Efficient Denoising Framework for Mammogram Images with a New Impulse Detector and Non-Local Means

Objective: The survival rates of breast cancer are increasing as screening and diagnosis improve. The removal of noise is revealed to be a significant step for automatic - computer aided detection (CAD) of microcalcification in digital mammography. Methods: In this paper, a combined approach for eradicating impulse noise from digital mammograms is proposed. The process is achieved in two stages, detection of noise followed by filtering of noise. The detection of noise is carried out by using Modified Robust Outlyingness Ratio (mROR) trailed by an extended NL (Non-Local)-means filter for filtering mechanism. Results: According to the value of mROR, all pixels in mammogram images are divided into four distinct groups. In each cluster, many decision rules are then applied for detecting the impulse noise. Filtering is done with NL-means filter by providing a reference mammogram image. Conclusion: The comparative analysis and evaluated results are compared with some existing filters which indicate that the proposed structure outperforms the analysed result of others.     

Does the video head impulse test replace caloric testing in the assessment of patients with chronic dizziness? A systematic review and meta-analysis

IntroductionCaloric testing is the most frequently used test to assess peripheral vestibular function since the beginning of the 20th century. However, the video head impulse test, vHIT, has gained prominence in the field of neurotology, as it is a faster examination, easier to perform and less uncomfortable for the patient.ObjectiveTo compare, through systematic review and meta-analysis, the proportion of altered cases between vHIT tests and caloric testing in patients with chronic dizziness, in addition to assessing the sensitivity and specificity of vHIT, with caloric testing as the gold standard.MethodsThe literature search was carried out in the PubMed, Scopus, BVS-Bireme, Web of Science, Embase, Cochrane and ProQuest indexed databases, with no restrictions regarding the publication period. All articles that contained the results of the two tests were included in the evaluation of patients with dizziness. Two researchers independently conducted data selection and extraction from the studies, strictly following the inclusion and exclusion criteria defined in the research protocol. In case of disagreement during the selection, a discussion was carried out with a third evaluator.ResultsEleven of the 1293 initial articles met the eligibility criteria and were analyzed. 2670 patients were evaluated, of which 1112 (41.6%) were males and 1558 (58.4%) females, with a mean age of 51.6 years. The proportion of altered results in the vHIT was 21% (95%CI 9% –33%), and 55% in the caloric testing (95%CI 43% –67%).ConclusionThe vHIT does not substitute for caloric testing. The tests are complementary in assessing the patient with dizziness, as they describe the tonotopy of the ampullary crest at different frequency ranges of stimulation. In chronic cases, the vHIT has a low sensitivity and high diagnostic specificity in comparison to caloric testing.     

脉冲振荡技术在儿童支气管舒张试验中的应用

目的：探讨脉冲振荡方法(IOS)在儿童支气管舒张试验中的应用及其与常规肺量计法结果的相关关系。方法：发作期的哮喘患儿同时应用两种方法做吸入支气管扩张剂前后肺功能测定，以FEV1改善≥15％判断为阳性，应用统计学处理对两种方法各指标作相关性分析。结果：IOS各指标舒张后改善明显，△Zrs、△R5与金标准△FEV1密切相关，经多元回归得出方程△FEV1=-1．527△Zrs 0．883△R5。结论：IOS法可以作为不能配合用力呼气动作的儿童行支气管舒张试验。     

Hydrodynamic aspects of pyelocalyceal peristalsis

This study was undertaken to determine the nature of pressure changes in manometric studies of renal pelvis and calyces. In previous studies in pigs it has been assumed that pressure increases occur in the contracting segments of the renal pelvis and calyces, but our observations suggested that these increases were actually due to distension of noncontracted segments. Pressures were recorded with two catheters introduced percutaneously into the pyelocalyceal system with simultaneous video recording of the fluoroscopic image. There was no pressure rise in the calyces or the renal pelvis when these segments contracted; however, pressure rose when the noncontracted calyces were distended by a remote contraction ring. These findings confirmed the observations at kinetic urography. They agreed with the hydrodynamic experience that the pressure in a ring-shaped contracted segment is lower than upstream and downstream of that segment. It was concluded that if the porcine pyelocalyceal system is a valid model of the human, the pressure increases, assumed to be contractions, were actually caused by the injection and distension of the noncontracted segments.     

Advection and Diffusion of Substances in Biological Tissues With Complex Vascular Networks

For highly diffusive solutes the kinetics of blood–tissue exchange is only poorly represented by a model consisting of sets of independent parallel capillary–tissue units. We constructed a more realistic multicapillary network model conforming statistically to morphometric data. Flows through the tortuous paths in the network were calculated based on constant resistance per unit length throughout the network and the resulting advective intracapillary velocity field was used as a framework for describing the extravascular diffusion of a substance for which there is no barrier or permeability limitation. Simulated impulse responses from the system, analogous to tracer water outflow dilution curves, showed flow-limited behavior over a range of flows from about 2 to 5 ml min^–1 g^–1, as is observed for water in the heart in vivo. The present model serves as a reference standard against which to evaluate computationally simpler, less physically realistic models. The simulated outflow curves from the network model, like experimental water curves, were matched to outflow curves from the commonly used axially distributed models only by setting the capillary wall permeability–surface area (PS) to a value so artifactually low that it is incompatible with the experimental observations that transport is flow limited. However, simple axially distributed models with appropriately high PSs will fit water outflow dilution curves if axial diffusion coefficients are set at high enough values to account for enhanced dispersion due to the complex geometry of the capillary network. Without incorporating this enhanced dispersion, when applied to experimental curves over a range of flows, the simpler models give a false inference that there is recruitment of capillary surface area with increasing flow. Thus distributed models must account for diffusional as well as permeation processes to provide physiologically appropriate parameter estimates. © 2000 Biomedical Engineering Society. PAC00: 8719-j, 8710+e     

Preponderance for either α or β-adrenoceptor mediated sensitization in the rat submaxillary gland

The sensitivity of the rat submaxillary gland was examined 3–4 weeks after either parasympathetic decentralization or sympathetic decentralization or denervation. The threshold doses for secretion of saliva of parasympathomimetic (methacholine) and sympathomimetic (noradrenaline, adrenaline, phenylephrine and isoprenaline) drugs were estimated and the amount of saliva secreted in response to supraliminal doses of these drugs was measured. Each type of operation caused the development of a supersensitivity that involved all three types of receptors, i.e. muscarinic cholinoceptors, alpha;-adrenoceptors and β-adrenoceptors. Following parasympathetic decentralization the sensitization was predominantly mediated via α-adrenoceptors, and also via cholinoceptors. Following sympathetic decentralization or denervation the postjunctional sensitization was predominantly mediated via β-adrenoceptors; most of the supersensitivity to noradrenaline, adrenaline and phenylephrine found after sympathetic denervation was of the prejunctional type. An increase in receptor density and an intracellular arrangement where the response of cholinoceptors and α-adrenoceptors is mediated via one pathway and the response of β-adrenoceptors via another are suggested as factors that may be of importance for the development of the postjunctional supersensitivity. The present study shows that the traffic of secretory impulses in the sympathetic nerve is of importance for the level of sensitivity of the secretory cells. Since postjunctional supersensitivity following sympathetic denervation did not exceed that following sympathetic decentralization it is suggested that under normal conditions a continuous release of noradrenaline from the nerve endings is of little importance for the level of sensitivity.     

神经脉冲波传播形态的研究

Hodgkin-Huxley模型（H—H模型）是研究神经电生理不可或缺的数学依据。但是，到目前为止，对H—H神经元模型的分析缺少解析研究。本文对经典的H-H模型进行具体分析，得到简化H—H模型以及Nagumo方程，利用齐次平衡方法首次求出简化H-H方程和Nagumo方程的孤波解。研究表明：神经冲动可以孤波的模式传播。     

Removal of cardiac beat artifact in oesophageal pressure measurement by frequency analysis

Oesophageal pressure (Pes) measurements are important in medical research and useful in clinical diagnosis. Measurements, however, are contaminated heavily by cardiac artifacts. The spectrum and waveform of the Pes signal is obtained from the oesophageal balloon. Adaptive finite impulse response (AFIR) filter and modified adaptive noise cancellation (MANC) methods are adopted to filter out cardiac beat interference. These results are compared. In the frequency domain, frequency variations and spectral overlap between the Pes components and cardiac beat signal components impact on the performance of the filter. From our experimental results on power strength, the fourth or higher harmonics did not have any significant effect on the filter performance. However, the second harmonics of these signals had a significant effect on the filtering result. Thus, in the design of AFIR filters, attention is needed to minimise these effects. In frequency analysis, these harmonics or overlapping frequencies do not affect MANC. MANC was the better method for eliminating cardiac beat artifact in Pes measurement. The dynamic compliance (Cdyn) was also used to evaluate the performance of MANC and AFIR. The standard deviation of Cdyn was less than 0.15 using MANC, compared with standard deviations as high as 0.57 for AFIR. We conclude that MANC performs better than AFIR.