To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The growing availability of mobile technologies has contributed to an increase in mobile-assisted language learning in which learners can autonomously study a second language (L2) anytime or anywhere (e.g. Kukulska-Hulme, Lee & Norris, 2017; Reinders & Benson, 2017). Research investigating the effectiveness of such study for L2 learning, however, has been limited, especially regarding large-scale commercial L2 learning apps, such as Duolingo. Although one commissioned research study found favorable language learning outcomes (Vesselinov & Grego, 2012), limited independent research has reported issues related to learner persistence, motivation, and program efficacy (Lord, 2015; Nielson, 2011). The current study investigates the semester-long learning experiences and results of nine participants learning Turkish on Duolingo. The participants showed improvement on L2 measures at the end of the study, and results indicate a positive, moderate correlation between the amount of time spent on Duolingo and learning gains. In terms of perceptions of their experiences, the participants generally viewed Duolingo’s flexibility and gamification aspects positively; however, variability in motivation to study and frustration with instructional materials were also expressed.
We previously demonstrated that electrode architectures comprising nanoscale birnessite-like MnOx affixed to three-dimensional carbon nanofoam (CNF) scaffolds offer performance advantages when used as cathodes in rechargeable zinc-ion cells. To discern chemical and physical changes at the MnOx@CNF electrode upon deep charge/discharge in aqueous Zn2+-containing electrolytes, we deploy electroanalytical methods and ex situ characterization by microscopy, elemental analysis, x-ray photoelectron spectroscopy, x-ray diffraction, and x-ray pair distribution function analyses. Our findings verify that redox processes at the MnOx are accompanied by reversible precipitation/dissolution of crystalline zinc hydroxide sulfate (Zn4(OH)6(SO4)·xH2O), mediated by the more uniformly reactive electrode structure inherent to the CNF scaffold.
A computational study was performed both of a single agglomerate and of the collision of two agglomerates in a shear flow. The agglomerates were extracted from a direct numerical simulation of a turbulent agglomeration process, and had the loosely packed fractal structure typical of agglomerate structures formed in turbulent agglomeration processes. The computation was performed using a discrete-element method for adhesive particles with four-way coupling, accounting both for forces between the fluid and the particles (and vice versa) as well as force transmission directly between particles via particle collisions. In addition to understanding and characterizing the particle dynamics, the study focused on illuminating the fluid flow field induced by the agglomerate in the presence of a background shear and the effect of collisions on this particle-induced flow. Perhaps the most interesting result of the current work was the observation that the flow field induced by a particle agglomerate rotating in a shear flow has the form of two tilted vortex rings with opposite-sign circulation. These rings are surrounded by a sea of stretched vorticity from the background shear flow. The agglomerate rotates in the shear flow, but at a slower rate than the ambient fluid elements. In the computations with two colliding agglomerates, we observed cases resulting in agglomerate merger, bouncing and fragmentation. However, the bouncing cases were all observed to also result in an exchange of particles between the two colliding agglomerates, so that they were influenced both by elastic rebound of the agglomerate structures as well as by tearing away of particulate matter between the agglomerates. Overall, the problems of agglomerate–flow interaction and of the collision of two agglomerates in a shear flow are considerably richer in physical phenomena and more complex than can be described by the common approximation that represents each agglomerate by an ‘equivalent sphere’.
Herbicide resistance is ‘wicked’ in nature; therefore, results of the many educational efforts to encourage diversification of weed control practices in the United States have been mixed. It is clear that we do not sufficiently understand the totality of the grassroots obstacles, concerns, challenges, and specific solutions needed for varied crop production systems. Weed management issues and solutions vary with such variables as management styles, regions, cropping systems, and available or affordable technologies. Therefore, to help the weed science community better understand the needs and ideas of those directly dealing with herbicide resistance, seven half-day regional listening sessions were held across the United States between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide resistance management. The major goals of the sessions were to gain an understanding of stakeholders and their goals and concerns related to herbicide resistance management, to become familiar with regional differences, and to identify decision maker needs to address herbicide resistance. The messages shared by listening-session participants could be summarized by six themes: we need new herbicides; there is no need for more regulation; there is a need for more education, especially for others who were not present; diversity is hard; the agricultural economy makes it difficult to make changes; and we are aware of herbicide resistance but are managing it. The authors concluded that more work is needed to bring a community-wide, interdisciplinary approach to understanding the complexity of managing weeds within the context of the whole farm operation and for communicating the need to address herbicide resistance.
Seven half-day regional listening sessions were held between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide-resistance management. The objective of the listening sessions was to connect with stakeholders and hear their challenges and recommendations for addressing herbicide resistance. The coordinating team hired Strategic Conservation Solutions, LLC, to facilitate all the sessions. They and the coordinating team used in-person meetings, teleconferences, and email to communicate and coordinate the activities leading up to each regional listening session. The agenda was the same across all sessions and included small-group discussions followed by reporting to the full group for discussion. The planning process was the same across all the sessions, although the selection of venue, time of day, and stakeholder participants differed to accommodate the differences among regions. The listening-session format required a great deal of work and flexibility on the part of the coordinating team and regional coordinators. Overall, the participant evaluations from the sessions were positive, with participants expressing appreciation that they were asked for their thoughts on the subject of herbicide resistance. This paper details the methods and processes used to conduct these regional listening sessions and provides an assessment of the strengths and limitations of those processes.
Posthodiplostomum minimum utilizes a three-host life cycle with multiple developmental stages. The metacercarial stage, commonly known as ‘white grub’, infects the visceral organs of many freshwater fishes and was historically considered a host generalist due to its limited morphological variation among a wide range of hosts. In this study, infection data and molecular techniques were used to evaluate the host and tissue specificity of Posthodiplostomum metacercariae in centrarchid fishes. Eleven centrarchid species from three genera were collected from the Illinois portion of the Ohio River drainage and necropsied. Posthodiplostomum infection levels differed significantly by host age, host genera and infection locality. Three Posthodiplostomum spp. were identified by DNA sequencing, two of which were relatively common within centrarchid hosts. Both common species were host specialists at the genus level, with one species restricted to Micropterus hosts and the other preferentially infecting Lepomis. Host specificity is likely dictated by physiological compatibility and deviations from Lepomis host specificity may be related to host hybridization. Posthodiplostomum species also differed in their utilization of host tissues. Neither common species displayed strong genetic structure over the scale of this study, likely due to their utilization of bird definitive hosts.
Evening-dosed DR/ER-MPH (formerly HLD200), a delayed-release and extended-release methylphenidate, was designed to provide efficacy upon awakening and through the evening. The objective was to evaluate whether treatment with DR/ER-MPH in children with attention-deficit/hyperactivity disorder (ADHD): (1) improves caregiver-rated ADHD symptoms, and (2) reduces caregiver strain, versus placebo.
Caregiver-rated ADHD symptoms (Conners’ Global Index–Parent [CGI-P]) and caregiver strain (Caregiver Strain Questionnaire [CGSQ]) were assessed as secondary endpoints following 3 weeks of treatment in a randomized, double-blind, multicenter, placebo-controlled, parallel-group, phase 3 trial of DR/ER-MPH in children (6-12 years) with ADHD (NCT02520388). Using the 10-item CGI-P, parents rated their child’s ADHD symptoms on a 4-point scale (0=never/seldom; 3=very often/frequently). Caregivers also rated the impact of caring for a child with emotional and behavioral challenges on the 21-item CGSQ (5-point scale: 1=not at all; 5=very much). A reduction on individual item and total scores for both measures indicated an improvement.
Of 163 children enrolled across 22 sites, 161 were included in the intent-to-treat population (DR/ER-MPH, n=81; placebo, n=80) and 138 completed the study. The mean DR/ER-MPH dose after 3 weeks of treatment was 68.1 mg. Mean CGI-P scores at baseline and CGSQ scores at screening (ie, before washout of prior ADHD therapy) were comparable for both DR/ER-MPH (CGI-P: 22.8, CGSQ: 54.5) and placebo (CGI-P: 21.8; CGSQ: 54.9) groups. After 3 weeks of treatment, caregivers of children onDR/ER-MPH reported significant reductions in CGI-P scores versus those on placebo (least-squares [LS] mean: 12.3 vs 17.4; P<0.001). Additionally, there was a significant reduction in CGSQ scores after 3 weeks of treatment with DR/ER-MPH versus placebo (LS mean: 41.2 vs 49.1; P<0.001). Post hoc analyses on the effect of DR/ER-MPHversus placebo on individual items of CGI-P and CGSQ, and the two subscales of CGI-P will be presented. No serious TEAEs were reported and all TEAEs were consistent with those of MPH.
Caregivers reported significant improvements in their child’s ADHD symptoms and these improvements coincided with reductions in caregiver strain after 3 weeks of treatment on evening-dosed DR/ER-MPH versus placebo.
In a phase 3 trial of children with ADHD, DR/ER-MPH (formerly HLD200), a delayed-release and extended-release methylphenidate, improved ADHD symptoms and reduced at-home early morning and late afternoon/evening functional impairments versus placebo, as measured by the validated Parent Rating of Evening andMorning Behaviors-Revised, Morning (PREMB-R AM) and Evening (PREMB-R PM) subscales. This post hoc analysis evaluated the effect of DR/ER-MPH versus placebo onindividual PREMB-R AM/PM item scores.
Data were analyzed from a pivotal, randomized, double-blind, multicenter, placebo-controlled, parallel-group, phase 3 trial of DR/ER-MPH in children (6-12 years) withADHD (NCT02520388). Using the 3-item PREMB-R AM and 8-item PREMB-R PM, both key secondary endpoints, investigators evaluated early morning and lateafternoon/evening functional impairment by scoring each item on a severity scale from 0 (none) to 3 (a lot). For post hoc analyses, treatment comparisons between DR/ER-MPH and placebo at endpoint were determined by using least squares mean changes from baseline on individual PREMB-R AM/PM items score derived from an analysis ofcovariance (ANCOVA) model with treatment as the main effect, and study center and baseline score as covariates.
Of 163 children enrolled across 22 sites, 161 were included in the intent-to-treat population (DR/ER-MPH, n=81; placebo, n=80) and 138 completed the study. The mean DR/ER-MPH dose achieved after 3 weeks of treatment was 68.1 mg. Following 3 weeks of treatment, DR/ER-MPH significantly reduced mean individual item scores from baseline versus placebo on all PREMB-R AM items (all P≤0.002; “getting out of bed”, “getting ready”, and “arguing or struggling in the morning”). Additionally, DR/ER-MPH significantly reduced mean individual item scores from baseline on 5 out of 8 PREMB-R PM items (P<0.01 in 2 items [“sitting through dinner” and “playing quietly”] and P<0.05 in 3 items [“inattentive/distractible”, “transitioning between activities”, and “settling down/getting ready for bed”]). There was a trend towards a reduction on 2 other items of the PREMB-R PM (P<0.09). Distributions of the ratings for each item will be presented. No serious TEAEs were reported; TEAEs were consistent withmethylphenidate.
Post hoc analyses revealed that DR/ER-MPH significantly reduced all PREMB-R AM item scores, including “getting out of bed”, and many PREMB-R PM items, including “getting ready for bed” in children with ADHD. These findings are worth further exploration.
In a phase 3 trial of children with attention-deficit/hyperactivity disorder (ADHD), DR/ER-MPH (formerly HLD200), a delayed-release and extended-release methylphenidate, improved ADHD symptoms and reduced at-home early morning and late afternoon/evening functional impairment versus placebo. The validated Before School Functioning Questionnaire (BSFQ), a key secondary endpoint, was used to measure early morning functional (EMF) impairment. This post hoc analysis evaluated the effect of DR/ER-MPH versus placebo on individual BSFQ item scores from baseline.
Data were analyzed from a pivotal, randomized, double-blind, multicenter, placebo-controlled, parallel-group, phase 3 trial of DR/ER-MPH in children (6-12 years) withADHD (NCT02520388). Using the 20-item BSFQ, investigators evaluated EMF impairment by scoring each item on a severity scale of 0 to 3, with 0 denoting “no impairment” and 3 denoting “severe impairment”. For post hoc analyses, treatment comparisons between DR/ER-MPH and placebo at endpoint were determined by using least squares mean changes from baseline on individual BSFQ items score derived from an analysis of covariance (ANCOVA) model with treatment as the main effect, and study center and baseline score as covariates.
Of 163 children enrolled across 22 sites, 161 were included in the intent-to-treat population (DR/ER-MPH, n=81; placebo, n=80) and 138 completed the study. The mean DR/ER-MPH dose achieved after 3 weeks of treatment was 68.1 mg. Following 3 weeks of treatment, DR/ER-MPH significantly reduced mean BSFQ item scores frombaseline on 18 out of 20 items versus placebo (P<0.001 in 8 items [listening, following directions, attention, forgetfulness, talkativeness, silliness, time awareness, getting to school]; P<0.01 in 7 items [overall organization, being quiet, distraction, interrupt/blurt out, breakfast, hygiene, independence]; P<0.05 in 3 items [procrastination, hyperactivity, awaiting turn]). Only “dressing” and “misplacing/losing items” showed no significant between-group differences (P=0.171 and P=0.175, respectively). Distributions of the severity ratings for each item will be presented. No serious TEAEs were reported; TEAEs were consistent with methylphenidate.
Post hoc analyses revealed that DR/ER-MPH significantly reduced 18 out of 20 individual BSFQ item scores versus placebo in children with ADHD. These findings are worth further exploration.
There is limited knowledge on vitamin D status of children residing in the Andes and its association with undernutrition. We evaluated the vitamin D status of children residing in a low socio-economic status (SES) setting in the Ecuadorian Andes and assessed the association between vitamin D status, stunting and underweight. We hypothesized that children who were underweight would have lower serum 25-hydroxyvitamin D (25(OH)D) levels and lower 25(OH)D levels would be associated with a higher risk of stunting.
We conducted a cross-sectional secondary analysis of a randomized controlled trial, the Vitamin A, Zinc and Pneumonia study. Children had serum 25(OH)D concentrations measured. A sensitivity analysis was undertaken to determine a vitamin D cut-off specific for our endpoints. Associations between serum 25(OH)D and underweight (defined as weight-for-age Z-score≤−1) and stunting (defined as height-for-age Z-score≤−2) were assessed using multivariate logistic regression.
Children residing in five low-SES peri-urban neighbourhoods near Quito, Ecuador.
Children (n 516) aged 6–36 months.
Mean serum 25(OH)D concentration was 58·0 (sd 17·7) nmol/l. Sensitivity analysis revealed an undernutrition-specific 25(OH)D cut-off of <42·5 nmol/l; 18·6 % of children had serum 25(OH)D<42·5 nmol/l. Children who were underweight were more likely to have serum 25(OH)D<42·5 nmol/l (adjusted OR (aOR)=2·0; 95 % CI 1·2, 3·3). Children with low serum 25(OH)D levels were more likely to be stunted (aOR=2·8; 95 % CI 1·6, 4·7).
Low serum 25(OH)D levels were more common in underweight and stunted Ecuadorian children.
To investigate the subsurface hydrological characteristics of an overdeepened cirque glacier, nine boreholes were drilled to the bed of West Washmawapta Glacier, British Columbia, Canada, in summer 2007. All holes were surveyed with a video camera, and four were subsequently instrumented with a combination of pressure transducers, thermistors and conductivity sensors. Diurnal pressure and temperature records indicate the presence of a hydraulically connected subglacial drainage system towards the northern glacier margin. Hydraulic jacking in the overdeepening, controlled by changing water volume in the marginal zone, potentially impacts basal ice flow and erosion. The presence of a sediment layer underlying the glacier also likely impacts hydrology and ice dynamics. Influx of warm groundwater into the basal system raises subglacial water temperatures above the pressure-melting point (pmp) and induces diurnal water temperature fluctuations of as much as 0.8°C; water temperatures above the pmp could affect basal melt rates and the development of subglacial drainage systems. These observations suggest that the characteristics of the subglacial drainage system substantially affect patterns of flow and erosion by this small cirque glacier.
One of the typical roles of industrial–organizational (I-O) psychologists working as practitioners is administering employee surveys measuring job satisfaction/engagement. Traditionally, this work has involved developing (or choosing) the items for the survey, administering the items to employees, analyzing the data, and providing stakeholders with summary results (e.g., percentages of positive responses, item means). In recent years, I-O psychologists moved into uncharted territory via the use of survey key driver analysis (SKDA), which aims to identify the most critical items in a survey for action planning purposes. Typically, this analysis involves correlating (or regressing) a self-report criterion item (e.g., “considering everything, how satisfied are you with your job”) with (or on) each of the remaining survey items in an attempt to identify which items are “driving” job satisfaction/engagement. It is also possible to use an index score (i.e., a scale score formed from several items) as the criterion instead of a single item. That the criterion measure (regardless of being a single item or an index) is internal to the survey from which predictors are drawn distinguishes this practice from linkage research. This methodology is not widely covered in survey methodology coursework, and there are few peer-reviewed articles on it. Yet, a number of practitioners are marketing this service to their clients. In this focal article, a group of practitioners with extensive applied survey research experience uncovers several methodological issues with SKDA. Data from a large multiorganizational survey are used to back up claims about these issues. One issue is that SKDA ignores the psychometric reality that item standard deviations impact which items are chosen as drivers. Another issue is that the analysis ignores the factor structure of survey item responses. Furthermore, conducting this analysis each time a survey is administered conflicts with the lack of situational and temporal specificity. Additionally, it is problematic to imply causal relationships from the correlational data seen in most surveys. Most surprisingly, randomly choosing items out of a hat yields validities similar to those from conducting the analysis. Thus, we recommend that survey providers stop conducting SKDA until they can produce science that backs up this practice. These issues, in concert with the lack of literature examining the practice, make rigorous evaluations of SKDA a timely inquiry.
To determine the impact of total household decolonization with intranasal mupirocin and chlorhexidine gluconate body wash on recurrent methicillin-resistant Staphylococcus aureus (MRSA) infection among subjects with MRSA skin and soft-tissue infection.
Three-arm nonmasked randomized controlled trial.
Five academic medical centers in Southeastern Pennsylvania.
Adults and children presenting to ambulatory care settings with community-onset MRSA skin and soft-tissue infection (ie, index cases) and their household members.
Enrolled households were randomized to 1 of 3 intervention groups: (1) education on routine hygiene measures, (2) education plus decolonization without reminders (intranasal mupirocin ointment twice daily for 7 days and chlorhexidine gluconate on the first and last day), or (3) education plus decolonization with reminders, where subjects received daily telephone call or text message reminders.
MAIN OUTCOME MEASURES
Owing to small numbers of recurrent infections, this analysis focused on time to clearance of colonization in the index case.
Of 223 households, 73 were randomized to education-only, 76 to decolonization without reminders, 74 to decolonization with reminders. There was no significant difference in time to clearance of colonization between the education-only and decolonization groups (log-rank P=.768). In secondary analyses, compliance with decolonization was associated with decreased time to clearance (P=.018).
Total household decolonization did not result in decreased time to clearance of MRSA colonization among adults and children with MRSA skin and soft-tissue infection. However, subjects who were compliant with the protocol had more rapid clearance
We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI.
A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Similarly, a greater mean BMI of up to 0.3 kg/m2 in childhood and adolescence and up to 0.2 kg/m2 in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes.
The Spacewatch Project uses four telescopes of apertures 0.9-m, 1.8-m, 2.3-m, and 4-m on Kitt Peak mountain in Arizona for followup astrometry of priority NEOs. Objects as faint as V=23 on the MPC's NEO Confirmation Page, targets of radar, potential impactors, targets of spacecraft observations or visits, and PHAs with future close approaches to Earth receive priority for astrometry.
For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes.