3,223 research outputs found

    Spectral tuning of plasmon-enhanced silicon quantum dot luminescence

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    In the presence of nanoscale silver island arrays, silicon quantum dots exhibit up to sevenfold luminescence enhancements at emission frequencies that correspond to the collective dipole plasmon resonance frequency of the Ag island array. Using electron-beam lithography to alter the pitch and particle diameter, this wavelength-selective enhancement can be varied as the metal array resonance wavelength is tuned from 600 to 900 nm. The luminescence intensity enhancement upon coupling is attributed to an increase in the radiative decay rate of the silicon quantum dots

    Swim Speed, Behavior, and Movement of North Atlantic Right Whales (\u3cem\u3eEubalaena glacialis\u3c/em\u3e) in Coastal Waters of Northeastern Florida, USA

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    In a portion of the coastal waters of northeastern Florida, North Atlantic right whales (Eubalaena glacialis) occur close to shore from December through March. These waters are included within the designated critical habitat for right whales. Data on swim speed, behavior, and direction of movement – with photo-identification of individual whales – were gathered by a volunteer sighting network working alongside experienced scientists and supplemented by aerial observations. In seven years (2001–2007), 109 tracking periods or “follows” were conducted on right whales during 600 hours of observation from shore-based observers. The whales were categorized as mother-calf pairs, singles and non-mother-calf pairs, and groups of 3 or more individuals. Sample size and amount of information obtained was largest for mother-calf pairs. Swim speeds varied within and across observation periods, individuals, and categories. One category, singles and non mother-calf pairs, was significantly different from the other two – and had the largest variability and the fastest swim speeds. Median swim speed for all categories was 1.3 km/h (0.7 kn), with examples that suggest swim speeds differ between within-habitat movement and migration-mode travel. Within-habitat right whales often travel back-and-forth in a north-south, along-coast, direction, which may cause an individual to pass by a given point on several occasions, potentially increasing anthropogenic risk exposure (e.g., vessel collision, fishing gear entanglement, harassment). At times, mothers and calves engaged in lengthy stationary periods (up to 7.5 h) that included rest, nursing, and play. These mother-calf interactions have implications for communication, learning, and survival. Overall, these behaviors are relevant to population status, distribution, calving success, correlation to environmental parameters, survey efficacy, and human-impacts mitigation. These observations contribute important parameters to conservation biology, predictive modeling, and management. However, while we often search for predictions, patterns, and means, the message here is also about variability and the behavioral characteristics of individual whales

    Socioeconomic status, blood pressure progression, and incident hypertension in a prospective cohort of female health professionals

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    Aims The aim of this study was to examine the association between socioeconomic status, blood pressure (BP) progression, and incident hypertension. Methods and results We included 27 207 female health professionals free of hypertension and cardiovascular disease at baseline. Participants were classified into five education and six income categories. The main outcome variables were BP progression at 48 months of follow-up and incident hypertension during the entire study period. At 48 months, 48.1% of women had BP progression. The multivariable adjusted relative risks [95% confidence intervals (CIs)] for BP progression were 1.0 (referent), 0.96 (0.92-1.00), 0.92 (0.88-0.96), 0.90 (0.85-0.94), and 0.84 (0.78-0.91) (P for trend <0.0001) across increasing education categories and 1.0 (referent), 1.01 (0.94-1.08), 0.99 (0.93-1.06), 0.97 (0.91-1.04), 0.96 (0.90-1.03), and 0.89 (0.83-0.96) across increasing income categories (P for trend = 0.0001). During a median follow-up of 9.8 years, 8248 cases of incident hypertension occurred. Multivariable adjusted hazard ratios (95% CI) were 1.0 (referent), 0.92 (0.86-0.99), 0.85 (0.79-0.92), 0.87 (0.80-0.94), and 0.74 (0.65-0.84) (P for trend <0.0001) across increasing education categories and 1.0 (referent), 1.07 (0.95-1.21), 1.07 (0.95-1.20), 1.06 (0.94-1.18), 1.04 (0.93-1.16), and 0.93 (0.82-1.06) (P for trend 0.08) across increasing income categories. In joint analyses, education but not income remained associated with BP progression and incident hypertension. Conclusion Socioeconomic status, as determined by education but not by income, is a strong independent predictor of BP progression and incident hypertension in wome

    Planning and establishment of a high throughput screening site

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    In 1996 and 1997, Glaxo Wellcome's US Research division planned and established their second generation research strategy. An important aspect of the strategy entailed development of two automated screening sites in Biochemistry in Research Triangle Park, NC. Development of the new operations required many decisions to be made very quickly, including automated process design, system selection and site preparation. Descriptions of the decision made in the development of one of the screening sites are presented in this paper

    An integrin-targeted photoactivatable Pt(IV) complex as a selective anticancer pro-drug: synthesis and photoactivation studies

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    A new anticancer agent based on the conjugation of a photoactivatable Pt(IV) pro-drug to a cyclic RGD-containing peptide is described. Upon visible light irradiation, phototoxicity was induced preferentially in SK-MEL-28 melanoma cancer cells overexpressing alphaVbeta3 integrin compared to control DU-145 human prostate carcinoma cells

    Extent and distribution of linkage disequilibrium in the Old Order Amish

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    Knowledge of the extent and distribution of linkage disequilibrium (LD) is critical to the design and interpretation of gene mapping studies. Because the demographic history of each population varies and is often not accurately known, it is necessary to empirically evaluate LD on a population-specific basis. Here we present the first genome-wide survey of LD in the Old Order Amish (OOA) of Lancaster County Pennsylvania, a closed population derived from a modest number of founders. Specifically, we present a comparison of LD between OOA individuals and US Utah participants in the International HapMap project (abbreviated CEU) using a high-density single nucleotide polymorphism (SNP) map. Overall, the allele (and haplotype) frequency distributions and LD profiles were remarkably similar between these two populations. For example, the median absolute allele frequency difference for autosomal SNPs was 0.05, with an inter-quartile range of 0.02–0.09, and for autosomal SNPs 10–20 kb apart with common alleles (minor allele frequency≥0.05), the LD measure r 2 was at least 0.8 for 15 and 14% of SNP pairs in the OOA and CEU, respectively. Moreover, tag SNPs selected from the HapMap CEU sample captured a substantial portion of the common variation in the OOA (∼88%) at r 2 ≥0.8. These results suggest that the OOA and CEU may share similar LD profiles for other common but untyped SNPs. Thus, in the context of the common variant-common disease hypothesis, genetic variants discovered in gene mapping studies in the OOA may generalize to other populations. Genet. Epidemiol . 34: 146–150, 2010. © 2009 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64895/1/20444_ftp.pd

    Modifications to student quarantine policies in K-12 schools implementing multiple COVID-19 prevention strategies restores in-person education without increasing SARS-CoV-2 transmission risk, January-March 2021

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    OBJECTIVE: To determine whether modified K-12 student quarantine policies that allow some students to continue in-person education during their quarantine period increase schoolwide SARS-CoV-2 transmission risk following the increase in cases in winter 2020-2021. METHODS: We conducted a prospective cohort study of COVID-19 cases and close contacts among students and staff (n = 65,621) in 103 Missouri public schools. Participants were offered free, saliva-based RT-PCR testing. The projected number of school-based transmission events among untested close contacts was extrapolated from the percentage of events detected among tested asymptomatic close contacts and summed with the number of detected events for a projected total. An adjusted Cox regression model compared hazard rates of school-based SARS-CoV-2 infections between schools with a modified versus standard quarantine policy. RESULTS: From January-March 2021, a projected 23 (1%) school-based transmission events occurred among 1,636 school close contacts. There was no difference in the adjusted hazard rates of school-based SARS-CoV-2 infections between schools with a modified versus standard quarantine policy (hazard ratio = 1.00; 95% confidence interval: 0.97-1.03). DISCUSSION: School-based SARS-CoV-2 transmission was rare in 103 K-12 schools implementing multiple COVID-19 prevention strategies. Modified student quarantine policies were not associated with increased school incidence of COVID-19. Modifications to student quarantine policies may be a useful strategy for K-12 schools to safely reduce disruptions to in-person education during times of increased COVID-19 community incidence

    RNA-Seq identifies SPGs as a ventral skeletal patterning cue in sea urchins

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    The sea urchin larval skeleton offers a simple model for formation of developmental patterns. The calcium carbonate skeleton is secreted by primary mesenchyme cells (PMCs) in response to largely unknown patterning cues expressed by the ectoderm. To discover novel ectodermal cues, we performed an unbiased RNA-Seq-based screen and functionally tested candidates; we thereby identified several novel skeletal patterning cues. Among these, we show that SLC26a2/7 is a ventrally expressed sulfate transporter that promotes a ventral accumulation of sulfated proteoglycans, which is required for ventral PMC positioning and skeletal patterning. We show that the effects of SLC perturbation are mimicked by manipulation of either external sulfate levels or proteoglycan sulfation. These results identify novel skeletal patterning genes and demonstrate that ventral proteoglycan sulfation serves as a positional cue for sea urchin skeletal patterning
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