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91.
A new one-step computational procedure is presented for estimating the parameters of the nonlinear three-element windkessel
model of the arterial system incorporating a pressure-dependent compliance. The data required are pulsatile aortic pressure
and flow. The basic assumptions are a steadystate periodic regime and a purely elastic compliant element. By stating two conditions,
zero mean flow and zero mean power in the compliant element, peripheral and characteristic resistances are determined through
simple closed form formulas as functions of mean values of the square of aortic pressure, the square of aortic flow, and the
product of aortic pressure with aortic flow. The pressure across as well as the flow through the compliant element can be
then obtained so allowing the calculation of volume variation and compliance as functions of pressure. The feasibility of
this method is studied by applying it to both simulated and experimental data relative to different circulatory conditions
and comparing the results with those obtained by an iterative parameter optimization algorithm and with the actual values
when available. The conclusion is that the proposed method appears to be effective in identifying the three-element windkessel
even in the case of nonlinear compliance. 相似文献
92.
Dr. B. K. van Kreel N. Cox-Reyven P. Soeters 《Medical & biological engineering & computing》1998,36(3):337-345
Multifrequency bio-electronic impedance analysis (MF BIA) measurements are taken from a heterogeneous group of patients, varying
in size between obese and slim. The measuring system uses four electrodes: two current and two potential electrodes. Three
new models are developed to calculate total body water (TBW) from the BIA data, and the resulting TBW values are compared
with TBW determined by D2O dilution. The results demonstrate that the most simple model provides the best TBW values. For individual patients, TBW
can be determined by means of bioimpedance measurement with an accuracy of 3 litres. In the most simple model (model 1), the
body is electrically represented by a cylinder, and corrections are made for the amount of fat. This is an extension of the
model used by Xitron. In the more advanced models (2 and 3), the body is represented by a cylinder for the trunk, and truncated
cones represent the arms and legs. In model 2, ΔTBW amounts to 3 litres. It is shown that the resistance of the trunk is proportional
to the square root of the length. In model 3, it is assumed that subcutaneous fat is a poor conductor if electric current.
An equation is developed that describes the partition of subcutaneous fat, and the fat layer is then removed from the cones
representing arms and legs and from the cylinder that models the trunk. 相似文献
93.
Zuochen Du Anwei Chen Lu Huang Xin Dai Qiuyue Chen Di Yang Liling Li Heather Miller Lisa Westerberg Yuan Ding Xuemei Tang Masato Kubo Liping Jiang Xiaodong Zhao Hua Wang Chaohong Liu 《The Journal of allergy and clinical immunology》2021,147(5):1907-1923.e6
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94.
目的比较3D打印个性化截骨工具辅助(patient-specific instrumentation,PSI)下人工全膝关节置换术(total knee arthroplasty,TKA)与传统TKA的手术精确度和临床疗效。方法自2017年9月至2018年12月,将40例拟接受初次膝关节置换患者随机分为2组,每组均为20人。一组应用个性化截骨工具辅助TKA手术(PSI组),另一组接受传统TKA(对照组)。比较两组患者的冠状面下肢机械轴线、手术时间、术中出血量、术后引流量以及HSS评分。结果对照组和PSI组的手术时间分别为(103.3±18.7) min和(91.3±15.7) min;术中出血量分别为(372.0±53.0)mL和(332.8±47.0)mL;术后引流量分别为(378.8±97.2)mL和(315.0±89.0)mL。两组手术时间、术中出血量、术后引流量比较差异均有统计学意义(P0.05)。对照组和PSI组术后2周HSS评分分别为(89.3±2.8)分和(88.7±2.9)分,两组比较差异无统计学意义(P0.05)。对照组和PSI组术后全下肢力线差值分别为(1.9±1.1)°和(1.2±1.0)°,冠状面股骨假体角度(frontal femoral component angle,FFC)差值分别为(2.1±1.1)°和(1.1±0.9)°,两组比较差异有统计学意义(P0.05)。冠状面胫骨假体角度(frontal tibia component angle,FTC)差值分别为(1.3±0.8)°和(1.4±0.8)°,两组比较差异无统计学意义(P0.05)。结论PSI辅助TKA较传统TKA手术时间更短、术中出血量更少,并且术后冠状面全下肢力线及股骨力线的改善优于传统TKA手术。 相似文献
95.
James W. Verbsky Mary K. Hintermeyer Pippa M. Simpson Mingen Feng Jody Barbeau Nagarjun Rao Carlyne D. Cool Luis A. Sosa-Lozano Dhiraj Baruah Erin Hammelev Alyssa Busalacchi Amy Rymaszewski Jeff Woodliff Shaoying Chen Mary Bausch-Jurken John M. Routes 《The Journal of allergy and clinical immunology》2021,147(2):704-712.e17
96.
The classification of some of the extractable birch pollen antigens as allergens was established by crossed radioimmunoelectrophoresis (CRIE). In CRIE the major allergen (antigen 23) exhibited the strongest “radiostaining” and only a few other components of birch pollen extract were visibly radiostained. The major allergen and a preparation containing mainly the minor allergens, antigens 25 and 19, were isolated from a crude aqueous birch pollen extract by a combination of anion-exchange, size-exclusion, and chelate chromatography. Antigen 23 was purified to near homogeneity. The molecular weights and the pIs of antigens 23, 25, and 19 were determined to be 17,000 daltons, pI 5.25 (5.5, 5.0); 25,000 daltons, pI 5.0 (4.9, 5.4); and 29,000 daltons, pI 6.2 (5.4), respectively. The classification of antigen 23 as the major allergen in birch pollen was supported by results of RAST inhibition experiments, RAST screening, and skin prick testing. 相似文献
97.
《The Knee》2021
BackgroundAs knee osteotomy surgery becomes increasingly accessible, more patients may turn to the Internet for information. This study examined the source, quality, content and readability of online information regarding osteotomy around the knee.MethodsThe first 70 websites returned by the top four search engines were identified using the key words: “knee osteotomy” and “high tibial osteotomy.” The websites were categorised by type and assessed using the DISCERN score, Journal of the American Medical Association (JAMA) benchmark criteria and a novel Knee Osteotomy-Specific Score (KOSS). The presence of the Health On the Net (HON) code accreditation seal was noted. Readability of each website was assessed using eight readability formulae. The mean reading grade level (RGL) was compared to the 6th and 8th grade reading levels. The mean RGL of each category was also compared.ResultsOf the 45 unique websites analysed, the majority were Physician (33%) and Journal websites (31%). The mean DISCERN score was 36.7 (±8.9) which is classified as ‘poor.’ The mean JAMA benchmark criteria score was 2.04 (±1.5) and Physician websites were most likely to be scored zero. The mean KOSS was 15.4 (±5.7). The highest scoring website was a Commercial site but, overall, Journal category sites provided the best quality information. Websites that bore the HONcode seal obtained higher DISCERN, JAMA benchmark criteria and Knee Osteotomy - Specific Scores.The cumulative mean RGL was 13.2 (±2.2) which exceeded the 6th grade level by an average of 7.2 grade levels and the 8th grade level by an average of 5.2 grade levels. No website (0%) was written at or below either the 6th or the 8th grade reading levels. The mean Flesch Reading Ease Score of all websites was 41.13 (±14.7) which is classified as ‘difficult.’ Journal websites had the highest RGL.ConclusionThe information available online regarding osteotomy around the knee varies tremendously in quality and completeness. Physician sites predominate, but these were among the lowest scoring of all websites. Even where high quality information is available, it is set at too high a level to be easily understood.Level of evidenceSurvey of materials – Internet. 相似文献
98.
Background
As assessment with inertial-measurement-units (IMUs) increases in research and in clinics, it is important to be aware of the repeatability of these sensors. The objectives of this experiment were to evaluate the measurement repeatability of IMU joint angles using a repeatable robot controller and an anthropomorphic leg phantom and to determine effects of joint speed and sensor positioning on the angles collected by these sensors. Comparisons to an electro-goniometer and three-dimensional (3D) motion capture cameras were also completed.Methods
Two dual-IMU setups (posterior and lateral) were tested concurrently with an electro-goniometer and 3D motion capture cameras using a repeatable robot controller and a leg phantom. All modalities were attached to the phantom, which was flexed 10 times using a pre-programmed motion pathway during each test. Mean angles were compared across tests. Effects of joint speed, sensor re-positioning, and anatomical placement of the sensors on repeatability were assessed.Results
Re-positioning caused greater deviation to the maximum and minimum angles than differences in speed. Overall, the means?±?standard deviations, and 95% confidence intervals of the maximum angles across all tests for the 3D camera markers, electro-goniometer, posterior IMUs, and lateral IMUs were 119.4?±?0.3° (119.4, 119.5), 112.4?±?0.5° (112.3, 112.5), 116.2?±?2.4° (115.7, 116.7), and 118.3?±?1.1° (118.1, 118.6).Conclusions
Both posterior and lateral IMU setups demonstrated acceptable repeatability in measurement of range of motion that was advantageous to manual goniometer methods. Posterior and lateral IMU setups demonstrated overlapping standard deviations about their means. 相似文献99.
The purpose of this study was to investigate the time course of skeletal muscle adaptations resulting from high-intensity,
upper and lower body dynamic resistance training (WT). A group of 17 men and 20 women were recruited for WT, and 6 men and
7 women served as a control group. The WT group performed six dynamic resistance exercises to fatigue using 8–12 repetition
maximum (RM). The subjects trained 3 days a week for 12 weeks. One-RM knee extension (KE) and chest press (CP) exercises were
measured at baseline and at weeks 2, 4, 6, 8, and 12 for the WT group. Muscle thickness (MTH) was measured by ultrasound at
eight anatomical sites. One-RM CP and KE strength had increased significantly at week 4 for the female WT group. For the men
in the WT group, 1 RM had increased significantly at week 2 for KE and at week 6 for CP. The mean relative increases in KE
and CP strength were 19% and 19% for the men and 19% and 27% for the women, respectively, after 12 weeks of WT. Resistance
training elicited a significant increase in MTH of the chest and triceps muscles at week 6 in both sexes. There were non-significant
trends for increases in quadriceps MTH for the WT groups. The relative increases in upper and lower body MTH were 12%–21%
and 7%–9% in the men and 10%–31% and 7%–8% in the women respectively, after 12 weeks of WT. These results would suggest that
increases in MTH in the upper body are greater and occur earlier compared to the lower extremity, during the first 12 weeks
of a total body WT programme. The time-course and proportions of the increase in strength and MTH were similar for both the
men and the women.
Accepted: 6 September 1999 相似文献
100.
T. Yambe S. Nanka S. Naganuma S. Kobayashi S. Nitta T. Fukuju N. Uchida K. Tabayashi A. Tanaka K. Abe H. Takayasu M. Yoshizawa H. Takeda 《Journal of artificial organs》2002,5(1):1-5
Artificial circulation has been analyzed by decomposing it into parts. However, the sum of the decomposed parts is not equal
to the whole system, especially in nonlinear dynamic systems such as biological systems. To evaluate prosthetic circulation
as an entity, not as decomposed parts, nonlinear mathematical analytic techniques, including fractal dimension analyzing theory,
were used. Two pneumatically actuated ventricular assist devices were implanted as biventricular bypasses (BVB) in chronic
animal experiments using four healthy adult goats. For comparison between natural and prosthetic circulation in the same experimental
animals, the BVB-type complete prosthetic circulation model with ventricular fibrillation was adopted. All hemodynamic parameters
with natural and prosthetic circulation were recorded under awake conditions and calculated by a personal computer system.
By the use of nonlinear mathematical techniques, time-series data of the hemodynamics were embedded into the phase space,
and correlation dimension analysis was performed to evaluate the reconstructed attractor. Our results suggest that the correlation
dimension of the arterial blood pressure does not linearly increase according to the increase of the embedding dimension,
even during artificial circulation, suggesting those are the fractal time series data. Dimensional analysis of the hemodynamics
revealed that lower dimensional fractal dynamics were observed during prosthetic circulation. Fractal time series data are
suggested to have robustness and error resistance. Thus, our results suggest that the circulatory regulatory system with the
artificial heart may have these desirable characteristics.
Accepted: July 14, 1995 相似文献