Phrenic afferent activation modulates cardiorespiratory output in the adult rat

2021 ◽  
Author(s):  
Kristi A Streeter ◽  
Michael D. Sunshine ◽  
Paul W. Davenport ◽  
David D. Fuller
Keyword(s):  
Blood Pressure ◽  
Pulse Width ◽  
Large Diameter ◽  
Small Diameter ◽  
Motor Output ◽  
Current Response ◽  
Burst Frequency ◽  
Afferent Activation ◽  
The Impact ◽  
Pulse Stimulation

Phrenic afferents project to brainstem areas responsible for cardiorespiratory control and the mid-cervical spinal cord containing the phrenic motor nucleus. Our purpose was to quantify the impact of small and large diameter phrenic afferent activation on phrenic motor output. Anesthetized and ventilated rats received unilateral phrenic nerve stimulation while contralateral phrenic motor output and blood pressure were recorded. Twelve currents of 40Hz inspiratory-triggered stimulation were delivered (20 seconds on, 5 minutes off) to establish current response curves. Stimulation pulse width was varied to preferentially activate large diameter phrenic afferents (narrow pulse width) and recruit small diameter fibers (wide pulse width). Contralateral phrenic amplitude was elevated immediately post-stimulation at currents above 35 µA for wide, and 70 µA for narrow pulse stimulation when compared to animals not receiving stimulation (time controls). Wide pulse width stimulation also increased phrenic burst frequency at currents ≥35 µA, caused a transient decrease in mean arterial blood pressure at currents ≥50 µA, and resulted in a small change in heart rate at 300 µA. Unilateral dorsal rhizotomy attenuated stimulation-induced cardiorespiratory responses, indicating phrenic afferent activation is required. Additional analyses compared phrenic motor amplitude to output before stimulation and showed that episodic activation of phrenic afferents with narrow pulse stimulation can induce short-term plasticity. We conclude that activation of phrenic afferents: 1) enhances contralateral phrenic motor amplitude when large diameter afferents are activated, and 2) when small diameter fibers are recruited the amplitude response is associated with changes in burst frequency and cardiovascular parameters.

scholarly journals Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1015
Author(s):  
Antonio Bulum ◽  
Gordana Ivanac ◽  
Eugen Divjak ◽  
Iva Biondić Špoljar ◽  
Martina Džoić Dominković ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Large Diameter ◽  
Small Diameter ◽  
Shear Wave Elastography ◽  
Lesion Size ◽  
Ultrasound Elastography ◽  
Breast Lesions ◽  
Malignant Breast ◽  
The Impact

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

Evaluation of Residual Stresses Induced by Repairs to Small Diameter Stainless Steel Pipe Welds

2015 ◽  
Author(s):  
Trevor G. Hicks ◽  
William R. Mabe ◽  
Jason R. Miller ◽  
John V. Mullen
Keyword(s):  
Stainless Steel ◽  
Residual Stresses ◽  
Large Diameter ◽  
Small Diameter ◽  
Steel Pipe ◽  
Limited Information ◽  
Diameter Pipe ◽  
Stainless Steel Pipe ◽  
Lower Magnitude ◽  
The Impact

Residual stresses within stainless steel pipe welds may cause or exacerbate in-service cracking. Significant investigative efforts have been devoted to the examination of piping residual stresses in large diameter piping using both finite element modeling and experimental techniques, but limited information is available for small diameter piping. Even less information is available for small diameter piping welds which have been repaired or re-worked during initial fabrication. This investigation used both experimental methods and analytical modeling to assess the impact of repair welding during initial fabrication on the residual stresses along the inner diameter (ID) of small diameter pipe specimens. The investigation showed that tensile axial residual stresses were located in the heat affected zone (HAZ) along the ID of the pipe specimens adjacent to regions which were excavated and re-welded. Such repair welds were also shown to markedly increase the magnitude of the tensile axial residual stresses for weld configurations which otherwise had lower magnitude residual stresses.

Advanced Pipeline Impact Design

2016 ◽  
Author(s):  
Ragnar T. Igland ◽  
Hagbart S. Alsos ◽  
Stig Olav Kvarme
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Impact Velocity ◽  
Large Diameter ◽  
Small Diameter ◽  
Energy Estimates ◽  
Dissipated Energy ◽  
Accurate Information ◽  
Cross Sectional ◽  
The Impact

The safety of pipelines and subsea structures are key elements in subsea field developments. As part of the safety engineering, protection from dropped objects and third party impact actions is required. This article addresses this aspect. Dropped object from a platform or a vessel is one of the design scenarios. The fall-pattern of the object is essential for the impact velocity and corresponding energy, model of the path and the effects of hydrodynamic behavior is outlined. In lieu of accurate information, the design code use energy band for energy estimates and may give extremely conservative impact energy. The falling objects structural flexibility and properties are discussed and evaluated regarding the energy dissipation and possible damage of the pipeline. The pipeline combined response from global deflection and denting regarding impacts are investigated. Analysis and testing methods applied in pipeline design are presented. Focus is placed on the overall interaction between the impacting object, the deformed pipeline and energy dissipation by coating and soil. Typically, pipeline damage from design codes provides conservative cross sectional damage estimates. This is confirmed from both simplified and detailed FE analyses, as well as fullscale impact experiments performed by REINERTSEN AS. One of the main objectives promoted by the authors is the importance of both impact velocity and mass during impact, and not only the kinetic energy of the impact. The kinetic energy from a dropped object is unlikely to be fully dissipated as cross sectional deformation of the pipeline. Global deformations will be triggered, which implies that the dissipated energy going into local denting is reduced to a fractional value. The effect is more pronounced for small diameter pipelines than for pipelines with large diameter. This paper discusses the impact mechanics and seeks to estimate the fractional value by using simplified element analysis.

scholarly journals Influence of polysiloxane microspheres on hydrophobicity, structure and mechanical properties of paper materials

Cellulose ◽  
2021 ◽  
Author(s):  
Piotr Pospiech ◽  
Konrad Olejnik ◽  
Urszula Mizerska ◽  
Joanna Zakrzewska
Keyword(s):  
Mechanical Properties ◽  
Large Diameter ◽  
Small Diameter ◽  
Average Diameter ◽  
Barrier Properties ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Material Structure ◽  
Liquid Penetration ◽  
The Impact

Abstract The aim of the study was to investigate the impact of three types of polysiloxane microspheres on the barrier properties, structure and mechanical properties of paper. An influence of new silicon filler on properties of cellulose paper sheet was analyzed. Polysiloxane microspheres were used as an additive introduced into the network of cellulosic fibers in order to obtain new functional properties of the paper. The following types of microspheres were used in the research: M1 hydrophilic of average diameter 23.5 µm, M2 hydrophobic of average diameter 3.1 µm and M3 hydrophobic of average diameter 23.5 µm. The obtained handsheets were analyzed for changes in apparent density, roughness, tensile strength, bursting strength, and tear resistance. Wettability and resistance to liquid were characterized by contact angle measurement, penetration dynamics analysis  and uniformity of liquid penetration measured using an extended liquid penetration analyser. It was found that the presence of M2 (small diameter) microspheres improved significantly the paper’s hydrophobicity without changing the mechanical properties. The addition of M1 and M3 (large diameter) microspheres decreased the mechanical properties of the paper samples and did not improve their hydrophobicity. However, M1 microspheres resulted in increased uniformity of liquid penetration through the paper structure. The presented studies also show that it is possible to obtain paper with high hydrophobic properties only through the filling application when polysiloxane microspheres are used for this purpose. The results also indicate that it is not necessary to hydrophobize the entire material structure in order to achieve its high hydrophobicity. Graphic abstract

Residual Stress Evaluation of Small Diameter Stainless Steel Piping by Experimental Measurements and Finite Element Analysis

2014 ◽  
Author(s):  
Trevor G. Hicks ◽  
William R. Mabe ◽  
Jason R. Miller ◽  
John V. Mullen
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Axial Stress ◽  
Large Diameter ◽  
Small Diameter ◽  
Thick Wall ◽  
Outer Diameter ◽  
Thin Wall ◽  
The Impact

Residual stresses within stainless steel pipe welds may impact both component inspections and in-service cracking. Various investigators have examined piping residual stresses in large diameter piping using both finite element modeling and experimental techniques, but limited information is available for small diameter piping. This investigation uses both experimental methods and analytical modeling to evaluate the impact of welding on the residual stresses along the inner diameter (ID) of two small diameter pipe specimens. Results of the investigation showed that tensile axial residual stresses were observed in the heat affected zone (HAZ) along the ID of the thin-wall pipe specimen with distinct regions of tensile and compressive axial stress which correlate well with the location where the last weld segments of the final weld pass were deposited. Higher stresses were also observed in the HAZ on the side where the final weld pass was deposited. By contrast, testing of the thick-wall pipe specimen showed significantly lower levels of tensile stresses along the pipe ID with the higher stress regions being biased toward the pipe outer diameter (OD).

Pulmonary Artery Stenosis: Early Interventions With Low Profile Stents Versus Delayed Interventions With Large Diameter Stents

2020 ◽  
Author(s):  
Ryan Pewowaruk ◽  
Kevin Pettit ◽  
Carolina Larrain ◽  
Cody Johnson ◽  
Christopher J. Francois ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Heart Surgery ◽  
Positive Impact ◽  
Large Diameter ◽  
Small Diameter ◽  
Artery Stenosis ◽  
Pulmonary Artery Stenosis ◽  
Low Profile ◽  
Significant Difference ◽  
The Impact

Abstract Pulmonary artery stenosis (PAS) is a common complication of heart surgery in infancy. With recent advances in low profile-small diameter stent technology, PA stenting is now often performed in infants. While PAS stenting in older children does not impact distal PA growth and multiplication, in infants still undergoing significant PA growth, the impact of PA stent timing on long term PA development is unknown and potentially important. In a swine PAS model, the effects of early and delayed stent interventions on PA growth and cardiac function were comprehensively assessed. PA stenting had a positive impact on hemodynamics, lung perfusion, and histology, but the timing of intervention, either early or late, does not make a significant difference.

scholarly journals Methods Optimization for Routine Sciatic Nerve Processing in General Toxicity Studies

2019 ◽  
Vol 48 (1) ◽  
pp. 19-29
Author(s):  
Jessica S. Fortin ◽  
Elizabeth A. Chlipala ◽  
Daniel P. Shaw ◽  
Brad Bolon
Keyword(s):  
Best Practice ◽  
Structural Integrity ◽  
Ethanol Concentration ◽  
Large Diameter ◽  
Small Diameter ◽  
Nerve Fibers ◽  
Water Bath ◽  
Nerve Preservation ◽  
Toxicity Studies ◽  
The Impact

Recent “best practice” recommendations for peripheral nervous system sampling and processing provide guidance regarding nerve preparation for animal toxicity studies. This study explored the impact of delayed fixation, type of fixative, processing cycle times, starting ethanol concentration, and water bath temperature to improve nerve preservation in routinely prepared (paraffin-embedded, hematoxylin and eosin [H&E]-stained) sections. Sciatic nerves from adult Wistar rats (diameter, 1.04 ± 0.1 mm) and young domestic pigs (diameter 5.9 ± 1.2 mm) fixed at necropsy (“0” hours) or 3, 6, 12, or 24 hours after death were immersed in neutral-buffered 10% formalin containing 1.2% methanol (NBF) or methanol-free 4% formaldehyde (MFF) at room temperature. After fixation for 24 hours (rat) or 48 hours (pig), specimens were processed into paraffin, and ∼5-μm-thick sections were flattened on water baths set at 35°C, 40°C, or 45°C before H&E staining. Large-diameter nerves (pig) required longer processing cycles to ensure sufficient paraffin infiltration. For both small-diameter (rat) and large-diameter nerves, structural integrity was optimal if fixation by NBF or MFF occurred within 3 hours and the initial ethanol concentration for tissue processing was lowered to 50%. At all time points, structural preservation of nerve fibers was acceptable using NBF but was better with MFF. Use of a water bath at 35°C reduced processing-related nerve fiber separation within sections.

Differences in the brain stem terminations of large- and small-diameter vestibular primary afferents

1995 ◽  
Vol 74 (3) ◽  
pp. 1362-1366 ◽  
Author(s):  
J. A. Huwe ◽  
E. H. Peterson
Keyword(s):  
Brain Stem ◽  
Large Diameter ◽  
Small Diameter ◽  
Movement Control ◽  
Three Dimensions ◽  
Significant Shift ◽  
Axon Diameter ◽  
Vestibular Complex ◽  
The Brain ◽  
Adjacent Brain

1. We visualized the central axons of 32 vestibular afferents from the posterior canal by extracellular application of horseradish peroxidase, reconstructed them in three dimensions, and quantified their morphology. Here we compare the descending limbs of central axons that differ in parent axon diameter. 2. The brain stem distribution of descending limb terminals (collaterals and associated varicosities) varies systematically with parent axon diameter. Large-diameter afferents concentrate their terminals in rostral regions of the medial/descending nuclei. As axon diameter decreases, there is a significant shift of terminal concentration toward the caudal vestibular complex and adjacent brain stem. 3. Rostral and caudal regions of the medial/descending nuclei have different labyrinthine, cerebellar, intrinsic, commissural, and spinal connections; they are believed to play different roles in head movement control. Our data help clarify the functions of large- and small-diameter afferents by showing that they contribute differentially to rostral and caudal vestibular complex.

scholarly journals Fast radio burst detection in the presence of coloured noise

2021 ◽  
Vol 503 (4) ◽  
pp. 5223-5231
Author(s):  
C F Zhang ◽  
J W Xu ◽  
Y P Men ◽  
X H Deng ◽  
Heng Xu ◽  
...  
Keyword(s):  
False Alarm ◽  
Radio Burst ◽  
Pulse Width ◽  
False Alarm Probability ◽  
False Positives ◽  
Parameter Distribution ◽  
Correlated Noise ◽  
Width Distribution ◽  
Fast Radio Burst ◽  
The Impact

ABSTRACT In this paper, we investigate the impact of correlated noise on fast radio burst (FRB) searching. We found that (1) the correlated noise significantly increases the false alarm probability; (2) the signal-to-noise ratios (S/N) of the false positives become higher; (3) the correlated noise also affects the pulse width distribution of false positives, and there will be more false positives with wider pulse width. We use 55-h observation for M82 galaxy carried out at Nanshan 26m radio telescope to demonstrate the application of the correlated noise modelling. The number of candidates and parameter distribution of the false positives can be reproduced with the modelling of correlated noise. We will also discuss a low S/N candidate detected in the observation, for which we demonstrate the method to evaluate the false alarm probability in the presence of correlated noise. Possible origins of the candidate are discussed, where two possible pictures, an M82-harboured giant pulse and a cosmological FRB, are both compatible with the observation.

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