Eutrophication-induced phosphorus limitation in the Mississippi River plume: Evidence from fast repetition rate fluorometry

We assessed nutrient limitation in the Mississippi River plurne and Louisiana continental shelf during the summer of 2002 (04-08 July). We measured nutrient concentrations, alkaline phosphatase (AP) activities, chlorophyll a (Chl a) concentrations, and four fast repetition rate fluorescence (FRRF) parameters: the maximum quantum yield of photochemistry in photosystem II (PSII), F-v:F-m; the functional absorption cross section for PSII, sigma(psII); the time for photosynthetic electron transport on the acceptor side of PSII, tau(Qa); and the connectivity factor, p, in 24-h-long nutrient addition bioassays near the Mississippi River delta. Low phosphorus (P) concentrations, elevated inorganic nitrogen-to-phosphorus ratios, high AP activities, and Chl a increases in response to P additions in the bioassays all indicated phosphorus limitation that was confirmed by the response of FRRF parameters. This is the first study to use FRRF to confirm results from basic oceanographic methods to demonstrate phosphorus limitation in a marine setting. F-v:F-m and p responded positively to phosphorus addition, while sigma(psII) and tau(Qa) decreased in the same treatments. When nitrate alone was added, none of the measured parameters differed significantly from the control. We therefore suggest that FRRF can be used to rapidly detect phosphorus limitation in marine ecosystems

Microbes and the marine phosphorus cycle

Author Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 2 (2007): 110-116.Phosphorus (P) is fundamental to life, and years of study in marine systems have built a broad understanding of the marine P cycle. Various aspects of marine P biogeochemistry have been reviewed previously (Benitez-Nelson, 2000; Paytan and McLaughlin, 2007). Here, we focus on recent advances in our understanding of marine P and the interactions between microbes and the P cycle. These advances come from a variety of disciplines, but generally highlight three main themes: (1) ocean microbes are adapted for surviving in a variable P environment, (2) the dissolved organic phosphorus (DOP) pool likely plays a critical role in driving growth, metabolism, and community composition of ocean microorganisms, and (3) P is very rapidly cycled, which highlights its importance in marine systems

Association Between Physical Activity and Proximity to Physical Activity Resources Among Low-Income, Midlife Women

INTRODUCTION: The association between levels of physical activity and perceived and objectively measured proximity to physical activity resources is unclear. Clarification is important so that future programs can intervene upon the measure with the greatest association. We examined correlations between perceived and objectively measured proximity to physical activity resources and then examined associations between both measures of proximity and objectively measured physical activity. METHODS: Participants (n = 199) were underinsured women from three counties in southeastern North Carolina. Perceived proximity to physical activity resources (e.g., parks, gyms, schools) was measured using surveys. Objectively measured proximity included geographic information systems road network distance to the closest resource and existence of resources within 1- and 2-mile buffers surrounding participants' homes. To examine the association between proximity to resources and activity, the dependent variable in multiple linear regression models was the natural logarithm of accelerometer-measured moderate to vigorous physical activity in minutes per day. RESULTS: Pearson correlation coefficients for perceptions of distance and objectively measured distance to physical activity resources ranged from 0.40 (gyms, schools) to 0.54 (parks). Perceived distance to gyms and objective number of schools within 1-mile buffers were negatively associated with activity. No statistically significant relationships were found between activity and perceived or objectively measured proximity to parks. CONCLUSION: Results indicate the need for both individual and environmental intervention strategies to increase levels of physical activity among underinsured, midlife women. More work is needed to determine the most effective strategies

Impact of lipid-based nutrient supplementation (LNS) on children\u27s diet adequacy in Western Uganda

Lipid-based nutrient supplements (LNS) can help treat undernutrition; however, the dietary adequacy of children supplemented with LNS, and household utilisation patterns are not well understood. We assessed diet adequacy and the quality of complementary foods by conducting a diet assessment of 128 Ugandan children, ages 6-59 months, who participated in a 10-week programme for children with moderate acute malnutrition (MAM, defined as weight-for-age z-score \u3c -2). Caregivers were given a weekly ration of 650 kcal day (-1) (126 g day(-1)) of a peanut/ soy LNS. Two 24-h dietary recalls were administered per child. LNS was offered to 86% of targeted children at least once. Among non-breastfed children, over 90% met their estimated average requirement (EAR) cut-points for all examined nutrients. Over 90% of breastfed children met EAR cut-points for nutrient density for most nutrients, except for zinc where 11.7% met cut-points. A lower proportion of both breastfed and non-breastfed children met adjusted EARs for the specific nutritional needs of MAM. Fewer than 20% of breastfed children met EAR nutrient-density guidelines for MAM for zinc, vitamin C, vitamin A and folate. Underweight status, the presence of a father in the child\u27s home, and higher programme attendance were all associated with greater odds of feeding LNS to targeted children. Children in this community-based supplemental feeding programme who received a locally produced LNS exhibited substantial micronutrient deficiencies given the special dietary needs of this population. These results can help inform programme strategies to improve LNS targeting, and highlight potential nutrient inadequacies for consumers of LNS in community-based settings

Reliability and validity of a nutrition and physical activity environmental self-assessment for child care

<p>Abstract</p> <p>Background</p> <p>Few assessment instruments have examined the nutrition and physical activity environments in child care, and none are self-administered. Given the emerging focus on child care settings as a target for intervention, a valid and reliable measure of the nutrition and physical activity environment is needed.</p> <p>Methods</p> <p>To measure inter-rater reliability, 59 child care center directors and 109 staff completed the self-assessment concurrently, but independently. Three weeks later, a repeat self-assessment was completed by a sub-sample of 38 directors to assess test-retest reliability. To assess criterion validity, a researcher-administered environmental assessment was conducted at 69 centers and was compared to a self-assessment completed by the director. A weighted kappa test statistic and percent agreement were calculated to assess agreement for each question on the self-assessment.</p> <p>Results</p> <p>For inter-rater reliability, kappa statistics ranged from 0.20 to 1.00 across all questions. Test-retest reliability of the self-assessment yielded kappa statistics that ranged from 0.07 to 1.00. The inter-quartile kappa statistic ranges for inter-rater and test-retest reliability were 0.45 to 0.63 and 0.27 to 0.45, respectively. When percent agreement was calculated, questions ranged from 52.6% to 100% for inter-rater reliability and 34.3% to 100% for test-retest reliability. Kappa statistics for validity ranged from -0.01 to 0.79, with an inter-quartile range of 0.08 to 0.34. Percent agreement for validity ranged from 12.9% to 93.7%.</p> <p>Conclusion</p> <p>This study provides estimates of criterion validity, inter-rater reliability and test-retest reliability for an environmental nutrition and physical activity self-assessment instrument for child care. Results indicate that the self-assessment is a stable and reasonably accurate instrument for use with child care interventions. We therefore recommend the Nutrition and Physical Activity Self-Assessment for Child Care (NAP SACC) instrument to researchers and practitioners interested in conducting healthy weight intervention in child care. However, a more robust, less subjective measure would be more appropriate for researchers seeking an outcome measure to assess intervention impact.</p

Louse- and flea-borne rickettsioses: biological and genomic analyses

In contrast to 15 or more validated and/or proposed tick-borne spotted fever group species, only three named medically important rickettsial species are associated with insects. These insect-borne rickettsiae are comprised of two highly pathogenic species, Rickettsia prowazekii (the agent of epidemic typhus) and R. typhi (the agent of murine typhus), as well as R. felis, a species with unconfirmed pathogenicity. Rickettsial association with obligate hematophagous insects such as the human body louse (R. prowazekii transmitted by Pediculus h. humanus) and several flea species (R. typhi and R. felis, as well as R. prowazekii in sylvatic form) provides rickettsiae the potential for further multiplications, longer transmission cycles and rapid spread among susceptible human populations. Both human body lice and fleas are intermittent feeders capable of multiple blood meals per generation, facilitating the efficient transmission of rickettsiae to several disparate hosts within urban/rural ecosystems. While taking into consideration the existing knowledge of rickettsial biology and genomic attributes, we have analyzed and summarized the interacting features that are unique to both the rickettsiae and their vector fleas and lice. Furthermore, factors that underlie rickettsial changing ecology, where native mammalian populations are involved in the maintenance of rickettsial cycle and transmission, are discussed

Atomic-Scale Terahertz Near Fields for Ultrafast Tunnelling Spectroscopy

Lightwave-driven terahertz scanning tunnelling microscopy (THz-STM) is capable of exploring ultrafast dynamics across a wide range of materials with angstrom resolution. In contrast to scanning near-field optical microscopy, where photons scattered by the tip apex are analyzed to access the local dielectric function on the nanoscale, THz-STM uses a strong-field single-cycle terahertz pulse to drive an ultrafast current across a tunnel junction, thereby probing the local density of electronic states. Yet, the terahertz field in a THz-STM junction may also be spectrally modified by the electromagnetic response of the sample. Here, we demonstrate a reliable and self-consistent approach for terahertz near-field waveform acquisition in an atomic tunnel junction that can be generally applied to electrically conductive surfaces. By combining waveform sampling and tailoring with terahertz scanning tunnelling spectroscopy (THz-STS), we comprehensively characterize the tunnel junction and distinguish local sample properties from effects due to terahertz pulse coupling and field enhancement. Through modelling, we verify the presence of an isolated unipolar terahertz-induced current pulse, facilitating straightforward interpretation for differential THz-STS with high spectral resolution. Finally, we demonstrate the feasibility of atomic-scale terahertz time-domain spectroscopy via the extremely localized near-fields in the tunnel junction

A randomized controlled trial of a physician-directed treatment program for low-income patients with high blood cholesterol: the Southeast Cholesterol Project

OBJECTIVE: To assess the effectiveness of a cholesterol-lowering intervention designed to facilitate the management of hypercholesterolemia by primary care clinicians. DESIGN: Randomized controlled trial, with randomization of clinician-patient groups. SETTING: Twenty-one community and rural health centers in North Carolina and Virginia. PARTICIPANTS: Primary care clinicians (n = 42, 71% physicians) and the patients they enrolled with high cholesterol (n = 372). Twenty-two clinicians were randomized to give the special intervention (184 patients) and 20 to give usual care (188 patients). Two thirds of participating patients were women, 40% were African American, and 11% were Native American. INTERVENTION: A 90-minute tutorial to train clinicians how to use a structured assessment and treatment program (Food for Heart Program) consisting of a brief dietary assessment and three 5- to 10-minute dietary counseling sessions given by the primary care clinician, referral to a local dietitian if the low-density lipoprotein cholesterol (LDL-C) remained elevated at 4-month follow-up, and a prompt for the clinician to consider lipid-lowering medication based on the LDL-C at 7-month follow-up. MAIN OUTCOME MEASURES: Changes in total and LDL cholesterol at 4-month follow-up and averaged over a 1-year follow-up period (4-, 7-, and 12-month follow-up). RESULTS: At 4-month follow-up, total cholesterol decreased 0.33 mmol/L (12.6 mg/dL) in the intervention group and 0.21 mmol/L (8.3 mg/dL) in the control group: the difference was 0.11 mmol/L (4.2 mg/dL) (90% confidence interval [CI], -0.02 to 0.24 mmol/L [-0.7 to 9.1 mg/dL]). The average reduction during the 1-year follow-up period was 0.09 mmol/L (3.6 mg/dL) greater in the intervention group (90% CI, -0.01 to 0.19 mmol/L [-0.3 to 7.5 mg/dL]). Eight percent of intervention patients were taking lipid-lowering medication at follow-up visits compared with 15% of control patients. In a subgroup analysis restricted to the 89% of returnees who were not taking lipid-lowering medication, the reduction in total cholesterol at 4-month follow-up was 0.14 mmol/L (5.5 mg/dL) greater in the intervention group (95% CI, 0.01 to 0.28 mmol/L [0.3 to 10.7 mg/dL]); averaged over 1 year, it was 0.14 mmol/L (5.3 mg/dL) greater (95% CI, 0.03 to 0.24 mmol/L [1.2 to 9.4 mg/dL]). Changes in LDL-C were similar. CONCLUSIONS: Total cholesterol and LDL-C decreased more in the intervention group than in the control group. Overall, the difference in lipid reduction between groups was modest and of borderline statistical significance; among participants who did not take lipid-lowering medication during follow-up, the difference in lipid reduction between groups was larger. We conclude that primary care clinicians can be trained to give a cholesterol-lowering intervention to low-income patients that results in modest, short-term reductions in total cholesterol and LDL-C