Reaction mechanisms are central to organic chemistry and organic chemistry education. Assessing understanding of reaction mechanisms can be evaluated holistically, wherein the entire mechanism is ...considered; however, we assert that such an evaluation does not account for how learners variably understand mechanistic components (
e.g.
, nucleophile, electrophile) or steps (
e.g.
, nucleophilic attack, proton transfer). For example, a learner may have proficiency of proton transfer steps without sufficient proficiency of a step where a nucleophile and electrophile interact. Herein, we report the development of a generalized rubric to assess the level of explanation sophistication for nucleophiles in written explanations of organic chemistry reaction mechanisms from postsecondary courses. This rubric operationalizes and applies chemistry education research findings by articulating four hierarchical levels of explanation sophistication: absent, descriptive, foundational, and complex. We provide evidence for the utility of the rubric in an assortment of contexts: (a) stages of an organic chemistry course (
i.e.
, first or second semester), (b) across nucleophile and reaction types, and (c) across prompt variations. We, as well, present a case study detailing how this rubric could be applied in a course to collect assessment data to inform learning and instruction. Our results demonstrate the practical implementation of this rubric to assess understanding of nucleophiles and offer avenues for establishing rubrics for additional mechanistic components, and understanding and evaluating curricula.
A deep understanding of organic chemistry requires a learner to understand many concepts and have fluency with multiple skills. This understanding is particularly necessary for constructing and using ...mechanisms to explain chemical reactions. Electrophilicity and nucleophilicity are two fundamental concepts to learning and understanding reaction mechanisms. Prior research suggests that learners focus heavily on explicit structural features (
e.g.
, formal charge) rather than implicit features (
e.g.
, an open p-orbital) when identifying and describing the role of electrophiles and nucleophiles in reaction mechanisms; however, these findings come from small-scale, interview-based investigations with a limited number of reaction mechanisms. The work reported herein seeks to further explore the meaning learners ascribe to electrophiles and nucleophiles by evaluating 19 936 written explanations from constructed-response items asking
what
is happening in reaction mechanisms and
why
it happens for 85 unique reaction mechanisms across a yearlong postsecondary organic chemistry course. To analyze these data, we developed an electrophile rubric to capture learners' level of explanation sophistication (
Absent, Descriptive, Foundational
, and
Complex
); this electrophile rubric is complementary to a nucleophile rubric previously reported in the literature. Our data show proportional levels of explanation sophistication for electrophiles and nucleophiles (
τ
b
= 0.402) across these written explanations of reaction mechanisms. We note that learners' explanations of nucleophiles tend to be at a higher level than their explanations of electrophiles. While this finding does support prior literature reports, we also found that explanations of mechanisms involving reductions of pi-bonds (
e.g.
, carbonyls) tended to be more sophisticated for electrophiles than for nucleophiles. Overall, our results support the claim that learners are able to discuss both electrophilicity and nucleophilicity; however, learners discuss electrophilicity and nucleophilicity at different levels of sophistication where nucleophilicity predominates for most reaction types.
Cardiovascular disease collectively accounts for a quarter of deaths worldwide. Genome-wide association studies across a range of cardiovascular traits and pathologies have highlighted the prevalence ...of common non-coding genetic variants within candidate loci. Here, we review genetic, epigenomic and molecular approaches to investigate the contribution of non-coding regulatory elements in cardiovascular biology. We then discuss recent insights on the emerging role of non-coding variation in predisposition to cardiovascular disease, with a focus on novel mechanistic examples from functional genomics studies. Lastly, we consider the clinical significance of these findings at present, and some of the current challenges facing the field.
Objective.
To conduct a systematic review of the literature to examine the influence of the built environment (BE) on the physical activity (PA) of adults in rural settings.
Data Source.
Key word ...searches of Academic Search Premier, PubMed, CINAHL, Web of Science, and Sport Discus were conducted.
Study Inclusion and Exclusion Criteria.
Studies published prior to June 2008 were included if they assessed one or more elements of the BE, examined relationships between the BE and PA, and focused on rural locales. Studies only reporting descriptive statistics or assessing the reliability of measures were excluded.
Data Extraction.
Objective(s), sample size, sampling technique, geographic location, and definition of rural were extracted from each study. Methods of assessment and outcomes were extracted from the quantitative literature, and overarching themes were identified from the qualitative literature.
Data Synthesis.
Key characteristics and findings from the data are summarized in Tables 1 through 3.
Results.
Twenty studies met inclusion and exclusion criteria. Positive associations were found among pleasant aesthetics, trails, safety/crime, parks, and walkable destinations.
Conclusions.
Research in this area is limited. Associations among elements of the BE and PA among adults appear to differ between rural and urban areas. Considerations for future studies include identifying parameters used to define rural, longitudinal research, and more diverse geographic sampling. Development and refinement of BE assessment tools specific to rural locations are also warranted.
Caffeine is the most widely used psychoactive substance in the world and currently the only one legally available to children and adolescents. The sale and use of caffeinated beverages has increased ...markedly among adolescents during the last decade. However, research on caffeine use and behaviors among adolescents is scarce. We investigate the relationship between adolescent caffeine use and self-reported violent behaviors and conduct disorders in a population-based cross-sectional sample of 3,747 10th grade students (15–16 years of age, 50.2 % girls) who were enrolled in the Icelandic national education system during February 2012. Through a series of multiple regression models, while controlling for background factors, Attention Deficit Hyperactivity Disorder symptoms and current medication and peer delinquency, and including measures on substance use, our findings show robust additive explanatory power of caffeine for both violent behaviors and conduct disorders. In addition, the association of caffeine to the outcomes is significantly stronger for girls than boys for both violent behaviors and conduct disorders. Future studies are needed to examine to what extent, if at all, these relationships are causal. Indication of causal connections between caffeine consumption and negative outcomes such as those reported here would call into question the acceptability of current policies concerning the availability of caffeine to adolescents and the targeting of adolescence in the marketing of caffeine products.
The mandatory reporting of intimate partner violence (IPV) is a controversial issue that is receiving increased attention. A related concern is whether children’s exposure to IPV constitutes child ...maltreatment, making it reportable to child protective services. These issues have been relatively unexplored within the context of home visitation programs. A secondary analysis of qualitative data collected from community stakeholders, clients, and home visiting nurses in the Nurse–Family Partnership program was carried out. Participants’ perceptions about mandatory reporting of IPV and reporting of children’s exposure to IPV are highlighted. Emergent themes and implications for research, practice, and policy are discussed.
CCN2
is a critical matricellular protein that is expressed in several cells with major implications in physiology and different pathologies. However, the transcriptional regulation of this gene ...remains obscure. We used the Encyclopaedia of DNA Elements browser (ENCODE) to visualise the region spanning from 300 kb upstream to the
CCN2
start site in silico in order to identify enhancer regions that regulate transcription of this gene. Selection was based on three criteria associated with enhancer regions: 1) H3K4me1 and H3K27ac histone modifications, 2) DNase I hypersensitivity of chromatin and 3) inter-species conservation. Reporter constructs were created with sequences spanning each of the regions of interest placed upstream of an
Hsp68
silent proximal promoter sequence in order to drive the expression of β-galactosidase transgene. Each of these constructs was subsequently used to create transgenic mice in which reporter gene production was assessed at the E15.5 developmental stage. Four functional enhancers were identified, with each driving distinct, tissue-specific patterns of transgene expression. An enhancer located -100 kb from the
CCN2
transcription start site facilitated expression within vascular tissue. An enhancer -135 kb upstream of
CCN2
drove expression within the articular chondrocytes of synovial joints. The other two enhancers, located at -198 kb and -229 kb, mediated transgene expression within dermal fibroblasts, however the most prevalent activity was found within hypertrophic chondrocytes and periosteal tissue, respectively. These findings suggest that the global expression of
CCN2
during development results from the activity of several tissue-specific enhancer regions in addition to proximal regulatory elements that have previously been demonstrated to drive transcription of the gene during development.
The focus of this paper is a novel pedagogical planner that we have developed called the CFLS planner (Collaborative Filtering based on Learning Sequences). The CFLS planner has been designed for an ...open-ended and unstructured learning environment based on the ecological approach (EA) architecture (McCalla
Journal of Interactive Media in Education, 7
,
2004
). The EA-based learning environment represents its content as learning objects (LOs), maintains models of its learners, and keeps track of learner interactions with the LOs by attaching traces of their behaviour to the LOs they have interacted with. The CFLS planner creates pedagogical plans for a target learner by looking back at the sequence of the
b
(for “backward”) most recent LOs that the target learner has interacted with and finding a neighbourhood of other learners who in the past have interacted with a similar sequence of
b
LOs. The CFLS planner then recommends to the target learner a sequence of
f
(for “forward”) LOs that was the most successful sequence (in terms of learning outcomes) that had been carried out next among the neighbourhood of similar learners. We implemented and tested the CFLS planner using a very simple simulation, in which simulated learners interact with simulated learning objects. We experimented with various settings for the
b
and
f
parameters. Intriguing patterns in the relationship between
b
and
f
emerged. Further, the settings for
b
and
f
that led to the best learning outcomes (on two different measures of success) varied according to the aptitude levels of the learners. Finally, we compared the CFLS planner to two baseline planners: a simple prerequisite planner (SPP) and a planner that randomly recommended the next learning object (Random). The CFLS planner readily outperformed Random (as expected), but also, more surprisingly, with appropriate settings of
b
and
f
, it outperformed SPP even though the CFLS planner did not know about the prerequisite relationships among the LOs that the SPP was able to access. This shows promise that a CFLS planner can find niche learning paths to recommend to learners based on interaction traces left behind by the learners, without needing externally engineered metadata about the learning objects or knowing very much about the learners, perhaps even finding paths based on patterns of learning activity never considered by a human designer. This is exactly the kind of planning system needed in open-ended, unstructured learning environments.
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