Deborah Balk

Global trends in emerging infectious diseases.

Emerging infectious diseases (EIDs) are a significant burden on global economies and public health. Their emergence is thought to be driven largely by socio-economic, environmental and ecological factors, but no comparative study has explicitly analysed these linkages to understand global temporal and spatial patterns of EIDs. Here we analyse a database of 335 EID ‘events’ (origins of EIDs) between 1940 and 2004, and demonstrate non-random global patterns. EID events have risen significantly over time after controlling for reporting bias, with their peak incidence (in the 1980s) concomitant with the HIV pandemic. EID events are dominated by zoonoses (60.3% of EIDs): the majority of these (71.8%) originate in wildlife (for example, severe acute respiratory virus, Ebola virus), and are increasing significantly over time. We find that 54.3% of EID events are caused by bacteria or rickettsia, reflecting a large number of drug-resistant microbes in our database. Our results confirm that EID origins are significantly correlated with socio-economic, environmental and ecological factors, and provide a basis for identifying regions where new EIDs are most likely to originate (emerging disease ‘hotspots’). They also reveal a substantial risk of wildlife zoonotic and vector-borne EIDs originating at lower latitudes where reporting effort is low. We conclude that global resources to counter disease emergence are poorly allocated, with the majority of the scientific and surveillance effort focused on countries from where the next important EID is least likely to originate.

The rising tide: assessing the risks of climate change and human settlements in low elevation coastal zones

Settlements in coastal lowlands are especially vulnerable to risks resulting from climate change, yet these lowlands are densely settled and growing rapidly. In this paper, we undertake the first global review of the population and urban settlement patterns in the Low Elevation Coastal Zone (LECZ), defined here as the contiguous area along the coast that is less than 10 metres above sea level. Overall, this zone covers 2 per cent of the worlds land area but contains 10 per cent of the worlds population and 13 per cent of the worlds urban population. A disproportionate number of the countries with a large share of their population in this zone are small island countries, but most of the countries with large populations in the zone are large countries with heavily populated delta regions. On average, the Least Developed Countries have a higher share of their population living in the zone (14 per cent) than do OECD countries (10 per cent), with even greater disparities in the urban shares (21 per cent compared to 11 per cent). Almost two-thirds of urban settlements with populations greater than 5 million fall, at least partly, in the zone. In some countries (most notably China), urbanization is driving a movement in population towards the coast. Reducing the risk of disasters related to climate change in coastal settlements will require a combination of mitigation, migration and settlement modification.

Urban growth, climate change, and freshwater availability

Nearly 3 billion additional urban dwellers are forecasted by 2050, an unprecedented wave of urban growth. While cities struggle to provide water to these new residents, they will also face equally unprecedented hydrologic changes due to global climate change. Here we use a detailed hydrologic model, demographic projections, and climate change scenarios to estimate per-capita water availability for major cities in the developing world, where urban growth is the fastest. We estimate the amount of water physically available near cities and do not account for problems with adequate water delivery or quality. Modeled results show that currently 150 million people live in cities with perennial water shortage, defined as having less than 100 L per person per day of sustainable surface and groundwater flow within their urban extent. By 2050, demographic growth will increase this figure to almost 1 billion people. Climate change will cause water shortage for an additional 100 million urbanites. Freshwater ecosystems in river basins with large populations of urbanites with insufficient water will likely experience flows insufficient to maintain ecological process. Freshwater fish populations will likely be impacted, an issue of special importance in regions such as Indias Western Ghats, where there is both rapid urbanization and high levels of fish endemism. Cities in certain regions will struggle to find enough water for the needs of their residents and will need significant investment if they are to secure adequate water supplies and safeguard functioning freshwater ecosystems for future generations.

Individual and Community Aspects of Women's Status and Fertility in Rural Bangladesh

This paper examines the relationship between womens status and fertility in two regions of rural Bangladesh. Based on individual and household-level survey data, womens status is measured through four constructs. The covariates of these four aspects of womens status vary considerably and confirm the view that womens status is conceptually and operationally complex. For all aspects, however, variation between villages accounts for the largest share of explainable variance. Proxy measures of status do not provide uniform relationships with all facets of status. Further, the paper shows that womens status is an important determinant of fertility; of the variance in total children ever born that can be explained by factors other than age, nearly 30 per cent is due to direct measures of womens status; this is as much as can be explained by all other socio-economic variables combined. Thus, models of fertility that rely solely on proxy measures of womens status will be underspecified. In addition, measur...

Confidentiality and spatially explicit data: Concerns and challenges

Recent theoretical, methodological, and technological advances in the spatial sciences create an opportunity for social scientists to address questions about the reciprocal relationship between context (spatial organization, environment, etc.) and individual behavior. This emerging research community has yet to adequately address the new threats to the confidentiality of respondent data in spatially explicit social survey or census data files, however. This paper presents four sometimes conflicting principles for the conduct of ethical and high-quality science using such data: protection of confidentiality, the social–spatial linkage, data sharing, and data preservation. The conflict among these four principles is particularly evident in the display of spatially explicit data through maps combined with the sharing of tabular data files. This paper reviews these two research activities and shows how current practices favor one of the principles over the others and do not satisfactorily resolve the conflict among them. Maps are indispensable for the display of results but also reveal information on the location of respondents and sampling clusters that can then be used in combination with shared data files to identify respondents. The current practice of sharing modified or incomplete data sets or using data enclaves is not ideal for either the advancement of science or the protection of confidentiality. Further basic research and open debate are needed to advance both understanding of and solutions to this dilemma.

Defying Gender Norms in Rural Bangladesh: A Social Demographic Analysis

This study explores the social and demographic determinants of a womans decision-making authority within the home and mobility outside ofthe home, in staunchly patriarchal rural Bangladesh, in an attempt to better understand which women defy existing gender norms and why they do so. Although the characteristics of individual women matter, institutional determinants-operating at several levels-are the most salient features in determining who defies gender norms in rural Bangladesh. I find that about 25 percent of the explainable variance in mobility and authority can be explained by individual level attributes-age, education, residing with her in-Iaws-and that 75 percent comes from a variety of broad ranging aspects of gender norms at the household, village, and regionalleveI. Countering the assumption often underlying demographic analysis of womens status, I find that those factors which determine a womans mobility in public do not necessarily determine her authority within her home. In particular, those characteristics closely related to social class, such as education and wealth, may work to enhance existing gender norms. Program on Population, East-West Center, 1777 East-West Road, Honolulu, ill 96848 USA; E-mail address: baIk@hawaii.edu; Fax: 808-944-7490; Tel: 808-944-7462 INTRODUCTION In the study of contemporary low-fertility societies, it has been observed that gender equality is a consequence-perhaps incidental-oflow fertility (e.g., Keyfitz 1986, Davis 1984). In contemporary high-fertility countries and historically in pre-demographic transition societie s, however, it is thought that the status of women is an important determinant in fostering demographic ch ange, and in particular, in lowering fertility (e.g., Arthur and McNico1l1978, Banks and Banks 1964). A related observation made about developed societies in the past and developing countries in the present, is that strongly patriarchal systems foster high fertility by the roles it gives men and women (e.g., Cain e t al. 1979, Keyfitz 1986). This poses two questions: How do changes in the roles of women and men ac t as both a cause and a consequence of fertility decline? What are the determinants of these changes ? This later question forms the basis of this paper. A predominantly rural, highly stratified, staunchly pat riarchal society, in which fertility has recently begun to fall-Bangladesh-is the focus of this study. While there are many analyses on the demography of Bangladesh that call fo r an improvement in the status of women as a means to foster demographic change, there are only a rew empirical analyses that explain the nature of this relationship with some degree of rigor. I This is large part due to complexities involved in conceptualizing and measuring womens status (e.g ., Mason 1986, SafiliosRothschild 1982, ty1ukherjee 1975, Whyte 1978, Sanday 1973), the lack of ap propriate and good data (United Nations 1988, United Nations 1991), and the lack of good, clear mod els (e.g., Greenhalgh 1995, Smith 1989) rather than in hypothesizing how womens status relates to ferti lity. This paper simply seeks a better understanding of the changing status of women in rural Bangladesh. An empirical analysis of the relationship between womens status and fertility, in the same context, is und ertaken elsewhere (see Balk 1994). The central question of this paper is what determines which women conform to prevailing gender norms in rural Bangladesh and why. Towards this end, I attempt to reveal un derlying theories and implicit assumptions about womens status in the demographic literature; I d o not attempt, however, to broadly review or synthesize the literature on this subject, or to take on the m ore challenging task of developing a general theory of the status(es) of women. I start with a discuss ion of what prevailing gender norms are in rural Bangladesh. Then, using survey data, I measure the degree to which women I For example, see Amin et aI. 1994, Balk 1994, Schuler and Hashemi 1994, Adnan 19 93, Ahmad 1991, Harbison et al. 1989, Abdullah and Zeidenstein 1982, Chaudhury and Ahmed 1980, Cain 1981, Cain et. a l1979, Arthur and McNicolll978, and Lindenbaum 1968, for the Bangladeshi context; Morgan and Niraula 1995, Basu 199 2, V1assoff 1992, Jejeebhoy 1991, Jeffery et al. 1988, Sathar et al. 1988, Dyson and Moore 1983, for examples in other parts of S outh Asia. Although most of these papers explicitly analyze some aspect of womens status and fertility, there is considerable var iation in the degree to which these paper succeed in describing and modeling status.

Setting the stage for equity-sensitive monitoring of the maternal and child health Millennium Development Goals

OBJECTIVE This analysis seeks to set the stage for equity-sensitive monitoring of the health-related Millennium Development Goals (MDGs). METHODS We use data from international household-level surveys (Demographic and Health Surveys (DHS) and Multiple Indicator Cluster Surveys (MICS)) to demonstrate that establishing an equity baseline is necessary and feasible, even in low-income and data-poor countries. We assess data from six countries using 11 health indicators and six social stratifiers. Simple bivariate stratification is complemented by simultaneous stratification to expose the compound effect of multiple forms of vulnerability. FINDINGS The data reveal that inequities are complex and interactive: inferences cannot be drawn about the nature or extent of inequities in health outcomes from a single stratifier or indicator. CONCLUSION The MDGs and other development initiatives must become more comprehensive and explicit in their analysis and tracking of inequities. The design of policies to narrow health gaps must take into account country-specific inequities.

Assessing the accuracy of multi-temporal built-up land layers across rural-urban trajectories in the United States

Global data on settlements, built-up land and population distributions are becoming increasingly available and represent important inputs to a better understanding of key demographic processes such as urbanization and interactions between human and natural systems over time. One persistent drawback that prevents user communities from effectively and objectively using these data products more broadly, is the absence of thorough and transparent validation studies. This study develops a validation framework for accuracy assessment of multi-temporal built-up land layers using integrated public parcel and building records as validation data. The framework is based on measures derived from confusion matrices and incorporates a sensitivity analysis for potential spatial offsets between validation and test data as well as tests for the effects of varying criteria of the abstract term built-up land on accuracy measures. Furthermore, the framework allows for accuracy assessments by strata of built-up density, which provides important insights on the relationship between classification accuracy and development intensity to better instruct and educate user communities on quality aspects that might be relevant to different purposes. We use data from the newly-released Global Human Settlement Layer (GHSL), for four epochs since 1975 and at fine spatial resolution (38m), in the United States for a demonstration of the framework. The results show very encouraging accuracy measures that vary across study areas, generally improve over time but show very distinct patterns across the rural-urban trajectories. Areas of higher development intensity are very accurately classified and highly reliable. Rural areas show low degrees of accuracy, which could be affected by misalignment between the reference data and the data under test in areas where built-up land is scattered and rare. However, a regression analysis, which examines how well GHSL can estimate built-up land using spatially aggregated analytical units, indicates that classification error is mainly of thematic nature. Thus, caution should be taken in using the data product in rural regions. The results can be useful in further improving classification procedures to create measures of the built environment. The validation framework can be extended to data-poor regions of the world using map data and Volunteered Geographic Information.

Urban Migration of Adolescent Girls: Quantitative Results from Developing Countries

This chapter assembles a quantitative portrait of the adolescent girls who migrate to the cities and towns of poor countries, drawing mainly on a large collection of data from demographic surveys and census micro-samples. For adolescent girls and young women, migration puts important urban resources within reach, in the form of access to higher levels of schooling, more varied labor markets and employment opportunities, and multiple levels of health-care institutions. But while the move is underway and until she locates a safe home in her new location, an adolescent girl can confront a range of social and sexual risks that can threaten her well-being and thwart hopes for advancement. Much of the literature on adolescent migration is focused on these risks but neglects the potential benefits. We find that in many countries, significant percentages of urban adolescent girls are recent in-migrants. In characterizing their life-circumstances, we give special attention to indicators of social isolation, the conditions of housing and neighborhood, and school enrollment. We show that adolescent girl migrants are a highly diverse group, advantaged in some respects and disadvantaged in others. Field studies in urban India shed light on the difficulties with which girls must cope as they strive to adapt to urban life.

Global Infrastructure: The Potential of SRTM Data to Break New Ground

This paper evolved out of a Global Infrastructure Mapping workshop organized by CIESIN of the Columbia Earth Institute and by NASA/JPL of the California Institute of Technology, held at Columbia University, New York, on 4-5 October 2000. The research by the Jet Propulsion Laboratory, California Institute of Technology, was carried out under a contract with the National Aeronautics and Space Administration. Partial funding for the workshop was provided by the NASA Socioeconomic Data and Applications Center (SEDAC) under contract NAS598162 to Columbia University.