients who received outpatient treatment for serious mental illness in FY 2001. A discrete choice model was employed to examine the likelihood of choosing one program over another. Quality was measured based on follow-up after hospital discharge and continuity of care in outpatient services. Maps showing the relationship between race and the quality of care were prepared to visually confirm the results of the statistical analysis. African American and Hispanic clients were less likely to travel further for treatment, while no significant difference was found between the Caucasian and other race groups. Caucasian subjects were more likely to choose programs with a higher quality of care compared to Hispanic or African American clients. Higher income clients were, on average, traveling longer and receiving better quality of care after controlling for race. The results suggested that clients living in higher income White neighborhoods are more likely to travel longer distances for mental health treatment. Special attention must be paid to improve the quality of care in lower income minority neighborhoods to insure equity of treatment in publicly funded programs.
Biological Trace Element Research | 2008
Naoru Koizumi; Koichi Murata; Chiyo Hayashi; Hisahide Nishio; Junko Goji
The majority of existing literature reports that cadmium (Cd) is toxic to humans and most living organisms. This paper reports the results of our study that measured Cd levels in the livers and kidneys of humans and other 50 mammalian species under normal conditions in Japan. The study tests the differences in the Cd concentrations across different mammalian species and sexes. Our results revealed that (1) there is a strong correlation between the Cd levels in the livers and kidneys across all examined species, (2) humans exhibit the highest Cd accumulation level in both organs, (3) primates also show a high Cd concentration at a level close to humans, (4) mice and rats show low Cd levels in both organs, indicating that humans accumulate about a few thousand times more Cd than mice and rats, and (5) the Cd concentration of female mammals is more than double of males for both organs. Our results indicate that these cross-sex as well as cross-species discrepancies cannot be explained by the difference in daily Cd intake. While further research is necessary to determine any potential role of Cd accumulation, we speculate that Cd plays some physiological function in the renal cortex of humans and primates.
World Medical & Health Policy | 2010
Naoru Koizumi
Background: Disparities in access to and in outcome of organ transplantation are widely discussed topics among transplant researchers in many Western countries. Among various types of disparities examined in existing studies, “geographic disparity,” i.e., disparity due to a recipients location, is most common. Despite a number of articles that acknowledge the existence of geographic disparities, the literature has been relatively silent about the historical and international efforts to address these issues. Literature discussing remedies or proposing analytical tools to identify remedies is even rarer. This paper investigates potential causes of geographic disparity and advocates possible methodological approaches to analyze and address the disparity. Methods: The paper conducts an in-depth review of geographic disparity and the policy efforts to reduce the disparity in the United States, Canada, France, Spain, the United Kingdom, and Australia. The current organ allocation systems in these countries are also reviewed and compared. Possible causes of the disparity and future analytical approaches are discussed based on the findings of these reviews. Findings: Geographic disparity in organ transplant service is ubiquitous in all countries studied. Many Western countries have a similar organ allocation system with some difference in the degree of interregional and national-level sharing enforced by the government. The organ allocation system in these countries tends to have some inherent mechanism to favor a “home region” where organs are harvested, implying that the locations of candidates matter in accessing a transplant. Geographic allocation boundaries prevalent in the United States were found to be another potential source of geographic disparity. Conclusions: Developing an equitable organ allocation system is a multifaceted problem. The allocation procedure needs to reflect priorities of urgent cases and some geographic areas, patients severity level, waiting time, cold ischemia time (CIT) and associated travel distance, condition of and compatibility between organ and recipient, etc. Failing to reflect these factors adequately results in disparity of some sort. The implications of geographic boundaries in organ allocation need to be studied further. Utilization of relatively new methodological approaches, such as Geographic Information Systems (GIS) and system dynamic modeling, would help develop a system that allocates organs more equitably.
Career Development International | 2010
Sruthi M. Thatchenkery; Naoru Koizumi
Purpose – This paper seeks to examine whether the primary factors motivating the career plans of high‐achieving Indian adolescents vary between academic specializations. Particular attention is to be paid to differences between science and business students.Design/methodology/approach – The study surveyed approximately 2,700 secondary school students in South India regarding their academic and career plans and their perceptions of business compared with science. Survey results were analyzed using both descriptive techniques and multinomial logistic regression.Findings – Students perceive business to be comparable with, but not superior to, science and engineering. The proportion of students choosing business over science increased among males and in some more economically developed cities. Engineering students were most likely to cite parents as a major influence, while business students more often pointed to salary and career prospects.Research limitations/implications – The studys scope was limited to ...
Environmental Health and Preventive Medicine | 2005
Naoru Koizumi; Hiroshi Iguchi; Tony E. Smith
ObjectiveThe objectives of this study are to (1) compare the BSE surveillance systems of Japan and the United States (US), and to (2) validate the US enhanced BSE Surveillance program.MethodsThis study compares the BSE surveillance systems in Japan and the US, specifically focusing on the procedures of initial test, diagnosis and confirmation. The study further examines the validity of statistical conclusions made in the US enhanced surveillance program based on the data collected from the BSE inspection performed by the Ministry of Health, Labor and Welfare of Japan (MHLW) and the Ministry of Agriculture, Forestry and Fisheries of Japan (MAFF) between October 18,2001 and July 31, 2004. The inspection targeted all slaughtered healthy and high risk cattle.ResultsThe US enhanced surveillance program assumes no BSE occurrence in the normal adult cattle population and thus its inspection focuses only on high risk cattle. The BSE inspection performed in Japan, however, revealed that 0.00022% of the normal adult cattle were BSE-infected using the US criteria. Assuming that the same ratio of cattle was BSE-infected in the US, the Japan finding indicates that approximately 30% of the US slaughtered normal cattle population aged 30 months and over needs to be tested to satisfy the statistical condition used by the US (i.e., 99% confidence level).On the other hand, in order for Japan to perform the surveillance with a 99% confidence level (the statistical condition used by US), Japan needs inspect: (1) 60,539 high risk cattle (i.e., 60% of 100,583 high risk cattle); (2) 78% of normal adult cattle aged 30 months and over (1,088,589/1,387,522) and (3) 90% of normal cattle aged 30 months or less (1,845,138/2,050,154).ConclusionThe US enhanced surveillance program launched in July 2004 is based on the premise that no BSE occurs in normal adult cattle population. In Japan, however, BSE cases satisfying the US criteria have been found among the normal adult cattle. This fact suggests that the US needs to consider inspections targeting the normal adult cattle. This fact suggests that the US needs to consider inspections targeting the normal adult cattle in the future. At the same time, for more efficient surveillance, Japan may need to consider BSE inspections targeting the high risk cattle population with a higher confidence level and normal adult cattle with a lower confidence level.
Transplantation direct | 2015
Naoru Koizumi; Debasree DasGupta; Amit Patel; Tony E. Smith; Jeremy D. Mayer; Clive Callender; Joseph K. Melancon
Background Regional variations in kidney and liver transplant outcomes have been reported, but their causes remain largely unknown. This study investigated variations in kidney and liver cold ischemia times (CITs) across organ procurement organizations (OPO) as potential causes of variations in transplant outcomes. Methods This retrospective study analyzed the Standard Transplant Analysis and Research data of deceased donor kidney (n = 61,335) and liver (n = 39,285) transplants performed between 2003 and 2011. The CIT variations between the 2 types of organs were examined and compared. Factors associated with CIT were explored using multivariable regressions. Spearman rank tests were used to associate CIT with graft failure at the OPO level. Results Significant CIT variations were found across OPOs for both organs (P < 0.05). The variation was particularly large for kidney CIT. Those OPOs with longer average kidney CIT were likely to have a lower graft survival rate (P = 0.01). For liver, this association was insignificant (P = 0.23). The regression analysis revealed sharp contrasts between the factors associated with kidney and liver CITs. High-risk kidney transplant recipients and marginal kidneys were associated with longer average CIT. The reverse was true for liver transplants. Conclusions Large variations in kidney CIT compared to liver CIT may indicate that there is a room to reduce kidney CIT. Reducing kidney CIT through managerial improvements could be a cost-effective way to improve the current transplant system.
Proceedings of the International Conference on Health Care Systems Engineering / Andrea Matta, Jingshan Li, Evren Sahin, Ettore Lanzarone, John Fowler, editors. International Conference on Health Care Systems Engineering (2013 : Milan, . | 2014
Naoru Koizumi; Rajesh Ganesan; Monica Gentili; Chun-Hung Chen; Nigel Waters; Debasree DasGupta; Dennis E. Nicholas; Amit Patel; Divya Srinivasan; Keith Melancon
Geographic disparities in access to and outcomes in transplantation have been a persistent problem widely discussed by transplant researchers and the transplant community. One of the alleged causes of disparities in the United States is administratively determined organ allocation boundaries that limit organ sharing across regions. This paper applies mathematical programming to construct alternative liver allocation boundaries that achieve more geographic equity in access to transplants than the current system. The performance of the optimal boundaries were evaluated and compared to that of current allocation system using discrete event simulation.
Archive | 2014
Jeremy D. Mayer; Naoru Koizumi; Ammar Anees Malik
Torture is perhaps best understood as a collection of practices designed to inflict suffering upon helpless subjects. It can include both physical and psychological pain, and, while torture has been conducted by private actors, our concern here is regarding torture authorized and carried out by governments. We examined two broad theories that have been put forth to explain public support for torture. First, torture has been understood as a practice that advanced societies should reject (whether they actually do so is another question), and thus part of the collection of post-materialistic values that characterize public attitudes in advanced liberal democracies. We label this explanation the “developmental hypothesis” of support for torture. Second, scholars such as Karen Greenberg and Stephen Holmes have posited that societies are driven to support torture when terrorism threatens them. In this study, we call this the “threat hypothesis” of support for torture.
Health Care Management Science | 2011
Naoru Koizumi; Aileen B. Rothbard; Tony E. Smith; Jeremy D. Mayer
A discrete-choice logit model was applied to study the determinants of mental health provider choice using data from a large urban county in the Northeast US. The study subjects were 9,544 adult Medicaid recipients who received outpatient treatment from the 20 Community Mental Health Center (CMHC) programs in 2001. In addition to a conventional set of variables representing client and provider characteristics, the regression model included several interaction terms to examine whether racial concordance level among patients influences the choice of an outpatient program. The results revealed that racial concordance among the clients seems to be a factor in choosing a program. In particular, Caucasian clients are much more likely to select a program with a higher percentage of Caucasian clients, even though they have to travel further. More generally, our results suggest that program choice may be driven more by the racial composition of the clients served than by spatial proximity to the program.
Archive | 2018
Amit Patel; Andrew Crooks; Naoru Koizumi
More than 900 million people or one third of the world’s urban population lives in either slum or squatter settlements. Urbanization rates in developing countries are often so rapid that formal housing development cannot meet the demand. In the past decades, international, national and local development communities have taken several policy actions in an attempt to improve the living conditions of people within slums or to eradicate them completely. However, such policies have largely failed and slum-free cities have remained a distant goal for many developing countries. This chapter argues that for informed policymaking, it is important to investigate questions related to slum formation such as: (1) How do slums form and expand? (2) Where and when are they formed? (3) What types of structural changes and/or policy interventions could improve housing conditions for the urban poor? In order to address these questions, this chapter develops a geosimulation model that is capable of exploring the spatio-temporal dynamics of slum formation and simulating future formation and expansion of slums within cities of the developing world. Our geosimulation model integrates agent-based modeling (ABM) and Geographic Information System (GIS), methods that are often applied separately to explore slums. In our model, ABM simulates human behavior and GIS provides a spatial environment for the housing market. GIS is also used to analyze empirical data using spatial analyses techniques, which is in turn used to validate the model outputs. The core of this framework is a linked dynamic model operating at both micro and macro geographic and demographic scales. The model explores the collective effect of many interacting inhabitants of slums as well as non-slum actors (e.g. local government) and how their interactions within the spatial environment of the city generate the emergent structure of slums at the macro scale. We argue that when empirical data is absent, geosimulation provides useful insights to study implications of various policies. The goal of this framework is to develop a decision support tool that could allow urban planners and policymakers to experiment with new policy ideas ex-ante in a simulated environment. We calibrate and validate the model using data from Ahmedabad, the sixth largest city of India, where 41% of its population lives in slums. This is one of the first attempts to develop an integrated and multi-scalar analytical framework to tackle slum issues in the developing world at multiple spatial scales.