Field-derived growth rates (RNA-DNA based) of cod (Gadus morhua) larvae collected on the southern flank of Georges Bank were higher on average in May 1993 than May 1994, despite the apparent higher abundance of potential prey in 1994. A biophysical modeling study is presented here in which factors are examined that may have led to the difference in population mean growth. A one-dimensional physical model, forced by winds and tides, was used to simulate the vertical structure (of currents, temperature field, and turbulent kinetic energy dissipation rate) following a column of water in a Lagrangian sense at a site on the southern flank of Georges Bank over 5-day periods in late May of 1993 and 1994. The biophysical model and observed zooplankton abundance allowed us to explore the vertical structure and temporal (hourly) evolution of feeding and growth for cod larvae in relation to environmental conditions. Our trophodynamic model is improved over previous versions and now includes the effect of light on larval feeding response, as well as the effect of temperature on larval metabolic costs, ingestion, and digestion. Larval prey profiles, comprising four copepod species, were used from a time series of 1/4-m 2 MOCNESS tows to define the prey field. Data from a collateral time-series of larval gut contents (1-m 2 MOCNESS tows) was used to define maximum ingestion (satiation level) and prey selection. Model outputs provide depth-dependent estimates of growth, prey biomass ingested, larval length, and larval weight. Watercolumn growth-rate profiles were made for four size classes of larvae (5, 6, 7 and 9 mm) under the environmental conditions observed in May 1993 and 1994. A weighted-mean growth rate based on the mean vertical distribution of larvae was estimated for each size class. In all cases, when using all available potential prey, the model-derived 1994 growth rates were higher (by 3-6% day )1 ) than those for 1993. However, simulations in which 7-mm larvae followed the field-derived weighted mean depth over the sampling period, and were limited to their preferred Pseudocalanus prey, resulted in average growth of 12.2% day )1 for 1993 and 9.7% day )1 for 1994. These compared closely to the field growth means of 11.3% day )1 in 1993 and 9.8% day )1 in 1994. Thus, the lower observed growth in May 1994 may have resulted from depth-dependent food limitation and prey-selectivity coupled with the greater metabolic costs induced by the higher temperature that year.
Background Patient navigation (PN) is an emerging strategy to overcome barriers to cancer care. We evaluated the efficacy of PN in improving time of key events in cancer care, including positive screening tests, definitive diagnosis, initiation of therapy, and completion of initial therapy. Methods We evaluated PN in a prospective observational study of predominantly poor Hispanic women with an abnormal breast cancer screening or untreated biopsy proven breast cancer (control = 200, intervention = 260). Controls were contemporary records-based patients with positive screening. Analyses were conducted for the entire cohort and separately by ethnic strata. We used Chi-Square tests to compare differences in proportions and Kaplan-Meier followed by Cox Regression to compare time-to-event curves of the intervention and control groups. Results The average days from definitive diagnosis to initiation of therapy was significantly reduced overall with PN (PN vs control, 57d vs 74d, p=.04). This effect was more pronounced in the Hispanic strata (56 vs 81 days, p=.02). More navigated Hispanic women were diagnosed within 60 days of abnormal screening (62.6% vs 47.5%, p< .01) and more began treatment within 60 days of diagnosis (80% vs 56.3%, p<.01). Navigated Hispanic and other ethnic minority women had a shorter time from positive screening test to definitive diagnosis (16 and 32 days, respectively). Conclusions Minority women may have benefitted from navigation with shorter times from definitive diagnosis to initiation of therapy.. Impact PN intervention may show promise in decreasing some delays that contribute to health disparities among minority women with breast cancer.
While foodborne illness is not traditionally tracked by race, ethnicity or income, analyses of reported cases have found increased rates of some foodborne illnesses among minority racial/ethnic populations. In some cases (Listeria, Yersinia) increased rates are due to unique food consumption patterns, in other cases (Salmonella, Shigella, Campylobacter) it is unclear why this health disparity exists. Research on safe food handling knowledge and behaviors among low income and minority consumers suggest that there may be a need to target safe food handling messages to these vulnerable populations. Another possibility is that these populations are receiving food that is less safe at the level of the retail outlet or foodservice facility. Research examining the quality and safety of food available at small markets in the food desert environment indicates that small corner markets face unique challenges which may affect the quality and potential safety of perishable food. Finally, a growing body of research has found that independent ethnic foodservice facilities may present increased risks for foodborne illness. This review of the literature will examine the current state of what is known about foodborne illness among, and food safety risks for, minority and low socioeconomic populations, with an emphasis on the United States and Europe.
The utility of individual based models (IBMs) is that properties of ecological systems can be derived by considering the properties of individuals constituting them. Individual differences may be physiological, behavioral or may arise from interactions among individuals. The differences result in unique life histories, which when considered as a whole give rise to growth and size distributions that provide a measure of the state of the population. Early IBMs generally did not consider the effect of a spatially variable physical environment. Recent advances in ocean circulation models that include realistic temporal and spatial variation of currents, turbulence, light, prey, etc., have enabled IBMs to be embedded in model flow fields and for unique, sometimes behaviorally modified, Lagrangian trajectories to be computed. The explicit consideration of realistic spatial heterogeneity provides an additional factor that contributes to the differentiation among individuals, to variances in population structure, and ultimately to our understanding of the recruitment process. This is particularly important in marine environments where fronts, boundary layers, pycnoclines, gyres and other smaller spatial features have been hypothesized to play a significant role in determining vital rates and population structure. In this paper we will review the status of research on spatiallyexplicit IBMs, their successes, limitations and future developments. Examples will be drawn from approaches used in the past decade in GLOBEC, FOCI, SABRE and other programs.
The MARMAP 11-yr time series (1977 to 1987) of cod and haddock egg/larval distributions was used as a basis for examining the consequences of spawning between eastern and western Georges Bank. For each year, from 1978 to 1987, weekly mean flow fields were based on linear interpolation of seasonal velocity fields with wind and upstream boundary-forcing anomalies. Particles were released from the Northeast Peak (NEP) and western Georges Bank (WGB) spawning areas to assess the relative number of larvae retained within the 70 m isobath after 8 wk. A scaled aggregate Georges Bank (AGB) retention index was also created by weighting the relative number of eggs spawned on the eastern and western halves. While there was considerable interannual variability, mean retention for particles released from NEP at the surface (0 to 10 m) was low (< 20%) during winter but increased in the spring to about 50% by mid-April, declining through May. Mean retention at 30 m, however, was consistently between 30 and 40%. Mean retention of particles from WGB was higher for surface releases than at depth, and reached 50% during May. The NEP usually had higher retention than WGB, but the WGB releases could contribute significantly to retention, especially near the surface during the winter period, when there was a loss of particles from NEP due to wind. The 2 yr of high recruitment for cod, 1980 and 1985, occurred during periods of high retention over the spawning season, despite the fact that in 1980 spawning was primarily in the eastern area, while, in 1985, spawning was split between the areas. The large year class of haddock in 1978 had high larval retention and the latest seasonal growth optima in the time series, extending through May.
SUMMARY: Using an individual-based model approach we consider trophodynamic effects on the growth and survival of larval cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) on Georges Bank during late winter/early spring. These studies represent an extension of results described in Werner et al. (1996; Deep-Sea Res. II), wherein the effect of turbulence-enhanced larval-prey contact rates increased the effective prey concentration resulting in growth of cod larvae consistent with observed rates in the field. We reformulated the feeding of the larvae to include existing relationships between maximum prey-length and larval-length and we examined: (i) larval search behaviour and its effect on encounter with prey, (ii) the ability of larvae to pursue and capture prey in a turbulent environment, and (iii) the effect of turbulence on the dispersion of larvae in the vertical. We find that search behaviour, the effect of turbulence on pursuit and capture, and vertical dispersion decrease the predicted larval growth rates compared to those observed in the earlier study. These results suggest that larval feeding behaviour, and especially the ability of larvae to pursue encountered prey, could be an important input to larval growth and survival models. The inclusion of turbulence in determining the position of passive larvae in the water column allows the larvae to sample the entire water column, contributing to a decrease in the variance of the size of the larvae over time. The ability of larvae to swim and aggregate in the vertical will be necessary to reproduce distributions observed in the field.
Nonthermal plasma has been shown to be effective in reducing pathogens on the surface of a range of fresh produce products. The research presented here investigated the effectiveness of nonthermal dielectric barrier discharge plasma on Salmonella enterica and Campylobacter jejuni inoculated onto the surface of boneless skinless chicken breast and chicken thigh with skin. Chicken samples were inoculated with antibiotic-resistant strains of S. enterica and C. jejuni at levels of 10(1) to 10(4) CFU and exposed to plasma for a range of time points (0 to 180 s in 15-s intervals). Surviving antibiotic-resistant pathogens were recovered and counted on appropriate agar. In order to determine the effect of plasma on background microflora, noninoculated skinless chicken breast and thighs with skin were exposed to air plasma at ambient pressure. Treatment with plasma resulted in elimination of low levels (10(1) CFU) of both S. enterica and C. jejuni on chicken breasts and C. jejuni from chicken skin, but viable S. enterica cells remained on chicken skin even after 20 s of exposure to plasma. Inoculum levels of 10(2), 10(3), and 10(4) CFU of S. enterica on chicken breast and chicken skin resulted in maximum reduction levels of 1.85, 2.61, and 2.54 log, respectively, on chicken breast and 1.25, 1.08, and 1.31 log, respectively, on chicken skin following 3 min of plasma exposure. Inoculum levels of 10(2), 10(3), and 10(4) CFU of C. jejuni on chicken breast and chicken skin resulted in maximum reduction levels of 1.65, 2.45, and 2.45 log, respectively, on chicken breast and 1.42, 1.87, and 3.11 log, respectively, on chicken skin following 3 min of plasma exposure. Plasma exposure for 30 s reduced background microflora on breast and skin by an average of 0.85 and 0.21 log, respectively. This research demonstrates the feasibility of nonthermal dielectric barrier discharge plasma as an intervention to help reduce foodborne pathogens on the surface of raw poultry.
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