Stress Distributions inside Intervertebral Discs: The Validity of Experimental ‘Stress Profilometry’

1996 ◽  
Vol 210 (2) ◽  
pp. 81-87 ◽  
Author(s):  
D W McMillan ◽  
D S McNally ◽  
G Garbutt ◽  
M A Adams
Keyword(s):  
Compressive Stress ◽  
Applied Load ◽  
Compressive Force ◽  
Intervertebral Discs ◽  
Calibration Coefficient ◽  
Similar Distribution ◽  
Stress Distributions ◽  
Cross Sectional ◽  
Transducer Output ◽  
Stress Profiles

This paper evaluates a technique for measuring the distribution of compressive stress within cadaveric intervertebral discs. A strain-gauged pressure transducer, side-mounted near the tip of a 1.3 mm diameter needle, was inserted into cubes of disc tissue and into intact discs. Regardless of the position and orientation of the transducer within the tissue or disc, its output was found to be proportional to the compressive force applied to the specimen. The distribution of compressive stress was measured by pulling the instrumented needle through the specimen and the resulting stress profiles were reproducible to within 20 per cent. Profiles obtained at different applied loads showed a similar distribution of stress within the disc, suggesting that the compressive stress at any location and direction increased in proportion to the applied load. Since transducer output was also proportional to applied load, it was reasoned that it must be proportional to compressive stress within the disc. The average vertical compressive stresses acting on various regions within a disc were calculated from the stress profiles and multiplied by the cross-sectional area of each region: the resulting force was then compared with the known applied force in order to assess the calibration coefficient of the transducer. Agreement between the two forces was good, indicating that the calibration coefficient established in a saline bath was applicable to disc tissues also. However, artifactual stress peaks could be generated if the transducer was pulled across a bony asperity. It is concluded that the transducer measures the mean compressive stress acting upon it within disc tissues. Errors associated with the technique are small compared to differences in stress distributions which occur naturally, for example when intervertebral discs are loaded to simulate different postures in a living person.

scholarly journals Evaluating the Hardness Characteristics of Hail through Compressive Strength Measurements

2015 ◽  
Vol 32 (11) ◽  
pp. 2100-2113 ◽  
Author(s):  
Ian M. Giammanco ◽  
Tanya M. Brown ◽  
Rosemarie G. Grant ◽  
Douglas L. Dewey ◽  
Jon D. Hodel ◽  
...  
Keyword(s):  
Compressive Stress ◽  
Field Measurement ◽  
Testing Machine ◽  
Impact Resistance ◽  
Compressive Load ◽  
Compressive Force ◽  
Measurement Device ◽  
Cross Sectional ◽  
Pass Filter ◽  
Low Pass Filter

AbstractThroughout historical literature anecdotal or visual observations have been used to describe the hardness property of hailstones (e.g., hard, soft, slushy). A unique field measurement device was designed and built to apply a compressive force to the point of fracture on hailstones in the field. The device uses a pistol-grip clamp to apply a compressive load to a hailstone and integrates a fast-response load cell and associated data acquisition components to measure the applied force through the point of fracture. The strain rate applied to the stone is fast enough to produce a brittle failure, and the peak compressive force is appropriately scaled by the cross-sectional area to produce a compressive stress value. When compared to an Instron universal testing machine (UTM), the field measurement device exhibited a low bias induced by measurement hardware sampling limits. When a low-pass filter was applied to the Instron data to replicate the hardware properties of the field measurement device, good agreement was found for compressive force tests performed on laboratory ice spheres, and it was clear the device was capturing a relative measure of strength. The mean compressive stress for natural hail was similar to that of pure ice spheres, but individual thunderstorm events exhibited variability. Laboratory ice spheres also showed significant variability, which argues for large sample sizes when testing any material for impact resistance.

scholarly journals Cauda equina redundant nerve roots are associated to the degree of spinal stenosis and to spondylolisthesis

2014 ◽  
Vol 72 (10) ◽  
pp. 782-787 ◽  
Author(s):  
Leonor Garbin Savarese ◽  
Geraldo Dias Ferreira-Neto ◽  
Carlos Fernando Pereira da Silva Herrero ◽  
Helton Luiz Aparecido Defino ◽  
Marcello H. Nogueira-Barbosa
Keyword(s):  
Spinal Stenosis ◽  
Cauda Equina ◽  
Intervertebral Discs ◽  
Observer Agreement ◽  
Nerve Roots ◽  
Cross Sectional ◽  
Dural Sac ◽  
Increased Risk ◽  
Independent Risk Factors ◽  
Lumbar Spinal

To evaluate the association of redundant nerve roots of cauda equina (RNRCE) with the degree of lumbar spinal stenosis (LSS) and with spondylolisthesis. Method After Institutional Board approval, 171 consecutive patients were retrospectively enrolled, 105 LSS patients and 66 patients without stenosis. The dural sac cross-sectional area (CSA) was measured on T2w axial MRI at the level of L2-3, L3-4 and L4-5 intervertebral discs. Two blinded radiologists classified cases as exhibiting or not RNRCE in MRI. Intra- and inter-observer reproducibility was assessed. Results RNRCE were associated with LSS. RRNCE was more frequent when maximum stenosis<55 mm2. Substantial intra- observer agreement and moderate inter-observer agreement were obtained in the classification of RNRCE. Spondylolisthesis was identified in 27 patients and represented increased risk for RRNCE. Conclusion LSS is a risk factor for RNRCE, especially for dural sac CSA<55 mm2. LSS and spondylolisthesis are independent risk factors for RNRCE.

scholarly journals Leisure physical activity of people with and without chronic non-communicable diseases

2020 ◽  
Vol 73 (suppl 6) ◽  
Author(s):  
Thainá Ferreira de Toledo Piza ◽  
Paula Parisi Hodniki ◽  
Sinval Avelino dos Santos ◽  
Maria Teresa da Costa Gonçalves Torquato ◽  
Adrielen Aparecida Silva Calixto ◽  
...  
Keyword(s):  
Physical Activity ◽  
Leisure Activities ◽  
Cross Sectional Study ◽  
Communicable Diseases ◽  
Study Data ◽  
Similar Distribution ◽  
Cross Sectional ◽  
Non Communicable Diseases ◽  
The City ◽  
Leisure Physical Activity

ABSTRACT Objectives: to analyze the leisure physical activity of people with and without chronic non-communicable diseases by the single health system of the city of Ribeirão Preto – São Paulo. Methods: observational cross-sectional study, data were collected by means of interviews in a sample for convenience and random of adults. Results: there were 719 people, where 70.1% had chronic non-communicable diseases, being 68.1% inactive. Physical inactivity presents a similar distribution between the groups with and without disease and a national average in leisure physical activity. Conclusions: these data are aimed at health services that do not encourage physical and auditory leisure activities, such as multiprofessional activities in the health area.

scholarly journals Epidemiology and outcomes of gastroparesis, as documented in general practice records, in the United Kingdom

Gut ◽  
2020 ◽  
pp. gutjnl-2020-321277 ◽  
Author(s):  
Yizhou Ye ◽  
Baoguo Jiang ◽  
Sudhakar Manne ◽  
Peter L Moses ◽  
Cristina Almansa ◽  
...  
Keyword(s):  
General Practice ◽  
Population Based ◽  
Pharmacological Therapy ◽  
Diabetic Gastroparesis ◽  
Practice Research ◽  
Mortality Data ◽  
Clinical Practice Research Datalink ◽  
Common Disease ◽  
Similar Distribution ◽  
Cross Sectional

ObjectiveTo generate real-world evidence for the epidemiology of gastroparesis in the UK, we evaluated the prevalence, incidence, patient characteristics and outcomes of gastroparesis in the Clinical Practice Research Datalink (CPRD) database.DesignThis was a retrospective, cross-sectional study. Prevalence and incidence of gastroparesis were evaluated in the CPRD database, with linkage to Hospital Episodes Statistics Admitted Patient Care and Office for National Statistics mortality data. Prevalence and incidence were age and sex standardised to mid-2017 UK population estimates. Descriptive analyses of demographics, aetiologies, pharmacological therapies and mortality were conducted.ResultsStandardised prevalence of gastroparesis, as documented in general practice records, was 13.8 (95% CI 12.6 to 15.1) per 100 000 persons in 2016, and standardised incidence of gastroparesis rose from 1.5 (95% CI 1.1 to 1.8) per 100 000 person-years in 2004 to 1.9 (95% CI 1.4 to 2.3) per 100 000 person-years in 2016. The most common disease aetiologies were idiopathic (39.4%) and diabetic gastroparesis (37.5%), with a similar distribution of type 1 and type 2 diabetes among the 90% who had type of diabetes documented. Patients with diabetic gastroparesis had a significantly higher risk of mortality than those with idiopathic gastroparesis after diagnosis (adjusted HR 1.9, 95% CI 1.2 to 3.0). Of those with gastroparesis, 31.6% were not offered any recognised pharmacological therapy after diagnosis.ConclusionThis is, to our knowledge, the first population-based study providing data on epidemiology and outcomes of gastroparesis in Europe. Further research is required to fully understand the factors influencing outcomes and survival of patients with gastroparesis.

Channel Strain Analysis in Damascene-gate pMOSFETs on Si (100) and (110) Substrate by Conventional and Cross-sectional Raman Spectroscopy

2009 ◽  
Vol 1194 ◽  
Author(s):  
Munehisa Takei ◽  
Daisuke Kosemura ◽  
Kohki Nagata ◽  
Hiroaki Akamatsu ◽  
Satoru Mayuzumi ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Compressive Stress ◽  
Measurement Data ◽  
Strain Analysis ◽  
Channel Length ◽  
Laser Exposure ◽  
Strain Component ◽  
Gate Stack ◽  
Cross Sectional ◽  
Channel Center

AbstractChannel strain in damascene gate pMOSFETs with compressive stress liner (c-SL) and embedded SiGe (eSiGe) were studied by micro-Raman spectroscopy with a quasi-line-shape UV excitation (λ=363.8nm). The channel strain profiles were obtained by the conventional mea-surement from the surface after dummy gate removal. The compressive strains at the channel edges were larger than that at the channel center for the relatively long gate length (Lgate). As the Lgate became smaller, although it became hard to recognize the strain profile, the compres-sive strain at the channel center increased by the superposition of the strain at the channel edges. However, channel strain disappeared in the measurement data for the channel length less than 160 nm. Thus, we extended the laser exposure time from 10 to 40 minutes to extract the channel strain component from obtained Raman spectra. The Raman peaks consisted of two or three peaks for the Lgate less than 160 nm. By multi peak fitting, we have succeeded in measuring the extremely large stress of - 2.4 GPa in the channel of Lgate = 30 nm pMOSFET. We also per-formed the cross-sectional measurements for the samples before and after metal-gate/high-k gate stack formation. Channel strain profiles were obtained similar to those by the conventional mea-surement. Extremely high device performance can be clearly explained by the compressive stress derived from the Raman measurements both in the Lgate dependence and eSiGe effect. We also demonstrated that Raman spectroscopy using cross-sectional measurement can evaluate the channel strain even in the MOSFETs after gate stack formation.

On the Linear Buckling of Circular Cylindrical Shells Under Asymmetric Axial Compressive Stress Distributions

1966 ◽  
Vol 70 (672) ◽  
pp. 1095-1097 ◽  
Author(s):  
D. J. Johns
Keyword(s):  
Compressive Stress ◽  
Cylindrical Shells ◽  
Bending Moment ◽  
Transverse Load ◽  
Stress Distributions ◽  
Pure Bending ◽  
Linear Buckling ◽  
Circular Cylindrical Shells ◽  
Axial Compressive Stress

The linear buckling of circular cylindrical shells is considered with particular attention to the cantilever shell subjected to either a pure bending moment (M) or transverse load (P)—see Fig. 1. It is believed that the conclusions reached have wider application to more general loading cases.

Effects of Freeze-Thaw Cycling on Material Properties of Cancellous Cervine Bone as Characterized by Nanoindentation

2013 ◽  
Author(s):  
Alexander K. Landauer ◽  
Philip A. Yuya ◽  
Laurel Kuxhaus
Keyword(s):  
Material Properties ◽  
Applied Load ◽  
Dynamic Testing ◽  
Small Scale ◽  
Phase Lag ◽  
Static Force ◽  
Cross Sectional ◽  
Freeze Thaw ◽  
Material Parameters ◽  
Storage And Loss Moduli

Cancellous bone is an important load-bearing component of whole bone, and due to the plate-and-rod nature of trabeculae, small-scale testing is required to measure material parameters for use in modern analytic techniques such as finite element modeling [1, 2]. These material properties are measurable via nanoindentation techniques. During nanoindentation, the indenter tip is forced into the surface of the material while the applied load and tip displacement are monitored. Using these data, along with the tip’s cross-sectional area, mechanical properties are determined. Dynamic testing quantifies viscoelastic response and can obtain material response parameters such as storage and loss moduli. During dynamic testing, a low magnitude sinusoidal force is superimposed on a constant static force. The displacement response is measured at the same frequency as the applied oscillating force, and the resulting phase lag is related to material damping [3].

Lateral grain growth in poly-Si films by gas flame high temperature annealing

1996 ◽  
Vol 441 ◽  
Author(s):  
W. F. Qu ◽  
A. Kitagawa ◽  
Y. Masaki ◽  
M. Suzuki
Keyword(s):  
High Temperature ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Grain Growth ◽  
Strain Energy ◽  
Driving Forces ◽  
Stress Distributions ◽  
High Temperature Annealing ◽  
Gas Flame ◽  
Si Films

AbstractPoly-Si films with the preferential orientation to a random, a (100) and a (110) texture were annealed using a flat gas flame. Remarkable lateral grain growth of (111) grains was observed for poly-Si films with a random and a (110) texture, while in (100) texture films the growth of (100) grains predominated over other grains. There existed tensile stress in as-prepared films. Grains with different orientation were under a different tensile stresses, and such stress distributions on the orientation of grains were different for different textures. The tensile stress was found to become larger in grown grains after high temperature annealing, while the stress on shrunken grains decreased or turned to compressive stress after annealing. These results indicate that strain energy stored in grains is one of the important driving forces in secondary grain growth.

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