Bone Resorption Induced by Fluid Flow

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Lars Johansson ◽  
Ulf Edlund ◽  
Anna Fahlgren ◽  
Per Aspenberg
Keyword(s):  
Fluid Flow ◽  
Soft Tissue ◽  
Bone Resorption ◽  
Energy Density ◽  
Fluid Pressure ◽  
Time History ◽  
State Of Stress ◽  
Fluid Flow Velocity ◽  
History Of ◽  
Tissue Interface

A model where bone resorption is driven by stimulus from fluid flow is developed and used as a basis for computer simulations, which are compared with experiments. Models for bone remodeling are usually based on the state of stress, strain, or energy density of the bone tissue as the stimulus for remodeling. We believe that there is experimental support for an additional pathway, where an increase in the amount of osteoclasts, and thus osteolysis, is caused by the time history of fluid flow velocity, fluid pressure, or other parameters related to fluid flow at the bone/soft tissue interface of the porosities in the bone.

A Model for Bone Resorption

2006 ◽  
Author(s):  
Lars Johansson ◽  
Ulf Edlund ◽  
Anna Fahlgren ◽  
Per Aspenberg
Keyword(s):  
Fluid Flow ◽  
Bone Resorption ◽  
Constitutive Model ◽  
Bone Tissue ◽  
Driving Force ◽  
Strain State ◽  
Bone Remodelling ◽  
Fluid Pressure ◽  
Fluid Flow Velocity ◽  
Surgical Implants

In the present paper a model for the resorption of bone, such as that observed at the interface between surgical implants and bone tissue, is developed. While there are many previous studies where models for bone remodelling calculations are proposed, these have been based on the stress or strain state of the bone tissue itself as the driving force for bone remodelling. We, instead, develop a constitutive model based on observations in recent experiments where it seems that fluid pressure, or possibly fluid flow velocity, is a major factor in the bone resorption process.

Transient Stresses and Displacement Around a Wellbore Due to Fluid Flow in Transversely Isotropic, Porous Media: I. Infinite Reservoirs

1968 ◽  
Vol 8 (01) ◽  
pp. 63-78 ◽  
Author(s):  
M.S. Seth ◽  
K.E. Gray
Keyword(s):  
Porous Media ◽  
Fluid Flow ◽  
Porous Body ◽  
Radial Displacement ◽  
Fluid Pressure ◽  
Transversely Isotropic ◽  
The State ◽  
Tangential Stresses ◽  
State Of Stress ◽  
Rock Formations

Abstract Equations of elasticity for transversely isotropic, axisymmetric, homogeneous, porous media exhibiting pore fluid pressure were formulated. Using an analogy between thermal and porous body stresses, it was shown that the solution for a transversely isotropic porous body may be obtained by incorporating body forces and the stresses due to a boundary load into the corresponding solution for the thermal stress problem. Equations of elasticity and the thermal analogy method were used to determine transient horizontal, tangential, and vertical s tresses and radial displacement in a semi-infinite cylindrical region when either a constant pressure or a constant rate of flow is maintained at the wellbore. The vertical and tangential displacements are zero from the conditions of the problem. A numerical analysis was made of the solutions obtained by using a digital computer to determine the relative influence of each system variable. Considering rock as a porous body with internal fluid pressure generally gives results significantly different than considering the rock to be nonporous; the directional character of rocks leads to significant differences as compared to results based upon the common assumption of isotropy. Stress gradients are high near the wellbore but die out away from the well. Radial stresses are compressive or neutral, whereas tangential stresses are tensile, neutral or compressive, depending upon the boundary conditions and physical properties of the system. Vertical stresses are compressive for an unbounded system. For constant wellbore injection rate, the vertical stress is proportional to the rate of fluid injection and decreases with time, whereas the radial and tangential stresses increase with time. At a given location, the radial displacement generally is very dependent upon time. INTRODUCTION A realistic appraisal of the state of stress in subsurface rock formations would be of considerable interest and use to the petroleum industry. For example, knowing the state of stress in proximity to a wellbore would be of fundamental importance in designing a fracturing operation or, more important, of clearly understanding the conditions necessary to produce rock failure of desired dimensions and geometry. Understanding conditions necessary for rock failure at the wellbore would also be of utility in a preventive sense. For example, borehole stability is an important consideration for many rock formations, and knowledge of the stress state at and near the wellbore under conditions of substantial pressure gradient due to fluid flow would be of great value. When fluid flows through a porous body which is initially at some uniform stress level, the following forces generate stresses at any point in the body.Forces due to nonuniform pressure distribution. With increasing pressure the elements of a body are compressed. Such compression cannot proceed freely in a continuum when the pressure is not uniform throughout, and thus, stresses due to flow of fluid are set up.Pore fluid pressure. This gives rise to normal stresses whose value at any point is the product of areal porosity and the fluid pressure. Although the fluid exerts uniform pressure, the stresses it creates in an anisotropic body may not be the same in all directions since the areal porosity in an anisotropic porous body is a direction-dependent quantity. This consideration leads to the concept of directional porosity.

U-Pb dating of overpressure veins in late Archean shales reveals six episodes of Paleoproterozoic deformation and fluid flow in the Pilbara craton

Geology ◽  
2020 ◽  
Vol 48 (10) ◽  
pp. 961-965 ◽  
Author(s):  
Birger Rasmussen ◽  
Jian-Wei Zi ◽  
Janet R. Muhling ◽  
Daniel J. Dunkley ◽  
Woodward W. Fischer
Keyword(s):  
Fluid Flow ◽  
Fluid Pressure ◽  
Ore Deposits ◽  
Banded Iron Formations ◽  
Mineral Growth ◽  
History Of ◽  
Iron Formations ◽  
Discrete Populations ◽  
Orogenic Events ◽  
Pilbara Craton

Abstract Fluid flow in the upper crust not only impacts the redistribution of heat and elements, driving the formation of economic ore deposits, but it also exerts control on metamorphism, metasomatism, and deformation. However, reconstructing the history of fluid flow in ancient basins is exceedingly difficult, particularly in Archean sedimentary rocks because of extensive overprinting and recrystallization. Here, we report U-Pb ages for monazite and xenotime that grew in bedding-parallel veins in 2.63–2.5-b.y.-old shales along the southern Pilbara craton, Australia. The U-Pb ages define six discrete populations, at 2.41 Ga, 2.30 Ga, 2.20 Ga, 2.10 Ga, 2.05 Ga, and 1.66 Ga, which formed ≥200 m.y. after deposition. The abundance of bedding-parallel crack-seal and fibrous veins in banded iron formations (BIFs) and underlying shales suggests a history of episodic buildup of fluid pressure followed by microfracturing, fluid expulsion, and mineral growth. Thermometry of vein minerals indicates temperatures between 230 °C and 320 °C, implicating the migration of hydrothermal fluids. The development of bedding-parallel veins at 2.41 Ga, 2.20 Ga, and 1.66 Ga was coeval with regional orogenic events known to have affected the craton, whereas vein growth at 2.30 Ga, 2.10 Ga, and 2.05 Ga reveals new episodes of deformation and fluid flow. Our results show that well-preserved Archean shales devoid of structural fabrics and >150 km inboard of the craton margin preserve a cryptic history of fluid overpressure, crack-seal vein development, and hydrothermal fluid flow between 2.41 and 1.66 b.y. ago.

A Rare Case of Spinal Leprosy Mimicking Spinal Tuberculosis

2019 ◽  
pp. 33
Author(s):  
K Thuraikumar ◽  
V Naveen ◽  
Mustaqim A ◽  
Arieff AA ◽  
K Shri ◽  
...  
Keyword(s):  
Back Pain ◽  
Soft Tissue ◽  
Histopathological Examination ◽  
Posterior Instrumentation ◽  
Spinal Tuberculosis ◽  
Previous History ◽  
Skin Lesions ◽  
Titanium Implants ◽  
Paravertebral Abscess ◽  
History Of

Introduction: Spinal tuberculosis is the most common manifestation of extrapulmonar y tuberculosis. A combination of leprosy and tuberculosis is a rare entity.Case report: A 44-year-old male patient working as a laborer presented to our hospital with complaints of severe back pain and swelling over the back, difficulty in walking, associated with constitutional symptoms. On admission, he was febrile and had leukocytosis. Initial spine X-ray showed end plate destruction and increase in soft tissue shadow at the level of T8-T9. CT spine revealed thoracic paravertebral collection extending from T7 to T9 levels, suggest ive of tuberculous spondylitis with cold abscess. Patient refused a transpedicular biopsy and was started on anti-tubercular therapy. Two weeks after commencement of treatment, he developed worsening back pain and weakness of the lower extremities. MRI spine showed a paravertebral abscess and posterior soft tissue edema involving level of T7 to T11. Patient underwent a posterior decompression, debridement and posterior instrumentation. He was discharged well, there was improvement of his lower limb power. Upon clinic review, he complained of multiple hyperpigmented, painless, nonpruritic skin lesions over the trunk and back. No previous history of eczema, psoriasis and Tinea corporis. Given the history of allergy, initial impression was hypersensitivity reaction towards the titanium implants, and he was started on anti-histamines. However, there was no improvements seen. Histopathological examination of skin lesions revealed presence of granuloma within the dermis layer, composed of epitheloid, histiocytes, lymphocytes and plasma cells. Wade-Fite stain for Mycobacterium leprae is positive. Slit skin smear shows multibacillary leprosy. Patient was started on multidrug therapy (rifampicin, clofazimine and dapsone) for 1 year. He has recovered well.International Journal of Human and Health Sciences Supplementary Issue: 2019 Page: 33

PROGRAM OF PREDICTION AND MANAGEMENT OF COINTEGED DYNAMIC ECONOMIC PROCESSES BASED ON THE CYBERNETIC APPROACH

2019 ◽  
Author(s):  
Olena Bundak ◽  
Nataliia Zubovetska
Keyword(s):  
Computer Program ◽  
Pair Correlation ◽  
Time History ◽  
Critical Area ◽  
Concrete Object ◽  
Graphic Arts ◽  
Ex Post ◽  
History Of ◽  
Successive Change ◽  
Rms Errors

A method and computer program ConRow, which prognostication of development of the dynamically CPLD economic transients is executed by, is described in the article. Such prognostication of economic processes is very important in the cases when their development can result in undesirable consequences, that to go out in the so-called critical area. Extrapolation in a critical area with the use of information about the conduct of the system at an area, near to it, allows to estimate to the lead through of experiment in the critical area of his consequence. For the imitation of conduct of object the function of review is set on entrance influence. For a concrete object this function can express, for example, dependence of change of level sale from time-history of charges on advertising and set as a numeral row. Statistics as a result of analysis of row are represented in a table, where the level of meaningfulness is set statistician, and also parameters of the handed over criteria. The graphic reflection of information is intended for visualization of analysis. Here represented on the points of graphic arts, the crooked smoothing which are calculated as полиномиальные regressions is added. The best approaching is controlled by sight on the proper graph, and also by minimization of their rms errors. Models of prognostication by sight and as formulas represented on graphic arts, the middle is here determined tailings and their chance is checked up on statistics of signs. After the got models determined also and prognosis values of influences and reviews. Establishing an order models of Сr(p) of co integrate regression is carried out separate custom controls. The coefficient of clay correlation of ruФ shows by itself pair correlation between lines with a successive change in relation to each other on a size to лагу of l = 1, 2, 3 . The program was tested on the example of ex-post prognosis at establishing an integration connection and possibility of prognostication of growth of nominal average monthly settlings on the basis of these statistical indexes of consumer inflation in Ukraine.

scholarly journals Comparison of Novel Seismic Protection Devices to Attenuate the Earthquake Induced Energy

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 73
Author(s):  
Osman Hansu ◽  
Esra Mete Güneyisi
Keyword(s):  
Lateral Displacement ◽  
Time History ◽  
Seismic Protection ◽  
Base Shear ◽  
Seismic Demands ◽  
Nonlinear Time History Analyses ◽  
History Of ◽  
Protection Devices ◽  
Nonlinear Time History ◽  
Better Than

This study addresses an alternative use of viscous dampers (VDs) associated with buckling restrained braces (BRBs) as innovative seismic protection devices. For this purpose, 4-, 8- and 12-story steel bare frames were designed with 6.5 m equal span length and 4 m story height. Thereafter, they were seismically improved by mounting the VDs and BRBs in three patterns, namely outer bays, inner bays, and all bays over the frame heights. The structures were modeled using SAP 2000 software and evaluated by the nonlinear time history analyses subjected to the six natural ground motions. The seismic responses of the structures were investigated for the lateral displacement, interstory drift, absolute acceleration, maximum base shear, and time history of roof displacement. The results clearly indicated that the VDs and BRBs reduced seismic demands significantly compared to the bare frame. Moreover, the all-bay pattern performed better than the others.

scholarly journals Development of a Field Deployable Firebrand Flux and Condition Measurement System

2020 ◽  
Author(s):  
Simone Zen ◽  
Jan C. Thomas ◽  
Eric V. Mueller ◽  
Bhisham Dhurandher ◽  
Michael Gallagher ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Time History ◽  
Infrared Camera ◽  
Thermal Conditions ◽  
Particle Characterization ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
New Instrument ◽  
History Of

AbstractA new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

scholarly journals P046 Pointing the finger: an unusual presentation of dactylitis

Rheumatology ◽  
2021 ◽  
Vol 60 (Supplement_1) ◽  
Author(s):  
Natalia Cernovschi - Feasey ◽  
Julekha Wajed
Keyword(s):  
Pleural Effusion ◽  
Soft Tissue ◽  
Middle Finger ◽  
Joint Involvement ◽  
Long Bones ◽  
History Of ◽  
Systemic Symptoms ◽  
The Right ◽  
Hands And Feet ◽  
Radiographic Changes

Abstract Background/Aims  Dactylitis is commonly associated with psoriatic arthritis, and regularly presents at Rheumatology clinics. We discuss a case where progressive systemic symptoms lead to the consideration of alternate diagnoses. Methods  A 46-year-old Nepalese woman presented to the Rheumatology department with a 3 month history of diffuse swelling of the right middle finger proximal interphalangeal joint, with the appearance of dactylitis. There was pain on movement, but no other joint involvement. Simultaneously she noticed blurred and decreased vision, which on review by the ophthalmologists, was diagnosed with bilateral uveitis. There was no history of psoriasis, inflammatory bowel disease, or other past medical history of note. There was no travel history in the past 12 months. A diagnosis of a presumed inflammatory arthritis was made. Results  Blood tests showed elevated c-reactive protein 55 (normal <4 mg/l), erythrocyte sedimentation rate 138 (normal 0-22 mm/hr) and an iron deficiency anaemia. Rheumatoid factor and Anti-CCP antibody were negative. Hand radiographs were reported as normal. MRI of the third digit confirmed an enhancing soft tissue collection at the proximal phalanx of the right middle finger. She was referred for a biopsy of this lesion. Interestingly over the subsequent few months, she developed progressive breathlessness. Chest radiograph showed a left pleural effusion. Further tests showed negative serum ACE, Lyme and Toxoplasma screen. Quantiferon test was negative. Pleural aspirate showed a transudate with negative Acid-fast bacillus (AFB) test and culture. CT chest and abdomen showed a persistent pleural effusion, inflammatory changes in the small bowel and thickening of the peritoneum and omentum. In view of the systemic involvement, a peritoneal tissue biopsy was performed. This confirmed chronic granulomatous inflammation with positive AFB stain for mycobacterium tuberculosis. Our patient was started on quadruple anti- TB antibiotics for 6 months. Her systemic symptoms and dactylitis have improved, although there is on-going treatment for her ocular involvement. Conclusion  Approximately 10% of all cases of extrapulmonary TB have osteoarticular involvement. Dactylitis is a variant of tuberculous osteomyelitis affecting the long bones of the hands and feet. It occurs mainly in young children; however adults may be affected also. The first manifestation is usually painless swelling of the diaphysis of the affected bone followed by trophic changes in the skin. The radiographic changes are known as spina ventosa, because of the ballooned out appearance of the bone, although this was not seen in our case. Fibrous dysplasia, congenital syphilis, sarcoidosis and sickle cell anaemia may induce similar radiographic changes in the metaphysis of long bones of hands and feet, but do not cause soft tissue swelling or periosteal reaction. This case highlights the importance of testing for TB, especially in atypical cases of dactylitis, with other systemic features. Disclosure  N. Cernovschi - Feasey: None. J. Wajed: None.

scholarly journals Hearing at threshold intensities: by slow mechanical traveling waves or by fast cochlear fluid pressure waves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haim Sohmer
Keyword(s):  
Soft Tissue ◽  
Hair Cells ◽  
Traveling Wave ◽  
Basilar Membrane ◽  
Fluid Pressure ◽  
Low Frequency ◽  
Frequency Discrimination ◽  
Outer Hair Cells ◽  
Common Mechanism ◽  
Frequency Stimulation

The three modes of auditory stimulation (air, bone and soft tissue conduction) at threshold intensities are thought to share a common excitation mechanism: the stimuli induce passive displacements of the basilar membrane propagating from the base to the apex (slow mechanical traveling wave), which activate the outer hair cells, producing active displacements, which sum with the passive displacements. However, theoretical analyses and modeling of cochlear mechanics provide indications that the slow mechanical basilar membrane traveling wave may not be able to excite the cochlea at threshold intensities with the frequency discrimination observed. These analyses are complemented by several independent lines of research results supporting the notion that cochlear excitation at threshold may not involve a passive traveling wave, and the fast cochlear fluid pressures may directly activate the outer hair cells: opening of the sealed inner ear in patients undergoing cochlear implantation is not accompanied by threshold elevations to low frequency stimulation which would be expected to result from opening the cochlea, reducing cochlear impedance, altering hydrodynamics. The magnitude of the passive displacements at threshold is negligible. Isolated outer hair cells in fluid display tuned mechanical motility to fluid pressures which likely act on stretch sensitive ion channels in the walls of the cells. Vibrations delivered to soft tissue body sites elicit hearing. Thus, based on theoretical and experimental evidence, the common mechanism eliciting hearing during threshold stimulation by air, bone and soft tissue conduction may involve the fast-cochlear fluid pressures which directly activate the outer hair cells.

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