This article presents a theoretical modelling framework for the previously unconsidered case of turbulent wall plumes that detrain continually with height in stably stratified environments. Built upon the classic turbulent plume model, our approach incorporates turbulent detrainment with a variable coefficient of detrainment. Based on a linear constitutive relationship between the ratio of the detrainment to entrainment coefficients and the ambient buoyancy gradient, it is found that for linear ambient stratifications, a dynamic quasi-equilibrium region, characterised by a near invariant local plume Richardson number, is achieved, downstream of which this equilibrium rapidly breaks down. With increasing ambient buoyancy gradient, while the plume becomes increasingly slender with weaker vertical motions, the level at which the plume breaks down to form a horizontal intrusion first decreases and then increases. Moreover, distinct from classic purely entraining plumes, a detraining wall plume can swell within the pre-equilibrium adjustment stage provided the local Richardson number is sufficiently low $({Ri\ll 6})$, behaviour which is in accordance with observations made in filling-box experiments.

The linear temporal and absolute/convective stability characteristics of a thermal plume generated along a heated vertical cylinder are investigated theoretically under the Boussinesq approximation. Special focus is given to the uniform-wall-buoyancy-flux case whereby the cylinder surface sustains the same linear temperature gradient as the environment. A competition between the axisymmetric and helical modes is a remarkable feature of the instability, distinguishing these ‘annular plumes’ from free plumes/jets for which the helical mode is generally dominant. It is found that higher surface curvature stabilises the temporal axisymmetric mode significantly, but only has moderate effects on the helical mode. The most temporally unstable perturbation mode switches from a helical into an axisymmetric mode when the Prandtl number increases beyond a critical value. Both the roles of shear and buoyancy during the destabilisation are identified through an energy analysis which indicates that, while the shear work is usually a major source of perturbation energy, the buoyancy work manifests for long-wave axisymmetric perturbation modes, and for thin cylinders and high Prandtl numbers. For the specific temperature configuration considered herein, an annular plume is always convectively unstable whereas decreasing the cylinder radius from the planar limiting case first decreases and then increases the tendency of the flow towards being absolutely unstable. The helical mode is especially susceptible to being absolutely unstable on very thin cylinders. Several conditions for the onset of cellular thermal convection and plume detrainment are proposed based on our results and a hypothesis which connects the absolute instability to the detrainment phenomenon.

ABSTRACT IMPACT: This study deepens knowledge with respect to the associations between depression, cardiometabolic conditions, and accelerated aging with a clinically accessible marker in a population with disproportionate risk for comorbidity. OBJECTIVES/GOALS: The aim of this secondary analysis is to examine associations between DNA methylation age acceleration (DNAm AA) and depressive symptoms in African American women (AAW) considering the presence of cardiometabolic conditions (CMCs) including hypertension, diabetes, obesity. METHODS/STUDY POPULATION: Genomic and longitudinal clinical data (collected 2015-2020) from the Intergenerational Impact of Genetic and Psychosocial Factors on Blood Pressure Study (InterGEN) cohort (n=227) were utilized for this analysis. DNA methylation age (estimated by the Horvath method) incorporates DNA methylation status at 353 CpG sites. DNAm AA is the residual of DNA methylation age regressed on chronological age in a linear model. Spearman’s correlations and linear regression examine the relationship between DNAm AA and depressive symptoms (Beck Depression Inventory) and cardiometabolic status. The potential association and impact of SES, trauma, substance use, and stress were also considered. RESULTS/ANTICIPATED RESULTS: Contrary to our hypothesis, DNAm AA did not associate with the severity of depressive symptoms. Correlation between DNAm AA and affective symptom subscore (BDI) approached significance (p = 0.06). We observed significant correlations between DNAm AA and specific depressive symptoms including participants’ reported disappointment, disgust, or hatred toward themselves (p < 0.05), difficulty with making decisions (p < 0.05), and worry about their physical health (p < 0.05). DNAm AA was also significantly correlated with BMI (p > 0.001). Significant relationships were not evident in the subsequent regression analysis examining potential relationships between DNAm AA and depression. To our knowledge, this is the first study to examine associations between DNAm AA and depressive symptoms in AAW. DISCUSSION/SIGNIFICANCE OF FINDINGS: Depression limits life quality and quantity and is highly comorbid in CMCs. AAW have a high risk of comorbidity. This study deepens knowledge with respect to the associations between depression, CMCs, and aging with a clinically accessible marker in a population with disproportionate risk.

A theoretical model is presented for the steady multi-layered flow induced by a plane vertically distributed buoyancy source producing a turbulent wall plume in a ventilated box. While aspects of the stratification and rate of fluid exchange between box and exterior have been studied previously, the streamline pattern and velocity field have not been considered until now, despite having potentially important practical implications for achieving comfort in naturally ventilated buildings and for the indoor spread of airborne contagions. The boundary condition at the wall for each layer is established by deducing the turbulent entrainment rate. Using conformal mapping techniques and Poisson's integral theorem, closed-form solutions for the streamfunction of the induced flow in each layer are established. While the flow near the ceiling was overlooked in the classic model for the multi-layered stratification, after considering the possible flow scenarios, the stratification is re-evaluated herein by incorporating an entraining ceiling current. With a markedly thinner top layer, the refined stratification matches well with the available experimental observations, the restrictions we place on the applicability of the model overcoming the previous over-prediction in the number of interfaces. The magnitude of the dimensionless flow velocity, independent of the wall buoyancy flux and physical scale of the box, decreases significantly with the number of layers. Three types of layer, each with a distinct induced flow pattern, are distinguished and their implications for room airflow considered. Notably, the flow in the base layer represents a continual and smooth flushing of air between the inlet opening and the wall plume, whereas an intermediate layer is almost entirely comprised of near-stagnant air.

OBJECTIVES/GOALS: The purpose of this secondary data analysis was to identify latent subgroups of seriously ill adults based on multiple chronic conditions and mortality risk using the CCI. This study was conducted by performing a secondary analysis of data from a randomized controlled trial of seriously ill patients receiving palliative care. METHODS/STUDY POPULATION: A cross-sectional analysis of baseline CCI data was conducted. 381 seriously ill adults receiving palliative care were in the original study. Latent subgroups were identified based on the CCI by conducting a latent class analysis in MPlus. The LCA was modeled on each of the 19 disease items as binary latent predictor variables, an additional binary variable representing presence of any disease not accounted for by the CCI, and a final categorical variable representing the total CCI score divided based on clinically significant cutoffs including zero, low (> = 1-<2), moderate (> = 2-<5), and high CCI (> = 5). RESULTS/ANTICIPATED RESULTS: Three distinct latent subgroups were identified based on the CCI. Latent subgroup 1 included those with a low-moderate CCI consisting of MCC and non-Metastatic Cancers (n = 178), with 45% of this group having chronic obstructive pulmonary disease. The second two subgroups included individuals with a high CCI or a score greater than or equal to 5. Latent subgroup 2 (n = 64) was comprised of individuals with MCC and non-metastatic cancer. Latent subgroup 3 (n = 139) included individuals with metastatic cancer. DISCUSSION/SIGNIFICANCE OF IMPACT: In a sample of seriously ill adults with MCC, latent subgroups were identified consisting of individuals with low, moderate, or high CCI. The low to moderate CCI group consists of individuals with chronic conditions including COPD, congestive heart failure, myocardial infarction, cardiovascular disease. There were two subgroups with high CCI scores and the differentiating factor between the two subgroups was the presence of metastatic cancer in latent subgroup 3. The identification of latent subgroups sets the groundwork for further analyses to compare differences in symptom burden, quality of life, and functional status between groups. The findings have the potential to inform future studies seeking to better characterize seriously adults with MCC based on their disease burden and mortality risk.

OBJECTIVES/GOALS: To examine the relationship between epigenetic age acceleration (EAA) and depressive symptoms in a cohort of African American women (AAW) with cardiometabolic conditions (CMC) including hypertension, diabetes, obesity; and to explore clinical phenotypes of depressive symptoms in this population. METHODS/STUDY POPULATION: This secondary analysis utilized genomic and longitudinal clinical data from AAW in the InterGEN cohort (n = 250). EWAS data was used to estimate EAA based on the Horvath method, which incorporates the DNA methylation statuses at 353 specific CpG sites and regresses this epigenetic age on chronological age to determine EAA. Pearson’s correlations and linear regression will be used to examine the relationship between EAA and depressive symptoms and a linear mixed model will investigate this relationship over four time points during a two-year period. Clinical phenotyping of depressive symptoms will be explored using a cluster analysis. RESULTS/ANTICIPATED RESULTS: Analysis is underway and will be complete by the time of presentation. We hypothesize that higher EAA will associate with higher depressive symptoms and poorer trajectories over time. We expect that this relationship may be meditated by the presence of CMCs. Exploratory analysis of clinical phenotyping is expected to provide descriptive evidence with respect to specific depressive symptoms or clusters which are most associated with EAA and CMCs. These results will address several gaps. To our knowledge, this is the first study to examine the relationship of EAA and depressive symptoms considering the role of CMC, in a historically understudied population with disproportionate risk. DISCUSSION/SIGNIFICANCE OF IMPACT: Depression limits life quality and quantity and is highly comorbid in CMC. AAW have high risk of comorbidity, and this study furthers knowledge of depression and aging with a clinically accessible marker and aids recognition of a heterogenous phenotype in an undertreated population.

Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88) presented a critique of our recently published paper in Cell Reports entitled ‘Large-Scale Cognitive GWAS Meta-Analysis Reveals Tissue-Specific Neural Expression and Potential Nootropic Drug Targets’ (Lam et al., Cell Reports, Vol. 21, 2017, 2597–2613). Specifically, Hill offered several interrelated comments suggesting potential problems with our use of a new analytic method called Multi-Trait Analysis of GWAS (MTAG) (Turley et al., Nature Genetics, Vol. 50, 2018, 229–237). In this brief article, we respond to each of these concerns. Using empirical data, we conclude that our MTAG results do not suffer from ‘inflation in the FDR [false discovery rate]’, as suggested by Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88), and are not ‘more relevant to the genetic contributions to education than they are to the genetic contributions to intelligence’.

This paper reports on the fabrication and characterization of thin-film nanocomposites comprised of tangled carbon nanotubes in a polymer matrix. The concentration of nanotubes in the polymer was significantly increased using detonation nanodiamonds. Nanodiamonds reduce the surface forces between the polymer and the nanotubes and mitigate the agglomeration problem of nanotubes in polymer. This resulted in thinner and more uniform networks that are efficient absorbers of infrared energy over a broad spectrum, ranging from the visible to the mid-wavelength infrared. An infrared absorbance of 97% was achieved for a 1.6 μm thick nanocomposite film across the spectral range of 714 nm to 5 μm. The films are mechanically and thermally stable up to 300 °C, and can be integrated with microbolometers to enhance their responsivity.

This work comprises the structural characterization of Eucalyptus and Pinus radiata pulp fibers and their corresponding fibrillated materials, based on quantitative electron microscopy techniques. Compared to hardwood fibers, the softwood fibers have a relatively open structure of the fiber wall outer layers. The fibrillation of the fibers was performed mechanically and chemi-mechanically. In the chemi-mechanical process, the pulp fibers were subjected to a TEMPO-mediated oxidation to facilitate the homogenization. Films were made of the fibrillated materials to evaluate some structural properties. The thicknesses and roughnesses of the films were evaluated with standardized methods and with scanning electron microscopy (SEM), in backscattered electron imaging mode. Field-emission SEM (FE-SEM) and transmission electron microscopy (TEM) were performed to quantify the nanofibril morphology. In this study, we give additional and significant evidences about the suitability of electron microscopy techniques for quantification of nanofibril structures. In addition, we conclude that standard methods are not suitable for estimating the thickness of films having relatively rough surfaces. The results revealed significant differences with respect to the morphology of the fibrillated material. The differences are due to the starting raw material and to the procedure applied for the fibrillation.

In densely-populated cities or indoor environments, limited visibility to satellites and severe multipath effects significantly affect the accuracy and reliability of satellite-based positioning systems. To meet the needs of “seamless navigation” in these challenging environments an advanced terrestrial positioning system is under development. This system is based upon Ultra-Wideband (UWB) technology, which is a promising candidate for this application due to good time domain resolution and immunity to multipath. This paper presents a detailed analysis of two key aspects of the UWB signal design that will allow it to be used as the basis of such a high performance positioning system: the modulation scheme and the multiple access technique. These two aspects are evaluated in terms of spectral efficiency and synchronisation performance over multipath channels. Thus this paper identifies optimal modulation and multiple access techniques for a long range, high performance terrestrial positioning system using UWB.