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differential geometry

Ivica Kostović, Iris Žunić Išasegi, Željka Krsnik
The objective of this paper was to collect normative data essential for analyzing the subplate (SP) role in pathogenesis of developmental disorders, characterized by abnormal circuitry, such as hypoxic-ischemic lesions, autism and schizophrenia. The main cytological features of the SP, such as low cell density, early differentiation of neurons and glia, plexiform arrangement of axons and dendrites, presence of synapses and a large amount of extracellular matrix (ECM) distinguish this compartment from the cell-dense cortical plate (CP; towards pia) and large fiber bundles of external axonal strata of fetal white matter (towards ventricle)...
December 13, 2018: Journal of Anatomy
Iryna Olyshevets, Nataliia Kariaka, Kateryna Znovjyak, Nikolay Gerasimchuk, Sergey Lindeman, Sergii Smola, Maksym Seredyuk, Tetiana Yu Sliva, Vladimir M Amirkhanov
A series of new anionic lanthanide(III) complexes with the general formula NEt4 [LnL4 ] (1-Ln; HL = dimethyl[(4-methylphenyl)sulfonyl]amidophosphate; Ln = La, Nd, Eu), were synthesized and characterized by IR, UV-vis, and NMR spectroscopies, the differential scanning calorimetry method, thermogravimetric and X-ray analysis, and photoluminescence measurements. Single-crystal structures of NEt4 [EuL4 ] (1-Eu) were determined at 293 and 100 K and evidenced the single-crystal-to-single-crystal phase transition...
December 13, 2018: Inorganic Chemistry
Dolores Parras-Burgos, Daniel G Fernández-Pacheco, Francisco Cavas-Martínez, José Nieto Martínez, Francisco J F Cañavate
Given current high market competitiveness, it is necessary to differentiate between products that perform the same function. For this objective, designer can recur to various sources of inspiration in the searching of the more attractive form during the conceptual design stage. One of these sources can be nature, which offers a large number of geometries and textures that can be used from a shape point of view to help the designer in the creative process. This work presents an agent-based approach for a design-aided tool to provide users with some ideas, beginning with simple parts/concepts, and then increasing the complexity level according to the answers offered by designer...
2018: PloS One
Stephen W C Walker, Ahdia Anwar, Jarrod M Psutka, Jeff Crouse, Chang Liu, J C Yves Le Blanc, Justin Montgomery, Gilles H Goetz, John S Janiszewski, J Larry Campbell, W Scott Hopkins
The fast and accurate determination of molecular properties is highly desirable for many facets of chemical research, particularly in drug discovery where pre-clinical assays play an important role in paring down large sets of drug candidates. Here, we present the use of supervised machine learning to treat differential mobility spectrometry - mass spectrometry data for ten topological classes of drug candidates. We demonstrate that the gas-phase clustering behavior probed in our experiments can be used to predict the candidates' condensed phase molecular properties, such as cell permeability, solubility, polar surface area, and water/octanol distribution coefficient...
November 30, 2018: Nature Communications
David Marlevi, Elira Maksuti, Matthew W Urban, Reidar Winter, Matilda Larsson
Ultrasound elastography has shown potential for improved plaque risk stratification. However, no clear consensus exists on what output metric to use, or what imaging parameters would render optimal plaque differentiation. For this reason we developed a combined ex vivo and in vitro setup, in which the ability to differentiate phantom plaques of varying stiffness was evaluated as a function of plaque geometry, push location, imaging plane, and analysed wave speed metric. The results indicate that group velocity or phase velocity  ⩾1 kHz showed the highest ability to significantly differentiate plaques of different stiffness, successfully classifying a majority of the 24 analysed plaque geometries, respectively...
November 23, 2018: Physics in Medicine and Biology
David Dannhauser, Domenico Rossi, Pasquale Memmolo, Andrea Finizio, Pietro Ferraro, Paolo Antonio Netti, Filippo Causa
We implemented a completely label-free biophysical (morphometric and optical) property characterization of living monocytes in flow, using measurements obtained from two coherent imaging techniques: a pure light scattering approach to obtain an optical signature (OS) of cells, and a digital holography (DH) approach to achieve optical cell reconstructions in flow. A precise 3D cell alignment platform, taking advantage of viscoelastic fluid properties and microfluidic channel geometry, was used to investigate the OS of cells to achieve their refractive index, ratio of the nucleus over cytoplasm, and overall cell dimension...
November 1, 2018: Biomedical Optics Express
Jose A Aznar-Moreno, Rosario Sánchez, Satinder K Gidda, Enrique Martínez-Force, Antonio J Moreno-Pérez, Mónica Venegas Calerón, Rafael Garcés, Robert T Mullen, Joaquín J Salas
Sunflower seeds ( Helianthus annuus L.) accumulate large quantities of triacylglycerols (TAG) between 12 and 28 days after flowering (DAF). This is the period of maximal acyl-acyl carrier protein (acyl-ACP) thioesterase activity in vitro , the enzymes that terminate the process of de novo fatty acid synthesis by catalyzing the hydrolysis of the acyl-ACPs synthesized by fatty acid synthase. Fatty acid thioesterases can be classified into two families with distinct substrate specificities, namely FatA and FatB...
2018: Frontiers in Plant Science
Andrzej Sławek, Karolina Grzybowska, José Manuel Vicent-Luna, Wacław Makowski, Sofía Calero
Adsorption of cyclohexane in pure silica zeolites was studied experimentally and by molecular simulations. Based on the adsorption isobars obtained from the quasi-equilibrated temperature adsorption and desorption (QE-TPDA) measurements and reported adsorption isotherms for high-silica zeolites Y, ZSM-5, and ZSM-11 we refined Lennard-Jones parameters for guest-host interactions available in the literature. Adsorption of cyclohexane from equimolar mixture of twisted-boat and chair conformations has been screened in 171 pure silica zeolitic structures using grand canonical Monte Carlo simulations...
November 20, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Ashley L Farris, Colin A Cook, Warren L Grayson
Polymer-based scaffolds are used extensively in the field of regenerative medicine. These biomaterials may induce therapeutic responses through modulating a wound microenvironment with or without the addition of cells. It has long been known that oxygen is a crucial component of the microenvironment that influences cellular and physiological processes such as metabolism, proliferation, differentiation, matrix deposition, phagocytic killing, and wound healing. Consequently, several studies have investigated the potential for using oxygen-eluting biomaterials to regulate the oxygen tension within a wound microenvironment and to tune the regenerative response...
November 20, 2018: Biotechnology Progress
Hojae Yi, Yue Rui, Baris Kandemir, James Z Wang, Charles T Anderson, Virendra M Puri
Stomata function as osmotically tunable pores that facilitate gas exchange at the surface of plants. Stomatal opening and closure are regulated by turgor changes in guard cells that result in mechanically regulated deformations of guard cell walls. However, how the molecular, architectural, and mechanical heterogeneities that exist in guard cell walls affect stomatal dynamics is unclear. In this work, stomata of wild type Arabidopsis thaliana plants or of mutants lacking normal cellulose, hemicellulose, or pectins were experimentally induced to close or open...
2018: Frontiers in Plant Science
Antoine Lagarde, Christophe Josserand, Suzie Protière
Many differential equations involved in natural sciences show singular behaviors; i.e., quantities in the model diverge as the solution goes to zero. Nonetheless, the evolution of the singularity can be captured with self-similar solutions, several of which may exist for a given system. How to characterize the transition from one self-similar regime to another remains an open question. By studying the classic example of the pinch-off of a viscous liquid thread, we show experimentally that the geometry of the system and external perturbations play an essential role in the transition from a symmetric to an asymmetric solution...
November 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
Lei Huang, Jialiang Li
It is often necessary to differentiate subjects from multiple categories using medical tests. We may then adopt statistical measures to characterize the performance of these tests. The three-way ROC analysis has been proposed to evaluate the diagnostic accuracy of medical tests with three categories, reflecting the correct classification probabilities across all possible decision thresholds. The geometry of the ROC surface is carefully studied, leading to numerical summary measures such as the volume under the surface...
November 20, 2018: Statistical Methods in Medical Research
Liping Wang, Marie Amalric, Wen Fang, Xinjian Jiang, Christophe Pallier, Santiago Figueira, Mariano Sigman, Stanislas Dehaene
Memory for spatial sequences does not depend solely on the number of locations to be stored, but also on the presence of spatial regularities. Here, we show that the human brain quickly stores spatial sequences by detecting geometrical regularities at multiple time scales and encoding them in a format akin to a programming language. We measured gaze-anticipation behavior while spatial sequences of variable regularity were repeated. Participants' behavior suggested that they quickly discovered the most compact description of each sequence in a language comprising nested rules, and used these rules to compress the sequence in memory and predict the next items...
October 25, 2018: NeuroImage
Joseph R Nasr, Daniel S Schulman, Amritanand Sebastian, Mark W Horn, Saptarshi Das
Mobility is a critical parameter that is routinely used for benchmarking the performance of field-effect transistors (FETs) based on novel nanomaterials. In fact, mobility values are often used to champion nanomaterials since high-performance devices necessitate high mobility values. The current belief is that the contacts can only limit the FET performance and hence the extracted mobility is an underestimation of the true channel mobility. However, here, such misconception is challenged through rigorous experimental effort, backed by numerical simulations, to demonstrate that overestimation of mobility occurs in commonly used geometries and in nanomaterials for which the contact interface, contact doping, and contact geometry play a pivotal role...
November 14, 2018: Advanced Materials
Mahdi Farahikia, Quang T Su
Effects of geometry-dependent diffraction on the performance of object-mounted Linear Differential Microphone Arrays (LDMAs) for far-field sound waves are investigated through the Finite Element Method. This is done by studying the acoustic pressure gradients corresponding to different orders of LDMAs and placement (azimuthal and radial) on an object (such as human head or voice activated devices). An optimized frequency-dependent adaptive-dimension finite element technique, innovated by the authors, is used to simulate acoustic scattering for two simple head-model geometries (sphere and ellipsoid)...
September 2018: Journal of the Acoustical Society of America
Xiaolu Zhu, Hao Yang
Four-dimensional (4D) biofabrication techniques aim to dynamically produce and control three-dimensional (3D) biological structures that would transform their shapes or functionalities with time, when a stimulus is imposed or cell post-printing self-assembly occurs. The evolution of 3D branching patterns via self-assembly of cells is critical for the 4D biofabrication of artificial organs or tissues with branched geometry. However, it is still unclear how the formation and evolution of these branching patterns are biologically encoded...
March 2, 2018: Micromachines
Rundong Zhao, Zixuan Cang, Yiying Tong, Guo-Wei Wei
Motivation: Protein pocket information is invaluable for drug target identification, agonist design, virtual screening and receptor-ligand binding analysis. A recent study indicates that about half holoproteins can simultaneously bind multiple interacting ligands in a large pocket containing structured sub-pockets. Although this hierarchical pocket and sub-pocket structure has a significant impact to multi-ligand synergistic interactions in the protein binding site, there is no method available for this analysis...
September 1, 2018: Bioinformatics
Matthew Becton, Rodney D Averett, Xianqiao Wang
Medical studies have consistently shown that the best defense against cancer is early detection. Due to this, many efforts have been made to develop methods of screening patient blood quickly and cheaply. These methods range from separation via differences in size, electrostatic potential, chemical potential, antibody-binding affinity, among others. We propose a method of separating cells which have similar size and outer coatings, but which differ in their elastic properties. Such a method would be useful in detecting cancerous cells, which may have similar properties to leukocytes or erythrocytes but differ in their stiffness and deformation response...
November 11, 2018: Biomechanics and Modeling in Mechanobiology
Jing Li, Tong Chen, Xiahe Huang, Yunshan Zhao, Bin Wang, Yanyun Yin, Yi Cui, Yannan Zhao, Ruiping Zhang, Xiujie Wang, Yingchun Wang, Jianwu Dai
Mesenchymal stem cells (MSCs) play important roles in tissue regeneration, and multi-lineage differentiation and immunomodulation are two major characteristics of MSCs that are utilized in stem cell therapy. MSCs in vivo have a markedly different three-dimensional (3D) niche compared to the traditional two-dimensional (2D) culture in vitro. A 3D scaffold is predicted to provide an artificial 3D environment similar to the in vivo environment. Significant changes in MSC differentiation are shown to be occurred when under 3D culture...
2018: PloS One
Lianjie Shi, Ying Ning, Liling Xu, Jianhong Li, Xuewu Zhang
Technetium-99 conjugated with methylene diphosphonate (99 Tc-MDP) is an effective anti-inflammatory drug in treating rheumatoid arthritis (RA) for over 15 years in China. However, as a special form of bisphosphonate, the antiosteoporotic effect of 99 Tc-MDP is unclear. We systematically investigated the effects of 99 Tc-MDP on cancellous and cortical bone, respectively, in glucocorticoid induced osteoporosis (GIO) animal models. Forty-eight Sprague-Dawley rats were randomly divided into six groups: blank, negative control, high dose, medium dose, low dose, and positive control groups...
2018: BioMed Research International
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