SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Compact space

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Martian habitats are ideally constructed using only locally available soils; extant attempts to process structural materials on Mars, however, generally require additives or calcination. In this work we demonstrate that Martian soil simulant Mars-1a can be directly compressed at ambient into a strong solid without additives, highlighting a possible aspect of complete Martian in-situ resource utilization. Flexural strength of the compact is not only determined by the compaction pressure but also significantly influenced by the lateral boundary condition of processing loading. The compression loading can be applied either quasi-statically or through impact. Nanoparticulate iron oxide (npOx), commonly detected in Martian regolith, is identified as the bonding agent. Gas permeability of compacted samples was measured to be on the order of 10(-16) m(2), close to that of solid rocks. The compaction procedure is adaptive to additive manufacturing.

Concepts: Oxygen, Soil, Mars, Geology, Compact space, Regolith, Geomorphology, In-situ resource utilization

32

Compaction of the preimplantation embryo is the earliest morphogenetic process essential for mammalian development, yet it remains unclear how round cells elongate to form a compacted embryo. Here, using live mouse embryo imaging, we demonstrate that cells extend long E-cadherin-dependent filopodia on to neighbouring cells, which control the cell shape changes necessary for compaction. We found that filopodia extension is tightly coordinated with cell elongation, whereas retraction occurs before cells become round again before dividing. Laser-based ablations revealed that filopodia are required to maintain elongated cell shapes. Moreover, molecular disruption of the filopodia components E-cadherin, α- and β-catenin, F-actin and myosin-X prevents cells from elongating and compacting the embryo. Finally, we show that early filopodia formation triggered by overexpressing myosin-X is sufficient to induce premature compaction. Our findings establish a role for filopodia during preimplantation embryonic development and provide an in vivo context to investigate the biological functions of filopodia in mammals.

Concepts: DNA, Gene, Cell, Embryo, Developmental biology, Cell biology, Mammal, Compact space

28

Objective  To compare the Welch Allyn SureSight™ wavefront autorefractor with retinoscopy in normal dogs. Animals studied  Fifty privately owned dogs (100 eyes) of 20 breeds, free of ocular disease. Mean ± SD age: 5.7 ± 3.25 years (range: 6 months-13 years). Procedures  The refractive error was determined in each eye by two experienced retinoscopists using streak retinoscopy as well as by an autorefractor operated by two different examiners. Measurements were performed before and approximately 30-45 min after cycloplegia was induced by cyclopentolate 0.5% and tropicamide 0.5% ophthalmic solutions. Results  Mean ± SD noncyclopleged retinoscopy net sphere was -0.55 ± 1.14 (range: -3.75 to 3.5) diopters (D). Mean cyclopleged retinoscopy net sphere was -0.52 ± 1.18 (range: -4.25 to 2) D. Mean ± SD noncyclopleged autorefractor spherical equivalent (SE) was -0.42 ± 1.13 D (range: -3.36 to 2.73) D. Mean cyclopleged autorefractor SE was 0.10 ± 1.47 (range: -5.62 to 3.19) D. Noncyclopleged autorefraction results were not significantly different from streak retinoscopy (whether noncyclopleged or cyclopleged, P = 0.80 and P = 0.26, respectively). Cyclopleged autorefraction results were significantly different from noncyclopleged or cyclopleged streak retinoscopy (P < 0.0001 in both states). There was no significant difference between noncyclopleged and cyclopleged streak retinoscopy (P = 0.97). Conclusions  Noncyclopleged autorefraction shows good agreement with streak retinoscopy in dogs and may be a useful clinical technique. Cycloplegia does not significantly affect streak retinoscopy results in dogs.

Concepts: Eye, Ophthalmology, Sphere, Cycloplegia, Refractive error, Welch Regiment, Compact space, Retinoscopy

27

Experimental verification of a novel sensor topology capable of measuring both the position and energy of an electron beam inside a compact electron linear accelerator for radiotherapy is presented. The method applies microwave sensing techniques and allows for non-interceptive monitoring of the respective beam parameters within compact accelerators for medical or industrial purposes. A state space feedback approach is described with the help of which beam displacements, once detected, can be corrected within a few system macropulses. The proof-of-principle experiments have been conducted with a prototype accelerator and customized hardware. Additionally, closed-loop operation with high accuracy is demonstrated.

Concepts: Electron, Mathematics, Control theory, Compact space, Particle accelerator, Synchrotron, Linear particle accelerator, Klystron

10

The mechanism by which chromatids and chromosomes are segregated during mitosis and meiosis is a major puzzle of biology and biophysics. Using polymer simulations of chromosome dynamics, we show that a single mechanism of loop extrusion by condensins can robustly compact, segregate and disentangle chromosomes, arriving at individualized chromatids with morphology observed in vivo. Our model resolves the paradox of topological simplification concomitant with chromosome ‘condensation’, and explains how enzymes a few nanometers in size are able to control chromosome geometry and topology at micron length scales. We suggest that loop extrusion is a universal mechanism of genome folding that mediates functional interactions during interphase and compacts chromosomes during mitosis.

Concepts: Chromosome, Cell cycle, Centromere, Topology, Mitosis, Meiosis, Compact space, Chromatid

7

As the quantity of data per sequencing experiment increases, the challenges of fragment assembly are becoming increasingly computational. The de Bruijn graph is a widely used data structure in fragment assembly algorithms, used to represent the information from a set of reads. Compaction is an important data reduction step in most de Bruijn graph based algorithms where long simple paths are compacted into single vertices. Compaction has recently become the bottleneck in assembly pipelines, and improving its running time and memory usage is an important problem.

Concepts: Computer, Graph theory, Compact space, Computational complexity theory, Algorithmic efficiency, De Bruijn graph, De Bruijn sequence, Nicolaas Govert de Bruijn

2

In order to exploit the vast body of currently inaccessible chemical information held in Electronic Laboratory Notebooks (ELNs) it is necessary not only to make it available but also to develop protocols for discovery, access and ultimately automatic processing. An aim of the Dial-a-Molecule Grand Challenge Network is to be able to draw on the body of accumulated chemical knowledge in order to predict or optimize the outcome of reactions. Accordingly the Network drew up a working group comprising informaticians, software developers and stakeholders from industry and academia to develop protocols and mechanisms to access and process ELN records. The work presented here constitutes the first stage of this process by proposing a tiered metadata system of knowledge, information and processing where each in turn addresses a) discovery, indexing and citation b) context and access to additional information and c) content access and manipulation. A compact set of metadata terms, called the elnItemManifest, has been derived and caters for the knowledge layer of this model. The elnItemManifest has been encoded as an XML schema and some use cases are presented to demonstrate the potential of this approach.

Concepts: Futurology, Chemistry, Research, The Network, Compact space, Notebooks, Notebook, Electronic lab notebook

1

Novel excipients are entering the market to enhance the bioavailability of drug particles by having a high porosity and thus providing a rapid liquid uptake and disintegration to accelerate subsequent drug dissolution. One example of such a novel excipient is functionalised calcium carbonate (FCC), which enables the manufacture of compacts with a bimodal pore size distribution consisting of larger inter-particle and fine intra-particle pores. Five sets of FCC tablets with a target porosity of 45% to 65% were prepared in 5% steps and characterised using terahertz time-domain spectroscopy (THz-TDS) and X- ray computed microtomography (XμCT). THz-TDS was employed to derive the porosity using effective medium approximations (EMAs), i.e., the traditional and an anisotropic Bruggeman model. The anisotropic Bruggeman model yields the better correlation with the nominal porosity (R(2) = 0.995) and it provided additional information about the shape and orientation of the pores within the powder compact. The spheroidal (ellipsoids of revolution) shaped pores have a preferred orientation perpendicular to the compaction direction causing an anisotropic behaviour of the dielectric porous medium. The results from XμCT confirmed the non-spherical shape as well as the orientation of the pores and it further revealed that the anisotropic behaviour is mainly caused by the inter-particle pores. The information from both techniques provide a detailed insight into the pore structure of pharmaceutical tablets. This is of great interest to study the impact of tablet microstructure on the disintegration and dissolution performance.

Concepts: Pharmacology, Hydrogeology, Porosity, Calcium carbonate, Compact space, Tablet, Excipient, Porous medium

0

In an era of unprecedented progress in sensing technology and communication, health services are now able to closely monitor patients and elderly citizens without jeopardizing their daily routines through health applications on their mobile devices in what is known as e-Health. Within this field, we propose an optical fiber sensor (OFS) based system for the simultaneous monitoring of shear and plantar pressure during gait movement. These parameters are considered to be two key factors in gait analysis that can help in the early diagnosis of multiple anomalies, such as diabetic foot ulcerations or in physical rehabilitation scenarios. The proposed solution is a biaxial OFS based on two in-line fiber Bragg gratings (FBGs), which were inscribed in the same optical fiber and placed individually in two adjacent cavities, forming a small sensing cell. Such design presents a more compact and resilient solution with higher accuracy when compared to the existing electronic systems. The implementation of the proposed elements into an insole is also described, showcasing the compactness of the sensing cells, which can easily be integrated into a non-invasive mobile e-Health solution for continuous remote gait monitoring of patients and elder citizens. The reported results show that the proposed system outperforms existing solutions, in the sense that it is able to dynamically discriminate shear and plantar pressure during gait.

Concepts: Health care, Optical fiber, Monitoring, Proposal, Compact space, Mobile device, Gait, Fiber Bragg grating

0

In this paper, a new ultra-thin and broadband wide-angle polarization-insensitive metasurface solar absorber is designed and optimized. The proposed metasurface absorber topology is optimized by using a genetic algorithm to enhance the bandwidth and decrease the unit cell area. The proposed unit cell is designed with fourfolded symmetric subunit cells rotated in the clockwise direction to achieve a polarization-independent response. The unit cell with 320×320  nm2area and 50 nm thickness has a broadband (≥90%) absorption response in the visible frequency region of the solar spectrum and infrared from 350 THz to 700 THz for normal incident angles and higher than 70% for incident angles up to 40° at both polarizations.

Concepts: DNA, Protein, Gene, Electromagnetic radiation, Geometry, Genetic algorithm, Compact space, Visible spectrum