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1.
In order to detect and assess the muscle fatigue state with the surface electromyography(sEMG) characteristic parameters,this paper carried out a series of isometric contraction experiments to induce the fatigue on the forearm muscles from four subjects,and recorded the sEMG signals of the flexor carpi ulnaris.sEMG's median frequency(MDF) and mean frequency(MF) were extracted by short term Fourier transform(STFT),and the root mean square(RMS) of wavelet coefficients in the frequency band of 5—45 Hz was obtained by continuous wavelet transform(CWT).The results demonstrate that both MDF and MF show downward trends within 1 min; however,RMS shows an upward trend within the same time.The three parameters are closely correlated with absolute values of mean correlation coefficients greater than 0.8.It is suggested that the three parameters above can be used as reliable indicators to evaluate the level of muscle fatigue during isometric contractions.  相似文献   

2.
研究了肌肉静态及动态收缩过程中表面EMG信号演化模式的变化,发现了疲劳进程中肌电信号趋于规则性变化的规律,信号的所有规则性演化模式之和（以Dreg表示）的增加反映了该规律.与传统的疲劳指标相比,Dreg在刻画不同人体的肌肉疲劳时变异性更小.此外,基于时域的Dreg的计算可以避免传统频域指标的使用局限性.EMG信号规则度增加的发现,不仅为检测疲劳进程中EMG信号的变化提供了一种新的简易方法,更为以往工作中通过非线性指标（包括熵和复杂度等）来评估肌肉疲劳提供了有力的证据.介绍的信号规则度检测方法同样适用于其他生理电信号.  相似文献   

3.
The purpose of this study was to evaluate the instructional effects of using animations, static figures, PowerPoint bulletins, and e-plus software as chemistry texts with the aid of computer-based technology. This study analyzed the characteristics of students involved in three multimedia courses and their achievement and attitude toward chemistry and learning chemistry. The three samples included in this study involved 257 undergraduate engineering students enrolled in the courses during the academic year in which the study occurred. The results indicate that: (a) students acquired a better understanding of targeted chemistry concepts during the multimedia courses, (b) some categories of students, based on their major area of study, computer use, and attendance status at orientation achieved significantly (p < 0.05) higher post-test scores when adjusted for pre-test performance, and (c) significant differences and Cohen’s effect sizes in attitudes toward chemistry and learning chemistry were detected for students’ level of computer use, disposition toward computer multimedia, gender, and attendance at the multimedia orientation session. It appears to be helpful to incorporate computer-based multimedia (animations, images, sounds) teaching while utilizing constructivist design principles to facilitate students’ chemistry understanding and attitude toward chemistry and learning chemistry.  相似文献   

4.
T. Ramasarma 《Resonance》1999,4(4):31-41
Nitric Oxide(NO), a small molecule and a water-soluble gas, is formed in traces in several animal tissues. Its arrival on the biological scene was heralded by the magazine,Science as the “molecule of 1992”. It is biologically active as a signal molecule in relaxing contracted smooth muscle. Furchgott, Ignarro and Murad were awarded the Nobel Prize in Medicine or Physiology in 1998 for discovering this effect. Convergence of three independent lines of investigation led to recognition of vital roles of NO in cellular function-relaxation of smooth muscle tissue, cytotoxic function in macrophages, and transmission of signals in brain cells. The performance of NO in these three major physiological roles will be briefly described here. It will become obvious that NO can be a saviour, a killer or a messenger.  相似文献   

5.
1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｔｈｅｆｕｎｄａｍｅｎｔａｌｐｈｙｓｉｃａｌｍｅｔａｌｌｕｒｇｙｏｆｔｈｅｒｍｏｍｅｃｈａｎｉｃａｌｐｒｏｃｅｓｓｉｎｇ(ＴＭＰ)ｈａｓｂｅｃｏｍｅｍｕｃｈｂｅｔｔｅｒｕｎｄｅｒｓｔｏｏｄｏｖｅｒｔｈｅｌａｓｔｔｗｏｄｅｃａｄｅｓ[1～8].ＩｔｉｓｗｅｌｌｃｏｍｍｏｎｌｙｒｅｃｏｇｎｉｚｅｄｔｈａｔｔｈｅｍｉｎｕｔｅａｄｄｉｔｉｏｎｏｆｓｔｒｏｎｇｃａｒｂｏｎｉｔｒｉｄｅｏｒｎｉｔｒｉｄｅｆｏｒｍｉｎｇｅｌｅｍｅｎｔｓｓｕｃｈａｓＮｂ,ＴｉａｎｄＶｔａｋｅｓｖｅｒｙｉｍｐ…  相似文献   

6.
Background This study investigates children’s ability to generate inferences from narratives containing counterfactual information. Methods 39 typically developing readers (mean age 10; 05) completed an on-line task in which they were asked to read short passages, followed by sentences which they had to judge as true or false. The sentences pertained to either a causal inference or a static inference that could have been made during the reading of the passage. The passages and corresponding sentences were either true in terms of real world knowledge, or were presented as fairy tales. Results Results indicated that overall children responded faster and more accurately to sentences related to causal inferences than to static inferences. Responses to both types of inferences were slower in the ‘fairy story’ condition. Conclusions Children’s pattern of inference generation appears to be the same irrespective of the factual basis of the passage. However, responses to sentences based on inferences in the preceding passage are slower in fairy stories.  相似文献   

7.
The proportion of students enrolled at university from the lowest quartile of socio-economic position has remained static at around 15% for at least the past 15 years (DEEWR, Transforming Australia’s higher education system, 2009). This paper argues that the apparent lack of progress towards equity of access has been exacerbated due to how socio-economic position (SEP) is measured within higher education. Three major methodological issues are identified: (a) the use of socio-economic indicator for areas (SEIFA) at an inappropriate unit of geographic area (postcode), (b) an inappropriate choice of index (education and occupation), and (c) using the index of education and occupation as the sole indicator of SEP thereby increasing the risk of misclassification of individuals through the operation of ecological fallacy. This paper argues that to address these methodological deficiencies, alternative methods of determining SEP are required at both the aggregate and individual level. Possible options are proposed for use as replacements for the geographic area (postcode) and index (education and occupation) as well as additional measures at the individual or household level.  相似文献   

8.
Learners’ ability in dealing with socio-scientific issues has been highlighted in contemporary science education. This study explored the effects of different on-line searching activities on high school students’ cognitive structure outcomes and informal reasoning outcomes. By using a quasi-experimental research approach, thirty-three students were assigned to a “guided searching task group”, while thirty-five students were assigned to an “unguided searching task group”. The treatments of this study were two different on-line searching activities. All the participants were asked to search relevant information regarding nuclear power usage on the Internet during the period of two classes (100 min). However, the students in the un-guided searching task group were asked to search freely, while those in the guided searching task group were provided with a searching guideline. The participants’ cognitive structures outcomes as well as their informal reasoning outcomes regarding nuclear power usage were assessed before and after the conduct of on-line searching tasks. The results of ANCOVA revealed that the students in the guided on-line searching task group significantly outperformed their counterparts in the extent (p < 0.01) and the richness of their cognitive structures (p < 0.01). Also, they significantly outperformed their counterparts in the usage of the two information processing strategies, “comparing” (p < 0.05) and “inferring or explaining” (p < 0.05). Moreover, it was also found that the students in the guided on-line searching task group only outperformed their counterparts in their supportive argument construction (p < 0.05). In other words, the guided searching tasks did help the students obtain better cognitive structure outcomes; however, the increments on their cognitive structure outcomes may only help them to propose more supportive arguments, but their rebuttal construction (an important indicator for their reasoning quality) was not particularly improved.  相似文献   

9.
Let K be a closed convex subset of a real reflexive Banach space E, T：K→K be a nonexpansive mapping, and f：K→K be a fixed weakly contractive （may not be contractive） mapping. Then for any t∈（0, 1）, let x1∈K be the unique fixed point of the weak contraction x1→tf（x）＋（1-t）Tx. If T has a fixed point and E admits a weakly sequentially continuous duality mapping from E to E^＊, then it is shown that {xt} converges to a fixed point of T as t→0. The results presented here improve and generalize the corresponding results in （Xu, 2004）.  相似文献   

10.
This study investigated preschool science environments in 20 preschool classrooms (N=20) in 13 midwestern child care centers. By operationalizing Neuman’s concept of “sciencing,” this study used The Preschool Classroom Science Materials/Equipment Checklist, the Preschool Classroom Science Activities Checklist, and the Preschool Teacher Classroom/Sciencing Form to analyze the availability of science materials, equipment, and activities for preschoolers in the classroom. Each teacher was videotaped for two consecutive days during free play time. The study showed that half of the preschool classrooms had a science area. The activities that the preschool teachers engaged were mostly unrelated to science activities (86.8%), 4.5% of the activities were related to formal sciencing, and 8.8% of the activities were related to informal sciencing.  相似文献   

11.
INTRODUCTION Some new emerging applications involve in- formation transmission in a network. Different from traditional single-cast applications, these new arising applications are called multicast as they contain a single sender and multiple receivers. In general, it is needed to construct a multicast routing tree to deliver information along the tree branches. Because links in the tree are shared by paths to different receivers, just one information copy is needed in the middle node. Th…  相似文献   

12.
This article employs qualitative research methods to explore the urban adaptation and adaptation processes of Chinese migrant children. Through twenty-one in-depth interviews with migrant children, the researchers discovered: The participant migrant children showed a fairly high level of adaptation to the city; their process of urban adaptation emerged as three categories: the U-Type, the J-type, and the “flat line” type. Also explored were long-term acquisition of explicit behaviors, implicit notions, adaptation to the socio-cultural environment, and success in education as difficult aspects of adaptation. After comparing these three processes, the research team developed a theory of migrant children urban adaptation. It hypothesizes that during the urban adaptation process, migrant children will encounter four stages of development: excitement and curiosity, shock and resistance, exploration and adaptation, and finally integration and assimilation. __________ Translated by Amanda Weiss from Beijing Shifan Daxue Xuebao (Shehui Kexue Ban) 北京师范大学学报 (社会科学版) (Journal of Beijing Normal University (Social Sciences)), 2008, (3): 9–20, revised by Deane Neubauer, Emeritus Professor, University of Hawaii  相似文献   

13.
This article explores the question: Why are students of worth? Educationally, an answer often involves a Kantian response: They are of worth because they are always ends and never means. This response is usually connected to a notion of autonomy interpreted as individual, rational self-determination. The article argues for a different answer. The essay begins with a recent educational example of construing worth as rational autonomy. Meira Levinson, in her book The Demands of Liberal Education (1999), argues for a version of rational autonomy which is taken in the essay as a Kantian response to the question. The essay then turns to Kant’s own understanding of intrinsic human worth as ends. Although the essay agrees in general with the notion of end, it criticizes Kant’s version of rational autonomy. Instead, it argues for a notion of worth as irreplaceable singularity. Both the critique of the Kantian answer and theessay’salternative are shaped by the philosophy of Emmanuel Levinas. Here technical notions of “the other,” proximity and singularity are brought to bear on the question of human worth. The Levinasian alternative, so the essay argues, better answers the question of student worth by highlighting the incomparability of the student as a singular other.  相似文献   

14.
Several different pharmacological effects have been described for Nigella sativa (Siah-Daneh), including an anti-inflammatory effect. In the present study, the effect of the extract of N. sativa on lung pathology and blood interleukin-4 (IL-4) and interferon-γ (IFN-γ) of sensitized guinea pigs was examined. Three groups (n=8 for each group) of guinea pigs sensitized to ovalbumin (OA) were given drinking water alone, and drinking water containing low and high concentrations of the plant extract, respectively. The animals of the control group (n=8) were treated with saline instead of OA and were given drinking water. The pathological changes of the lung, including infiltration of eosinophils and lymphocytes, local epithelial necrosis, the presence of oedema, thickening of the basement membrane, smooth muscle layer hypertrophy, mucosal secretion, and the presence of mucosal plug, and blood IL-4 and IFN-γ of sensitized guinea pigs were evaluated. The lungs of the sensitized group showed significant pathological changes (P<0.001). Blood IL-4 and IFN-γ were increased in sensitized animals compared to the controls (P<0.01 and P<0.001, respectively). Treatment of sensitized animals with the extract led to a significant decrease in pathological changes of the lung (P<0.01 to P<0.001), except for the oedema in the sensitized group treated with low concentration of the extract, but an increased IFN-γ. These results confirm a preventive effect of N. sativa extract on lung inflammation of sensitized guinea pigs.  相似文献   

15.
Objective: The functional relationship between calculated alpha band spectral power and inter-/intra-hemispheric coherence during a three-level working memory task of patients with mild cognitive impairment (MCI) was investigated. Methods: Subjects included 35 MCI patients according to the DSM-IV criteria (mean age: 62.3, SD: 6.5) and 34 healthy controls (mean age: 57.4, SD: 4.0) were selected from the community at large. All subjects performed a simple calculation and recall task with three levels of working memory load while electroencephalograph (EEG) signal was recorded. The spectral EEG power was computed over alpha1 (8.0～10.0 Hz) and alpha2 (10.5～13.0 Hz) frequency bands and was compared between rest stage and working memory processing stage by two-way ANOVA. Post hoc testing analyzed the differences between each two levels of working memory load during task processing. The inter-hemisphere EEG coherence of frontal (F3-F4), central (C3-C4), parietal (P3-P4), temporal (T5-T6) as well as occipital (O1-O2) was compared between MCI patients and normal controls. The EEG signals from F3-C3, F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs resulted from the intra-hemispheric action for alpha1 and alpha2 frequency bands. Result: There was significantly higher EEG power from MCI patients than from normal controls both at rest and during working memory processing. Significant differences existed between rest condition and three-level working memory tasks (P<0.001). The inter-and intra-hemispheric coherence during working memory tasks showed a "drop to rise" tendency compared to that at rest condition. There was significantly higher coherence in MCI patients than in the controls. When task difficulties increased, the cortical connectivity of intra-hemispheric diminished while the inter-hemispheric connectivity dominantly maintained the cognitive processing in MCI patients. Conclusion: The results of the present study indicate that the alpha frequency band may be the characteristic band in distinguishing MCI patients from normal controls during working memory tasks. MCI patients exhibit greater inter-hemispheric connectivity than intra-hemispheric connectivity when memory demands increase. MCI patients mobilize a compensatory mechanism to maintain the processing effectiveness while the processing efficiency is reduced.  相似文献   

16.
INTRODUCTION A number of experimental fatigue studies were conducted on plain concrete as well as on steel fibre reinforced concrete (SFRC) beams of different sizes under different loading conditions. Murdock and Kesler (1958) investigated the effect of stress ratio on the fatigue strength of plain concrete. Batson et al.(1972) reported fatigue strength of 74% and 83% of the first crack static flexural strength at 2 million cycles of complete reversed and not-reversed loads respectively…  相似文献   

17.
Archive-based, historical research of materials produced during the Golden Age of Geology (1788–1840) uncovered scientific caricatures (SCs) which may serve as a unique form of knowledge representation for students today. SCs played important roles in the past, stimulating critical inquiry among early geologists and fueling debates that addressed key theoretical issues. When historical SCs were utilized in a large-enrollment college Earth History course, student response was positive. Therefore, we offered SCs as an optional assessment tool. Paired t-tests that compared individual students’ performances with the SC option, as well as without the SC option, showed a significant positive difference favoring scientific caricatures (α = 0.05). Content analysis of anonymous student survey responses revealed three consistent findings: (a) students enjoyed expressing science content correctly but creatively through SCs, (b) development of SCs required deeper knowledge integration and understanding of the content than conventional test items, and (c) students appreciated having SC item options on their examinations, whether or not they took advantage of them. We think that incorporation of SCs during assessment may effectively expand the variety of methods for probing understanding, thereby increasing the mode validity of current geoscience tests.  相似文献   

18.
It is of great importance to investigate an effective and reliable medication against chronic renal failure (CRF)-related erectile dysfunction (ED), which aims to improve patients’ life qualities. The concentrations of cyclic guanosine monophosphate (cGMP) in the corpus cavernosal smooth muscle of both CRF and control rabbits were measured. The effects of various concentrations of tadalafil, papaverine, and sodium nitroprusside on the relaxation responses of corpus cavernosal smooth muscle pre-contracted with phenylephrine in CRF rabbits were observed. There was significant difference in the concentration of cGMP between CRF and control rabbits (P<0.01). Tadalafil had the greatest impacts on CRF rabbits when given the same concentration of papaverine or sodium nitroprusside and particularly significant differences were identified under the concentration levels of 10−5 and 10−4 mol/L (P<0.01). The results suggest that the cGMP concentrations of the corpus cavernosum had been greatly reduced in CRF rabbits compared with control rabbits and that tadalafil may be an ideal medication for use in the treatment of CRF-related ED.  相似文献   

19.
In order to comply with the requirements for a drug listed in China, the study was developed to compare the pharmacokinetics and relative bioavailability of two different enteric formulations of omeprazole (OPZ) in healthy Chinese subjects. A total of 32 volunteers participated in the study. Plasma concentrations were analyzed by nonstereospecific liquid chromatography/tandem mass spectrometric (LC-MS/MS) method. After administration of a single 40-mg dose of the two OPZ formulations, the comparative bioavailability was assessed by calculating individual AUC0−t (the area under the concentration-time curve from time zero to the last measurable concentration), AUC0−∞ (the area under the concentration-time curve extrapolated to infinity), C max (the maximum observed concentration), and T peak (the time to C max) values of OPZ, 5-hydroxyomeprazole (OH-OPZ), and omeprazole sulfone (OPZ-SFN), respectively. The 90% confidence intervals (CIs) of AUC0−t , AUC0−∞, and C max were 85.4%–99.0%/88.8%–98.6%/87.6%–99.4%, 85.5%–99.2%/89.0%–98.6%/88.5%–101.3%, and 72.3%–87.6%/79.6%–91.1%/88.4%–99.1% for OPZ/OH-OPZ/OPZ-SFN, respectively, and T peak values did not differ significantly. In this study, the test formulation of OPZ in fasting healthy Chinese male volunteers met the Chinese bioequivalance standard to the reference formulation based on AUC, C max, and T peak.  相似文献   

20.
Objective: To observe the effect of Yangxueqingnao particles on rat vascular smooth muscle cell (VSMC) proliferation induced by lysophosphatidic acid (LPA). Methods: The amount of3H-TdR (3H-thymidine) admixed in cultured rat VSMC was measured and mitogen-activated protein kinase (MAPK) activity and lipid peroxidation end product malondialdehyde (MDA) content of the VSMC were assayed. Results: 1×10−9, 1×10−8, 1×10−7 mol/L LPA in a concentration dependent manner, induced the amount of3H-TdR admixed, MAP kinase activity, and MDA content of the cultured rat VSMC to increase. However, 5%, 10%, and 15% Yangxueqingnao serum preincubation resulted in a decrease of 23.0%, 42.0%, and 52.0% (P<0.01) respectively in the amount of3H-TdR admixed, a decline in VSMC MAP kinase activity of 13.9% (P<0.05), 29.6% (P<0.01), and 48.9% (P<0.01) respectively, and also, a decrease in MDA content of VSMC of 19.4%, 24.7%, and 43.2% (P<0.01) respectively, in the 1×10−7 mol/L LPA-treated VSMC. Conclusions: LPA activates the proliferation and lipid peroxidation of VSMC in a concentration dependent manner. The LPA-induced VSMC proliferation is related to the activity of MAP kinases, enzymes involved in an intracellular signalling pathway. The results of the present study showed that Yangxueqingnao particles can effectively inhibit LPA-induced VSMC proliferation, MAP kinase activation, and reduce lipid peroxidative lesion. Project (No. 491010-W50339) supported by Chinese Traditional Medicine Administration Bureau of Zhejiang Province, China  相似文献   

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