Interactive computer-based simulations as exploratory learning activities.

Typical college lectures follow a direct instruction framework, where instructors deliver a lecture, followed by an activity. Exploratory learning flips this routine by providing students with an activity prior to instruction. Research suggests that this inversion benefits students’ conceptual understanding and ability to transfer their knowledge. The majority of exploratory learning tasks in the literature are problem-solving activities. The current work investigates the use of computer-based simulations during exploratory learning, and whether manipulating the cognitive load of the activity impacts learning. In Experiment 1, undergraduate students (N=66) were randomly assigned to explore a simulation-based circuit construction activity prior to instruction (explore-first) or receive instructions on the topic prior to the activity (instruct-first). The learning assessment consisted of conceptual knowledge and transfer of knowledge to a similar topic. Participants in the instruct-first condition scored higher on the assessment than participants in the explore-first condition, and reported lower cognitive load. In Experiment 2, participants received one of two versions of the exploration activity, designed to provide stronger guidance and reduce intrinsic or extraneous cognitive load. Undergraduate students (N=195) were randomly assigned to one of four conditions based on order (explore-first or instruct-first) and cognitive load reduction type (intrinsic load reduction or extraneous load reduction). Participants in the intrinsic load reduction conditions scored at an equal level on conceptual knowledge, and higher on transfer, compared to participants in the extrinsic load reduction conditions, regardless of order. Across both experiments, participants in the explore-first conditions reported motivational benefits (higher curiosity and higher perceived knowledge gaps). Yet the instruct-first approach led to higher learning, suggesting that these components are not enough for effective exploratory learning, even when reducing intrinsic cognitive load through guidance. Simulation environments may be too complex for students to effectively explore the deep problem features that otherwise provide conceptual advantages

Cost Analysis of Stratospheric Albedo Modification Delivery Systems

We perform engineering cost analyses of systems capable of delivering 1–5 million metric tonnes (Mt) of albedo modification material to altitudes of 18–30 km. The goal is to compare a range of delivery systems evaluated on a consistent cost basis. Cost estimates are developed with statistical cost estimating relationships based on historical costs of aerospace development programs and operations concepts using labor rates appropriate to the operations. We evaluate existing aircraft cost of acquisition and operations, perform in-depth new aircraft and airship design studies and cost analyses, and survey rockets, guns, and suspended gas and slurry pipes, comparing their costs to those of aircraft and airships. Annual costs for delivery systems based on new aircraft designs are estimated to be $1–3B to deliver 1 Mt to 20–30 km or$2–8B to deliver 5 Mt to the same altitude range. Costs for hybrid airships may be competitive, but their large surface area complicates operations in high altitude wind shear, and development costs are more uncertain than those for airplanes. Pipes suspended by floating platforms provide low recurring costs to pump a liquid or gas to altitudes as high as ~ 20 km, but the research, development, testing and evaluation costs of these systems are high and carry a large uncertainty; the pipe system's high operating pressures and tensile strength requirements bring the feasibility of this system into question. The costs for rockets and guns are significantly higher than those for other systems. We conclude that (a) the basic technological capability to deliver material to the stratosphere at million tonne per year rates exists today, (b) based on prior literature, a few million tonnes per year would be sufficient to alter radiative forcing by an amount roughly equivalent to the growth of anticipated greenhouse gas forcing over the next half century, and that (c) several different methods could possibly deliver this quantity for less than $8B per year. We do not address here the science of aerosols in the stratosphere, nor issues of risk, effectiveness or governance that will add to the costs of solar geoengineering.Engineering and Applied Science

Phylogenetics Applied to Genotype/Phenotype Association and Selection Analyses with Sequence Data from Angptl4 in Humans

Genotype/phenotype association analyses (Treescan) with plasma lipid levels and functional site prediction methods (TreeSAAP and PolyPhen) were performed using sequence data for ANGPTL4 from 3,551 patients in the Dallas Heart Study. Biological assays of rare variants in phenotypic tails and results from a Treescan analysis were used as “known” variants to assess the site prediction abilities of PolyPhen and TreeSAAP. The E40K variant in European Americans and the R278Q variant in African Americans were significantly associated with multiple lipid phenotypes. Combining TreeSAAP and PolyPhen performed well to predict “known” functional variants while reducing noise from false positives

High prevalence of chronic kidney disease in Iran: a large population-based study

<p>Abstract</p> <p>Background</p> <p>Chronic kidney disease (CKD) is a global public health threat, associated with an alarming increase in morbidity and mortality. The importance is the worldwide increase in its incidence and prevalence.</p> <p>Methods</p> <p>In this cross-sectional study, we estimate the prevalence and determine the associated factors of chronic kidney disease in a representative sample of 10063 participants aged over 20 years, in Tehran, Iran. Chronic kidney disease was defined as estimated glomerular filtration rate less than 60 mL/min/1.73 m2. Glomerular filtration rate was estimated from abbreviated prediction equation provided by the Modification of Diet in Renal Disease study (MDRD).</p> <p>Results</p> <p>Overall prevalence of CKD with the abbreviated MDRD equation was 18.9% (95% confidence interval (CI) 18.2, 20.6). Age adjusted prevalence of CKD was 14.9% (95%CI 14.2, 15.6). Factors associated to CKD include age(years)(odds ratio(OR) 1.1, 95% CI 1.0 to 1.2), female gender (OR 3.1, 95% CI 2.6, 3.7), BMI (BMI 25 to <30 OR 1.5, 95% CI 1.3, 1.8 and BMI ≥ 30 OR 1.6, 95% CI 1.3, 2.0), high waist circumference (OR 1.2, 95% CI 1.1, 1.4), hypertension (OR 1.2, 95% CI 1.1, 1.4), and dyslipidemia (OR 1.3, 95% CI 1.1, 1.5).</p> <p>Conclusion</p> <p>CKD with its high prevalence poses a definite health threat in Iran.</p

Protocol of a Randomized Controlled Trial of Culturally Sensitive Interventions to Improve African Americans' and Non-African Americans' Early, Shared, and Informed Consideration of Live Kidney Transplantation: The talking about Live Kidney Donation (TALK) study

<p>Abstract</p> <p>Background</p> <p>Live kidney transplantation (LKT) is underutilized, particularly among ethnic/racial minorities. The effectiveness of culturally sensitive educational and behavioral interventions to encourage patients' early, shared (with family and health care providers) and informed consideration of LKT and ameliorate disparities in consideration of LKT is unknown.</p> <p>Methods/Design</p> <p>We report the protocol of the Talking About Live Kidney Donation (TALK) Study, a two-phase study utilizing qualitative and quantitative research methods to design and test culturally sensitive interventions to improve patients' shared and informed consideration of LKT. Study Phase 1 involved the evidence-based development of culturally sensitive written and audiovisual educational materials as well as a social worker intervention to encourage patients' engagement in shared and informed consideration of LKT. In Study Phase 2, we are currently conducting a randomized controlled trial in which participants with progressing chronic kidney disease receive: 1) usual care by their nephrologists, 2) usual care plus the educational materials, or 3) usual care plus the educational materials and the social worker intervention. The primary outcome of the randomized controlled trial will include patients' self-reported rates of consideration of LKT (including family discussions of LKT, patient-physician discussions of LKT, and identification of an LKT donor). We will also assess differences in rates of consideration of LKT among African Americans and non-African Americans.</p> <p>Discussion</p> <p>The TALK Study rigorously developed and is currently testing the effectiveness of culturally sensitive interventions to improve patients' and families' consideration of LKT. Results from TALK will provide needed evidence on ways to enhance consideration of this optimal treatment for patients with end stage renal disease.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov number, <a href="http://www.clinicaltrials.gov/ct2/show/NCT00932334">NCT00932334</a></p

Prevalence of chronic kidney disease in population-based studies: Systematic review

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Chronic kidney disease (CKD) is becoming a major public health problem worldwide. This article reviews the published evidence of prevalence of CKD in population-based study samples that used the standardized definition from the Kidney Disease Outcomes Quality Initiative of the National Kidney Foundation (K/DOQI) practice guideline, and particularly focus on performance of serum-creatinine based equations for GFR estimation. We provide a summary of available data about the burden of CKD in various populations. Methods: We performed a systematic review of available published data in MEDLINE. A combination of various keywords relevant to CKD was used in this research. Related data of included studies were extracted in a systematic way. Results: A total of 26 studies were included in this review. The studies were conducted in different populations, and the number of study participants ranged from 237 to 65181. The median prevalence of CKD was 7.2 % in persons aged 30 years or older. In persons aged 64 years or older prevalence of CKD varied from 23.4 % to 35.8%. Importantly, the prevalence of CKD strongl

The international politics of geoengineering: The feasibility of Plan B for tackling climate change

Geoengineering technologies aim to make large-scale and deliberate interventions in the climate system possible. A typical framing is that researchers are exploring a ‘Plan B’ in case mitigation fails to avert dangerous climate change. Some options are thought to have the potential to alter the politics of climate change dramatically, yet in evaluating whether they might ultimately reduce climate risks, their political and security implications have so far not been given adequate prominence. This article puts forward what it calls the ‘security hazard’ and argues that this could be a crucial factor in determining whether a technology is able, ultimately, to reduce climate risks. Ideas about global governance of geoengineering rely on heroic assumptions about state rationality and a generally pacific international system. Moreover, if in a climate engineered world weather events become something certain states can be made directly responsible for, this may also negatively affect prospects for ‘Plan A’, i.e. an effective global agreement on mitigation