Spatial clustering patterns and regional variations for food and physical activity environments across the United States.

This study examined spatial patterns of obesogenic environments for US counties. We mapped the geographic dispersion of food and physical activity (PA) environments, assessed spatial clustering, and identified food and PA environment differences across U.S. regions and rurality categories. Substantial low food score clusters were located in the South and high score clusters in the Midwest and West. Low PA score clusters were located in the South and high score clusters in the Northeast and Midwest (p < .0001). For region, the South had significantly lower food and PA environment scores. For rurality, rural counties had significantly higher food environment scores and metropolitan counties had significantly higher PA environment scores (p < .0001). This study highlights geographic clustering and disparities in food and PA access nationwide. State and region-wide environmental inequalities may be targeted using structural interventions and policy initiatives to improve food and PA access.

Neighborhood air pollution and household environmental health as it relates to respiratory health and healthcare utilization among elderly persons with asthma.

Objective: The study investigated the associations between fine particulate matter (PM2.5; <2.5 µm in diameter), indoor environment, pulmonary function, and healthcare utilization in a vulnerable group of elderly persons with asthma. We hypothesized that environmental conditions were associated with adverse pulmonary health outcomes. Methods: The study involved elderly (n = 76; mean age 64.6 years; 48 women) vulnerable persons in Detroit, Michigan, USA, with physician-diagnosed asthma. Exposure variables included measured outdoor PM2.5, self-rated outdoor and household environmental pollutants. Outcome variables were self-rated and measured pulmonary function, and asthma-related healthcare utilization. Results: Mean ambient PM2.5 concentrations during the study was 14.14 ± (S.D. 6.36) µg/m3 during the summer and 14.20 (6.33) during the winter (p = 0.95). In multiple regression analyses, adjusting for age and gender, mean 6-month concentration of PM2.5 was related to shortness of breath (SHOB; standardized ß = 0.26, p = 0.02) and inversely with self-rated respiratory health (SRRH; ß = 0.28, p = 0.02). However, PM2.5 did not predict lung function (FEV1% predicted and FEV1/FVC). However, PM2.5 was related to use of asthma controller drugs (ß = 0.38, p = 0.001). Participants' air pollution ratings predicted total healthcare utilization (ß = 0.33, p = 0.01). Conclusions: In elderly persons with asthma, living near heavy industry and busy highways, objective and perceived environmental pollution relate to participants' respiratory health and healthcare utilization. Importantly, air pollution might increase use of asthma controller drugs containing corticosteroids with implication for elderly persons' risk to develop osteoporosis and cardiovascular disease.

Environmental health literacy and household air pollution-associated symptoms in Kenya: a cross-sectional study.

BACKGROUND: Household air pollution (HAP) is a significant source of the global burden of disease. Our objective was to evaluate the association between environmental health literacy (EHL), a domain of health literacy (HL) that describes the ability to use environmental health information to reduce health risks, and symptoms associated with HAP. METHODS: We performed a cross-sectional population-based study of 353 households in Kasarani, Kenya. One individual from each household was surveyed using our novel EHL survey tool. Baseline characteristics were compared between individuals who were symptomatic (i.e., experiencing cough, shortness of breath, phlegm production, wheeze, chest tightness, headache, eye irritation, or burns from cooking at least 5 times per month) versus individuals who were asymptomatic (i.e., experiencing none or symptoms no more than once per month). Multivariate logistic regression was used to determine the odds ratios (OR) of self-reported symptoms associated with HL, stratified by median EHL, adjusting for education, self-perceived health and solid fuel use. RESULTS: A total of 100 individuals (28%) reported experiencing one or more symptoms at least 5 times per month, including 31.2% of solid fuel users and 30.3% of non-solid fuel users. Among individuals with high EHL, higher HL was associated with lower risk of experiencing symptoms (OR = 0.26; 95% CI 0.10-0.67), however, there was no association among individuals with low EHL (OR = 0.85; 95% CI 0.34-2.13). Among solid fuel users, the association between HL and risk of experiencing symptoms was driven by individuals with high EHL (OR = 0.30; 95% CI 0.05-1.84), rather than those with low EHL (OR = 1.22; 95% CI 0.36-4.16). CONCLUSIONS: To the best of our knowledge, this was the first study to assess the association between EHL, HL, and HAP-associated symptoms. Our findings highlight the potential importance of EHL in promoting sustainable interventions to reduce symptoms associated with HAP from solid fuel use among communities in Kenya.

Reaching the sustainable development goals through healthy environments: are we on track?

The adoption of the 2030 Agenda for Sustainable Development in 2015 opened new opportunities to work towards healthy environments through 'whole of government' and 'whole of society' approaches. It created a strong policy platform that acknowledges health as a result and an enabler of sustainable policies across all sectors of government. Five years into the process, an initial analysis of emerging trends indicates that, despite some encouraging developments in policy as well as overall progress in economy and technology, there remains a gap between rhetoric, ambition and reality. In particular, the monitoring system for environment and health-related sustainable development goals (SDGs) and targets requires further development; inequalities in environment and health persist and in some areas have increased; equity is not yet a central element of implementation and reporting on the achievement of the SDGs; and, most worrying of all, trends in key environmental indicators that are vital to the survival of the human species, such as those related to climate change and biodiversity, are still on an overall negative path. In summary, governments must significantly and rapidly increase action to secure the habitability and safety of planet Earth. The public health community assumes an unprecedented role in placing and maintaining health and equity at the heart of the political agenda. This demands new governance models conferring on the health sector a clear mandate and legitimacy to operate across sectors. It also requires enhancing capacities among health professionals to embrace this new level of complexity, understand the multiple links between sectoral policies and health, and successfully engage with other government sectors and stakeholders.

Fungal spores and pollen are correlated with meteorological variables: effects in human health at Hermosillo, Sonora, Mexico.

We conducted the first study of air pollen and fungal spores for Hermosillo, Sonora, where the human population is exposed to high temperatures and high levels of dust and suffers from diseases related to air quality. We sampled pollen and fungal spores daily in the air during 2016 using a volumetric spore trap Hirst-type sampler. We used simple linear correlation to investigate the association between pollen and spore counts and daily weather conditions. We found an Annual Pollen Integral of 16,243 pollen day/m3 and an Annual Spore Integral higher 222,365 spore day/m3. We identified 32 pollen taxa and 15 different spores. We found two periods of higher pollen and spore concentrations: March to May and August to October, the latter was the most severe. Spore and pollen concentrations in the air increased at higher temperature and higher relative humidity but decreased at higher precipitation. We detected negative impacts during summer and fall on population health, with 13,454 cases of people who presented diseases related to allergies. A peak in allergies is centered during October and correlates well with our peaks in pollen and spore concentrations; it seems that pollen of Poaceae is the one that generates most effects in allergic people.

Causal Modeling in Environmental Health.

The field of environmental health has been dominated by modeling associations, especially by regressing an observed outcome on a linear or nonlinear function of observed covariates. Readers interested in advances in policies for improving environmental health are, however, expecting to be informed about health effects resulting from, or more explicitly caused by, environmental exposures. The quantification of health impacts resulting from the removal of environmental exposures involves causal statements. Therefore, when possible, causal inference frameworks should be considered for analyzing the effects of environmental exposures on health outcomes.

Cohort profile: Beyond birth cohort study - The Korean CHildren's ENvironmental health Study (Ko-CHENS).

The Korean CHildren's ENvironmental health Study (Ko-CHENS) is a nationwide prospective birth cohort showing the correlation between the environmental exposures and the health effects to prevent the environmental diseases in children, and it provides the guidelines for the environmental hazardous factors, applying the life-course approach to the environmental-health management system. The Ko-CHENS consists of 5000 Core and 65,000 Main Cohorts. The children in the Core Cohort are followed up at 6 months, every year before their admission into the elementary school, and every 3 years from the first year after this admission. The children in the Cohort will be followed up through the data links (Statistics Korea, National Health Insurance Service [NHIS], and Ministry of Education). The individual biospecimens will be analyzed for 19 substances. The long-term-storage biological samples will be used for the further substance analysis. The Ko-CHENS will investigate whether the environmental variables including the perinatal outdoor and indoor factors and the greenness contribute causally to the health outcomes in the children and adolescents. In addition to the individual surveys, the assessments of the outdoor exposures and health outcomes will use the national air-quality monitoring data and claim data of the NHIS, respectively. The two big-data forms of the Ko-CHENS are as follows: The Ko-CHENS data that can be linked with the nationally registered NHIS health-related database, including the medical utilization and the periodic health screening, and the birth/mortality database in the Statistics; the other is the Big-CHENS dataset that is based on the NHIS mother delivery code, for which the follow-up of almost 97% of the total birth population is expected. The Ko-CHENS is a very cost-effective study that fully exploits the existing national big-data systems with the data linkage.

Assessing the national capacity for disaster research response (DR2) within the NIEHS Environmental Health Sciences Core Centers.

INTRODUCTION: Disaster research response (DR2) is necessary to answer scientific questions about the environmental health impacts of disasters and the effectiveness of response and recovery strategies. This research explores the preparedness and capacity of National Institute of Environmental Health Sciences (NIEHS) P30 Core Centers (CCs) to conduct DR2 and engage with communities in the context of disasters. METHODS: In early 2018, we conducted an online survey of CC Directors (n = 16, 69.5% response rate) to identify their DR2 relevant scientific assets, capabilities, and activities. Summary statistics were calculated. We also conducted in-depth, semi-structured interviews with 16 (69.5%) CC Community Engagement Core directors to identify facilitators and barriers of DR2 community engagement. Interview notes were coded and thematically analyzed. RESULTS: Survey: While 56% of responding CCs reported prior participation in DR2 and preparedness to repurpose funding to support DR2, less than one third reported development of a disaster-specific data collection protocol, deployment plan, or concept of operations plan, participation in an exercise to test DR2 capacity, development of academic partnerships to conduct DR2, development of a process for fast-tracking institutional review board approvals for DR2, or maintenance of formal agreements with state, local, or community-based partner(s). A number of CCs reported developing or considering developing capacity in these areas. Barriers to, and tools and resources to enhance, CC engagement in DR2 were identified. Interviews: Four key components for community engaged DR2 were identified: pre-existing community relationships, responsive research that benefits communities, coordination among researchers, and coordination with community response partners. Several roles for, benefits of, and barriers to Community Engagement Rapid Response Teams (CERRT) were described. CONCLUSIONS: CCs have significant scientific assets and community partnerships that can be leveraged for DR2; however, additional planning is necessary to ensure that these scientific assets and community partnerships are leveraged when disasters strike.

Using machine learning to examine the relationship between asthma and absenteeism.

In this study, we found that machine learning was able to effectively estimate student learning outcomes geo-spatially across all the campuses in a large, urban, independent school district. The machine learning showed that key factors in estimating the student learning outcomes included the number of days students were absent from school. In turn, one of the most important factors in estimating the number of days a student was absent was whether or not the student had asthma. This highlights the importance of environmental public health for student learning outcomes.

Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016.

BACKGROUND: The Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) provides a comprehensive assessment of risk factor exposure and attributable burden of disease. By providing estimates over a long time series, this study can monitor risk exposure trends critical to health surveillance and inform policy debates on the importance of addressing risks in context. METHODS: We used the comparative risk assessment framework developed for previous iterations of GBD to estimate levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2016. This study included 481 risk-outcome pairs that met the GBD study criteria for convincing or probable evidence of causation. We extracted relative risk (RR) and exposure estimates from 22 717 randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources, according to the GBD 2016 source counting methods. Using the counterfactual scenario of theoretical minimum risk exposure level (TMREL), we estimated the portion of deaths and DALYs that could be attributed to a given risk. Finally, we explored four drivers of trends in attributable burden: population growth, population ageing, trends in risk exposure, and all other factors combined. FINDINGS: Since 1990, exposure increased significantly for 30 risks, did not change significantly for four risks, and decreased significantly for 31 risks. Among risks that are leading causes of burden of disease, child growth failure and household air pollution showed the most significant declines, while metabolic risks, such as body-mass index and high fasting plasma glucose, showed significant increases. In 2016, at Level 3 of the hierarchy, the three leading risk factors in terms of attributable DALYs at the global level for men were smoking (124·1 million DALYs [95% UI 111·2 million to 137·0 million]), high systolic blood pressure (122·2 million DALYs [110·3 million to 133·3 million], and low birthweight and short gestation (83·0 million DALYs [78·3 million to 87·7 million]), and for women, were high systolic blood pressure (89·9 million DALYs [80·9 million to 98·2 million]), high body-mass index (64·8 million DALYs [44·4 million to 87·6 million]), and high fasting plasma glucose (63·8 million DALYs [53·2 million to 76·3 million]). In 2016 in 113 countries, the leading risk factor in terms of attributable DALYs was a metabolic risk factor. Smoking remained among the leading five risk factors for DALYs for 109 countries, while low birthweight and short gestation was the leading risk factor for DALYs in 38 countries, particularly in sub-Saharan Africa and South Asia. In terms of important drivers of change in trends of burden attributable to risk factors, between 2006 and 2016 exposure to risks explains an 9·3% (6·9-11·6) decline in deaths and a 10·8% (8·3-13·1) decrease in DALYs at the global level, while population ageing accounts for 14·9% (12·7-17·5) of deaths and 6·2% (3·9-8·7) of DALYs, and population growth for 12·4% (10·1-14·9) of deaths and 12·4% (10·1-14·9) of DALYs. The largest contribution of trends in risk exposure to disease burden is seen between ages 1 year and 4 years, where a decline of 27·3% (24·9-29·7) of the change in DALYs between 2006 and 2016 can be attributed to declines in exposure to risks. INTERPRETATION: Increasingly detailed understanding of the trends in risk exposure and the RRs for each risk-outcome pair provide insights into both the magnitude of health loss attributable to risks and how modification of risk exposure has contributed to health trends. Metabolic risks warrant particular policy attention, due to their large contribution to global disease burden, increasing trends, and variable patterns across countries at the same level of development. GBD 2016 findings show that, while it has huge potential to improve health, risk modification has played a relatively small part in the past decade. FUNDING: The Bill & Melinda Gates Foundation, Bloomberg Philanthropies.

A class of semiparametric tests of treatment effect robust to confounder measurement error.

When assessing the presence of an exposure causal effect on a given outcome, measurement error of a confounder can inflate the type I error rate of a treatment effect in even the simplest of settings. In this paper, we develop a large class of semiparametric test statistics of an exposure causal effect, which are completely robust to additive unbiased measurement error of a subset of confounders. A unique and appealing feature of our proposed methodology is that it requires no external information such as validation data or replicates of error-prone confounders. We present a doubly robust form of this test that requires the exposure mean model to be linear in the mismeasured confounders, and only one of two models involving error-free confounders to be correctly specified for the resulting test statistic to have correct type I error rate. We demonstrate validity within our class of test statistics through simulation studies. We apply the methods to a multi-US-city time-series data set to test for an effect of temperature on mortality while adjusting for atmospheric particulate matter with diameter of 2.5 micrometres or less, which is known to be measured with error.

Capturing exposure in environmental health research: challenges and opportunities of different activity space models.

BACKGROUND: The built environment health promotion has attracted notable attention across a wide spectrum of health-related research over the past decade. However, the results about the contextual effects on health and PA are highly heterogeneous. The discrepancies between the results can potentially be partly explained by the diverse use of different spatial units of analysis in assessing individuals' exposure to various environment characteristics. This study investigated whether different residential and activity space units of analysis yield distinct results regarding the association between the built environment and health. In addition, this study examines the challenges and opportunities of the different spatial units of analysis for environmental health-related research. METHODS: Two common residential units of analysis and two novel activity space models were used to examine older adults' wellbeing in relation to the built environment features in the Helsinki Metropolitan Area, Finland. An administrative unit, 500 m residential buffer, home range model and individualized residential exposure model were used to assess the associations between the built environment and wellbeing of respondent's (n = 844). RESULTS: All four different spatial units of analysis yield distinct results regarding the associations between the built environment characteristics and wellbeing. A positive association between green space and health was found only when exposure was assessed with individualized residential exposure model. Walkability index and the length of pedestrian and bicycle roads were found to positively correlate with perceived wellbeing measures only with a home range model. Additionally, all units of analysis differed from each other in terms of size, shape, and how they capture different contextual measures. CONCLUSIONS: The results show that different spatial units of analysis result in considerably different measurements of built environment. In turn, the differences derived from the use of different spatial units seem to considerably affect the associations between environment characteristics and wellbeing measures. Although it is not easy to argue about the correctness of these measurements, what is evident is that they can reveal different wellbeing outcomes. While some methods are especially usable to determine the availability of environmental opportunities that promote active travel and the related health outcomes, others can provide us with insight into the mechanisms how the actual exposure to green structure can enhance wellbeing.

A Social-Ecological Review of Cancer Disparities in Kentucky.

Cancer continuously ranks among the top 10 leading causes of death in the United States. The burden of cancer is particularly elevated in the Commonwealth of Kentucky and its 54-county Appalachian region, where cancer is the leading cause of death. Kentucky's high rates of cancer have been attributed to a wide range of socioeconomic, behavioral, environmental, and policy influences, resulting in numerous disparities. The present review specifically evaluates the burden of lung, colorectal, cervical, and head and neck cancers in Kentucky, along with resultant cancer control research and community outreach efforts conducted by the state's only National Cancer Institute-designated cancer center using an adapted version of McLeroy's Social-Ecological Model. Here, we categorize disparities and identify relevant intervention approaches based on their level of influence (ie, individual, community, and policy).

The Potential for Proactive Housing Inspections to Inform Public Health Interventions.

Municipal housing inspection data can inform planning, targeting, and evaluating interventions aimed at reducing housing hazards (lead paint, mold, pests, etc) that may affect residents' health. However, the potential of these data to inform public health initiatives is underexplored. We determined whether home health hazards identified by city inspectors during proactive inspections of single-family private rental housing are predicted by housing age, assessed value, or location in one of 26 geographic "inspector areas" in Rochester, New York. A comparison of linear mixed models, using housing inspector area as a random effect and assessment and construction year as fixed effects, shows that while a large proportion of variation (64%) in violations is due to housing stock, inspectors provide significant additional information about the presence of potential health hazards, particularly in the highest-risk housing stock. This suggests that inspector-generated housing hazard data may be valuable in designing public health interventions.

Voices from Flint: Community Perceptions of the Flint Water Crisis.

We describe the self-reported socioeconomic and health impacts, as well as the coping mechanisms employed by a drug-using cohort of adults during the Flint water crisis (FWC) in Flint, Michigan. Participants from an ongoing longitudinal Emergency Department study were contacted between April 2016 and July 2016 and completed a survey focusing on exposure, consequences, and coping strategies. One hundred thirty-three participants (mean age = 26, 65% African-American, 61% public assistance) completed the survey (37.9% response rate). Of these, 75% reported exposure to water with elevated lead levels. Of these, 75% reported additional monthly expenses resulting from exposure. Almost 40% of parents reported changes in their children's health and 65% reported changes to their health since the FWC. Participants indicated the use of both positive (e.g., advice from trusted neighbors, 99.0%) and negative coping mechanisms (e.g., increased substance use, 20.0%) in response to this public health emergency. High-risk Flint residents reported multiple social, economic, and health-related consequences stemming from the FWC. Policymakers should consider additional resources for those affected, including increased access to mental health to aid recovery within the community.

"These Power Lines Make Me Ill": A Typology of Residents' Health Responses to a New High-Voltage Power Line.

Little attention has been devoted to the potential diversity in residents' health responses when exposed to an uncertain environmental health risk. The present study explores whether subgroups of residents respond differently to a new high-voltage power line (HVPL) being put into operation. We used a quasi-experimental prospective field study design with two pretests during the construction of a new HVPL, and two posttests after it was put into operation. Residents living nearby (0-300 m, n = 229) filled out questionnaires about their health and their perception of the environment. We applied latent class growth models to investigate heterogeneity in the belief that health complaints were caused by a power line. Classes were compared on a wide range of variables relating to negative-oriented personality traits, perceived physical and mental health, and perceptions of the environment. We identified five distinct classes of residents, of which the largest (49%) could be described as emotionally stable and healthy with weak responses to the introduction of a new power line. A considerable minority (9%) responded more strongly to the new line being activated. Residents in this class had heard more about the health effects of power lines beforehand, were more aware of the activation of the new line, and reported a decrease in perceived health afterwards. Based on our findings we can conclude that there is a considerable heterogeneity in health responses to a new HVPL. Health risk perceptions appear to play an important role in this typology, which has implications for risk management.

Health Impact of Climate Change in Older People: An Integrative Review and Implications for Nursing.

PURPOSE: Older people account for the highest proportion of mortality from extreme weather events associated with climate change. This article aims to describe the health impacts of climate change on older people. TYPE OF STUDY: An integrative review was conducted with 30 studies retrieved from PubMed, EBSCO, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) on climate stressors, determinants of resilient capacity, risk factors, and health outcomes. FINDINGS: Heat, temperature variability, and air pollution increase mortality risk in older people, especially from cardiovascular and respiratory diseases. Floods are linked with increasing incidence of post-traumatic stress disorder, depression, and anxiety. Facing these adversities, older people exhibit both vulnerability and resilience. CONCLUSIONS: Research gaps exist in understanding the full spectrum of the resilience experience of older people, and appreciating areas wherein nursing can play a pivotal role. CLINICAL RELEVANCE: Recognizing the vulnerabilities of older people in the context of climate change is important. Identifying opportunities to promote resilience is an important focus for nurses to develop tailored and targeted nursing interventions.

Islam and Environmental Consciousness: A New Scale Development.

This research proposed a new construct, Islamic environmental consciousness (IEC), and developed a measurement scale to support this construct. Churchill's (J Mark Res 16(1):64-73, 1979) paradigm, adapted by Negra and Mzoughi (Internet Res 22(4):426-442, 2012), was utilized. A total of 32 items were generated based on the verses of the Qur'an from nine interviews with teachers in an Islamic seminary. This set of items was reduced to 19 after dropping redundant or non-representative items. In a pilot study, factor analysis of the 19-item scale yielded a two-factor structure scale of seven items with a reliability ranging from 0.7 to 0.8. The Islamic environmental consciousness scale (IECS) was statistically confirmed and validated in a subsequent investigation. The proposed measurement scale warrants further exploratory study. Future research should assess the IECS's validity across different Muslim countries, locales, and various Islamic schools of thought and practice. IEC is proposed as a new construct that focuses primarily on the Qur'an and seeks to achieve acceptance by both Sunni and Shia denominations. In this study, both cognitive attitudes and behavioral aspects were considered in the design of the IECS.

[SCREENING LEVEL ENVIRONMENTAL HEALTH RISK ASSESSMENT BY HEALTH DATA IN SOME SMALL AREAS OF UPPER IMERETI (CHIATURA DISTRICT)].

The article presents the results of a comparative analysis of health data in villages Rgani, Perevisa and Khreiti population (Chiatura municipality), Which were obtained by the initiative group of the ak. N. Kipshidze Republican Hospital within the framework of the universal healthcare program of population insurance. The villages differ as by their remoteness from sources of ecological danger - manganese quarries, and scales of its achievement, which gives grounds to rank them according to the degree of ecological tension The purpose of the research is to develop optimal for Georgia approach to obtain and analyze information for site-specific environmental health risks assessment The analysis of the data was carried out using exploratory and evidentiary statistics: Cluster analysis, Logarithmic linear analysis and 2x2 conjugacy tables, correlation analysis, nonparametric statistics methods. As a measure of the adverse environmental impact on the health of the population, the ratio of the chances of developing pathologies was used. Statistical analysis and graphical visualization of the results were carried out using the STATISTICA-10 SPSS software. It was found that in the villages the surveyed population differ statistically significantly in the levels of chronic obstructive pulmonary disease (J44) and chronic bronchitis (J42), which according to the recommendations of the World Health Organization are among the direct indices of indoor and outdoor air pollution. It was found that the values of the odds ratio (by prevalence) of the development of chronic lung diseases in the samples are associated with the degree of possible external exposure to them. A subsample (a population of people over 50 years old) representative of the corresponding population group was identified and on the basis of which it was established that the chance of developing chronic obstructive lung diseases in the village of Ragani is about 5-7 times higher than in the village of Khreiti. The obtained results testify to the high information content of the survey data for site-specific assessments of environmental health risks. Specific directions for increasing their information content are outlined.