Monitoring Virologic Responses to Antiretroviral Therapy in HIV-Infected Adults in Kenya: Evaluation of a Low-Cost Viral Load Assay

A key advantage of monitoring HIV viral load (VL) in persons receiving antiretroviral therapy (ART) is the ability to detect virologic failure before clinical deterioration or resistance occurs. Detection of virologic failure will help clarify the need for enhanced adherence counseling or a change to second- line therapy. Low-cost, locally performable alternates to expensive VL assays are needed where resources are limited.We monitored the response to 48-week ART in 100 treatment-naïve Kenyan adults using a low-cost VL measurement, the Cavidi reverse transcriptase (RT) assay and gold-standard assays, Roche RNA PCR and Bayer Versant HIV-1 RNA (bDNA) assays. In Altman-Bland plots, the mean difference in viral loads between the three assays was small (<0.5 log(10) copies/mL). However, the limits of agreement between the methods exceeded the biologically relevant change of 0.5 log copies/ml. Therefore, the RT assay cannot be used interchangeably with the other assays to monitor individual patients. The RT assay was 100% sensitive in detecting viral loads of > or =400 copies/ml compared to gold-standard assays. After 24 weeks of treatment, viral load measured by the RT assay was undetectable in 95% of 65 patients with undetectable RNA PCR VL (<400 copies/ml), 90% of 67 patients with undetectable bDNA VL, and 96% of 57 patients with undetectable VL in both RNA PCR and bDNA assays. The negative predictive value of the RT assay was 100% compared to either assay; the positive predictive value was 86% compared to RNA PCR and 70% compared to bDNA.The RT assay compared well with gold standard assays. Our study highlights the importance of not interchanging viral load assays when monitoring an individual patient. Furthermore, the RT assay may be limited by low positive predictive values when used in populations with low prevalence of virologic failure

EUSEDcollab: a network of data from European catchments to monitor net soil erosion by water

As a network of researchers we release an open-access database (EUSEDcollab) of water discharge and suspended sediment yield time series records collected in small to medium sized catchments in Europe. EUSEDcollab is compiled to overcome the scarcity of open-access data at relevant spatial scales for studies on runoff, soil loss by water erosion and sediment delivery. Multi-source measurement data from numerous researchers and institutions were harmonised into a common time series and metadata structure. Data reuse is facilitated through accompanying metadata descriptors providing background technical information for each monitoring station setup. Across ten European countries, EUSEDcollab covers over 1600 catchment years of data from 245 catchments at event (11 catchments), daily (22 catchments) and monthly (212 catchments) temporal resolution, and is unique in its focus on small to medium catchment drainage areas (median=43km2, min=0.04km2, max=817km2) with applicability for soil erosion research. We release this database with the aim of uniting people, knowledge and data through the European Union Soil Observatory (EUSO)

Naar nieuwe eindtermen aardrijkskunde: het referentiekader 'ruimtelijk bewustzijn' als basis?

In het kader van de onderwijshervorming worden gradueel nieuwe eindtermen ontwikkeld. Deze nieuwe eindtermen bouwen verder op de Europese sleutelcompetenties. Als tussenstap tussen deze Europese sleutelcompetenties en de eindtermen, werden er referentiekaders opgesteld. Elk referentiekader vat de visie op een vakdomein samen voor leerlingen van het kleuteronderwijs tot leerlingen aan het einde van het secundair onderwijs. Het referentiekader dat het vak aardrijkskunde omvat, is het referentiekader ruimtelijk bewustzijn. In dit artikel wordt de opbouw en de visie van dit referentiekader weergegeven, evenals een bredere kadering in de Europese sleutelcompetenties.status: publishe

De eindtermen van Project Algemene Vakken

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Digital excursions and geographical rese arch assignments in an online learning environment

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Addressing key concepts in physical geography through interactive learning activities in an online geo-ICT environment

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Systems thinking in geography: can high school students do it?

An increasing interconnectedness of people and goods enhances the complexity of many geographical problems. For students to understand geography, systems thinking is a promising approach. It helps to understand increasing complexity by looking at the entire system and at the interconnectedness between the elements in the system. In order to develop adequate systems oriented teaching and learning the current state of the art of students’ systems thinking ability needs to be better understood. The authors developed a measuring tool in the form of a paper-and-pencil test in which 735 students in the last or penultimate year of secondary school (age 16–18 year) in Flanders, Belgium, took part. The main findings reveal a rather poor general level of students’ systems thinking ability. Students have many difficulties recognizing relationships between variables when several elements of systems thinking come together such as in feedback loops, interactions between human and physical environment, and a combination of different information sources. Rather great differences were found according to the students’ study background as well as an interaction effect between grade and gender of the students.status: publishe

Systeemdenken als benadering voor het vak aardrijkskunde in het secundair onderwijs

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Using causal diagrams to foster systems thinking in geography education

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