Structural characterization and statistical-mechanical model of epidermal patterns

In proliferating epithelia of mammalian skin, cells of irregular polygonal-like shapes pack into complex nearly flat two-dimensional structures that are pliable to deformations. In this work, we employ various sensitive correlation functions to quantitatively characterize structural features of evolving packings of epithelial cells across length scales in mouse skin. We find that the pair statistics in direct and Fourier spaces of the cell centroids in the early stages of embryonic development show structural directional dependence, while in the late stages the patterns tend towards statistically isotropic states. We construct a minimalist four-component statistical-mechanical model involving effective isotropic pair interactions consisting of hard-core repulsion and extra short-ranged soft-core repulsion beyond the hard core, whose length scale is roughly the same as the hard core. The model parameters are optimized to match the sample pair statistics in both direct and Fourier spaces. By doing this, the parameters are biologically constrained. Our model predicts essentially the same polygonal shape distribution and size disparity of cells found in experiments as measured by Voronoi statistics. Moreover, our simulated equilibrium liquid-like configurations are able to match other nontrivial unconstrained statistics, which is a testament to the power and novelty of the model. We discuss ways in which our model might be extended so as to better understand morphogenesis (in particular the emergence of planar cell polarity), wound-healing, and disease progression processes in skin, and how it could be applied to the design of synthetic tissues

Improved delineation of short cortical association fibers and gray/white matter boundary using whole-brain three-dimensional diffusion tensor imaging at submillimeter spatial resolution.

Recent emergence of human connectome imaging has led to a high demand on angular and spatial resolutions for diffusion magnetic resonance imaging (MRI). While there have been significant growths in high angular resolution diffusion imaging, the improvement in spatial resolution is still limited due to a number of technical challenges, such as the low signal-to-noise ratio and high motion artifacts. As a result, the benefit of a high spatial resolution in the whole-brain connectome imaging has not been fully evaluated in vivo. In this brief report, the impact of spatial resolution was assessed in a newly acquired whole-brain three-dimensional diffusion tensor imaging data set with an isotropic spatial resolution of 0.85 mm. It was found that the delineation of short cortical association fibers is drastically improved as well as the definition of fiber pathway endings into the gray/white matter boundary-both of which will help construct a more accurate structural map of the human brain connectome

Presentation of glaucoma in the greater Accra Metropolitan Area of Ghana

Background: This study addresses the prevalence and clinical presentation of patients with primary open angle glaucoma (POAG) in the greater Accra metropolitan area.Methods: This is a retrospective case series of 455 patients (813 eyes) at the Emmanuel Eye Clinic. Patients were diagnosed from May 2008 to Nov 2011. The definition of POAG conformed to the International Society of Geographical and Epidemiological Ophthalmology (ISGEO) criteria. Information collected included basic demographic data, distribution of glaucoma subtypes, measured intraocular pressure (IOP), best corrected visual acuity (BCVA) and optic disc measurements.Results: Nearly 24% presented blind in at least one eye. The average age was 56.7 +/-16.7 years and the average IOP was 33.9 mmHg +/- 12.7 mmHg for right eyes and 33.5 mmHg +/-12.0 mmHg for left eyes. Themean vertical cup to disc ratio (vCDR) was 0.83 for right eyes versus 0.82 for left eyes. A total of 32 patients (53 eyes) were diagnosed with normal tension glaucoma (NTG). Statistically significant differences between the NTG and high tension groups included age (45.3 +/- 16.7 vs. 56.7 +/-16.7, p<0.001), mean IOP (19.1 mmHg +/- 4.5 mmHg vs. 33.7 +/- 12.4 mmHg,p<0.001) and mean vCDR (0.76 +/- 0.17 vs. 0.83 +/- 0.10, p<0.01). Comparing age-matched NTG patients with high tension glaucoma patients showed no significant difference in vCDR.Conclusions: The clinical presentation of POAG at the Emmanuel Eye Center is characterized by elevated IOP and grossly advanced optic neuropathy. Significant differences between high tension glaucoma and NTG were identified.Keywords: Primary Open Angle Glaucoma, Normal Tension Glaucoma, Ghana, Accra, Afric

Transcatheter Closure of a Secundum Atrial Septal Defect with Deficient Aortic Rim Through the Left Internal Jugular Vein in a Child with Situs Inversus and Interrupted Inferior Vena Cava: Device's Choice Matters

Percutaneous closure of secundum atrial septal defect (sASD) in children with interrupted inferior vena cava is challenging, especially in case of deficient aortic rim. Trans-jugular access is generally preferred in this scenario. Patients with situs inversus and sASD also carry technical difficulties for transcatheter closure because of the orientation of the atrial septum. We report a successful case of percutaneous closure of a sASD with deficient aortic rim using an occlutech figulla flex II ASD device through the left internal jugular vein in a child with situs inversus, dextrocardia, and interrupted IVC. This case was facilitated by the absence of left-sided hub of the Occlutech device to provide stable opening of the device into the left atrium, whereas the ball-connection of the delivery system allowed an angle of almost 180 degrees between the device and the atrial septum

Asymmetric dynamics of DNA entering and exiting a strongly confining nanopore.

In nanopore sensing, changes in ionic current are used to analyse single molecules in solution. The translocation dynamics of polyelectrolytes is of particular interest given potential applications such as DNA sequencing. In this paper, we determine how the dynamics of voltage driven DNA translocation can be affected by the nanopore geometry and hence the available configurational space for the DNA. Using the inherent geometrical asymmetry of a conically shaped nanopore, we examine how DNA dynamics depends on the directionality of transport. The total translocation time of DNA when exiting the extended conical confinement is significantly larger compared to the configuration where the DNA enters the pore from the open reservoir. By using specially designed DNA molecules with positional markers, we demonstrate that the translocation velocity progressively increases as the DNA exits from confinement. We show that a hydrodynamic model can account for these observations.Translocation of a charged polymer through confined nanoenvironments is highly dependent on their geometrical parameters. Here, the authors investigate experimentally the translocation dynamics of DNA through conical nanopores and provide a quantitative model for the translocation into and out of confinement

Decomposed Prompting for Machine Translation Between Related Languages using Large Language Models

This study investigates machine translation between related languages i.e., languages within the same family that share linguistic characteristics such as word order and lexical similarity. Machine translation through few-shot prompting leverages a small set of translation pair examples to generate translations for test sentences. This procedure requires the model to learn how to generate translations while simultaneously ensuring that token ordering is maintained to produce a fluent and accurate translation. We propose that for related languages, the task of machine translation can be simplified by leveraging the monotonic alignment characteristic of such languages. We introduce DecoMT, a novel approach of few-shot prompting that decomposes the translation process into a sequence of word chunk translations. Through automatic and human evaluation conducted on multiple related language pairs across various language families, we demonstrate that our proposed approach of decomposed prompting surpasses multiple established few-shot baseline approaches. For example, DecoMT outperforms the strong few-shot prompting BLOOM model with an average improvement of 8 chrF++ scores across the examined languages.Comment: EMNLP 2023 (Main, Long paper

Comparison of Primary Open Angle Glaucoma Patients in Rural and Urban Ghana

Purpose: To compare the clinical features of glaucoma patients who present at a rural hospital in North Eastern Ghana and an urban hospital in the capital city of Accra.Methods: This is a multi-center retrospective case series involving records of newly diagnosed glaucoma patients with emphasis on primary open angle glaucoma (POAG). Information collected included basic demographic data, intraocular pressures and optic disc measurements.Results: A total of 949 patients (437 rural; 512 urban; 1868 eyes) were included. Rural vs. urban comparisons, respectively: mean age, 53.2 ± 16.3 vs. 54.5 ± 16.4 years; male: female ratio, 3:2 vs. 1:1; POAG, 78.1% vs. 50.6%; POAG suspect, 10.3% vs. 41.9%; IOP, 39.2 ± 7.1 vs. 31.8 ± 7.3 mmHg; bilateral blindness, 34.1% vs. 17.5%; uniocular blindness, 52.2% vs. 32.9%. Females at the rural hospital were twice as likely to present blind in at least one eye (OR 2.04, CI 1.36 - 3.07, p<0.001).Conclusions: Patients with POAG at the rural hospital present with more advanced disease characteristics.Keywords: glaucoma, open angle,Ghana, Urban, rura

Study on Wideband THz Backward Wave Oscillator Driven by Pseudospark-Sourced Sheet Electron Beam

A backward wave oscillator (BWO) based on a double-staggered grating (DSG) slow wave structure (SWS) is investigated as a high-power wideband terahertz (THz) source, driven by a sheet electron beam emitting from a pseudospark plasma cathode. First, the DSG SWS is optimized in simulation to have a suitable dispersion characteristic. Then, the BWO with a wideband output structure consisting of a tapered section of DSG and an L-shaped connector is modeled under an operating voltage of 24-38 kV and a current density of 2- 5\times 10 {{7}} A/m 2 (beam current of 1.5-3.8 A). A maximum power of 3.9 kW is obtained, and a wide bandwidth of over 38 GHz (343-381 GHz) is achieved. The impact of fabricating errors of the SWS on the performance of the BWO is analyzed in simulation. The effects of the plasma in the interaction space on the BWO performance are also analyzed, showing that the plasma causes an increase in the oscillation frequency by 1.0-1.2