scholarly journals Preterm Birth Impacts the Timing and Excursion of Oropharyngeal Structures during Infant Feeding

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
C E Edmonds ◽  
E A Catchpole ◽  
F D H Gould ◽  
L E Bond ◽  
B M Stricklen ◽  
...  
Keyword(s):  
Soft Palate ◽  
High Speed ◽  
Neural Control ◽  
Three Dimensional ◽  
Healthy Population ◽  
Term Infants ◽  
Postnatal Maturation ◽  
Pharyngeal Manometry ◽  
The Impact

Synopsis Swallowing in mammals requires the precise coordination of multiple oropharyngeal structures, including the palatopharyngeal arch. During a typical swallow, the activity of the palatopharyngeus muscle produces pharyngeal shortening to assist in producing pressure required to swallow and may initiate epiglottal flipping to protect the airway. Most research on the role of the palatopharyngeal arch in swallowing has used pharyngeal manometry, which measures the relative pressures in the oropharynx, but does not quantify the movements of the structures involved in swallowing. In this study, we assessed palatopharyngeal arch and soft palate function by comparing their movements in a healthy population to a pathophysiological population longitudinally through infancy (term versus preterm pigs). In doing so, we test the impact of birth status, postnatal maturation, and their interaction on swallowing. We tracked the three-dimensional (3D) movements of radiopaque beads implanted into relevant anatomical structures and recorded feeding via biplanar high-speed videofluoroscopy. We then calculated the total 3D excursion of the arch and soft palate, the orientation of arch movement, and the timing of maximal arch constriction during each swallow. Soft palate excursion was greater in term infants at both 7 and 17 days postnatal, whereas arch excursion was largely unaffected by birth status. Maximal arch constriction occurred much earlier in preterm pigs relative to term pigs, a result that was consistent across age. There was no effect of postnatal age on arch or soft palate excursion. Preterm and term infants differed in their orientation of arch movement, which most likely reflects both differences in anatomy and differences in feeding posture. Our results suggest that the timing and coordination of oropharyngeal movements may be more important to feeding performance than the movements of isolated structures, and that differences in the neural control of swallowing and its maturation in preterm and term infants may explain preterm swallowing deficits.

Studying the Impact of Return Current Path on the EM Simulation of High-speed Package Designs

2011 ◽  
Vol 2011 (1) ◽  
pp. 000061-000068
Author(s):  
Darryl Kostka ◽  
Antonio Ciccomancini Scogna
Keyword(s):  
High Speed ◽  
Ground Plane ◽  
Three Dimensional ◽  
Simulation Models ◽  
Current Path ◽  
Cavity Resonances ◽  
Simulation Results ◽  
The Impact ◽  
Simulation Time

Three-dimensional electromagnetic simulation models are often simplified in order to reduce the simulation time and memory requirements without sacrificing the accuracy of the results. A commonly adopted methodology in the simulation of electronic package designs is to truncate the size of the package model leaving only a few important features surrounding the nets of interest. In this paper we demonstrate that this simplification can have a significant impact of the simulation results if it is not performed carefully and it can introduce spurious/non physical resonances. The interaction between cavities and signals is first studied using a simple coupled differential via test structure. It is demonstrated that the return currents generated by these vias excite cavity resonances in power-ground plane pairs causing them to behave as parallel-plate waveguides. The role of interplane shorting vias in suppressing cavity resonances is then investigated and the impact of boundary conditions on the simulation results of package models is also shown and discussed. Finally, a realistic complex multilayer package model is analyzed and it is demonstrate that through proper truncation of the geometry, accurate results can be obtained.

Studying the Impact of Return Current Path on the EM Simulation of High-Speed Package and Board Designs

2012 ◽  
Vol 9 (2) ◽  
pp. 52-64
Author(s):  
Darryl Kostka ◽  
Antonio Ciccomancini Scogna
Keyword(s):  
High Speed ◽  
Ground Plane ◽  
Three Dimensional ◽  
Simulation Models ◽  
Combined Model ◽  
Current Path ◽  
Cavity Resonances ◽  
Simulation Results ◽  
The Impact

Three-dimensional electromagnetic simulation models are often simplified in order to reduce simulation time and memory requirements without sacrificing the accuracy of the results. A commonly adopted methodology in the simulation of complex electronic package and board designs is to truncate the size of the model, leaving only a few important features surrounding the nets of interest. In this paper we demonstrate that this simplification can have a significant impact on the simulation results if it is not performed carefully, and it can introduce spurious nonphysical resonances. The interaction between cavities and signals is first studied using a simple coupled differential via test structure. It is demonstrated that the return currents generated by these vias excite cavity resonances in power-ground plane pairs causing them to behave as parallel-plate waveguides. The role of interplane shorting vias in suppressing cavity resonances is then investigated and the impact of boundary conditions on the simulation results of package models is also shown and discussed. The focus is then shifted to PCB/package cosimulation and the impact of different truncation schemes is discussed through the simulation of test structures of varying complexity. A simulation methodology is then proposed and is verified for a combined model of a realistic complex multilayer package and board and it is demonstrated that accurate results can be obtained through proper truncation of the geometry.

A Sociocultural Perspective on Negotiating Digital Identities in a Community of Learners

2013 ◽  
pp. 210-224 ◽  
Author(s):  
Anna Peachey ◽  
Greg Withnail
Keyword(s):  
Social Interaction ◽  
Identity Development ◽  
Three Dimensional ◽  
Digital Identity ◽  
Sociocultural Perspective ◽  
Regular Feature ◽  
Virtual World Environments ◽  
The Impact ◽  
Digital Identities

Three dimensional virtual world environments are becoming an increasingly regular feature of the education landscape, providing the opportunity for richly graphical augmented and immersive learning activities. Those who participate in these experiences must mediate through an avatar, negotiating and managing the complexities of this new variation of digital identity alongside their more familiar identity as learner and/or teacher/facilitator. This chapter describes some key moments in the construction of digital identities as a lecturer and a student in the Open University’s community in Second LifeTM. The authors explore experiences in relation to the impact of trust and consistency from a sociocultural perspective, privileging the role of social interaction and context where meaning is socially produced and situationally interpreted, concluding that social interaction is pivotal to any meaningful identity development that takes place. The chapter ends with thoughts for future issues surrounding digital identity in relation to lifelong learning.

The effect analysis of an engine jet on an aircraft blast deflector

2018 ◽  
Vol 41 (4) ◽  
pp. 990-1001
Author(s):  
Song Ma ◽  
Jianguo Tan ◽  
Xiankai Li ◽  
Jiang Hao
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
High Speed ◽  
Deflection Angle ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Experimental Results ◽  
Exhaust Gases ◽  
The Impact

This paper establishes a novel mathematical model for computing the plume flow field of a carrier-based aircraft engine. Its objective is to study the impact of jet exhaust gases with high temperature, high speed and high pressure on the jet blast deflector. The working condition of the nozzle of a fully powered on engine is first determined. The flow field of the exhaust jet is then numerically simulated at different deflection angle using the three-dimensional Reynolds averaged Navier–Stokes equations and the standard [Formula: see text]-[Formula: see text] turbulence method. Moreover, infra-red temperature tests are further carried out to test the temperature field when the jet blast deflector is at the [Formula: see text] deflection angle. The comparison between the simulation results and the experimental results show that the proposed computation model can perfectly describe the system. There is only 8–10% variation between them. A good verification is achieved. Moreover, the experimental results show that the jet blast deflector plays an outstanding role in driving the high-temperature exhaust gases. It is found that [Formula: see text] may be the best deflection angle to protect the deck and the surrounding equipment effectively. These data results provide a valuable basis for the design and layout optimization of the jet blast deflector and deck.

Role of Through Silicon Via in 3D Integration: Impact on Delay and Power

2020 ◽  
pp. 2150051
Author(s):  
Shivangi Chandrakar ◽  
Deepika Gupta ◽  
Manoj Kumar Majumder
Keyword(s):  
Power Dissipation ◽  
Three Dimensional ◽  
Propagation Delay ◽  
Model Parameters ◽  
3D Integration ◽  
Coupling Behavior ◽  
Power Delay Product ◽  
Silicon Vias ◽  
The Impact

The metal–semiconductor (MES)-based through silicon vias (TSV) has provided attractive solutions over conventional metal–insulator–semiconductor (MIS) TSVs in recent three-dimensional (3D) integration. This paper aims a comprehensive performance analysis of MIS and MES structures considering different TSV shapes such as cylindrical, tapered, annular, and square. At 32[Formula: see text]nm technology, a CMOS-based coupled driver-via-load (DVL) setup is introduced wherein each via is represented an equivalent RLGC model of MIS- and MES-based TSV shapes. The proposed electrical model accurately considers the impact of micro bump and inter-metal dielectric (IMD) effects at 32[Formula: see text]nm technology as per the fabrication house. A 3D electromagnetic (EM) structural wave simulation is performed to validate the RLGC model parameters of different TSV structures for an operating frequency of up to 20[Formula: see text]GHz. The proposed DVL setup is used to analyze the propagation delay, power dissipation, and dynamic crosstalk for different MIS- and MES-based TSV shapes. A significant improvement in the cross-coupling behavior can be obtained using the MES-based tapered TSV compared to the other MIS structures. Additionally, the power delay product (PDP) of the tapered MES is reduced by 92.4% compared to the conventional MIS-based cylindrical TSV.

scholarly journals The Role of Nanoparticle Shapes and Structures in Material Characterisation of Polyvinyl Alcohol (PVA) Bionanocomposite Films

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 264 ◽  
Author(s):  
Mohanad Mousa ◽  
Yu Dong
Keyword(s):  
Polyvinyl Alcohol ◽  
Three Dimensional ◽  
Halloysite Nanotubes ◽  
Mechanical And Thermal Properties ◽  
Cloisite 30B ◽  
Bionanocomposite Films ◽  
The Impact ◽  
Nanoparticle Shapes ◽  
Selection Of

Three different types of nanoparticles, 1D Cloisite 30B clay nanoplatelets, 2D halloysite nanotubes (HNTs), and 3D nanobamboo charcoals (NBCs) were employed to investigate the impact of nanoparticle shapes and structures on the material performance of polyvinyl alcohol (PVA) bionanocomposite films in terms of their mechanical and thermal properties, morphological structures, and nanomechanical behaviour. The overall results revealed the superior reinforcement efficiency of NBCs to Cloisite 30B clays and HNTs, owing to their typical porous structures to actively interact with PVA matrices in the combined formation of strong mechanical and hydrogen bondings. Three-dimensional NBCs also achieved better nanoparticle dispersibility when compared with 1D Cloisite 30B clays and 2D HNTs along with higher thermal stability, which was attributed to their larger interfacial regions when characterised for the nanomechanical behaviour of corresponding bionanocomposite films. Our study offers an insightful guidance to the appropriate selection of nanoparticles as effective reinforcements and the further sophisticated design of bionanocomposite materials.

High Speed Liquid Impact Onto Wetted Solid Surfaces

1994 ◽  
Vol 116 (2) ◽  
pp. 345-348 ◽  
Author(s):  
H. H. Shi ◽  
J. E. Field ◽  
C. S. J. Pickles
Keyword(s):  
Shock Wave ◽  
Liquid Layer ◽  
Solid Surface ◽  
High Speed ◽  
Shear Failure ◽  
Soda Lime ◽  
Liquid Jet ◽  
Soda Lime Glass ◽  
The Impact

The mechanics of impact by a high-speed liquid jet onto a solid surface covered by a liquid layer is described. After the liquid jet contacts the liquid layer, a shock wave is generated, which moves toward the solid surface. The shock wave is followed by the liquid jet penetrating through the layer. The influence of the liquid layer on the side jetting and stress waves is studied. Damage sites on soda-lime glass, PMMA (polymethylmethacrylate) and aluminium show the role of shear failure and cracking and provide evidence for analyzing the impact pressure on the wetted solids and the spatial pressure distribution. The liquid layer reduces the high edge impact pressures, which occur on dry targets. On wetted targets, the pressure is distributed more uniformly. Despite the cushioning effect of liquid layers, in some cases, a liquid can enhance material damage during impact due to penetration and stressing of surface cracks.

scholarly journals Impacts of a railway tunnel on the streams baseflow verified by means of numerical modelling

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Leonardo Piccinini ◽  
Valentina Vincenzi
Keyword(s):  
Numerical Modelling ◽  
High Speed ◽  
Three Dimensional ◽  
Tracer Tests ◽  
Maximum Flow ◽  
Mitigation Strategies ◽  
Railway Tunnel ◽  
Flow Measurements ◽  
Railway Line ◽  
The Impact

The high-speed railway line between Bologna and Florence (Italy) is mostly developed underground through the Tuscan-Emilian Apennine, and the tunnels severely impacted groundwater and surface water. The 15-km-long Firenzuola tunnel crosses siliciclastic turbidites: during drilling, water inrushes occurred at fault and fracture zones, and the tunnel continues to drain the aquifer. The water table dropped below the level of the valleys, and gaining streams transformed into losing streams or ran completely dry, as did many springs. Hydrological observations and two multitracer tests have previously characterized the stream-tunnel connections and the impact processes. In the framework of planning mitigation strategies to minimize impacts on stream baseflow, three-dimensional numerical modelling with MODFLOW (the EPM approach) is applied to evaluate the artificial minimum flow needed to maintain flow continuity along the stream during the recession phase. The establishment of the two presented models is based on hydrogeological monitoring data and the results of flow measurements and tracer tests. Maximum flow rates subtracted from stream baseflow by the tunnel along the connection structures are calculated for two streams with major impacts.

A modified Fresnel-based algorithm for 3D microwave imaging of metal objects

2018 ◽  
Vol 11 (4) ◽  
pp. 313-325
Author(s):  
Farshad Zamiri ◽  
Abdolreza Nabavi
Keyword(s):  
High Speed ◽  
Fourier Transforms ◽  
Low Cost ◽  
Three Dimensional ◽  
Computation Time ◽  
Microwave Imaging ◽  
Reconstruction Algorithms ◽  
Clock Frequency ◽  
Pipeline Architecture ◽  
The Impact

AbstractMicrowave holography technique reconstructs a target image using recorded amplitudes and phases of the signals reflected from the target with Fast Fourier Transform (FFT)-based algorithms. The reconstruction algorithms have two or more steps of two- and three-dimensional Fourier transforms, which have a high computational load. In this paper, by neglecting the impact of target depth on image reconstruction, an efficient Fresnel-based algorithm is proposed, involving only one-step FFT for both single- and multi-frequency microwave imaging. Numerous tests have been performed to show the effectiveness of the proposed algorithm including planar and non-planar targets, using the raw data gathered by means of a scanner operating in X-band. Finally, a low-cost and high-speed hardware architecture based on fixed-point arithmetic is introduced which reconstructs the planar targets. This pipeline architecture was tested on field programmable gate arrays operating at 200 MHz clock frequency, which illustrates more than 30 times improvement in computation time compared with a computer.

Formation of cavities and microjets in liquids and their role in initiation and growth of explosion

1967 ◽  
Vol 298 (1452) ◽  
pp. 38-50 ◽  
Keyword(s):  
High Speed ◽  
Solid Surfaces ◽  
Pressure Waves ◽  
Liquid Explosive ◽  
Rarefaction Waves ◽  
Burning Zone ◽  
Rapid Transition ◽  
High Pressure Zone ◽  
The Impact

The role of discontinuities, such as bubbles of gas and cavities, in the initiation and growth of explosion in liquids has been studied experimentally by means of high speed framing photography. It is shown that micro Munroe jets can be formed at the surface of a gas bubble which has been trapped in the liquid explosive between two impacting surfaces and is being rapidly compressed. As the compression continues these jets are projected at high speed into the gas. Similar jets can be produced between two drops of explosive which are coalescing during impact. These jets may facilitate the initiation of burning both by increasing the impact velocity of the liquid and by dispersing the liquid within a pocket of compressed and heated gas. The reaction grows first as an accelerating burning. The pressure developed in this burning zone has, in the early stages, the effect of closing up and removing any cavities which may exist in the explosive directly ahead of the flame front, so that the reaction advances into a homogeneous zone of liquid that is free from discontinuities. It is not until the comparatively slow burning breaks through the homogeneous high pressure zone, and reaches a zone of liquid containing numerous cavities and bubbles, that the burning is able to transform quickly into a much faster and more violent explosion. The discontinuities are then able to sustain the rapid propagation of explosion. This region of discontinuities can be created in initially homogeneous liquids enclosed between solid surfaces by pressure waves which travel through the confining solids and ahead of the subsonic burning. If these pressure waves increase the distance between the confining surfaces substantially or are converted into rarefaction waves by reflexion, they can produce regions of tension in the unreacted liquid and disrupt it well ahead of the reaction zone. The bubbles of gas or cavities that are formed in this way by the precursor waves create an environment which is conducive to the rapid transition from burning to explosion.

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