Structural equation modeling (SEM) is a powerful statistical approach for the testing of networks of direct and indirect theoretical causal relationships in complex data sets with intercorrelated ...dependent and independent variables. SEM is commonly applied in ecology, but the spatial information commonly found in ecological data remains difficult to model in a SEM framework. Here we propose a simple method for spatially explicit SEM (SE-SEM) based on the analysis of variance/covariance matrices calculated across a range of lag distances. This method provides readily interpretable plots of the change in path coefficients across scale and can be implemented using any standard SEM software package. We demonstrate the application of this method using three studies examining the relationships between environmental factors, plant community structure, nitrogen fixation, and plant competition. By design, these data sets had a spatial component, but were previously analyzed using standard SEM models. Using these data sets, we demonstrate the application of SE-SEM to regularly spaced, irregularly spaced, and ad hoc spatial sampling designs and discuss the increased inferential capability of this approach compared with standard SEM. We provide an R package, sesem, to easily implement spatial structural equation modeling.
The article from this special issue was previously published in Polymers for Advanced Technologies, Volume 28, Issue 3, 2017. For completeness we are including the title page of the article below. ...The full text of the article can be read in Issue 28:3 on Wiley Online Library: http://onlinelibrary.wiley.com/doi/10.1002/pat.3893/full
This research focuses on the development of an environmentally friendly composite directly from recycled high density polyethylene (rHDPE) grocery bags without changing their film form. Untreated and ...alkali‐treated hemp fibers are used as reinforcement for a composite with recycled High Density Polyethylene (rHDPE) and a combination of rHDPE and virgin HDPE (vHDPE). Grocery bags and hemp fibers are characterized using Fourier transform infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and thermogravimetric analysis (TGA). Fiber preforms are produced using a hydro‐entanglement method and compression molded with HDPE and/or rHDPE at weight fractions of 30, 40, and 50%. The hemp fiber HDPE composites are characterized and tested for their tension and flexure performance. The results show an improvement in mechanical properties when using treated fibers as well as the addition of vHDPE to the polymer matrix. The highest tensile and flexural strength values for the pure rHDPE composite were acquired after adding 40 and 50% weight fraction of treated fibers, respectively. An increase of around 10 MPa on both of these properties was found when using the optimized combination of the recycled and virgin matrix materials with 40 and 50% weight fraction of reinforcement, respectively. It is concluded that the composite made of hemp fibers and recycled plastic bag has relatively good mechanical properties and can be potentially used for secondary structural use.
Four different metal oxide nanoparticles, copper oxide (CuO), aluminum oxide (Al
2
O
3
), nickel oxide (NiO), and titanium dioxide (TiO
2
), were added to poly (2,5-dimethyl aniline) (P25DMA) during ...synthesis to create different polymer nanocomposites. These polymer nanocomposites were evaluated as potential sensing materials for six different gas analytes (acetaldehyde, acetone, benzene, ethanol, formaldehyde, and methanol). It was found that CuO did not incorporate into the P25DMA and only a small percentage of Al
2
O
3
was incorporated. However, both NiO and TiO
2
were incorporated into the P25DMA at the same concentration as during the synthesis step. Overall, the type of metal oxide significantly affected the morphology of the sensing material and the amount of each analyte sorbed. For example, P25DMA doped with 5 wt% Al
2
O
3
had high selectivity towards ethanol, whereas P25DMA doped with 20 wt% TiO
2
sorbed the most ethanol. However, P25DMA doped with 20 wt% TiO
2
also sorbed a high amount of formaldehyde, making P25DMA doped with 20 wt% TiO
2
less selective than P25DMA doped with 5 wt% Al
2
O
3
towards ethanol with respect to formaldehyde.
Cardiac injury leads to the loss of cardiomyocytes, which are rapidly replaced by the proliferation of the surviving cells in zebrafish, but not in mammals. In both the regenerative zebrafish and ...non-regenerative mammals, cardiac injury induces a sustained macrophage response. Macrophages are required for cardiomyocyte proliferation during zebrafish cardiac regeneration, but the mechanisms whereby macrophages facilitate this crucial process are fundamentally unknown. Using heartbeat-synchronized live imaging, RNA sequencing, and macrophage-null genotypes in the larval zebrafish cardiac injury model, we characterize macrophage function and reveal that these cells activate the epicardium, inducing cardiomyocyte proliferation. Mechanistically, macrophages are specifically recruited to the epicardial-myocardial niche, triggering the expansion of the epicardium, which upregulates vegfaa expression to induce cardiomyocyte proliferation. Our data suggest that epicardial Vegfaa augments a developmental cardiac growth pathway via increased endocardial notch signaling. The identification of this macrophage-dependent mechanism of cardiac regeneration highlights immunomodulation as a potential strategy for enhancing mammalian cardiac repair.
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•Heart regeneration in larval zebrafish is characterized in detail•Macrophage ablation blocks cardiomyocyte proliferation after cardiac injury•Macrophages synapse with epicardial cells and promote their proliferation•Epicardial Vegfaa drives cardiomyocyte proliferation during cardiac regeneration
In this study, Bruton et al. test the requirement for macrophages for cardiac regeneration in larval zebrafish, finding macrophages to be necessary for cardiomyocyte proliferation via the activation of the epicardium. The identification of this macrophage-dependent mechanism of cardiac regeneration supports immunomodulation as a promising strategy for enhancing mammalian cardiac repair.
Background:
Occupational science and occupational therapy typically perceive occupations as promoting health and well-being. However, this perspective overlooks the many occupations that are viewed ...as illegal, unhealthy, or risky, such as drug use. Due to its negative association with health, drug use is perceived as not holding significance or meaning in people’s lives.
Objective:
This study explores how individuals perceive and describe the meaning of their cannabis use in the context of their lives, from an occupational perspective.
Methods:
A scoping review was conducted using Levac et al.’ modifications to Arksey and O’Malley’s framework. To examine the peer-reviewed literature, 7 databases were searched using terms related to cannabis and meaning. Descriptive statistics were used to describe the selected studies, and reflexive thematic analysis identified cross-study themes.
Results:
Fourteen studies were selected. Most studies have been published since 2008, with 5 published in the last 2 years. Four themes were identified across the studies: (a) preserving life; (b) navigating the routines of everyday life; (c) understanding the self, identity, and belonging; and (d) expanding the view of the world.
Conclusions:
Cannabis use was revealed in this study as a support for navigating occupational routines and enhancing occupational repertoires and engagement, feelings of belonging, and collective user identities. As such, substance abuse treatment practices, including those provided by occupational therapists, should recognize the potential significance of cannabis use within people’s lives. Using a harm reduction approach, occupational therapists can acknowledge the ways in which clients use cannabis to manage their daily routines, while also focusing on supporting clients to reduce the ill-effects of cannabis. As individuals become more engaged in occupations that are significant in their lives, their need for and meaning of cannabis use may change leading to a possible reduction in its use and a shift in their identity construction.
Isolation of high quality cardiac endothelial cells is a prerequisite for successful bulk and single cell sequencing for RNA (scRNA-seq). We describe a protocol using both enzymatic and mechanical ...dissociation and fluorescence-activated cell sorting (FACS) to isolate endothelial cells from larval and adult zebrafish hearts and from healthy and ischemic adult mouse hearts. Endothelial cells with high viability and purity can be obtained using this method for downstream transcriptional analyses applications.
This paper suggests and empirically supports the propositions that a link between two organizations' Web sites will have simultaneous effects on trust in both the link sender and the link recipient, ...and that these effects result from interactions among the reputation of the link recipient, trust in the link sender, and the perceived relationship of the linked organizations. The study finds that the perceived relationship caused by a link leads to positive effects for the less reputable of the linked organizations, but negative effects for the more reputable organization. These effects are exaggerated or attenuated depending on the reputation of the organization that sends the link. The effect of presenting the link as an advertisement or a link to a partner was also examined, but no effect was uncovered, raising the question of how organizations may effectively differentiate links on their Web sites.
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