Coupled modeling for investigation of blast induced traumatic brain injury

Modeling of human body biomechanics resulting from blast exposure is very challenging because of the complex geometry and the substantially different materials involved. We have developed anatomy based high-fidelity finite element model (FEM) of the human body and finite volume model (FVM) of air around the human. The FEM model was used to accurately simulate the stress wave propagation in the human body under blast loading. The blast loading was generated by simulating C4 explosions, via a combination of 1-D and 3-D computational fluid dynamics (CFD) formulations. By employing the coupled Eulerian-Lagrangian fluid structure interaction (FSI) approach we obtained the parametric response of the human brain by the blast wave impact. We also developed the methodology to solve the strong interaction between cerebrospinal fluids (CSF) and the surrounding tissue for the closed-head impact. We presented both the arbitrary Lagrangian Eulerian (ALE) method and a new unified approach based on the material point method (MPM) to solve fluid dynamics and solid mechanics simultaneously. The accuracy and efficiency of ALE and MPM solvers for the skull-CSF-brain coupling problem was compared. The presented results suggest that the developed coupled models and techniques could be used to predict human biomechanical responses in blast events, and help design the protection against the blast induced TBI

A Local Hubble Bubble from SNe Ia?

We analyze the monopole in the peculiar velocities of 44 Type Ia supernovae (SNe Ia) to test for a local void. The sample extends from 20 to 300 Mpc/h, with distances, deduced from light-curve shapes, accurate to ~6%. Assuming Omega_m=1 and Omega_lambda=0, the most significant deviation we find from the Hubble law is an outwards flow of (6.6+/-2.2)% inside a sphere of radius 70 Mpc/h as would be produced by a void of ~20% underdensity surrounded by a dense shell. This shell roughly coincides with the local Great Walls. Monte Carlo analyses, using Gaussian errors or bootstrap resampling, show the probability for chance occurrence of this result out of a pure Hubble flow to be ~2%. The monopole could be contaminated by higher moments of the velocity field, especially a quadrupole, which are not properly probed by the current limited sky coverage. The void would be less significant if Omega_m is low and Omega_lambda is high. It would be more significant if one outlier is removed from the sample, or if the size of the void is constrained a-priori. This putative void is not in significant conflict with any of the standard cosmological scenarios. It suggests that the Hubble constant as determined within 70 Mpc/h could be overestimated by ~6% and the local value of Omega may be underestimated by ~20%. While the present evidence for a local void is marginal in this data set, the analysis shows that the accumulation of SNe Ia distances will soon provide useful constraints on elusive and important aspects of regional cosmic dynamics.Comment: 21 pages, 3 figures. Slightly revised version. To appear in ApJ, 503, Aug. 20, 199

Retinal Nerve Fiber Layer Features Identified by Unsupervised Machine Learning on Optical Coherence Tomography Scans Predict Glaucoma Progression.

Purpose:To apply computational techniques to wide-angle swept-source optical coherence tomography (SS-OCT) images to identify novel, glaucoma-related structural features and improve detection of glaucoma and prediction of future glaucomatous progression. Methods:Wide-angle SS-OCT, OCT circumpapillary retinal nerve fiber layer (cpRNFL) circle scans spectral-domain (SD)-OCT, standard automated perimetry (SAP), and frequency doubling technology (FDT) visual field tests were completed every 3 months for 2 years from a cohort of 28 healthy participants (56 eyes) and 93 glaucoma participants (179 eyes). RNFL thickness maps were extracted from segmented SS-OCT images and an unsupervised machine learning approach based on principal component analysis (PCA) was used to identify novel structural features. Area under the receiver operating characteristic curve (AUC) was used to assess diagnostic accuracy of RNFL PCA for detecting glaucoma and progression compared to SAP, FDT, and cpRNFL measures. Results:The RNFL PCA features were significantly associated with mean deviation (MD) in both SAP (R2 = 0.49, P < 0.0001) and FDT visual field testing (R2 = 0.48, P < 0.0001), and with mean circumpapillary RNFL thickness (cpRNFLt) from SD-OCT (R2 = 0.58, P < 0.0001). The identified features outperformed each of these measures in detecting glaucoma with an AUC of 0.95 for RNFL PCA compared to an 0.90 for mean cpRNFLt (P = 0.09), 0.86 for SAP MD (P = 0.034), and 0.83 for FDT MD (P = 0.021). Accuracy in predicting progression was also significantly higher for RNFL PCA compared to SAP MD, FDT MD, and mean cpRNFLt (P = 0.046, P = 0.007, and P = 0.044, respectively). Conclusions:A computational approach can identify structural features that improve glaucoma detection and progression prediction

Deep-Layer Microvasculature Dropout by Optical Coherence Tomography Angiography and Microstructure of Parapapillary Atrophy.

Purpose:To investigate the association between the microstructure of β-zone parapapillary atrophy (βPPA) and parapapillary deep-layer microvasculature dropout assessed by optical coherence tomography angiography (OCT-A). Methods:Thirty-seven eyes with βPPA devoid of the Bruch's membrane (BM) (γPPA) ranging between completely absent and discontinuous BM were matched by severity of the visual field (VF) damage with 37 eyes with fully intact BM (βPPA+BM) based on the spectral-domain (SD) OCT imaging. Parapapillary deep-layer microvasculature dropout was defined as a dropout of the microvasculature within choroid or scleral flange in the βPPA on the OCT-A. The widths of βPPA, γPPA, and βPPA+BM were measured on six radial SD-OCT images. Prevalence of the dropout was compared between eyes with and without γPPA. Logistic regression was performed for evaluating association of the dropout with the width of βPPA, γPPA, and βPPA+BM, and the γPPA presence. Results:Eyes with γPPA had significantly higher prevalence of the dropout than did those without γPPA (75.7% versus 40.8%; P = 0.004). In logistic regression, presence and longer width of the γPPA, worse VF mean deviation, and presence of focal lamina cribrosa defects were significantly associated with the dropout (P < 0.05), whereas width of the βPPA and βPPA+BM, axial length, and choroidal thickness were not (P > 0.10). Conclusions:Parapapillary deep-layer microvasculature dropout was associated with the presence and larger width of γPPA, but not with the βPPA+BM width. Presence and width of the exposed scleral flange, rather than the retinal pigmented epithelium atrophy, may be associated with deep-layer microvasculature dropout

Optical Coherence Tomography Angiography Vessel Density in Healthy, Glaucoma Suspect, and Glaucoma Eyes.

PurposeThe purpose of this study was to compare retinal nerve fiber layer (RNFL) thickness and optical coherence tomography angiography (OCT-A) retinal vasculature measurements in healthy, glaucoma suspect, and glaucoma patients.MethodsTwo hundred sixty-one eyes of 164 healthy, glaucoma suspect, and open-angle glaucoma (OAG) participants from the Diagnostic Innovations in Glaucoma Study with good quality OCT-A images were included. Retinal vasculature information was summarized as a vessel density map and as vessel density (%), which is the proportion of flowing vessel area over the total area evaluated. Two vessel density measurements extracted from the RNFL were analyzed: (1) circumpapillary vessel density (cpVD) measured in a 750-μm-wide elliptical annulus around the disc and (2) whole image vessel density (wiVD) measured over the entire image. Areas under the receiver operating characteristic curves (AUROC) were used to evaluate diagnostic accuracy.ResultsAge-adjusted mean vessel density was significantly lower in OAG eyes compared with glaucoma suspects and healthy eyes. (cpVD: 55.1 ± 7%, 60.3 ± 5%, and 64.2 ± 3%, respectively; P < 0.001; and wiVD: 46.2 ± 6%, 51.3 ± 5%, and 56.6 ± 3%, respectively; P < 0.001). For differentiating between glaucoma and healthy eyes, the age-adjusted AUROC was highest for wiVD (0.94), followed by RNFL thickness (0.92) and cpVD (0.83). The AUROCs for differentiating between healthy and glaucoma suspect eyes were highest for wiVD (0.70), followed by cpVD (0.65) and RNFL thickness (0.65).ConclusionsOptical coherence tomography angiography vessel density had similar diagnostic accuracy to RNFL thickness measurements for differentiating between healthy and glaucoma eyes. These results suggest that OCT-A measurements reflect damage to tissues relevant to the pathophysiology of OAG

ICYMI: RT and Youth-Oriented International Broadcasting as (Geo)Political Culture Jamming

Research in political communication has recently begun to explore the role of non-Western English-language state-funded international broadcasters (NEIBs) in influencing international audiences. Despite this, there has been little attention given to understanding how NEIBs engage and influence young people in ‘Western’ democracies. Our article addresses this gap by providing a detailed analysis of RT's English-language, youth-orientated news product ICYMI. Launched in 2018, ICYMI is a social media-based news brand that consists of a series of 2–3-min videos that deliver satirical takes on recent global events including military conflict, financial scandals, and culture clashes. Our findings, which examine the first year of the platform's activity, show that ICYMI is a novel form of engagement, one that is not easily categorised as either public diplomacy or propaganda, nor can it be described as traditional journalism. Instead, we label this approach as geopolitical culture jamming. In this article, we conduct a discourse analysis of 45 videos published on YouTube by ICYMI over its first year to examine how the platform attempts to influence how young people relate to traditional foreign policy discourses. Our empirical analysis centres on how viewers engage with and interpret ICYMI's videos with the aim of addressing how RT may be influencing younger audiences, particularly its core demographic of Anglophone white males whose comments reflect an attachment to ICYMI's populist, anti-elite worldvie

Molecular cloning of a human homologue of Drosophila heterochromatin protein HP1 using anti-centromere autoantibodies with anti-chromo specificity

We have identified a novel autoantibody specificity in scleroderma that we term anti-chromo. These antibodies recognize several chromosomal antigens with apparent molecular mass of between 23 and 25 kDa, as determined by immunoblots. Anti-chromo autoantibodies occur in 10-15% of sera from patients with anti-centromere antibodies (ACA). We used anti-chromo antibodies to screen a human expression library and obtained cDNA clones encoding a 25 kDa chromosomal autoantigen. DNA sequence analysis reveals this protein to be a human homologue of HP1, a heterochromatin protein of Drosophila melanogaster. We designate our cloned protein HP1Hs alpha. Epitope mapping experiments using both human and Drosophila HP1 reveal that anti-chromo antibodies target a region at the amino terminus of the protein. This region contains a conserved motif, the chromo domain (or HP1/Pc box), first recognized by comparison of Drosophila HP1 with the Polycomb gene product. Both proteins are thought to play a role in creating chromatin structures in which gene expression is suppressed. Anti-chromo thus defines a novel type of autoantibody that recognizes a conserved structural motif found on a number of chromosomal proteins

On the Origin of the Treponematoses: A Phylogenetic Approach

For 500 years, controversy has raged around the origin of T. pallidum subsp. pallidum, the bacterium responsible for syphilis. Did Christopher Columbus and his men introduce this pathogen into Renaissance Europe, after contracting it during their voyage to the New World? Or does syphilis have a much older history in the Old World? This paper represents the first attempt to use a phylogenetic approach to solve this question. In addition, it clarifies the evolutionary relationships between the pathogen that causes syphilis and the other T. pallidum subspecies, which cause the neglected tropical diseases yaws and endemic syphilis. Using a collection of pathogenic Treponema strains that is unprecedented in size, we show that yaws appears to be an ancient infection in humans while venereal syphilis arose relatively recently in human history. In addition, the closest relatives of syphilis-causing strains identified in this study were found in South America, providing support for the Columbian theory of syphilis's origin