Cancer death rates in US congressional districts.

Knowledge of the cancer burden is important for informing and advocating cancer prevention and control. Mortality data are readily available for states and counties, but not for congressional districts, from which representatives are elected and which may be more influential in compelling legislation and policy. The authors calculated average annual cancer death rates during 2002 to 2011 for each of the 435 congressional districts using mortality data from the National Center for Health Statistics and population estimates from the US Census Bureau. Age-standardized death rates were mapped for all sites combined and separately for cancers of the lung and bronchus, colorectum, breast, and prostate by race/ethnicity and sex. Overall cancer death rates vary by almost 2-fold and are generally lowest in Mountain states and highest in Appalachia and areas of the South. The distribution is similar for lung and colorectal cancers, with the lowest rates consistently noted in districts in Utah. However, for breast and prostate cancers, while the highest rates are again scattered throughout the South, the geographic pattern is less clear and the lowest rates are in Hawaii and southern Texas and Florida. Within-state heterogeneity is limited, particularly for men, with the exceptions of Texas, Georgia, and Florida. Patterns also vary by race/ethnicity. For example, the highest prostate cancer death rates are in the West and north central United States among non-Hispanic whites, but in the deep South among African Americans. Hispanics have the lowest rates except for colorectal cancer in Wyoming, eastern Colorado, and northern New Mexico. These data can facilitate cancer control and stimulate conversation about the relationship between cancer and policies that influence access to health care and the prevalence of behavioral and environmental risk factors.

Effect of soil particle size and extraction method on the oral bioaccessibility of arsenic.

Recent findings indicate that incidental ingestion of soil by humans primarily involves soil particles <150 µm, rather than <250 µm-sized fraction previously used for most oral bioaccessibility and bioavailability studies. It was postulated that a greater soil surface area in the finer fraction (<150 versus <250 µm) might increase oral bioaccessibility of arsenic (As) in soil. Bioaccessibility and concentrations of As were compared in <150 and <250 µm fractions of 18 soil samples from a variety of arsenic-contaminated sites. The two methods used to measure bioaccessibility were compared - EPA Method 1340 and the California Arsenic Bioaccessibility (CAB) method. Arsenic concentrations were nearly the same or higher in the <150 fraction compared with <250 µm. EPA Method 1340 and the CAB method presented significantly different bioaccessibility results, as well as estimated relative oral bioavailability (RBA) based upon algorithms specific to the methods, but there was no marked difference for <150 and <250 µm soil fractions within either method. When compared with RBA determined previously for these soil samples in vivo in non-human primates, EPA Method 1340 was generally more predictive than the CAB method. Data suggest that soil- or site-specific factors control bioaccessibility under either method and that the test method selected is more important than the particle size fraction (<150 or <250) in using these in vitro methods to predict As RBA for use in risk assessment.

Investigating relationships among cancer survivors' engagement in an online support community, social support perceptions, well-being, and moderating effects of existing (offline) social support.

PURPOSE: Socially supportive relationships help cancer survivors cope with their diagnosis and may improve quality of life; however, many survivors report unmet support and information needs. Online communities of survivors may address these needs, but research on their benefits have been equivocal. This cross-sectional, self-report study investigated relationships among cancer survivors' level of engagement in an online survivor community (The American Cancer Society Cancer Survivors Network®; CSN), perceptions of emotional/informational support available from online communities ("online social support"), well-being, and moderating effects of "offline social support." METHODS: Participants were 1255 registered users of the CSN who completed surveys between 2013 and 2014. Three types of engagement with the CSN-social/communal, interpersonal communication, and informational/search engagement-were identified through principal components analysis. Regression analyses examined hypotheses. RESULTS: More frequent social/communal and interpersonal communication engagement were associated with increased online social support (p < .0001), and the relationship between interpersonal communication engagement and online social support was strongest for survivors reporting lower offline social support (interaction ß = - .35, p < .001). Greater online social support was associated with increased well-being, but only among survivors reporting low offline social support (interaction ß = - .35, p < .0001). CONCLUSIONS: Engagement in online survivor communities may increase support perceptions that promote well-being, but benefits may accrue more to survivors reporting low offline social support. IMPLICATIONS FOR CANCER SURVIVORS: Newly diagnosed cancer survivors, particularly those with unmet emotional/informational support needs, should be given the opportunity to communicate with other survivors through online survivor support networks.

Dose-response assessment for impaired memory from chronic exposure to domoic acid among native American consumers of razor clams.

Domoic acid (DA) is a marine neurotoxin that accumulates in filtering shellfish during harmful algal blooms. A health protection limit of 20 ppm DA in razor clams (RC) has been set based principally upon an episode of acute DA toxicity in humans that included Amnesic Shellfish Poisoning among survivors. The objective of this study was to determine the dose-response relationship between estimated DA exposure through RC consumption and memory loss in Washington state Native Americans from 2005 to 2015. Results from total learning recall (TLR) memory scores were compared before and after the highest DA exposures. A decrease in TLR was related to DA dose (p < 0.01) regardless whether the effect was assumed to be transient or lasting, and whether the dose was expressed as an average daily dose or an average dose per meal. Benchmark dose modeling identified BMDL10 values of 167 ng/kg-day and 2740 ng/kg-meal assuming a transient effect, and 196 ng/kg-day and 2980 ng/kg-meal assuming no recovery of function occurs. These DA dose thresholds for a measurable memory function reduction observed in this study of clam consumers are well below the safe acute dose underpinning the current regulatory DA limit of 20 ppm (ca. 60 µg/kg).

Preparedness and Cancer-Related Symptom Management among Cancer Survivors in the First Year Post-Treatment.

BACKGROUND: Many cancer survivors feel unprepared for the physical and psychosocial challenges that accompany the post-treatment care transition (i.e., re-entry phase), including management of cancer-related symptoms. Few studies have investigated personal and contextual factors associated with the extent of preparedness for re-entry or how they are related to cancer-related symptom management. PURPOSE: Data from the American Cancer Society's Cancer Survivor Transition Study examined (1) characteristics of breast, prostate, and colorectal cancer survivors (n = 1188) within the first year of completing treatment who are most and least prepared for re-entry; and (2) how preparedness level and other characteristics are related to cancer-related symptom management. METHODS: Stanton and colleagues' [1] conceptual model of survivorship guided the selection of interpersonal/environmental, individual, and disease/treatment-related characteristics as potential contributors to levels of preparedness and cancer-related symptom management using regression tree and multivariate linear regression analyses. RESULTS: Survivors, on average, felt moderately prepared for the transition to post-treatment care. Lowest levels of preparedness were found among survivors with relatively high depressive symptoms, low perceived quality of oncology-provided survivorship care, and limited discussion about potential side effects with a health professional. Poorer symptom management was associated with younger age, having more comorbid conditions, and lower preparedness, social support, and spirituality. CONCLUSION: Survivors who feel unprepared for the transition to post-treatment care report poorer cancer-related symptom management. Identification of factors associated with low perceived preparedness and poor cancer-related symptom management will assist in risk stratification and development of tailored interventions to meet the needs of cancer survivors during re-entry.

Topic Modeling of Smoking- and Cessation-Related Posts to the American Cancer Society's Cancer Survivor Network (CSN): Implications for Cessation Treatment for Cancer Survivors Who Smoke.

INTRODUCTION: Smoking is a risk factor in at least 18 cancers, and approximately two-thirds of cancer survivors continue smoking following diagnosis. Text mining of survivors' online posts related to smoking and quitting could inform strategies to reduce smoking in this vulnerable population. METHODS: We identified posts containing smoking/cessation-related keywords from the Cancer Survivors Network (CSN), an online cancer survivor community of 166 000 members and over 468 000 posts since inception. Unsupervised topic model analysis of posts since 2000 using Latent Dirichlet Allocation extracted 70 latent topics which two subject experts inspected for themes based on representative terms. Posterior analysis assessed the distribution of topics within posts, and the range of themes discussed across posts. RESULTS: Less than 1% of posts (n = 3998) contained smoking/cessation-related terms, and covered topics related to cancer diagnoses, treatments, and coping. The most frequent smoking-related topics were quit smoking methods (5.4% of posts), and the environment for quitters (2.9% of posts), such as the stigma associated with being a smoker diagnosed with cancer and lack of empathy experienced compared to nonsmokers. Smoking as a risk factor for one's diagnosis was a primary topic in only 1.7% of smoking/cessation-related posts. CONCLUSIONS: The low frequency of smoking/cessation-related posts may be due to expected criticism/stigma for smoking but may also suggests a need for health care providers to address smoking and assist with quitting in the diagnostic and treatment process. Topic model analysis revealed potential barriers that should be addressed in devising clinical or population-level interventions for cancer survivors who smoke. IMPLICATIONS: Although smoking is a major risk factor for cancer, little is known about cancer patients' or survivors' views or concerns about smoking and quitting. This study used text mining of posts to an online community of cancer patients and survivors to investigate contexts in which smoking or quitting is discussed. Results indicated that smoking and quitting discussions were relatively rare, but nevertheless provide insight into barriers that may need to be addressed in cessation interventions for survivors.

American Cancer Society perspectives on environmental factors and cancer.

Cancer prevention is central to the mission of the American Cancer Society (ACS). The ACS's prevention activities take many forms, but are primarily focused on modifiable risk factors that have been demonstrated to have the largest impact on cancer risk in the general population (with particular emphasis on tobacco use because of its large impact on cancer), and well-proven policy and program interventions. The ACS addresses nutrition, physical inactivity and obesity, alcohol consumption, excessive sun exposure, prevention of certain chronic infections, and selected other environmental factors through a variety of venues, including consensus guidelines (eg, nutrition and physical activity, human papillomavirus vaccination) and developing educational materials for health care providers and the general public. In contrast to the broad definition of environmental factors used by the ACS and most other public health agencies, some members of the general public associate the term "environmental" only with toxic air and water pollutants and other, predominantly manmade, hazards that people encounter, often involuntarily, in their daily life. This article will provide an overview of the ACS's approach to the prevention of cancer associated with such toxic pollutants in the context of its mission and priorities with respect to cancer prevention.

The development and acceptability of symptom management quality improvement reports based on patient-reported data: an overview of methods used in PROSSES.

PURPOSE: Patient experiences with symptom care need to be assessed and documented to ensure successful management of cancer-related symptoms. This paper details one method for creating symptom management quality improvement (SMQI) reports, including case-mix adjustment of patient-reported measures. Qualitative data regarding the acceptability of these reports at participating cancer centers (CCs) are also provided. METHODS: Data were collected from 2226 patients treated at 16 CCs via mailed/Web questionnaires. Twelve items assessing patient perceptions of symptom management-pain, fatigue, emotional distress-served as key quality indicators. Medico-demographic variables suitable for case-mix adjustment were selected using an index score combining predictive power and heterogeneity across CCs. SMQI reports were designed with staff feedback and produced for each CC, providing crude and adjusted CC-specific rates, along with study-wide rates for comparison purposes. RESULTS: Cancer type and participant educational level were selected for case-mix adjustment based upon high index scores. The Kendall rank correlation coefficient showed that case-mix adjustments changed the ranking of CCs on the key quality indicators (% Δ rank range: 5-22 %). The key quality indicators varied across CCs (all p < 0.02). SMQI reports were well received by CC staff, who described plans to share them with key personnel (e.g., cancer committee, navigator). CONCLUSIONS: This paper provides one method for creating hospital-level SMQI reports, including case-mix adjustment. Variation between CCs on key quality indicators, even after adjustment, suggested room for improvement. SMQI reports based on patient-reported data can inform and motivate efforts to improve care through professional/patient education and applying standards of care.

Association between urologist characteristics and radiation oncologist consultation for patients with locoregional prostate cancer.

BACKGROUND: Physicians managing patients with prostate cancer play a critical role in subsequent specialist consultations and initial treatment choice, especially in cases for which no consensus exists regarding optimal treatment strategy. The NCCN Guidelines for Prostate Cancer recommend radiation as a therapy option for patients with locoregional prostate cancer. PURPOSE: The authors examined the association of urologist characteristics with the likelihood that patients would consult radiation oncologists. METHODS: A retrospective cohort of 39,934 patients aged 66 years or older who were diagnosed with locoregional prostate cancer between 2004 and 2007, and the 2405 urologists who performed the patient diagnostic biopsies were constructed using the SEER-Medicare linked database and the American Medical Association Physician Masterfile. Logistic multilevel regression analysis was used to evaluate the influence of urologists' characteristics on radiation oncologist consultation within 9 months of locoregional prostate cancer diagnosis. RESULTS: Overall, 24,549 (61.5%) patients consulted a radiation oncologist. After adjusting for patient and urologist characteristics, patients diagnosed by urologists in noninstitutional settings (eg, physician office) were significantly more likely to consult a radiation oncologist (odds ratio [OR], 1.40; 95% CI, 1.17-1.67; P=.0002) compared with those diagnosed by urologists in institutional settings with a major medical school affiliation. In addition, patients diagnosed by urologists older than 57 years were significantly more likely to consult a radiation oncologist (OR, 1.21; 95% CI, 1.07-1.38, P=.003).

Determinants of the combined use of external beam radiotherapy and brachytherapy for low-risk, clinically localized prostate cancer.

BACKGROUND: Prostate cancer treatment choices have been shown to vary by physician and patient characteristics. For patients with low-risk, clinically localized prostate cancer, the authors examined the impact of their clinical, sociodemographic, and radiation oncologists' (RO) characteristics on the likelihood that the patients would receive combined external beam radiotherapy and brachytherapy, a treatment regimen that is at variance with clinical guidelines. METHODS: The Surveillance, Epidemiology and End Results (SEER)-Medicare linked database and the American Medical Association Physician Masterfile were used in a retrospective analysis of 5531 patients with low-risk, clinically localized prostate cancer who were diagnosed between 2004 and 2007, and the 708 ROs who treated them. Hierarchical logistic regression analyses were used to evaluate the relationship between patient and RO characteristics and the use of combined therapy within 6 months of diagnosis. RESULTS: Overall, 356 patients (6.4%) received combined therapy. Nonclinical factors were found to be associated with combined therapy. After adjusting for patient and RO characteristics, the odds of receiving combined therapy for patients residing in Georgia were found to be significantly greater than for all other SEER regions. Black patients were significantly less likely to receive combined therapy (odds ratio, 0.62; 95% confidence interval, 0.40-0.96 [P= .03]) compared with white patients. In addition, ROs accounted for 36.6% of the variation in patients receiving combined therapy. CONCLUSIONS: Geographic and sociodemographic factors were found to be significantly associated with guideline-discordant combined therapy for patients diagnosed with low-risk, clinically localized prostate cancer. Which RO a patient consults is important in determining whether they receive combined therapy.

Racial/ethnic differences in spiritual well-being among cancer survivors.

This study examined racial/ethnic differences in spiritual well-being (SWB) among survivors of cancer. We hypothesized higher levels of Peace and Faith, but not Meaning, among Black and Hispanic survivors compared to White survivors, differences that would be reduced but remain significant after controlling for sociodemographic and medical factors. Hypotheses were tested with data from the American Cancer Society's Study of Cancer Survivors-II. The FACIT-Sp subscale scores, Meaning, Peace, and Faith assessed SWB, and the SF-36 Physical Component Summary measured functional status. In general, bivariate models supported our initial hypotheses. After adjustment for sociodemographic and medical factors, however, Blacks had higher scores on both Meaning and Peace compared to Hispanics and Whites, and Hispanics' scores on Peace were higher than Whites' scores. In contrast, sociodemographic and medical factors had weak associations with Faith scores. The pattern with Faith in bivariate models persisted in the fully adjusted models. Racial/ethnic differences in Meaning and in Peace, important dimensions of SWB, were even stronger after controlling for sociodemographic and medical factors. However, racial/ethnic differences in Faith appeared to remain stable. Further research is needed to determine if racial/ethnic differences in SWB are related to variations in quality of life in survivors of cancer.

Predicting US- and state-level cancer counts for the current calendar year: Part I: evaluation of temporal projection methods for mortality.

BACKGROUND: A study was undertaken to evaluate the temporal projection methods that are applied by the American Cancer Society to predict 4-year-ahead projections. METHODS: Cancer mortality data recorded in each year from 1969 through 2007 for the United States overall and for each state from the National Center for Health Statistics was obtained. Based on the mortality data through 2000, 2001, 2002, and 2003, Projections were made 4 years ahead to estimate the expected number of cancer deaths in 2004, 2005, 2006, 2007, respectively, in the United States and in each state, using 5 projection methods. These predictive estimates were compared to the observed number of deaths that occurred for all cancers combined and 47 cancer sites at the national level, and 21 cancer sites at the state level. RESULTS: Among the models that were compared, the joinpoint regression model with modified Bayesian information criterion selection produced estimates that are closest to the actual number of deaths. Overall, results show the 4-year-ahead projection has larger error than 3-year-ahead projection of death counts when the same method is used. However, 4-year-ahead projection from the new method performed better than the 3-year-ahead projection from the current state-space method. CONCLUSIONS: The Joinpoint method with modified Bayesian information criterion model has the smallest error of all the models considered for 4-year-ahead projection of cancer deaths to the current year for the United States overall and for each state. This method will be used by the American Cancer Society to project the number of cancer deaths starting in 2012.

Predicting US- and state-level cancer counts for the current calendar year: Part II: evaluation of spatiotemporal projection methods for incidence.

BACKGROUND: The current study was undertaken to evaluate the spatiotemporal projection models applied by the American Cancer Society to predict the number of new cancer cases. METHODS: Adaptations of a model that has been used since 2007 were evaluated. Modeling is conducted in 3 steps. In step I, ecologic predictors of spatiotemporal variation are used to estimate age-specific incidence counts for every county in the country, providing an estimate even in those areas that are missing data for specific years. Step II adjusts the step I estimates for reporting delays. In step III, the delay-adjusted predictions are projected 4 years ahead to the current calendar year. Adaptations of the original model include updating covariates and evaluating alternative projection methods. Residual analysis and evaluation of 5 temporal projection methods were conducted. RESULTS: The differences between the spatiotemporal model-estimated case counts and the observed case counts for 2007 were < 1%. After delays in reporting of cases were considered, the difference was 2.5% for women and 3.3% for men. Residual analysis indicated no significant pattern that suggested the need for additional covariates. The vector autoregressive model was identified as the best temporal projection method. CONCLUSIONS: The current spatiotemporal prediction model is adequate to provide reasonable estimates of case counts. To project the estimated case counts ahead 4 years, the vector autoregressive model is recommended to be the best temporal projection method for producing estimates closest to the observed case counts.

An examination of the 3-factor model and structural invariance across racial/ethnic groups for the FACIT-Sp: a report from the American Cancer Society's Study of Cancer Survivors-II (SCS-II).

OBJECTIVES: Recent confirmatory factor analysis (CFA) of the Functional Assessment of Chronic Illness Therapy-Spiritual Well-Being (FACIT-Sp) Scale in a sample of predominantly white women demonstrated that three factors, Meaning, Peace, and Faith, represented a psychometric improvement over the original 2-factor model. The present study tested these findings in a more diverse sample, assessed the stability of the model across racial/ethnic groups, and tested the contribution of a new item. METHODS: In a study by the American Cancer Society, 8805 cancer survivors provided responses on the FACIT-Sp, which we tested using CFA. RESULTS: A 3-factor model provided a better fit to the data than the 2-factor model in the sample as a whole and in the racial/ethnic subgroups (Deltachi(2), p<0.001, for all comparisons), but was not invariant across the groups. The model with equal parameters for racial/ethnic groups was a poorer fit to the data than a model that allowed these parameters to vary (Deltachi(2)(81)=2440.54, p<0.001), suggesting that items and their associated constructs might be understood differently across racial/ethnic groups. The new item improved the model fit and loaded on the Faith factor. CONCLUSIONS: The 3-factor model is likely to provide more specific information for studies in the field. In the construction of scales for use with diverse samples, researchers need to pay greater attention to racial/ethnic differences in interpretation of items.

Density-dependent habitat selection and performance by a large mobile reef fish.

Many exploited reef fish are vulnerable to overfishing because they concentrate over hard-bottom patchy habitats. How mobile reef fish use patchy habitat, and the potential consequences on demographic parameters, must be known for spatially explicit population dynamics modeling, for discriminating essential fish habitat (EFH), and for effectively planning conservation measures (e.g., marine protected areas, stock enhancement, and artificial reefs). Gag, Mycteroperca microlepis, is an ecologically and economically important warm-temperate grouper in the southeastern United States, with behavioral and life history traits conducive to large-scale field experiments. The Suwannee Regional Reef System (SRRS) was built of standard habitat units (SHUs) in 1991-1993 to manipulate and control habitat patchiness and intrinsic habitat quality, and thereby test predictions from habitat selection theory. Colonization of the SRRS by gag over the first six years showed significant interactions of SHU size, spacing, and reef age; with trajectories modeled using a quadratic function for closely spaced SHUs (25 m) and a linear model for widely spaced SHUs (225 m), with larger SHUs (16 standardized cubes) accumulating significantly more gag faster than smaller 4-cube SHUs (mean = 72.5 gag/16-cube SHU at 225-m spacing by year 6, compared to 24.2 gag/4-cube SHU for same spacing and reef age). Residency times (mean = 9.8 mo), indicative of choice and measured by ultrasonic telemetry (1995-1998), showed significant interaction of SHU size and spacing consistent with colonization trajectories. Average relative weight (W(r)) and incremental growth were greater on smaller than larger SHUs (mean W(r) = 104.2 vs. 97.7; incremental growth differed by 15%), contrary to patterns of abundance and residency. Experimental manipulation of shelter on a subset of SRRS sites (2000-2001) confirmed our hypothesis that shelter limits local densities of gag, which, in turn, regulates their growth and condition. Density-dependent habitat selection for shelter and individual growth dynamics were therefore interdependent ecological processes that help to explain how patchy reef habitat sustains gag production. Moreover, gag selected shelter at the expense of maximizing their growth. Thus, mobile reef fishes could experience density-dependent effects on growth, survival, and/or reproduction (i.e., demographic parameters) despite reduced stock sizes as a consequence of fishing.

Attributable fraction estimation from complex sample survey data.

PURPOSE: A review of methods for the estimation of attributable fraction (AF) statistics from case-control, cross-sectional, or cohort data collected under a complex sample design. Provide guidance on practical methods of complex sample AF estimation and inference using contemporary software tools. METHODS: Statistical literature on AF estimation from complex samples for the period 1980 to 2014 is reviewed. A general approach based on weighted sum estimators of the AF and application of Jackknife repeated replication and Bootstrap resampling methods for estimating the variance of AF estimates is outlined and applied to an example analysis of risk factors for alcohol dependency. RESULTS: The literature lays the theoretical foundation to address the problem of AF estimation and inference from complex samples. To date, major statistical software packages do not provide a complete program but the approach is easily implemented using the modeling software and macro/function language capabilities available in major statistical analysis packages. In an example application, weighted sum estimation and inference for the population AF showed stable and consistent results under both Jackknife repeated replication and Bootstrap methods of variance estimation. CONCLUSIONS: Future work on AF estimation for complex samples should focus on simulation studies and empirical testing to investigate the properties of the resampling variance estimation methods across a range of complex study design features and populations.

Effects of local extinction of the plains vizcacha (Lagostomus maximus) on vegetation patterns in semi-arid scrub.

We studied spatial and temporal effects of local extinction of the plains vizcacha (Lagostomus maximus) on plant communities following widespread, natural extinctions of vizcachas in semi-arid scrub of Argentina. Spatial patterns in vegetation were examined along transects extending outward from active and extinct vizcacha burrow systems. Responses of vegetation to removal of vizcachas were assessed experimentally with exclosures and by documenting vegetation dynamics for 6 years following extinctions. Transect data demonstrated clear spatial patterns in plant cover, particularly an increase in perennial grasses, outward from active vizcacha burrows. These patterns were consistent with predictions based on foraging theory and studies that document grasses as the preferred food of vizcachas. Removal of vizcachas, experimentally and with extinctions, resulted in an immediate increase in perennial and annual forbs indicating that intense herbivory can depress forb cover, as well as grasses. After a 1-year lag following cessation of herbivory, cover of grasses increased. Forbs declined as grasses increased. The long-term effect of extinction of vizcachas was a conversion of colony sites from open patches dominated by forbs to dense bunch grass characteristic of the matrix. Major changes in vegetation occurred within 2-3 years after extinction, resulting in a large pulse of landscape change. However, some species of grasses were uncommon until 5-6 years after the vizcacha extinction. With extinction and colonization, vizcachas generate a dynamic mosaic of patches on the landscape and create temporal, as well as spatial, heterogeneity in semi-arid scrub.

Nitrogen removal and nitrate leaching for two perennial, sod-based forage systems receiving dairy effluent.

In northern Florida, year-round forage systems are used in dairy effluent sprayfields to reduce nitrate leaching. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentration below the rooting zone for two perennial, sod-based, triple-cropping systems over four 12-mo cycles (1996-2000). The soil is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzip-samment). Effluent N rates were 500, 690, and 910 kg ha(-1) per cycle. Differences in N removal between a corn (Zea mays L.)-bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (CBR) and corn-perennial peanut (Arachis glabrata Benth.)-rye system (CPR) were primarily related to the performance of the perennial forages. Nitrogen removal of corn (125-170 kg ha(-1)) and rye (62-90 kg ha(-1)) was relatively stable between systems and among cycles. The greatest N removal was measured for CBR in the first cycle (408 kg ha(-1)), with the bermudagrass removing an average of 191 kg N ha(-1). In later cycles, N removal for bermudagrass declined because dry matter (DM) yield declined. Yield and N removal of perennial peanut increased over the four cycles. Nitrate N concentrations below the rooting zone were lower for CBR than CPR in the first two cycles, but differences were inconsistent in the latter two. The CBR system maintained low NO3(-)-N leaching in the first cycle when the bermudagrass was the most productive; however, it was not a sustainable system for long-term prevention of NO3(-)-N leaching due to declining bermudagrass yield in subsequent cycles. For CPR, effluent N rates > or = 500 kg ha(-1) yr(-1) have the potential to negatively affect ground water quality.

Nitrogen removal and nitrate leaching for forage systems receiving dairy effluent.

Florida dairies need year-round forage systems that prevent loss of N to ground water from waste effluent sprayfields. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentrations in soil water below the rooting zone for two forage systems during four 12-mo cycles (1996-2000). Soil in the sprayfield is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzipsamment). Over four cycles, average loading rates of effluent N were 500, 690, and 910 kg ha(-1) per cycle. Nitrogen removed by the bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (BR) during the first three cycles was 465 kg ha(-1) per cycle for the low loading rate, 528 kg ha(-1) for the medium rate, and 585 kg ha(-1) for the high. For the corn (Zea mays L.)-forage sorghum [Sorghum bicolor (L.) Moench]-rye system (CSR), N removals were 320 kg ha(-1) per cycle for the low rate, 327 kg ha(-1) for the medium, and 378 kg ha(-1) for the high. The higher N removals for BR were attributed to higher N concentration in bermudagrass (18.1-24.2 g kg(-1)) than in corn and forage sorghum (10.3-14.7 g kg(-1)). Dry matter yield declined in the fourth cycle for bermudagrass but N removal continued to be higher for BR than CSR. The BR system was much more effective at preventing NO3(-)-N leaching. For CSR, NO3(-)-N levels in soil water (1.5 m below surface) increased steeply during the period between the harvest of one forage and canopy dosure of the next. Overall, the BR system was better than CSR at removing N from the soil and maintaining low NO3(-)-N concentrations below the rooting zone.

Finding influential users of online health communities: a new metric based on sentiment influence.

OBJECTIVE: Online health communities (OHCs) have become a major source of support for people with health problems. This research tries to improve our understanding of social influence and to identify influential users in OHCs. The outcome can facilitate OHC management, improve community sustainability, and eventually benefit OHC users. METHODS: Through text mining and sentiment analysis of users' online interactions, the research revealed sentiment dynamics in threaded discussions. A novel metric--the number of influential responding replies--was proposed to directly measure a user's ability to affect the sentiment of others. RESULTS: Using the dataset from a popular OHC, the research demonstrated that the proposed metric is highly effective in identifying influential users. In addition, combining the metric with other traditional measures further improves the identification of influential users.