129 research outputs found

    In situ studies of algal biomass in relation to physicochemical characteristics of the Salt Plains National Wildlife Refuge, Oklahoma, USA

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    This is the first in a series of experiments designed to characterize the Salt Plains National Wildlife Refuge (SPNWR) ecosystem in northwestern Oklahoma and to catalogue its microbial inhabitants. The SPNWR is the remnant of an ancient ocean, encompassing ~65 km(2 )of variably hypersaline flat land, fed by tributaries of the Arkansas River. Relative algal biomass (i.e., chlorophyll concentrations attributed to Chlorophyll-a-containing oxygenic phototrophs) and physical and chemical parameters were monitored at three permanent stations for a one-year period (July 2000 to July 2001) using a nested block design. Salient features of the flats include annual air temperatures that ranged from -10 to 40°C, and similar to other arid/semi-arid environments, 15–20-degree daily swings were common. Shade is absent from the flats system; intense irradiance and high temperatures (air and sediment surface) resulted in low water availability across the SPNWR, with levels of only ca. 15 % at the sediment surface. Moreover, moderate daily winds were constant (ca. 8–12 km h(-1)), sometimes achieving maximum speeds of up to 137 km h(-1). Typical of freshwater systems, orthophosphate (PO(4)(3-)) concentrations were low, ranging from 0.04 to <1 μM; dissolved inorganic nitrogen levels were high, but spatially variable, ranging from ca. 250–600 μM (NO(3)(- )+ NO(2)(-)) and 4–166 μM (NH(4)(+)). Phototroph abundance was likely tied to nutrient availability, with high-nutrient sites exhibiting high Chl-a levels (ca. 1.46 mg m(-2)). Despite these harsh conditions, the phototrophic microbial community was unexpectedly diverse. Preliminary attempts to isolate and identify oxygenic phototrophs from SPNWR water and soil samples yielded 47 species from 20 taxa and 3 divisions. Our data indicate that highly variable, extreme environments might support phototrophic microbial communities characterized by higher species diversity than previously assumed

    Change in Emiliania huxleyi virus assemblage diversity but not in host genetic composition during an ocean acidification mesocosm experiment

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    Effects of elevated pCO2 on Emiliania huxleyi genetic diversity and the viruses that infect E. huxleyi (EhVs) have been investigated in large volume enclosures in a Norwegian fjord. Triplicate enclosures were bubbled with air enriched with CO2 to 760 ppmv whilst the other three enclosures were bubbled with air at ambient pCO2; phytoplankton growth was initiated by the addition of nitrate and phosphate. E. huxleyi was the dominant coccolithophore in all enclosures, but no difference in genetic diversity, based on DGGE analysis using primers specific to the calcium binding protein gene (gpa) were detected in any of the treatments. Chlorophyll concentrations and primary production were lower in the three elevated pCO2 treatments than in the ambient treatments. However, although coccolithophores numbers were reduced in two of the high-pCO2 treatments; in the third, there was no suppression of coccolithophores numbers, which were very similar to the three ambient treatments. In contrast, there was considerable variation in genetic diversity in the EhVs, as determined by analysis of the major capsid protein (mcp) gene. EhV diversity was much lower in the high-pCO2 treatment enclosure that did not show inhibition of E. huxleyi growth. Since virus infection is generally implicated as a major factor in terminating phytoplankton blooms, it is suggested that no study of the effect of ocean acidification in phytoplankton can be complete if it does not include an assessment of viruses

    Effectiveness and reach of a directed-population approach to improving dental health and reducing inequalities: a cross sectional study

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    Background Childsmile School adopts a directed-population approach to target fluoride varnish applications to 20% of the primary one (P1) population in priority schools selected on the basis of the proportion of enrolled children considered to be at increased-risk of developing dental caries. The study sought to compare the effectiveness of four different methods for identifying individuals most in need when a directed-population approach is taken. &lt;p&gt;&lt;/p&gt; Methods The 2008 Basic National Dental Inspection Programme (BNDIP) cross-sectional P1 Scottish epidemiological survey dataset was used to model four methods and test three definitions of increased-risk. Effectiveness was determined by the positive predictive value (PPV) and explored in relation to 1-sensitivity and 1-specificity. &lt;p&gt;&lt;/p&gt; Results Complete data was available on 43470 children (87% of the survey). At the Scotland level, at least half (50%) of the children targeted were at increased-risk irrespective of the method used to target or the definition of increased-risk. There was no one method across all definitions of &lt;i&gt;increased-risk&lt;/i&gt; that maximised PPV. Instead, PPV was highest when the targeting method complimented the definition of &lt;i&gt;increased-risk&lt;/i&gt;. There was a higher percentage of children at &lt;i&gt;increased-risk&lt;/i&gt; who were not targeted (1-sensitivity) when caries experience (rather than deprivation) was used to define &lt;i&gt;increased-risk&lt;/i&gt;, irrespective of the method used for targeting. Over all three definitions of &lt;i&gt;increased-risk&lt;/i&gt;, there was no one method that minimised (1-sensitivity) although this was lowest when the method and definition of &lt;i&gt;increased-risk&lt;/i&gt; were complimentary. The false positive rate (1-specificity) for all methods and all definitions of &lt;i&gt;increased-risk&lt;/i&gt; was consistently low (&#60;20%), again being lowest when the method and definition of &lt;i&gt;increased-risk&lt;/i&gt; were complimentary. &lt;p&gt;&lt;/p&gt; Conclusion Developing a method to reach all (or even the vast majority) of individuals at &lt;i&gt;increased-risk&lt;/i&gt; defined by either caries experience or deprivation is difficult using a directed-population approach at a group level. There is a need for a wider debate between politicians and public health experts to decide how best to reach those most at need of intervention to improve health and reduce inequalities. &lt;p&gt;&lt;/p&gt

    Miel de melon Monona

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    130 p.Se planteo como objetivo general de la investigación "Analizar el Marketing Mix actual del producto Miel de Melón Monona". Para cumplir con dicho objetivo se realizo en primera instancia una investigación bibliográfica, continuando con un estudio no estructurado directo en el que se establecieron los parámetros necesarios para el desarrollo de un cuestionario estructurado, el cual fue aplicado en forma aleatoria a una muestra representativa del mercado objetivo, correspondiente a los individuos cuyas viviendas se localicen en sectores residenciales pertenecientes al estrato socioeconómico alto en la ciudad de Talca. A nivel general este estudio arrojo los siguientes resultados: • Alrededor del 50% de la muestra conoce la Miel de Melón Monona. • Este producto se considera por los entrevistados un producto artesanal y de alta calidad, con una procedencia y elaboración confiable. • Su sabor es del completo agrado de los consumidores, al igual que su aroma, textura y color, siendo estos atributos determinantes en la decisión de compra. • La marca "Monona" es bien aceptada, sin embargo una porción significativa de la muestra no identifica su nombre con el producto. • Refiriéndonos al envase, la presentación es bonita y el vidrio se considera el material mas apto para envasar la Miel de Melón Monona, pero el envase en si es considerado poco original, muy grande para el consumo e incomodo para servir y llevar a la mesa • La etiqueta presenta una serie de carencias, no dice en forma explicita las cualidades de ser un producto artesanal sin aditivos ni preservantes, el nombre "Monona" no se resalta, los colores del símbolo son muy opacos y el material del papel no es ad hoc con el estilo artesanal del envase. • Este producto utiliza dos canales de distribución, directo e indirecto, siendo el mas utilizado por sus consumidores el canal directo a troves de su productora. • El precio que gaga el consumidor es bien aceptado y no se considera un producto costoso por la muestra entrevistada. • Los competidores indirectos mas importantes son la Miel de Palma, Miel de Papaya, el Arrope y la Chancaca. • La Miel de Melón Monona ha utilizado cuatro herramientas de la mezcla promocional en distintos periodos, pero en los últimos cinco altos no ha utilizado promoción, por lo cual una porción muy poco significativa de la muestra recuerda alguna de las herramientas promocionales. Finalmente, se da a conocer una recomendación de como posicionar el producto a futuro basándose en los resultados de esta investigación por medio de un plan de mercadeo propuesto

    Standardisation of rates using logistic regression: a comparison with the direct method

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    <p>Abstract</p> <p>Background</p> <p>Standardisation of rates in health services research is generally undertaken using the direct and indirect arithmetic methods. These methods can produce unreliable estimates when the calculations are based on small numbers. Regression based methods are available but are rarely applied in practice. This study demonstrates the advantages of using logistic regression to obtain smoothed standardised estimates of the prevalence of rare disease in the presence of covariates.</p> <p>Methods</p> <p>Step by step worked examples of the logistic and direct methods are presented utilising data from BETS, an observational study designed to estimate the prevalence of subclinical thyroid disease in the elderly. Rates calculated by the direct method were standardised by sex and age categories, whereas rates by the logistic method were standardised by sex and age as a continuous variable.</p> <p>Results</p> <p>The two methods produce estimates of similar magnitude when standardising by age and sex. The standard errors produced by the logistic method were lower than the conventional direct method.</p> <p>Conclusion</p> <p>Regression based standardisation is a practical alternative to the direct method. It produces more reliable estimates than the direct or indirect method when the calculations are based on small numbers. It has greater flexibility in factor selection and allows standardisation by both continuous and categorical variables. It therefore allows standardisation to be performed in situations where the direct method would give unreliable results.</p

    Effective bridging therapy can improve CD19 CAR-T outcomes while maintaining safety in patients with large B-cell lymphoma

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    The impact of bridging therapy (BT) on CD19-directed chimeric antigen receptor T-cell (CD19CAR-T) outcomes in large B-cell lymphoma (LBCL) is poorly characterised. Current practice is guided by physician preference rather than established evidence. Identification of effective BT modalities and factors predictive of response could improve CAR-T intention to treat and clinical outcomes. We assessed BT modality and response in 375 adult LBCL patients in relation to outcomes following axicabtagene ciloleucel (Axi-cel) or tisagenlecleucel (Tisa-cel). The majority of patients received BT with chemotherapy (57%) or radiotherapy (17%). We observed that BT was safe for patients, with minimal morbidity/mortality. We showed that complete or partial response to BT conferred a 42% reduction in disease progression and death following CD19CAR-T therapy. Multivariate analysis identified several factors associated with likelihood of response to BT, including response to last line therapy, the absence of bulky disease, and the use of Polatuzumab-containing chemotherapy regimens. Our data suggested that complete/partial response to BT may be more important for Tisa-cel than Axi-cel, as all Tisa-cel patients with less than partial response to BT experienced frank relapse within 12 months of CD19CAR-T infusion. In summary, BT in LBCL should be carefully planned towards optimal response and disease debulking, to improve CD19CAR-T patient outcomes. Polatuzumab-containing regimens should be strongly considered for all suitable patients, and failure to achieve complete/partial response to BT pre-Tisa-cel may prompt consideration of further lines of BT where possible

    Phosphorylation of AMPA Receptors Is Required for Sensory Deprivation-Induced Homeostatic Synaptic Plasticity

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    Sensory experience, and the lack thereof, can alter the function of excitatory synapses in the primary sensory cortices. Recent evidence suggests that changes in sensory experience can regulate the synaptic level of Ca2+-permeable AMPA receptors (CP-AMPARs). However, the molecular mechanisms underlying such a process have not been determined. We found that binocular visual deprivation, which is a well-established in vivo model to produce multiplicative synaptic scaling in visual cortex of juvenile rodents, is accompanied by an increase in the phosphorylation of AMPAR GluR1 (or GluA1) subunit at the serine 845 (S845) site and the appearance of CP-AMPARs at synapses. To address the role of GluR1-S845 in visual deprivation-induced homeostatic synaptic plasticity, we used mice lacking key phosphorylation sites on the GluR1 subunit. We found that mice specifically lacking the GluR1-S845 site (GluR1-S845A mutants), which is a substrate of cAMP-dependent kinase (PKA), show abnormal basal excitatory synaptic transmission and lack visual deprivation-induced homeostatic synaptic plasticity. We also found evidence that increasing GluR1-S845 phosphorylation alone is not sufficient to produce normal multiplicative synaptic scaling. Our study provides concrete evidence that a GluR1 dependent mechanism, especially S845 phosphorylation, is a necessary pre-requisite step for in vivo homeostatic synaptic plasticity

    Lake salinization drives consistent losses of zooplankton abundance and diversity across coordinated mesocosm experiments

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    Human-induced salinization increasingly threatens inland waters; yet we know little about the multifaceted response of lake communities to salt contamination. By conducting a coordinated mesocosm experiment of lake salinization across 16 sites in North America and Europe, we quantified the response of zooplankton abundance and (taxonomic and functional) community structure to a broad gradient of environmentally relevant chloride concentrations, ranging from 4 to ca. 1400 mg Cl- L-1. We found that crustaceans were distinctly more sensitive to elevated chloride than rotifers; yet, rotifers did not show compensatory abundance increases in response to crustacean declines. For crustaceans, our among-site comparisons indicate: (1) highly consistent decreases in abundance and taxon richness with salinity; (2) widespread chloride sensitivity across major taxonomic groups (Cladocera, Cyclopoida, and Calanoida); and (3) weaker loss of functional than taxonomic diversity. Overall, our study demonstrates that aggregate properties of zooplankton communities can be adversely affected at chloride concentrations relevant to anthropogenic salinization in lakes.Peer reviewe
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