This study examined the extent to which instructional conditions influence the prediction of academic success in nine undergraduate courses offered in a blended learning model (n=4134). The study ...illustrates the differences in predictive power and significant predictors between course-specific models and generalized predictive models. The results suggest that it is imperative for learning analytics research to account for the diverse ways technology is adopted and applied in course-specific contexts. The differences in technology use, especially those related to whether and how learners use the learning management system, require consideration before the log-data can be merged to create a generalized model for predicting academic success. A lack of attention to instructional conditions can lead to an over or under estimation of the effects of LMS features on students' academic success. These findings have broader implications for institutions seeking generalized and portable models for identifying students at risk of academic failure.
•Predictive models in learning analytics need to account for instructional conditions.•Instructional conditions are based in the theory of self-regulated learning.•The study was conducted with a nine undergraduate blended learning (n=4139) courses.•Generalized predictive models were not suitable to inform practice and research.•Course specific models better detected variables of relevance for teaching practice.•Further implications for educational research and practice are discussed.
Recruiting and retaining participants in randomised controlled trials (RCTs) is challenging. Digital tools, such as social media, data mining, email or text-messaging, could improve recruitment or ...retention, but an overview of this research area is lacking. We aimed to systematically map the characteristics of digital recruitment and retention tools for RCTs, and the features of the comparative studies that have evaluated the effectiveness of these tools during the past 10 years.
We searched Medline, Embase, other databases, the Internet, and relevant web sites in July 2018 to identify comparative studies of digital tools for recruiting and/or retaining participants in health RCTs. Two reviewers independently screened references against protocol-specified eligibility criteria. Included studies were coded by one reviewer with 20% checked by a second reviewer, using pre-defined keywords to describe characteristics of the studies, populations and digital tools evaluated.
We identified 9163 potentially relevant references, of which 104 articles reporting 105 comparative studies were included in the systematic map. The number of published studies on digital tools has doubled in the past decade, but most studies evaluated digital tools for recruitment rather than retention. The key health areas investigated were health promotion, cancers, circulatory system diseases and mental health. Few studies focussed on minority or under-served populations, and most studies were observational. The most frequently-studied digital tools were social media, Internet sites, email and tv/radio for recruitment; and email and text-messaging for retention. One quarter of the studies measured efficiency (cost per recruited or retained participant) but few studies have evaluated people's attitudes towards the use of digital tools.
This systematic map highlights a number of evidence gaps and may help stakeholders to identify and prioritise further research needs. In particular, there is a need for rigorous research on the efficiency of the digital tools and their impact on RCT participants and investigators, perhaps as studies-within-a-trial (SWAT) research. There is also a need for research into how digital tools may improve participant retention in RCTs which is currently underrepresented relative to recruitment research.
Not registered; based on a pre-specified protocol, peer-reviewed by the project's Advisory Board.
Intron retention (IR) occurs when an intron is transcribed into pre-mRNA and remains in the final mRNA. We have developed a program and database called IRFinder to accurately detect IR from mRNA ...sequencing data. Analysis of 2573 samples showed that IR occurs in all tissues analyzed, affects over 80% of all coding genes and is associated with cell differentiation and the cell cycle. Frequently retained introns are enriched for specific RNA binding protein sites and are often retained in clusters in the same gene. IR is associated with lower protein levels and intron-retaining transcripts that escape nonsense-mediated decay are not actively translated.
Although we frequently take advantage of memory for objects locations in everyday life, understanding how an object's identity is bound correctly to its location remains unclear. Here we examine how ...information about object identity, location and crucially object-location associations are differentially susceptible to forgetting, over variable retention intervals and memory load. In our task, participants relocated objects to their remembered locations using a touchscreen. When participants mislocalized objects, their reports were clustered around the locations of other objects in the array, rather than occurring randomly. These 'swap' errors could not be attributed to simple failure to remember either the identity or location of the objects, but rather appeared to arise from failure to bind object identity and location in memory. Moreover, such binding failures significantly contributed to decline in localization performance over retention time. We conclude that when objects are forgotten they do not disappear completely from memory, but rather it is the links between identity and location that are prone to be broken over time.
Because of the potential increased incidence of acute urinary retention, optimal timing of urinary catheter removal after major pelvic colorectal surgery remains unclear.
This study aims to compare ...the incidence of urinary retention following early catheter removal on postoperative day 1 vs standard catheter removal on day 3.
This is a randomized, noninferiority trial.
This study was conducted at an urban teaching hospital.
Patients undergoing colorectal surgery below the peritoneal reflection were selected.
A 1:1 randomization to early or standard catheter removal was performed. Patients in the early arm were administered an α-antagonist (prazosin 1 mg oral) 6 hours before catheter removal.
The primary outcome measured was the incidence of acute urinary retention.
One hundred forty-two patients were randomly assigned to early (n = 71) or standard (n = 71) catheter removal. Mean age was 44.8 ± 16.9 years, and the study cohort included 54% men. The most common operations were IPAA (66%) and low anterior resection (18%). The overall rate of retention was 9.2% (n = 13), with no difference between early (n = 6; 8.5%) or standard (n = 7; 9.9%) catheter removal (RR, 0.86; 95% CI, 0.30-2.42). The risk difference was -1.4% (95% CI, -8.3 to 11.1), confirming noninferiority. The rate of infection was significantly lower in early vs standard catheter removal (0% vs 11.3%; p = 0.01). Length of stay was significantly shorter after early vs standard catheter removal (4 days, interquartile range = 3-6 vs 5 days, interquartile range = 4-7; p = 0.03).
Patients and investigators were not blinded; a nonselective oral α-antagonist was used.
Following pelvic colorectal surgery, early urinary catheter removal, when combined with the addition of an oral α-antagonist, is noninferior to standard urinary catheter removal and carries a lower risk of symptomatic infection and shorter hospital stay.
http://www.clinicaltrials.gov (NCT01923129). See Video Abstract at http://links.lww.com/DCR/A738.
Increased loading of nitrogen (N) and phosphorus (P) from agricultural and urban intensification has led to severe degradation of inland and coastal waters. Lakes, reservoirs, and wetlands (lentic ...systems) retain these nutrients, thus regulating their delivery to downstream waters. While the processes controlling N and P retention are relatively well‐known, there is a lack of quantitative understanding of how these processes manifest across spatial scales. We synthesized data from 600 lentic systems around the world to gain insight into the relationship between hydrologic and biogeochemical controls on nutrient retention. Our results indicate that the first‐order reaction rate constant, k T−1, is inversely proportional to the hydraulic residence time, τ T, across 6 orders of magnitude in residence time for total N, total P, nitrate, and phosphate. We hypothesized that the consistency of the relationship points to a strong hydrologic control on biogeochemical processing, and validated our hypothesis using a sediment‐water model that links major nutrient removal processes with system size. Finally, the k‐τ relationships were upscaled to the landscape scale using a wetland size‐frequency distribution. Results suggest that small wetlands play a disproportionately large role in landscape‐scale nutrient processing—50% of nitrogen removal occurs in wetlands smaller than 102.5 m2 in our example. Thus, given the same loss in wetland area, the nutrient retention potential lost is greater when smaller wetlands are preferentially lost from the landscape. Our study highlights the need for a stronger focus on small lentic systems as major nutrient sinks in the landscape.
Plain Language Summary
Excess nutrient pollution from intensive fertilizer use and farming operations poses an increasing threat to water quality worldwide. Lakes, streams, and wetlands restrict the movement of nutrients, and thus protect downstream waters. We have a limited understanding, however, of how removal processes are affected by the size and type of the water body. Based on a synthesis of data from lakes, reservoirs, and wetlands worldwide, we found that smaller water bodies tend to have higher nutrient removal rates. We applied our findings to the landscape scale and found that for the same wetland area lost, the loss of small wetlands corresponds to a greater loss in wetland nutrient removal potential. Such findings are significant to wetland protection and restoration efforts, which have historically focused on maximizing total wetland area rather than on preserving a distribution of different wetlands sizes within a landscape.
Key Points:
Nutrient removal rate constants scale inversely with water residence times and size for wetlands, lakes, and reservoirs
Modeling highlights hydrological controls on nutrient processing such that smaller water bodies are more reactive
At the landscape scale, small wetlands account for a disproportionately large fraction of the overall nutrient removal potential
The current short-term longitudinal study investigated the role of college students' identity development and motivational beliefs in predicting their chemistry achievement and intentions to leave ...science, technology, engineering, and math (STEM) majors. We collected 4 waves of data over 1 semester from 363 diverse undergraduate STEM students enrolled in a chemistry lab course. The results of analyses that examined the reciprocal relations among the variables over time (i.e., cross-lagged path analysis) suggested that identity development that involved exploration (e.g., information-seeking, reflection) was positively related to students' beliefs about their competence and value for the STEM major and negatively related to perceptions of effort cost (drawbacks associated with time and effort) for the major. Identity development that did not involve exploration was related to low competence beliefs and high perceptions of costs for the STEM major. Competence beliefs, values, and perceptions of cost for the major were dynamically related to chemistry achievement and to students' intentions to leave the STEM major over the semester, with different kinds of cost perceptions (drawbacks associated with effort, lost opportunities, and stress and anxiety) relating differentially to students' intentions. The results support the role of identity development in students' motivation for a STEM major and address a gap in the literature regarding the role of perceived cost in students' academic choices.
The hollow fiber filter is the primary cell-retention device used in high-density perfusion cell culture and often used in an alternating tangential flow (ATF) configuration. The limited commercially ...available diaphragm pumps for ATF prevent utilization of vertical space when scaling beyond 500 L. Stacking hollow fiber filters coupled with viscous cell culture imposes vacuum pressure exceeding facility capabilities. Additionally, the longer filter assembly increases the hold-up volume and exceeds the diaphragm pump's fluid exchange capacity. The conventional tangential flow filtration (TFF) configuration circumvents this issue by exchanging culture from the bioreactor and cell-retention device in a unidirectional recirculation loop; however, the increased filter length when scaled up exacerbates the TFF's inherent issue with product retention from Starling flow. Stacking commercially available 20 cm TFF filters to make up the similar single-module length TFF used for the platform 3 and 50 L perfusion process at 41.5 and 65 cm, respectively, attempts to reduce fouling caused by Starling flow. The permeate of a single-module filter is partitioned into short independent segments through serially stacked filters, each harvested separately. By partitioning the permeate, the sieving coefficient increased for both 3 and 50 L scales. Reduction of Starling flow was confirmed with lower total hydraulic membrane resistance throughout the culture. This work demonstrates a method for increasing sieving coefficient and filter capacity by stacking TFF filters with independent permeate streams.
Nanoplastics as emerging pollutants have caused growing concerns and posed potential threats to the environment. Nonetheless, only few studies investigated transport behaviors of nanoplastics in ...natural soils. In this study, column experiments were conducted to investigate the effect of soil properties, ionic strength and cation type on the transport of polystyrene nanoplastics (PSNPs) in a desert soil (DS), a black soil (BS) and a red soil (RS). The effluent recovery of PSNPs in three soils followed the order of DS (0%–96.8%) > BS (0%–87.5%) > RS (0%). The retention of PSNPs was positively correlated with Fe/Al oxides contents (DS: Fe-2.69%, Al-12.6%; BS: Fe-4.04%, Al-15.9%; RS: Fe-6.57%, Al-26.9%), whereas negatively correlated with soil pH (DS: 9.75; BS: 6.57; RS: 4.97). Soil minerals and pH were thus identified as the crucial soil properties determining transport of PSNPs, due to their coupled effects on surface charges to affect electrostatic interactions between soils and PSNPs. In addition, increasing solution ionic strength strongly inhibited the transport of PSNPs in the DS (0%–96.8%) and BS (0%–87.5%). Ca2+ (IS: 1–5 mM) was more pronounced in enhancing PSNP retention than Na+ (IS: 1–20 mM). Our findings highlight that the transport and fate of PSNPs in natural soils are highly sensitive to soil physicochemical properties, ionic strength and cation type, and reveal that nanoplastics have strong mobility ability in soils with high pH and low Fe/Al oxides contents, which may pose potential risks to the soil and groundwater environment.
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•PSNPs retention in soils was positively correlated with Fe/Al oxides contents.•PSNPs retention in soils was negatively correlated with soil pH.•PSNPs transport decreased with increasing ionic strength in soils.•Ca2+ was more pronounced in inhibiting PSNPs transport than Na+ in soils.
Abstract
Rainfall infiltration, rainwater retention, runoff and evapotranspiration (ET) are important components of the water balance in green roofs. These components are expected to be influenced by ...variations in the structural configurations (i.e., substrate layers) of green roofs. This study explores the influence of layered soil and green roof configurations on the rainwater retention capacity (RRC) of the roofs as compared to conventional improvements (i.e., soil conditioning and enhanced substrate depth). Ten different extensive green roof modules were designed by varying the substrate materials, substrate depths, storage/drainage layers and vegetation layers. For all modules, the RRCs ranged from 34 to 59%. The RRCs of layered soil were 1–4% higher than that for single-layer soil. The RRC increased by 13% in the presence of a water storage module. It can be concluded that highest RRC corresponds to a combination of high-permeability soil in the upper layer along with a relatively large water holding capacity in the deep layer. Water storage layer and layered soil could significantly delay the water stress in vegetation. The importance of wick irrigation, vegetation types, back-to-back rain events and the ET rate on the RRC were also discussed.
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