Background:A previous study has reported a 50% reduction in disuse atrophy of the quadriceps during the first 14 days after anterior cruciate ligament(ACL) reconstruction.A follow-up trial is needed to confirm these p...Background:A previous study has reported a 50% reduction in disuse atrophy of the quadriceps during the first 14 days after anterior cruciate ligament(ACL) reconstruction.A follow-up trial is needed to confirm these promising results.The present study aims to investigate the effect of an occlusion stimulus on quadriceps atrophy after ACL reconstruction.Methods:A total of 24 subjects participated in the study.They were randomized into two groups.Starting the 2nd day after surgery,the occlusion group received an occlusion stimulus for 5 min,followed by removal of the occlusive pressure for 3 min.This was repeated five times in one training session,twice daily.During the period of occlusive stimulus,the subjects performed 20 low load exercises for the quadriceps.The control group followed the same exercise protocol,but without the occlusion stimulus.Changes in quadriceps anatomical cross section area(ACSA) were measured using axial magnetic resonance(MR) images at 40% and 50% of the length of the femur.Results:Both groups had a significant reduction of quadriceps ACSA from 2 days before surgery to 16 days after surgery.During the intervention period,the occlusion group lost 13.8% ± 1.1%(mean ± SEM) and the control group lost 13.1% ± 1.0% of their quadriceps ACSA,respectively.There was no significant difference between the occlusion and control groups with regards to atrophy of the quadriceps muscles.Conclusion:In conflict with other studies using a similar protocol,application of blood flow restriction the first 14 days after ACL reconstruction did not reduce quadriceps ACSA muscle atrophy measured by MR in a population of athletes.展开更多
This review discusses the pathophysiology,epidemiology,risk factors,classification,clinical evaluation,and current non-operative and operative treatment of hemorrhoids.Hemorrhoids are defined as the symptomatic enlarg...This review discusses the pathophysiology,epidemiology,risk factors,classification,clinical evaluation,and current non-operative and operative treatment of hemorrhoids.Hemorrhoids are defined as the symptomatic enlargement and distal displacement of the normal anal cushions.The most common symptom of hemorrhoids is rectal bleeding associated with bowel movement.The abnormal dilatation and distortion of the vascular channel,together with destructive changes in the supporting connective tissue within the anal cushion,is a paramount finding of hemorrhoids.It appears that the dysregulation of the vascular tone and vascular hyperplasia might play an important role in hemorrhoidal development,and could be a potential target for medical treatment.In most instances,hemorrhoids are treated conservatively,using many methods such as lifestyle modification,fiber supplement,suppositorydelivered anti-inflammatory drugs,and administration of venotonic drugs.Non-operative approaches include sclerotherapy and,preferably,rubber band ligation.An operation is indicated when non-operative approaches have failed or complications have occurred.Several surgical approaches for treating hemorrhoids have been introduced including hemorrhoidectomy and stapled hemorrhoidopexy,but postoperative pain is invariable.Some of the surgical treatments potentially cause appreciable morbidity such as anal stricture and incontinence.The applications and outcomes of each treatment are thoroughly discussed.展开更多
The present work introduces a mathematical model for ionic fluid that flows under the effect of both pulsating pressure and axial electromagnetic field. The fluid is treated as a Newtonian fluid applying Navier-Stokes...The present work introduces a mathematical model for ionic fluid that flows under the effect of both pulsating pressure and axial electromagnetic field. The fluid is treated as a Newtonian fluid applying Navier-Stokes equation. The fluid is considered as a neutral mixture of positive and negative ions. The effect of axial electric field is investigated to determine velocity profiles. Hydroelectric equation of the flow is deduced under dc and ac external electric field. Hence the effect of applied frequency (0-1 GHz) and amplitude (10-350 V/m) is illustrated. The ultimate goal is to approach the problem of EMF field interaction with blood flow. The applied pressure waveform is represented as such to simulate the systolic-diastolic behavior. Simulation was carried out using Maple software using blood plasma parameters; hence velocity profiles under various conditions are reported.展开更多
A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell (RBC) in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calcula...A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell (RBC) in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calculated by our model agree with those computed by a shooting method very well. Our simulation results show that in a shear flow, biconcave RBC becomes highly flattened and undergoes tank-treading motion. With intrinsically parallel dynamics, this lattice Boltzmann method is expected to find wide applications to both single and multi-vesicles suspension as well as complex open membranes in various fluid flows for a wide range of Reynolds numbers.展开更多
Objective:To explore the therapeutic methods, surgical indications and clinical practice of minimally invasive surgery on traumatic epidural hematoma(EDH). Methods:Retrospective study was made on 135 patients with tra...Objective:To explore the therapeutic methods, surgical indications and clinical practice of minimally invasive surgery on traumatic epidural hematoma(EDH). Methods:Retrospective study was made on 135 patients with traumatic EDH admitted into our hospital from June 2002 to August 2005.Sixty-five patients were treated with mini-invasive negative pressure drainage (treatment group),70 patients with comparable condition used traditional craniotomy(control group).The mean time of operation,average days in hospital,expenditure and prognosis of two groups were recorded and analyzed. Results:There was no significant difference in therapeutic efficacy between two groups.Patients in treatment group had a shorter hospital stay and less expenditure than those in control group. Conclusion:Mini-invasive negative pressure drainage is simple,effective,economical and applicable to some traumatic EDH patients.展开更多
By using the lattice Boltzmann method(LBM)pulsatile blood flows were simulated in three-dimensional moderate stenosed and recanalized carotid bifurcations to understand local hemodynamics and its relevance in arterial...By using the lattice Boltzmann method(LBM)pulsatile blood flows were simulated in three-dimensional moderate stenosed and recanalized carotid bifurcations to understand local hemodynamics and its relevance in arterial atherosclerosis formation and progression.The helical flow patterns,secondary flow and wall dynamical pressure spatiotemporal distributions were investigated,which leads to the disturbed shear forces in the carotid artery bifurcations.The wall shear stress distributions indicated by time-averaged wall shear stress(TAWSS),oscillatory shear index(OSI),and the relative residence time(RRT)in a cardiac cycle revealed the regions where atherosclerotic plaques are prone to form,extend or rupture.This study also illustrates the point that locally disturbed flow may be considered as an indicator for early atherosclerosis diagnosis.Additionally the present work demonstrates the robust and highly efficient advantages of the LBM for the hemodynamics study of the human blood vessel system.展开更多
This paper constructs a mathematical model for blood flow through an artery with mild stenosis. Constitutive equations for Carreau fluid are employed in the mathematical modeling. Analysis has been carried out in the ...This paper constructs a mathematical model for blood flow through an artery with mild stenosis. Constitutive equations for Carreau fluid are employed in the mathematical modeling. Analysis has been carried out in the presence of constant magnetic field. Symmetric and asymmetric shapes of stenosis are taken. Governing flow model is computed for the series solution. Whe flow quantities of interest, for instance, axial velocity, pressure gradient, pressure drop, impedance and shear stress at the walls of stenotic artery are described for various pertinent parameters entering into the problem.展开更多
In this paper, a smooth repetitive osciflating wave traveling down the elastic walls of a non-uniform two- dimensional channels is considered. It is assumed that the fluid is electrically conducting and a uniform magn...In this paper, a smooth repetitive osciflating wave traveling down the elastic walls of a non-uniform two- dimensional channels is considered. It is assumed that the fluid is electrically conducting and a uniform magnetic field is perpendicular to flow. The Sisko fluid is grease thick non-Newtonian fluid can be considered equivalent to blood. Taking long wavelength and low Reynolds number, the equations are reduced. The analytical solution of the emerging non-linear differential equation is obtained by employing Homotopy Perturbation Method (HPM). The outcomes for dimensionless flow rate and dimensionless pressure rise have been computed numerically with respect to sundry concerning parameters amplitude ratio , Hartmann number M, and Sisko fluid parameter bl. The behaviors for pressure rise and average friction have been discussed in details and displayed graphically. Numerical and graphical comparison of Newtonian and non-Newtonian has also been evaluated for velocity and pressure rise. It is observed that the magnitude of pressure rise is maximum in the middle of the channel whereas for higher values of fluid parameter it increases. Further, it is also found that the velocity profile shows converse behavior along the walls of the channel against multiple values of fluid parameter.展开更多
This paper deals with the theoretical investigation of a fundamental problem of magne- tohydrodynamic (MHD) flow of blood in a capillary in the presence of thermal radiation and chemical reaction. The unsteadiness i...This paper deals with the theoretical investigation of a fundamental problem of magne- tohydrodynamic (MHD) flow of blood in a capillary in the presence of thermal radiation and chemical reaction. The unsteadiness in the flow and temperature fields is caused by the time-dependence of the stretching velocity and the surface temperature. The fluid is considered to be non-Newtonian, whose flow is governed by the equation of a third-order fluid. The problem is first reduced to solving a system of coupled nonlinear differential equations involving several parameters. Considering blood as an electrically conducting fluid and using the present analysis, an attempt is made to compute some parameters of the blood flow by developing a suitable numerical method and by devising an appropri- ate finite difference scheme. The computational results are presented in graphical form, and thereby some theoretical predictions are made with respect to the hemodynamical flow of the blood in a hyperthermal state under the action of a magnetic field. Com- putational results for the variation in velocity, temperature, concentration, skin-friction coefi^icient, Nusselt number and Sherwood number are presented in graphical/tabular form. Since the study takes care of thermal radiation in blood flow, the results reported here are likely to have an important bearing on the therapeutic procedure of hyperthermia, particularly in understanding blood flow and heat transfer in capillaries.展开更多
文摘Background:A previous study has reported a 50% reduction in disuse atrophy of the quadriceps during the first 14 days after anterior cruciate ligament(ACL) reconstruction.A follow-up trial is needed to confirm these promising results.The present study aims to investigate the effect of an occlusion stimulus on quadriceps atrophy after ACL reconstruction.Methods:A total of 24 subjects participated in the study.They were randomized into two groups.Starting the 2nd day after surgery,the occlusion group received an occlusion stimulus for 5 min,followed by removal of the occlusive pressure for 3 min.This was repeated five times in one training session,twice daily.During the period of occlusive stimulus,the subjects performed 20 low load exercises for the quadriceps.The control group followed the same exercise protocol,but without the occlusion stimulus.Changes in quadriceps anatomical cross section area(ACSA) were measured using axial magnetic resonance(MR) images at 40% and 50% of the length of the femur.Results:Both groups had a significant reduction of quadriceps ACSA from 2 days before surgery to 16 days after surgery.During the intervention period,the occlusion group lost 13.8% ± 1.1%(mean ± SEM) and the control group lost 13.1% ± 1.0% of their quadriceps ACSA,respectively.There was no significant difference between the occlusion and control groups with regards to atrophy of the quadriceps muscles.Conclusion:In conflict with other studies using a similar protocol,application of blood flow restriction the first 14 days after ACL reconstruction did not reduce quadriceps ACSA muscle atrophy measured by MR in a population of athletes.
基金Supported by Faculty of Medicine Siriraj Hospital,Mahidol University,Bangkok,Thailand
文摘This review discusses the pathophysiology,epidemiology,risk factors,classification,clinical evaluation,and current non-operative and operative treatment of hemorrhoids.Hemorrhoids are defined as the symptomatic enlargement and distal displacement of the normal anal cushions.The most common symptom of hemorrhoids is rectal bleeding associated with bowel movement.The abnormal dilatation and distortion of the vascular channel,together with destructive changes in the supporting connective tissue within the anal cushion,is a paramount finding of hemorrhoids.It appears that the dysregulation of the vascular tone and vascular hyperplasia might play an important role in hemorrhoidal development,and could be a potential target for medical treatment.In most instances,hemorrhoids are treated conservatively,using many methods such as lifestyle modification,fiber supplement,suppositorydelivered anti-inflammatory drugs,and administration of venotonic drugs.Non-operative approaches include sclerotherapy and,preferably,rubber band ligation.An operation is indicated when non-operative approaches have failed or complications have occurred.Several surgical approaches for treating hemorrhoids have been introduced including hemorrhoidectomy and stapled hemorrhoidopexy,but postoperative pain is invariable.Some of the surgical treatments potentially cause appreciable morbidity such as anal stricture and incontinence.The applications and outcomes of each treatment are thoroughly discussed.
文摘The present work introduces a mathematical model for ionic fluid that flows under the effect of both pulsating pressure and axial electromagnetic field. The fluid is treated as a Newtonian fluid applying Navier-Stokes equation. The fluid is considered as a neutral mixture of positive and negative ions. The effect of axial electric field is investigated to determine velocity profiles. Hydroelectric equation of the flow is deduced under dc and ac external electric field. Hence the effect of applied frequency (0-1 GHz) and amplitude (10-350 V/m) is illustrated. The ultimate goal is to approach the problem of EMF field interaction with blood flow. The applied pressure waveform is represented as such to simulate the systolic-diastolic behavior. Simulation was carried out using Maple software using blood plasma parameters; hence velocity profiles under various conditions are reported.
基金supported by National Natural Science Foundation of China under Grant No. 10747004the Guangxi Science Foundation under Grant Nos. 0640064 and 0542045
文摘A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell (RBC) in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calculated by our model agree with those computed by a shooting method very well. Our simulation results show that in a shear flow, biconcave RBC becomes highly flattened and undergoes tank-treading motion. With intrinsically parallel dynamics, this lattice Boltzmann method is expected to find wide applications to both single and multi-vesicles suspension as well as complex open membranes in various fluid flows for a wide range of Reynolds numbers.
文摘Objective:To explore the therapeutic methods, surgical indications and clinical practice of minimally invasive surgery on traumatic epidural hematoma(EDH). Methods:Retrospective study was made on 135 patients with traumatic EDH admitted into our hospital from June 2002 to August 2005.Sixty-five patients were treated with mini-invasive negative pressure drainage (treatment group),70 patients with comparable condition used traditional craniotomy(control group).The mean time of operation,average days in hospital,expenditure and prognosis of two groups were recorded and analyzed. Results:There was no significant difference in therapeutic efficacy between two groups.Patients in treatment group had a shorter hospital stay and less expenditure than those in control group. Conclusion:Mini-invasive negative pressure drainage is simple,effective,economical and applicable to some traumatic EDH patients.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars
文摘By using the lattice Boltzmann method(LBM)pulsatile blood flows were simulated in three-dimensional moderate stenosed and recanalized carotid bifurcations to understand local hemodynamics and its relevance in arterial atherosclerosis formation and progression.The helical flow patterns,secondary flow and wall dynamical pressure spatiotemporal distributions were investigated,which leads to the disturbed shear forces in the carotid artery bifurcations.The wall shear stress distributions indicated by time-averaged wall shear stress(TAWSS),oscillatory shear index(OSI),and the relative residence time(RRT)in a cardiac cycle revealed the regions where atherosclerotic plaques are prone to form,extend or rupture.This study also illustrates the point that locally disturbed flow may be considered as an indicator for early atherosclerosis diagnosis.Additionally the present work demonstrates the robust and highly efficient advantages of the LBM for the hemodynamics study of the human blood vessel system.
文摘This paper constructs a mathematical model for blood flow through an artery with mild stenosis. Constitutive equations for Carreau fluid are employed in the mathematical modeling. Analysis has been carried out in the presence of constant magnetic field. Symmetric and asymmetric shapes of stenosis are taken. Governing flow model is computed for the series solution. Whe flow quantities of interest, for instance, axial velocity, pressure gradient, pressure drop, impedance and shear stress at the walls of stenotic artery are described for various pertinent parameters entering into the problem.
文摘In this paper, a smooth repetitive osciflating wave traveling down the elastic walls of a non-uniform two- dimensional channels is considered. It is assumed that the fluid is electrically conducting and a uniform magnetic field is perpendicular to flow. The Sisko fluid is grease thick non-Newtonian fluid can be considered equivalent to blood. Taking long wavelength and low Reynolds number, the equations are reduced. The analytical solution of the emerging non-linear differential equation is obtained by employing Homotopy Perturbation Method (HPM). The outcomes for dimensionless flow rate and dimensionless pressure rise have been computed numerically with respect to sundry concerning parameters amplitude ratio , Hartmann number M, and Sisko fluid parameter bl. The behaviors for pressure rise and average friction have been discussed in details and displayed graphically. Numerical and graphical comparison of Newtonian and non-Newtonian has also been evaluated for velocity and pressure rise. It is observed that the magnitude of pressure rise is maximum in the middle of the channel whereas for higher values of fluid parameter it increases. Further, it is also found that the velocity profile shows converse behavior along the walls of the channel against multiple values of fluid parameter.
文摘This paper deals with the theoretical investigation of a fundamental problem of magne- tohydrodynamic (MHD) flow of blood in a capillary in the presence of thermal radiation and chemical reaction. The unsteadiness in the flow and temperature fields is caused by the time-dependence of the stretching velocity and the surface temperature. The fluid is considered to be non-Newtonian, whose flow is governed by the equation of a third-order fluid. The problem is first reduced to solving a system of coupled nonlinear differential equations involving several parameters. Considering blood as an electrically conducting fluid and using the present analysis, an attempt is made to compute some parameters of the blood flow by developing a suitable numerical method and by devising an appropri- ate finite difference scheme. The computational results are presented in graphical form, and thereby some theoretical predictions are made with respect to the hemodynamical flow of the blood in a hyperthermal state under the action of a magnetic field. Com- putational results for the variation in velocity, temperature, concentration, skin-friction coefi^icient, Nusselt number and Sherwood number are presented in graphical/tabular form. Since the study takes care of thermal radiation in blood flow, the results reported here are likely to have an important bearing on the therapeutic procedure of hyperthermia, particularly in understanding blood flow and heat transfer in capillaries.