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151.
基于霍尔传感器微阵列的呼吸频率检测系统设计 总被引:1,自引:0,他引:1
基于呼吸感应体积描记技术原理,在一条腹带内部嵌入了永磁铁,腹带系在患者腰部,在呼吸过程中,由于体积的变化引起腹带中永磁铁的位置运动,通过霍尔传感器阵列对永磁铁位置进行检测,从而判断呼气和吸气的过程,采用单片机对传感器信号进行分析处理,计算出呼吸频率。经10名受试者重复实验,并与呼吸检测设备的检测结果进行比较,本系统的平均精确度高于95%,证明了本系统的可靠性。所设计的呼吸频率检测系统可用于睡眠呼吸检测仪、慢呼吸高血压治疗仪等设备。 相似文献
152.
Jeffrey Barrell Jon Grant Alan Hanson Matthew Mahoney 《International journal of remote sensing》2013,34(16):4069-4094
Accurate maps representing seagrass spatial distribution are essential components for effective monitoring and management of coastal vegetated habitats. Satellite and acoustic remote sensing provide valuable spatial data for seagrass mapping, though few studies have evaluated the complementarity of these methods. In this study, the complementarity of seagrass mapping was assessed through comparison of acoustic and satellite remote-sensing data sets. QuickBird® satellite imagery representing the seagrass landscape of the Richibucto estuary, New Brunswick, Canada, was classified through an object-based procedure and evaluated against a single-beam sonar data set. Acoustic percentage cover values were classified into binary presence/absence format through the application of a decision threshold, allowing comparison with satellite data using the error matrix and derived metrics. Though the binary satellite classification resulted in relatively high accuracy compared with independent ground reference data, agreement between satellite and acoustic data sets was limited. Local differences in seagrass prevalence and patchiness affected classification accuracy, highlighting the potential for under- or overestimating seagrass cover when applying bay-scale classification to areas with different landscape structure. These results emphasize the importance of landscape context in seagrass mapping. Satellite and acoustic remote sensing were seen to fundamentally differ in their depiction of the landscape. Comparison of multiple remote-sensing methods allowed for assessment of complementarity as well as ecologically relevant insight to seagrass spatial dynamics, with implications for mapping and monitoring of seagrass habitats. 相似文献
153.
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155.
Despite difficulties in using the Web, older adults are motivated to use it. This paper reports on work underway to ease Web access for this population. Although Web accessibility standards provide specifications that Web content providers must incorporate if their pages are to be accessible, these standards do not guarantee a good experience for all Web users. This paper will discuss user controls that make a number of dynamic adaptations to page presentation and input that can greatly increase the usability of Web pages for older users. The paper will discuss the authors original work on the topic, lessons learned, and usage patterns. Current extensions to that work are also discussed. 相似文献
156.
为筛选适于鲜食大豆采后贮藏保鲜的自发气调保鲜包装材料,研究微孔膜和不同厚度聚乙烯(polyethylene,PE)膜包装对鲜食大豆在冷藏(0.0±0.2) ℃期间采后生理及品质变化规律。结果表明:与微孔膜相比,PE膜包装对鲜食大豆具有更好的自发气调保鲜效果,O2体积分数平衡值为16%~17.5%,CO2体积分数平衡值为4.3%~5.8%时,能够更有效地抑制呼吸作用,延缓腐烂进程,降低质量损失率,抑制叶绿素的降解,保持鲜食大豆的水分和色泽。采用0.03 mm和0.05 mm PE膜包装的鲜食大豆无腐烂保鲜期达50 d,鲜食大豆腐烂率比微孔膜包装降低11%。综合来看,0.03 mm PE膜包装鲜食大豆的保鲜效果最好,适合于鲜食大豆贮藏流通过程中的保鲜。 相似文献
157.
基于Hough变换和遗传算法的SAR图像道路检测 总被引:3,自引:0,他引:3
提出了一种新的星载合成孔径雷达(SAR)图像中道路网的三步提取算法,即道路中心线检测、道路片段提取和道路片段连接。首先对含有斑点噪声的SAR图像进行两次滤波获得较细的道路中心线,然后对该二值图像进行Hough变换以获得道路片段,道路片段经过简单的初步连接后,再次运用遗传算法得到进一步连接。实践证明了这种方法的有效性。 相似文献
158.
PI Mitchell L León Vintró H Dahlgaard C Gascó JA Sánchez-Cabeza 《Canadian Metallurgical Quarterly》1997,202(1-3):147-153
Diabetes complicates 2-3% of all pregnancies and is associated with an increase in both perinatal morbidity and mortality, though reasons for these adverse outcomes are unknown. Estrogen biosynthesis is a critical factor during pregnancy and is carried out in the placenta via aromatase (cytochrome P450 19A1), which catalyzes the conversion of C-19 androgens to C-18 estrogens. Previous studies have shown that hormones such as insulin-like growth factors and insulin regulate aromatase activity when studied in vitro. Interestingly, levels of these hormones are altered in patients with diabetes. Thus, we hypothesized that the presence of maternal diabetes may alter placental aromatase activity and thus estrogen biosynthesis, possibly serving as one factor in the adverse outcomes of babies born to mothers with diabetes. To this end, we measured the production of 19-hydroxyandrostenedione, 19-oxoadrostenedione and estrone in 30 placental tissues from diabetic patients, using [7-3H]androst-4-ene-3,17-dione as a model substrate for aromatase (P450 19A1). A statistical difference was detected in the percentage of 19-oxoandrostenedione formed between the overt and control groups (P < 0.05). Additionally, NADPH P450-reductase levels were measured in these same tissues to determine whether alterations in this enzyme necessary for aromatase activity could be affected by diabetes. No differences in reductase levels were detected among the patient groups. However, a statistical correlation was found between NADPH P450-reductase activity and the formation velocities of all three estrogen products (P < 0.05). Thus, it appears that the presence of diabetes does not affect placental aromatase activity. 相似文献
159.
SD Gettings RA Lordo KL Hintze DM Bagley PL Casterton M Chudkowski RD Curren JL Demetrulias LC Dipasquale LK Earl PI Feder CL Galli SM Glaza VC Gordon J Janus PJ Kurtz KD Marenus J Moral WJ Pape KJ Renskers LA Rheins MT Roddy MG Rozen JP Tedeschi J Zyracki 《Canadian Metallurgical Quarterly》1996,34(1):79-117
The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data. 相似文献
160.
JA Chinn JA Sauter RE Phillips WJ Kao JM Anderson SR Hanson TR Ashton 《Canadian Metallurgical Quarterly》1998,39(1):130-140
OBJECTIVE: The effects of BRL-32872, azimilide and a selective blocker of the delayed rectifier potassium current, E-4031, were measured at two different basic cycle lengths (BCL), 300 and 1000 ms. Calcium channel antagonists of sarcolemmal (verapamil and nitrendipine) and sarcoplasmic reticulum (ryanodine) membranes were used to investigate whether the inhibition of the calcium current or the calcium release from the sarcoplasmic reticulum could alter the reverse-rate dependence of E-4031 on action potential duration (APD). METHODS: Guinea pig isolated papillary muscles were superfused with a Tyrode solution maintained at 37 degrees C and stimulated at a BCL of 300 or 1000 ms. The standard microelectrode technique was used to record action potential parameters and to study the effects of azimilide, BRL-32872 and E-4031. E-4031 was superfused at increasing concentrations (0.01, 0.03, 0.1 and 0.3 microM) in the absence or in the presence of verapamil (0.3 microM), nitrendipine (0.03 microM) or ryanodine (0.1 microM). RESULTS: BRL-32872 and azimilide induced a self-limited concentration-dependent increase in APD. The effect of BRL-32872 was not dependent on the stimulation frequency whereas the effect of azimilide was significantly reduced at the shorter BCL. E-4031 induced a concentration-dependent increase in APD at both stimulation BCL. The increase in APD was significantly more pronounced in fibres stimulated at a BCL of 1000 ms than in fibres stimulated at a BCL of 300 ms, characterising the reverse-frequency dependent effect of class III antiarrhythmic agents. The reverse-frequency dependence in action potential prolongation induced by E-4031 was significantly reduced in the presence of a low concentration of verapamil (0.3 microM), nitrendipine (0.03 microM), or ryanodine (0.1 microM. CONCLUSION: The results show that BRL-32872, in contrast to azimilide, does not induce the reverse-rate dependency of action potential prolongation typically produced by class III antiarrhythmic agents such as E-4031. Our results also show that reverse-rate dependency induced by E-4031 can be reduced by the simultaneous administration of a low concentration of a calcium channel antagonist or an inhibitor of the release of calcium from the sarcoplasmic reticulum. It is thus suggested that compounds with a suitable balance of potassium and calcium antagonistic activities may have less adverse effects than purely selective potassium channel blockers. 相似文献