Molecular modelling of dendrimers for nanoscale applications

Dendrimers are well defined, highly branched macromolecules that radiate from a central core and are synthesized through a stepwise, repetitive reaction sequence that guarantees complete shells for each generation, leading to polymers that are monodisperse. The synthetic procedures developed for dendrimer preparation permit nearly complete control over the critical molecular design parameters, such as size, shape, surface/interior chemistry, flexibility, and topology. Recent results suggest that dendritic polymers may provide the key to developing a reliable and economical fabrication and manufacturing route to functional nanoscale materials that would have unique properties (electronic, optical, opto-electronic, magnetic, chemical, or biological). In turn, these could be used in designing new nanoscale devices. In this paper, we determine the 3D molecular structure of various dendrimers with continuous configurational Boltzmann biased direct Monte Carlo method and study their energetic and structural properties using molecular dynamics after annealing these molecular representations

VIRTUAL REALITY GROUND FORCE COMMANDER TRAINER

The complexity of battlespace is guaranteed to increase over time. The problem arising is that with today’s innovative battlefield and the ever-connected environment, our junior officers are receiving more information, data, and feedback than ever before. With this increased amount of information at their fingertips, we expect them to process this information and make these real-world decisions faster and more precisely than before. Suppose we do not train our leaders to properly handle this information and prioritize tasks, and help them to avoid becoming overwhelmed by the multiple tasks they address. In that case, we run the risk of them becoming cognitively overloaded and making bad decisions based on poor judgment or emotions. These impulsive decisions highly increase the chance of mission failure. Today, we are expecting more out of our ground force commanders (GFCs) in their doctrinal skill set, decision making abilities under pressure, and cognitive performance; however, we are failing to adapt and advance our training at the same pace and level that we expect them to perform. If we cannot teach it, how can we expect our operators to perform at this new level in a new environment? The question: How can Special Operations Forces improve cognitive decision processing under stress and prepare GFCs for future conflicts? Our conclusion is that the adoption of advanced training and technology will help to keep SOF GFCs at the leading edge of combat proficiency.Lieutenant Junior Grade, United States NavyLieutenant, United States NavyApproved for public release. Distribution is unlimited

Actualizaciones sobre las supuestas ocurrencias de tiburón toro (Carcharhinus leucas) en la cuenca superior del río Mississippi de América del Norte

A previous paper in this journal by Shell and Gardner assessed various factors around the exploration of the Mississippi River by bull sharks (Carcharhinus leucas Müller and Henle, 1839) based on two twentieth-century occurrences. Recent evidence has suggested one of these occurrences is a probable hoax. Here, we provide a correction to our earlier paper, as well as additional comments on extralimital euryhaline vertebrates in the Mississippi River system, the environmental and historical contexts for their exploration into riverine systems, and suggest steps for any future effort to detect the usage of these river systems by bull sharks.En un artículo anterior de Shell y Gardner en esta revista, se evaluaron varios factores en torno a la exploración del Río Mississippi por parte de los tiburones toro (Carcharhinus leucas Müller y Henle, 1839) basados en dos sucesos del siglo XX. La evidencia reciente sugiere que una de estas ocurrencias es un probable engaño. Brindamos aquí una corrección a nuestro artículo anterior, así como comentarios adicionales sobre los vertebrados eurihalinos extralimitantes en el sistema del Río Mississippi, los contextos ambientales e históricos para su exploración en los sistemas fluviales, y sugerimos los pasos para cualquier esfuerzo futuro en detectar el uso de estos sistemas fluviales por los tiburones toro

Single-Cell Transcriptomes Reveal a Complex Cellular Landscape in the Middle Ear and Differential Capacities for Acute Response to Infection.

Single-cell transcriptomics was used to profile cells of the normal murine middle ear. Clustering analysis of 6770 transcriptomes identified 17 cell clusters corresponding to distinct cell types: five epithelial, three stromal, three lymphocyte, two monocyte, two endothelial, one pericyte and one melanocyte cluster. Within some clusters, cell subtypes were identified. While many corresponded to those cell types known from prior studies, several novel types or subtypes were noted. The results indicate unexpected cellular diversity within the resting middle ear mucosa. The resolution of uncomplicated, acute, otitis media is too rapid for cognate immunity to play a major role. Thus innate immunity is likely responsible for normal recovery from middle ear infection. The need for rapid response to pathogens suggests that innate immune genes may be constitutively expressed by middle ear cells. We therefore assessed expression of innate immune genes across all cell types, to evaluate potential for rapid responses to middle ear infection. Resident monocytes/macrophages expressed the most such genes, including pathogen receptors, cytokines, chemokines and chemokine receptors. Other cell types displayed distinct innate immune gene profiles. Epithelial cells preferentially expressed pathogen receptors, bactericidal peptides and mucins. Stromal and endothelial cells expressed pathogen receptors. Pericytes expressed pro-inflammatory cytokines. Lymphocytes expressed chemokine receptors and antimicrobials. The results suggest that tissue monocytes, including macrophages, are the master regulators of the immediate middle ear response to infection, but that virtually all cell types act in concert to mount a defense against pathogens

Sparse Plus Low Rank Matrix Decomposition: A Discrete Optimization Approach

We study the Sparse Plus Low-Rank decomposition problem (SLR), which is the problem of decomposing a corrupted data matrix into a sparse matrix of perturbations plus a low-rank matrix containing the ground truth. SLR is a fundamental problem in Operations Research and Machine Learning which arises in various applications, including data compression, latent semantic indexing, collaborative filtering, and medical imaging. We introduce a novel formulation for SLR that directly models its underlying discreteness. For this formulation, we develop an alternating minimization heuristic that computes high-quality solutions and a novel semidefinite relaxation that provides meaningful bounds for the solutions returned by our heuristic. We also develop a custom branch-and-bound algorithm that leverages our heuristic and convex relaxations to solve small instances of SLR to certifiable (near) optimality. Given an input $n$-by-$n$ matrix, our heuristic scales to solve instances where $n=10000$ in minutes, our relaxation scales to instances where $n=200$ in hours, and our branch-and-bound algorithm scales to instances where $n=25$ in minutes. Our numerical results demonstrate that our approach outperforms existing state-of-the-art approaches in terms of rank, sparsity, and mean-square error while maintaining a comparable runtime

Central Executive Dysfunction and Deferred Prefrontal Processing in Veterans with Gulf War Illness.

Gulf War Illness is associated with toxic exposure to cholinergic disruptive chemicals. The cholinergic system has been shown to mediate the central executive of working memory (WM). The current work proposes that impairment of the cholinergic system in Gulf War Illness patients (GWIPs) leads to behavioral and neural deficits of the central executive of WM. A large sample of GWIPs and matched controls (MCs) underwent functional magnetic resonance imaging during a varied-load working memory task. Compared to MCs, GWIPs showed a greater decline in performance as WM-demand increased. Functional imaging suggested that GWIPs evinced separate processing strategies, deferring prefrontal cortex activity from encoding to retrieval for high demand conditions. Greater activity during high-demand encoding predicted greater WM performance. Behavioral data suggest that WM executive strategies are impaired in GWIPs. Functional data further support this hypothesis and suggest that GWIPs utilize less effective strategies during high-demand WM