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Thomas Varé, Chérif Nouar, Christel Métivier
Rayleigh-Bénard convection in a horizontal layer of a non-Newtonian fluid between slabs of arbitrary thickness and finite thermal conductivity is considered. The first part of the paper deals with the primary bifurcation and the relative stability of convective patterns at threshold. Weakly nonlinear analysis combined with Stuart-Landau equation is used. The competition between squares and rolls, as a function of the shear-thinning degree of the fluid, the slabs' thickness, and the ratio of the thermal conductivity of the slabs to that of the fluid is investigated...
October 2017: Physical Review. E
S A Piriz, A R Piriz, N A Tahir
We develop the linear theory for the asymptotic growth of the incompressible Rayleigh-Taylor instability of an accelerated solid slab of density ρ_{2}, shear modulus G, and thickness h, placed over a semi-infinite ideal fluid of density ρ_{1}<ρ_{2}. It extends previous results for Atwood number A_{T}=1 [B. J. Plohr and D. H. Sharp, Z. Angew. Math. Phys. 49, 786 (1998)ZAMPA80044-227510.1007/s000330050121] to arbitrary values of A_{T} and unveil the singular feature of an instability threshold below which the slab is stable for any perturbation wavelength...
December 2017: Physical Review. E
Jonathan C Taylor, Nicholas Vennart, Ian Negus, Robin Holmes, Oliver Bandmann, Christine Lo, John Fenner
The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer...
January 17, 2018: Nuclear Medicine Communications
C M Wang, Hai-Peng Sun, Hai-Zhou Lu, X C Xie
The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surface has an open Fermi surface, which cannot host the quantum Hall effect. Via a "wormhole" tunneling assisted by the Weyl nodes, the Fermi arcs at opposite surfaces can form a complete Fermi loop and support the quantum Hall effect. The edge states of the Fermi arcs show a unique 3D distribution, giving an example of (d-2)-dimensional boundary states...
September 29, 2017: Physical Review Letters
Qinqin Zhang, Fang Zheng, Elie H Motulsky, Giovanni Gregori, Zhongdi Chu, Chieh-Li Chen, Chunxia Li, Luis de Sisternes, Mary Durbin, Philip J Rosenfeld, Ruikang K Wang
Purpose: To achieve reproducible imaging of the choriocapillaris and associated flow voids using swept-source OCT angiography (SS-OCTA). Methods: Subjects were enrolled and SS-OCTA was performed using the 3 × 3 mm scan pattern. Blood flow was identified using the complex optical microangiography (OMAG) algorithm. The choriocapillaris was defined as a slab from the outer boundary of Bruch's membrane (BM) to approximately 20 μm below BM. Compensation for the shadowing effect caused by the RPE and BM complex on the choriocapillaris angiogram was achieved by using the structural information from the same slab...
January 1, 2018: Investigative Ophthalmology & Visual Science
Omnia M Nawwar, Hossam M H Shalaby, Ramesh K Pokharel
A strip waveguide-based bi-directional mode-division multiplexer is proposed. A mathematical model has been proposed to analyze the performance, and the results are simulated. The design concept of this device to (de)multiplex three modes simultaneously has been studied previously for slab waveguides, both mathematically using the perturbative mode-coupled theory and by simulation using 2D FDTD Solutions (FDTD, finite difference time domain). As slab waveguides are not suitable for extracting fabrication parameters for most silicon-on-insulator applications, we apply the concept to a more practical device that involves strip waveguides rather than slab waveguides...
January 1, 2018: Applied Optics
Yue Sun, Yue Cao, Qi Wang, Yunji Yi, Xiaoqiang Sun, Yuanda Wu, Fei Wang, Daming Zhang
Flexible and wearable optoelectronic devices are the new trend for an active lifestyle. These devices are polymer-based for flexibility. We demonstrated flexible polymer waveguide optical switches for a flexible photonic integrated circuit. The optical switches are composed of a single-mode inverted waveguide with dimensions of 5 μm waveguide width, 3 μm ridge height, and 3 μm slab height. A Mach-Zehnder structure was used in the device, with the Y-branch horizontal length of 0.1 cm, the distance between two heating branches of 30 μm, and the heating branch length of 1 cm...
January 1, 2018: Applied Optics
Kasper Wigh Lipsø, Esben Søvsø Szocska Hansen, Rasmus Stilling Tougaard, Christoffer Laustsen, Jan Henrik Ardenkjaer-Larsen
PURPOSE: To investigate dynamic coronary MR angiography using hyperpolarized water as a positive contrast agent. Hyperpolarization can increase the signal by several orders of magnitude, and has recently been translated to human cardiac application. The aim was to achieve large 1 H signal enhancement to allow high-resolution imaging of the coronary arteries. METHODS: Protons in D2 O were hyperpolarized by dissolution dynamic nuclear polarization. A total of 18 mL of hyperpolarized water was injected into the coronary arteries of healthy pigs (N = 9; 3 injections in 3 animals)...
January 12, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Hengyun Zhou, Chao Peng, Yoseob Yoon, Chia Wei Hsu, Keith A Nelson, Liang Fu, John D Joannopoulos, Marin Soljačić, Bo Zhen
The ideas of topology have found tremendous success in closed physical systems, but even richer properties exist in the more general open or dissipative framework. We theoretically propose and experimentally demonstrate a bulk Fermi arc that develops from non-Hermitian radiative losses in an open system of photonic crystal slabs. Moreover, we discover half-integer topological charges in the polarization of far-field radiation around the bulk Fermi arc. Both phenomena are shown to be direct consequences of the non-Hermitian topological properties of exceptional points, where resonances coincide in their frequencies and linewidths...
January 11, 2018: Science
Zhutian Ding, James M Stubbs, Danielle McRae, Johanna M Blacquiere, François Lagugné-Labarthet, Silvia Mittler
A plasmonic sensing system that allows the excitation of localized surface plasmon resonance (LSPR) by individual waveguide modes is presented conceptually and experimentally. Any change in the local environment of the gold nanoparticles (AuNPs) alters the degree of coupling between LSPR and a polymer slab waveguide, which then modulates the transmission-output signal. In comparison to conventional LSPR sensors, this system is less susceptible to optical noise and positional variation of signals. Moreover, it enables more freedom in the exploitation of plasmonic hot spots with both transverse electric (TE) and transverse magnetic (TM) modes...
January 10, 2018: ACS Sensors
Zheng Xu, Yong-Fei Zheng, Zi-Fu Zhao
Crustal components may be incorporated into continental basalts by either shallow contamination or deep mixing. While the former proceeds at crustal depths with common preservation of refractory minerals, the latter occurs at mantle depths with rare survival of relict minerals. Discrimination between the two mechanisms has great bearing to subcontinental mantle geochemistry. Here we report the occurrence of relict zircons in Cenozoic continental basalts from eastern China. A combined study of zircon U-Pb ages and geochemistry indicates that detrital zircons were carried by terrigenous sediments into a subcontinental subduction zone, where the zircon were transferred by fluids into the magma sources of continental basalts...
January 9, 2018: Scientific Reports
Cornelius von Morze, Michael A Ohliger, Irene Marco-Rius, David M Wilson, Robert R Flavell, David Pearce, Daniel B Vigneron, John Kurhanewicz, Zhen J Wang
PURPOSE: The purpose of this study was to investigate the hyperpolarized ketone body 13 C-acetoacetate (AcAc) and its conversion to 13 C-β-hydroxybutyrate (βOHB) in vivo, catalyzed by β-hydroxybutyrate dehydrogenase (BDH), as a novel direct marker of mitochondrial redox state. METHODS: [1,3-13 C2 ]AcAc was synthesized by hydrolysis of the ethyl ester, and hyperpolarized via dissolution DNP. Cold storage under basic conditions resulted in sufficient chemical stability for use in hyperpolarized (HP) MRI studies...
January 3, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Stefanie Langenstück, Chenchen Zhao, Ulli Englert
Evaporation of an aqueous solution of sulfanilic acid (systematic name: 4-aminobenzene-1-sulfonic acid) at 273 K affords a crystalline dihydrate, C6H7NO3S·2H2O. The organic molecule exists as a zwitterion; two zwitterions are aligned in an antiparallel fashion about a crystallographic centre of inversion. They interact directly via two N-H...O hydrogen bonds between the ammonium group of one zwitterion and the sulfonate group of its symmetry-related counterpart, and their aromatic rings are π-stacked, with an interplanar distance of 3...
January 1, 2018: Acta Crystallographica. Section C, Structural Chemistry
Jonathan M Carrere, Kyle T Lewis
Complete extraocular muscle transection is uncommon in the setting of blunt trauma. We report a case of a 53-year-old male that developed diplopia after hitting his face directly on a concrete slab after a fall. On examination, he had a right hypertropia with a complete infraduction deficit. A CT scan of the face showed an orbital floor blowout fracture with complete inferior rectus transection. On surgical exploration, the distal and proximal ends of the muscle were identified and sutured together, and the floor fracture was repaired...
January 5, 2018: Orbit
C L Poyser, W B York, D Srikanthreddy, B A Glavin, T L Linnik, R P Campion, A V Akimov, A J Kent
Picosecond duration compressive and shear phonon wave packets injected into (311) GaAs slabs transform after propagation through ∼1  mm into chirped acoustic pulses with a frequency increasing in time due to phonon dispersion. By probing the temporal optical response to coherent phonons in a near surface layer of the GaAs slab, we show that phonon chirping opens a transformational route for high-sensitivity terahertz and subterahertz phonon spectroscopy. Temporal gating of the chirped phonon pulse allows the selection of a narrow band phonon spectrum with a central frequency up to 0...
December 22, 2017: Physical Review Letters
Gianluca Turco, Milena Cadenaro, Tatjana Maravić, Andrea Frassetto, Eleonora Marsich, Annalisa Mazzoni, Roberto Di Lenarda, Franklin R Tay, David H Pashley, Lorenzo Breschi
OBJECTIVE: The present study evaluated the influence of time, mass and surface area of demineralized dentin collagen matrices on telopeptides release. The hypotheses tested were that the rates of ICTP and CTX release by matrix bound endogenous proteases are 1) not time-dependent, 2) unrelated to specimen mass, 3) unrelated to specimen surface area. METHODS: Non-carious human molars (N=24) were collected and randomly assigned to three groups. Dentin slabs with three different thicknesses: 0...
January 1, 2018: Dental Materials: Official Publication of the Academy of Dental Materials
Dries Van Baelen, Sam Lemey, Jo Verhaevert, Hendrik Rogier
A novel manufacturing procedure for the fabrication of ultra-wideband cavity-backed substrate integrated waveguide antennas on textile substrates is proposed. The antenna cavity is constructed using a single laser-cut electrotextile patch, which is folded around the substrate. Electrotextile slabs protruding from the laser-cut patch are then vertically folded and glued to form the antenna cavity instead of rigid metal tubelets to implement the vertical cavity walls. This approach drastically improves mechanical flexibility, decreases the antenna weight to slightly more than 1 g and significantly reduces alignment errors...
January 3, 2018: Materials
Taís Fonseca Mantilla, Cecilia Pedroso Turssi, Thayanne Monteiro Ramos-Oliveira, Camila Vieira da Silva, Luis Cláudio Suzuki, Patricia Moreira de Freitas
Erosion incidence is increasing and its control is still a challenge in clinical practice. This study evaluated 4% TiF4-gel effects on eroded human dentin subjected to in situ erosive/abrasive episodes. Seventy-two previously eroded dentin slabs (0.05 M citric acid, pH 2.3, 20 min) were allocated to 6 groups (n=12) according to the treatment to be performed during the in situ phase and number of erosive/abrasive cycles, as follows: 4% TiF4-gel applied once (TiF41), twice (TiF42) or three times (TiF43) followed by 1, 2 and 3 erosive/abrasive cycles, respectively...
May 2017: Brazilian Dental Journal
Maurizio Battaglia Parodi, Francesco Romano, Maria Vittoria Cicinelli, Alessandro Rabiolo, Alessandro Arrigo, Luisa Pierro, Pierluigi Iacono, Francesco Bandello
PURPOSE: To evaluate vascular abnormalities at superficial (SCP), deep (DCP) capillary plexuses and choriocapillaris (CC) in patients with Best vitelliform macular dystrophy (BVMD) by means of optical coherence tomography angiography (OCT-A). DESIGN: Cross-sectional case series. METHODS: Sixty-six eyes of 33 patients with BVMD (sixteen males) and 33 controls were consecutively enrolled. Patients were subdivided in classic stages and underwent best-corrected visual acuity (BCVA), fundus autofluorescence and spectral domain-optical coherence tomography (Spectralis HRA+OCT; Heidelberg Engineering), and 4...
December 27, 2017: American Journal of Ophthalmology
Vinuta Hiremath, G Vinayakumar, Mallikarjuna Ragher, Sounyala Rayannavar, Mahantesh Bembalagi, B L Ashwini
Background: Latex protective barriers such as gloves and rubber dam material have been used widely in restorative procedures for crown and bridge. However, the chemical used during latex glove fabrication is thought to inhibit the polymerization of elastomeric impression materials used for impression making which has a detrimental effect on the dimensional accuracy and surface definition of resultant casts used for restorative procedures. The objectives of the study were to examine the surface of different elastomeric impressions on contact with various gloves...
November 2017: Journal of Pharmacy & Bioallied Sciences
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