A finite element analysis of the vibration behaviour of a cementless hip system

An early diagnosis of aseptic loosening of a total hip replacement (THR) by plain radiography, scintigraphy or arthography has been shown to be less reliable than using a vibration technique. However, it has been suggested that it may be possible to distinguish between a secure and a loose prosthesis using a vibration technique. In fact, vibration analysis methods have been successfully used to assess dental implant stability, to monitor fracture healing and to measure bone mechanical properties. Several studies have combined the vibration technique with the finite element (FE) method in order to better understand the events involved in the experimental technique. In the present study, the main goal is to simulate the change in the resonance frequency during the osseointegration process of a cementless THR (Zweymüller). The FE method was used and a numerical modal analysis was conducted to obtain the natural frequencies and mode shapes under vibration. The effects were studied of different bone and stem material properties, and different contact conditions at the bone–implant interface. The results were in agreement with previous experimental and computational observations, and differences among the different cases studied were detected. As the osseointegration process at the bone–implant interface evolved, the resonance frequency values of the femur–prosthesis system also increased. In summary, vibration analysis combined with the FE method was able to detect different boundary conditions at the bone–implant interface in cases of both osseointegration and loosening.     

Monitoring of fracture healing by lateral and axial vibration analysis

The ability to monitor the healing of bone fractures is crucially important in their treatment. The aim of the present study was to develop and validate an objective method for monitoring fracture healing based on bone vibrational response. An analytic model was formulated, with which the mechanical parameters at the fracture site could be studied in relation to both lateral and axial bone vibration. Non-uniformities in the stiffness of the bone at the fracture site can be detected since they produce shifting of the vibration and the phase spectrum and result in strong coupling between the lateral and axial vibration response spectra. The validity of the model was tested in experiments using fresh cadaver tibiae with transverse osteotomy and materials simulating fracture callus. The results of the study of vibration amplitude and phase angle and the coupling of axial and lateral vibration in these experiments confirm our analytic projection. Preliminary results of in vivo investigations using the described method are encouraging.     

Dynamics of the head-neck complex in response to the trunk horizontal vibration: modeling and identification

Although many studies exist concerning the influence of seat vibration on the head in the seated human body, the dynamic response of the head-neck complex (HNC) to the trunk vibration has not been well investigated. Little quantitative knowledge exists about viscoelastic parameters of the neck. In this study, the dynamics of the HNC is identified when it is exposed to the trunk horizontal (fore-and-aft) vibration. The frequency response functions between the HNC angular velocity and the trunk horizontal acceleration, corresponding to four volunteers, are obtained in the frequency range of 0.5 Hz to 10 Hz. A fourth-order mathematical model, derived by considering a double-inverted-pendulum model for the HNC, is designed to simulate the dynamic response of the HNC to the trunk horizontal vibration. The frequency domain identification method is used to determine the coefficients of the mathematical model of the HNC. Good agreement has been obtained between experimental and simulation results. This indicates that the system, similar to the designed fourth-order model, has mainly two resonance frequencies. The viscoelastic parameters of the neck, including the spring and damping coefficients, are then obtained by use of the optimization method.     

Effect of boundary conditions,impact loading and hydraulic stiffening on femoral fracture strength

Patient specific quantitative CT (QCT) imaging data together with the finite element (FE) method may provide an accurate prediction of a patient's femoral strength and fracture risk. Although numerous FE models investigating femoral fracture strength have been published, there is little consent on the effect of boundary conditions, dynamic loading and hydraulic strengthening due to intra-medullary pressure on the predicted fracture strength. We developed a QCT-derived FE model of a proximal femur that included node-specific modulus assigned based on the local bone density. The effect of three commonly used boundary conditions published in literature were investigated by comparing the resulting strain field due to an applied fracture load. The models were also augmented with viscoelastic material properties and subject to a realistic impact load profile to determine the effect of dynamic loads on the strain field. Finally, the effect of hydraulic strengthening was investigated by including node specific permeability and performing a coupled pore diffusion and stress analysis of the FE model. Results showed that all boundary conditions yield the same strain field patterns, but peak strains were 22% lower and fracture load was 18% higher when loaded at the greater trochanter than when loaded at the femoral head. Comparison of the dynamic models showed that material viscoelasticity was important, but inertial effects (vibration and shock) were not. Finally, pore pressure changes did not cause significant hydraulic strengthening of bone under fall impact loading.     

Treatment of mandibular angle fractures with a matrix miniplate: a preliminary report

Mandibular angle fractures are technically challenging, and a spectrum of techniques for treatment of these fractures has been proposed in the literature. Currently, fixation with one or two miniplates has become a widely accepted method of providing internal fixation and eliminating the need for postoperative maxillomandibular fixation. In this study, the utility of a single 2.0-mm matrix miniplate for mandibular angle fracture management was examined. In a laboratory biomechanical analysis, the overall stability of the single 2.0-mm matrix miniplate compared favorably with two 2.0-mm miniplates in a simulated fracture setting. The matrix miniplate demonstrated an overall better intrinsic stability, more resistance to out-of-plane fracture movement, and a higher load tolerance when motion out-of-plane was challenged. Clinically, the matrix miniplate performed well. In a series of 22 consecutive patients, there were no cases of nonunion, malunion, or plate failure. Two patients developed infection that was managed in both cases by drainage with maintenance of the miniplate. Both went on to full union. These results compare very favorably to previously published series using one or two miniplates.     

Clinical Utility of Insulin-Like Growth Factor 1 and 2; Determination by High Resolution Mass Spectrometry

Measurement of insulin-like growth factor-1 (IGF-I) has utility for the diagnosis and management of growth disorders, but inter-assay comparison of results has been complicated by a multitude of reference standards, antibodies, detection methods, and pre-analytical preparation strategies. We developed a quantitative LC-MS method for intact IGF-I, which has advantages in throughput and complexity when compared to mass spectrometric approaches that rely on stable isotope dilution analysis of tryptic peptides. Since the method makes use of full-scan data, the assay was easily extended to provide quantitative measurement of IGF-II using the same assay protocol. The validated LC-MS assay for IGF-I and IGF-II provides accurate results across the pediatric and adult reference range and is suitable for clinical use.     

An analytical study of blasting vibration using deep mining and drivage rules

For the study on the propagation–attenuation rule of the blasting vibration wave in the deep mining roadway of Shizishan copper mine, and the analysis of the influences of different maximum explosive charges and different underground systems on the propagation of blasting vibration signals, blasting vibration monitoring of the two different situations has been carried out respectively. Firstly, the Sadov’s Formula has been applied to analyzing the monitoring results of the mining roadway, and thus the value of its excavation blasting vibration attenuation index K and \(\alpha \) and its corresponding regression formula were attained; then, the appropriate regression formula was used to calculate the maximum explosive charge which could ensure the safety of the principal chambers underground the mine. Meanwhile, on the basis of the HHT analysis method, the rule of vibration wave propagation under these two different situations was analyzed. And the results indicated that, whether with an increase in the single charge, or with an increase in the number of the underground systems to cross, blasting seismic wave had a tendency for spreading to the low-frequency band. Through the regression analysis of the Sadov’s Formula and the HHT Method, the results provided a reliable basis for the safe and efficient production of the mine.     

核酸探针传感器的构建

依据石英振子的晶体谐振频率是其表面沉积物的函数,建立了简便、特异、敏感性达100pg,并能对受检样品相对定量的核酸杂交检测新方法,即压电晶体式核酸探针传感器,该方法的主要特点是以快速、敏感的频变信息作为核酸杂交的显示系统.     

Quantification of proteins using data-independent analysis (MSE) in simple andcomplex samples: a systematic evaluation

A MS‐based method for the quantification of proteins termed data‐independent analysis (or MS^E) has been introduced recently. Although this method has been applied to the analysis of various types of biological samples, a thorough evaluation to assess the performance of this approach has yet to be conducted. Presented here is the first systematic and comprehensive study investigating the MS^E approach for quantitative analysis of low‐, medium‐, and high‐complexity samples. We demonstrate that this method has a linear dynamic range spanning three orders of magnitude with a limit of quantification of 61 amol/uL in low‐complexity samples and 488 amol/uL in high‐complexity samples. In addition, comprehensive sequence coverage was obtained and accurate quantification achieved for expression ratios ranging from 1:1.5 to 1:6. However, underestimation of ratios was detected independent of sample type, consistent with other quantitative proteomic methods. The present study provides validation of the MS^E approach for accurate quantitative proteomic analysis of biological samples while, at the same time, proving high sequence coverage of target proteins.     

T-lymphocytes enable osteoblast maturation via IL-17F during the early phase of fracture repair

While it is well known that the presence of lymphocytes and cytokines are important for fracture healing, the exact role of the various cytokines expressed by cells of the immune system on osteoblast biology remains unclear. To study the role of inflammatory cytokines in fracture repair, we studied tibial bone healing in wild-type and Rag1(-/-) mice. Histological analysis, μCT stereology, biomechanical testing, calcein staining and quantitative RNA gene expression studies were performed on healing tibial fractures. These data provide support for Rag1(-/-) mice as a model of impaired fracture healing compared to wild-type. Moreover, the pro-inflammatory cytokine, IL-17F, was found to be a key mediator in the cellular response of the immune system in osteogenesis. In vitro studies showed that IL-17F alone stimulated osteoblast maturation. We propose a model in which the Th17 subset of T-lymphocytes produces IL-17F to stimulate bone healing. This is a pivotal link in advancing our current understanding of the molecular and cellular basis of fracture healing, which in turn may aid in optimizing fracture management and in the treatment of impaired bone healing.     

Measurement of whole-body vibration by double-pulsed holography

A technique for registering vibration and deformation patterns has been adapted for the measurement of whole-body vibration in humans. Double-exposure holographic interferometry produces three dimensional pictures of the body, allowing exact measurement of the subject's movement between the two pulses. In this study an interval of 600 microseconds between the two pulses was used, producing measurements with a resolution of less than 0.3 X 10(-6)m. The subject standing in a fixed posture, was exposed to the laser beams first without vibration and then with vibration. The picture without vibration is needed as certain movements due to life functions of the body such as heartbeat, blood circulation etc are involved therein. This basic pattern should be considered when analysing the pictures with vibration. Different types of vibration in various postures were studied. Tests were also conducted when a reflective coating was applied to the skin. The results show that the method is applicable for measuring whole-body vibration and suggests further tests with more modern laser equipment which is now available. Such equipment can produce pulses with a high repetition rate and of much better quality than those obtained in this study. Once coordinated to the heartbeat and to the working frequency of the vibrating object, a reliable analysis of whole-body vibration can be maintained.     

Decision Analysis: A Method for Taking Uncertainties into Account in Risk-Based Decision Making

The assessment of human and ecological risks and associated risk-management decisions are characterized by only partial knowledge of the relevant systems. Typically, large variability and measurement errors in data create challenges for estimating risks and identifying appropriate management strategies. The formal quantitative method of decision analysis can help deal with these challenges because it takes uncertainties into account explicitly and quantitatively. In recent years, research in several areas of natural resource management has demonstrated that decision analysis can identify policies that are appropriate in the presence of uncertainties. More importantly, the resulting optimal decision is often different from the one that would have been chosen had the uncertainties not been taken into account quantitatively. However, challenges still exist to effective implementation of decision analysis.     

Assessing the current status of urban forest resources in the context of Parco Nord, Milan, Italy

During the early part of the 1980s, a major project called Parco Nord was undertaken by the Lombardia Region to establish forest resources within an industrial area located in the northern part of the city of Milan. Since 1983, more than 60 ha of formerly industrial land has been converted into urban forest plantations, thus creating large patches of trees with the potential to sustain a wide range of functions and services. This paper describes an integrative study aimed to assess the current status of forest resources in Parco Nord. It focuses on the actions taken to determine whether forest resources significantly changed their status 20 years after their establishment, considering historical field data and records of management practices. Analyses have been conducted at both stand and tree level by collecting quantitative and qualitative parameters. Stand-level analysis gave a quantitative estimation of the response of species to ecological conditions and management practices while tree-level analysis provided evidence of species renovation after thinning operations.     

New statistical approach to discriminate between protein coding and non-coding regions in DNA sequences and its evaluation

We propose a new approach to study protein coding and non-coding regions in DNA sequences, by making use of two complementary statistical methods. The principal component analysis (PCA) is a graphical method to represent DNA sequences which are characterized by some quantitative parameters: it is a help to the intuition. The discriminating analysis (DA) is a quantitative method which permits to classify the DNA sequences. It leads to an evaluation of the first method and to a decision. The value of this approach has been confirmed since we also have found some results which had been described recently in the literature. Furthermore, this general methodology has permitted us to show the existence of parameters which identify the nucleic acid sequence functional domains, without having to make use of the properties of the genetic code.     

A non-invasive acoustic and vibration analysis technique for evaluation of hip joint conditions

The performance evaluation of THA outcome is difficult and surgeons often use invasive methods to investigate effectiveness. A non-invasive acoustic and vibration analysis technique has recently been developed for more-in-depth evaluation of in vivo hip conditions.Gait kinematics, corresponding vibration and sound measurement of five THA subjects were analyzed post-operatively using video-fluoroscopy, sound and accelerometer measurements while walking on a treadmill. The sound sensor and a pair of tri-axial accelerometers, externally attached to the pelvic and femoral bone prominences, detected frequencies that are propagated through the femoral head and acetabular cup interactions. A data acquisition system was used to amplify the signal and filter out noise generated by undesired frequencies. In vivo kinematics and femoral head sliding quantified using video fluoroscopy were correlated to the sound and acceleration measurements.Distinct variations between the different subjects were identified. A correlation of sound and acceleration impulses with separation has been achieved. Although, in vivo sounds are quite variable in nature and all correlated well with the visual images.This is the first study to document and correlate visual and audible effects of THA under in-vivo conditions. This study has shown that the development of the acoustic and vibration technique provides a practical method and generates new possibilities for a better understanding of THA performance.     

我国城市可持续发展能力评估指标的元数据分析与管理

在我国大力推动城市可持续发展,推进国家可持续发展实验区建设的同时,采用何种评估方法和数据开展城市可持续发展能力评估是需要重点解决的问题。近年来兴起的元数据理论与技术在解决评估数据质量控制方面被视为是一种行之有效的方法。针对我国现阶段使用的一些城市可持续发展能力评估指标体系的特点,通过深入剖析每一个指标数据的来源、获取手段、适用方法等特征,提出从软件工程学思路研发城市可持续发展能力评估元数据管理系统的具体方法,帮助可持续发展实验区高效获取和管理评估所需数据信息;以"十二五"科技支撑计划项目"城市可持续发展能力评估及信息管理关键技术研究与示范"中所建立的元数据规范,对其所包含的"数据发布日期"、"数据发布形式"、"空间范围"、"时间范围(起始时间、结束时间)"、"统计频率"、"数据安全限制分级"、"数据志说明"、"在线资源链接地址"和"数据统计单位信息(单位名称、联络人、联系电话、单位地址、邮件地址)"共14项为评估数据的关键元数据项,以此追踪对标的评估数据。并通过量化数据质量评分法针对数据质量在运用元数据追踪法前后的评价结果对比发现,被评估指标的数据质量在获得元数据支持时,其数据可靠性、可比性和可持续性方面的评价分值都获得了十分显著的改善。研究认为采用元数据理论在控制和保障城市可持续发展能力评估数据质量方面具有优势作用,开发有针对性的城市可持续发展能力评估元数据管理系统能够有效提高评估数据的综合评价结果。     

A quantitative method for the analysis of glycated and glutathionylated hemoglobin by matrix-assisted laser desorption ionization-time of flight mass spectrometry

The quantization of glycated isoforms of hemoglobin has been increasingly used in clinical practice in recent years. Glycated hemoglobin is currently considered the most important measurement for long-term control of the glycemic state and it has become a reference tool for the management of diabetes. Glutathionylated hemoglobin is an increasingly clinically relevant covalent adduct of glutathione with beta chain of the globin and its concentration has been correlated with oxidative stress. We have developed an innovative technique based on linear mode matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry for quantitative analysis of hemoglobin species. This method was applied to the quantification of glycated and glutathionylated hemoglobin. A rigorous comparison was pursued to evaluate the analytical performances in quantifying glycated hemoglobin in comparison to an established high-performance liquid chromatography method. Our results indicated a complete equivalence between the two methods. The same analysis enabled the quantitative determination of the glutathionylated hemoglobin fraction. This isoform was investigated in an adult Italian population (184 individuals, 101 males and 83 females), indicating a bimodal distribution of this species. In fact 65.22% of screened individuals had glutathionylated hemoglobin levels lower than 0.50% while 34.78% had glutathionylated hemoglobin levels higher than 0.50%. A semiautomatic robotic procedure was developed for fast analysis of a large number of samples. This is the first report of a quantitative application of linear MALDI-TOF mass spectrometry for the determination of glutathionylated hemoglobin in blood samples. This method allows fast screening of this hemoglobin isoform, therefore opening the route to explore its specificity and sensitivity as a molecular biomarker.     

Analysis of current status data with missing covariates

Statistical inference based on right-censored data for the proportional hazards (PH) model with missing covariates has received considerable attention, but interval-censored or current status data with missing covariates has not yet been investigated. Our study is partly motivated by the analysis of fracture data from the 2005 National Health Interview Survey Original Database in Taiwan, where the occurrence of fractures was interval censored and the covariate osteoporosis was not reported for all residents. We assume that the data are realized from a PH model. A semiparametric maximum likelihood estimate implemented by a hybrid algorithm is proposed to analyze current status data with missing covariates. A comparison of the performance of our method with full-cohort analysis, complete-case analysis, and surrogate analysis is made via simulation with moderate sample sizes. The fracture data are then analyzed.     

Quantitative analysis of Tenecteplase in rat plasma samples using LC-MS/MS as an alternative for ELISA

An LC-MS/MS method has been developed for the quantitative determination of a protein drug (Tenecteplase; M(W) 58,777 Da) in rat plasma. The protein was digested with trypsin without prior clean-up of the plasma sample, without the use of a label nor internal standard. A limited validation was performed to assess the linearity, the sensitivity and the specificity of the method. In addition, the developed method was applied to the quantitative analysis of Tenecteplase in rat plasma samples originating from a single-dose study in rats.     

A critical distance study of stress concentrations in bone

The Theory of Critical Distances (TCD) is a method used to study the failure of material in situations where stress concentrations, such as holes and notches, are present. This method uses two material constants: a critical length and a critical stress. The elastic stress field close to the stress concentration is examined, applying a fracture criterion. The TCD has been applied to predict brittle fracture in various different materials and various types of notches but it has not previously been applied to bone. Since bone fails by brittle fracture with limited plasticity, it is expected that the TCD will be applicable. Experimental data were obtained from the literature on the effects of sharp notches and holes loaded in various ways (tension, torsion and bending). These tests were modelled using finite element analysis. It was found that the TCD could be successfully applied to predict the load required for brittle fracture as a function of the type and size of the stress concentration feature. The critical distance was found to be almost constant, about 0.3-0.4mm, for all types of bone studied: the critical stress was found to be related to the material's ultimate tensile strength by a constant factor of T=1.33. The results of this study will be of practical value in the assessment of stress concentration features introduced during surgery and of naturally occurring bone defects.