Low back pain(LPB)is a common and impactful health concern globally,affecting individuals across various demographics and imposing a significant burden on the health care system.Nonspecific chronic LBP(NCLBP),charac-t...Low back pain(LPB)is a common and impactful health concern globally,affecting individuals across various demographics and imposing a significant burden on the health care system.Nonspecific chronic LBP(NCLBP),charac-terized as pain lasting over 12 weeks without an identifiable cause,leads to notable functional limitations and reduced quality of life.Traditional rehabil-itation programs,often focusing on dynamic exercises for lumbar strengthening,typically do not target the deep stabilizing muscles crucial for lumbar support and effective recovery.Multi-angular isometric lumbar exercise(MAILE)offers a low-impact method for strengthening lumbar stabilizers through multi-angular isometric contractions,reducing risks from dynamic movements.This article examines MAILE’s potential in addressing motor control dysfunctions in NCLBP,highlighting studies on lumbar muscle activation,core stability,and isometric exercises.The article explores the prevalence and socioeconomic impact of NCLBP in the Middle East,highlighting the need for affordable treatment options in areas like Qatar and Saudi Arabia.This article aims to validate the efficacy of MAILE in reducing pain,enhancing mobility,and improving lumbar stability,offering a valuable option for NCLBP management.Future research should focus on large-scale clinical trials to substantiate these findings and guide clinical practice.展开更多
The short communication discusses the interrelationships of loxodromes,isometric latitudes and the normal aspect of Mercator projection.It is shown that by applying the isometric latitude,a very simple equation of the...The short communication discusses the interrelationships of loxodromes,isometric latitudes and the normal aspect of Mercator projection.It is shown that by applying the isometric latitude,a very simple equation of the loxodrome on the sphere is reached.The consequence of this is that the isometric latitude can be defined using the generalized longitude,and not only using the latitude,as was common until now.Generalized longitude is the longitude defined for every real number;modulo 2πof generalized and usual longitude are congruent.Since the image of the loxodrome in the plane of the Mercator projection is a straight line,the isometric latitude can also be defined using this projection.Finally,a new definition of theMercator projection is given,according to which it is a normal aspect cylindrical projection in which the images of the loxodromes on the sphere are straight lines in the plane of the projection that,together with the images of the meridians in the projection,form equal angles,as do the loxodromes with the meridians on the sphere.The short communication provides additional knowledge to all those who are interested in the theory of maps in navigation and have a piece of requisite mathematical knowledge,as well as an interest in map projections.It will be useful for teachers and students studying cartography and GIS,navigation or applied mathematics.展开更多
In this paper, we deal with isommetric immersions of globally null warped product manifolds into Lorentzian manifolds with constant curvature c in codimension k≥3. Under the assumptions that the globally null warped ...In this paper, we deal with isommetric immersions of globally null warped product manifolds into Lorentzian manifolds with constant curvature c in codimension k≥3. Under the assumptions that the globally null warped product manifold has no points with the same constant sectional curvature c as the Lorentzian ambient, we show that such isometric immersion splits into warped product of isometric immersions.展开更多
In this paper, some characterizations of isometric operators and ε-isometric opertors from 2-dim Banach Space E2 into L1[0, 1] are given, where E2 denotes a Banach Spacewhose unit ball is the union of a polygon C and...In this paper, some characterizations of isometric operators and ε-isometric opertors from 2-dim Banach Space E2 into L1[0, 1] are given, where E2 denotes a Banach Spacewhose unit ball is the union of a polygon C and the region enclosd by C in the plane. Also,the answer for IAP(Isometric Approximation Problem) on B(E2,L1 [0, 1]) is obtained.展开更多
The formed principle and CNC grinding machining method of isometric polygonal profile are studied deeply and systematically. Equation about section curve of isometric polygon profile is set up by means of geometric pr...The formed principle and CNC grinding machining method of isometric polygonal profile are studied deeply and systematically. Equation about section curve of isometric polygon profile is set up by means of geometric principle. With the use of differential geometry theory, the curve is proved to be with geometric feature of convex curve. It is referred to as Isometric Polygonal Curve (IPC), because that is a kind of convex curve on which the distance between any parallel tangent lines is equal. Isometric Polygonal Profile (IPP) or Isometric Polygonal Cone Profile (IPCP) or Isometric Polygonal Topless Cone (IPTC) is formed with the IPC and straight line as generating curve. But the machining and measuring of the IPCP are so inconvenient that it has little value. Keeping in mind the characteristic of the IPP and IPTC, this paper puts forward the program method of CNC grinding machining. Isometric polygonal profile connection is a kind of polygonal profile connection. It has the superiority over keys (prismatic key & spline etc), and can be suit for the situations such as high rotative velocity, large torque, high precision, and small fixed room and vibration. Nowadays, some countries such as America, Russia, German and Switzerland applied CNC machining to the machining of polygon surface coupling parts, which makes their applications in machine productions such as motor engine, heavy machine increase day by day. But reports about concrete machining technology of isometric polygonal profile and programming of CNC machining program are very few. CNC grinding of the IPP and IPTC is one kind of the precision machining technology. It is of great importance to the popularization of the IPP and IPTC connection. From the forming mechanism, we can see that the machining and measuring of the IPP and IPTC are convenient, and therefore they have the value of the popularization. But the machining and measuring of the IPCP are so inconvenient that it has little value. In the programming the CNC grinding of the IPP and IPTC, it is more reasonable to calculate the coordinate of node according to the approaching method of equal error arc. According to the method of CNC grinding mentioned above to design the grinding machine, the structure is simple and of economical and practical.展开更多
Let X be a Banach space. If there exists a quotient space of X which is asymptotically isometric to l^1, then X contains complemented asymptotically isometric copies of l^1. Every infinite dimensional closed subspace ...Let X be a Banach space. If there exists a quotient space of X which is asymptotically isometric to l^1, then X contains complemented asymptotically isometric copies of l^1. Every infinite dimensional closed subspace of l1. contains a complemented subspace of l1 which is asymptotically isometric to l1. Let X be a separable Banach space such that X^＊ contains asymptotically isometric copies of lp （1 〈 p 〈∞）. Then there exists a quotient space of X which is asymptotically isometric to lq （1/p ＋ 1/q=1）. Complemented asymptotically isometric copies of co in K（X, Y） and W（X, Y） are discussed. Let X be a Gelfand-Phillips space. If X contains asymptotically isometric copies of co, it has to contain complemented asymptotically isometric copies of co.展开更多
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 th...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.展开更多
Some problems connect ed with production of new light-weight filler type are considered for sandwich layers. Constructively, the filler is the folded structure that can be developed on a plane. This feature makes it...Some problems connect ed with production of new light-weight filler type are considered for sandwich layers. Constructively, the filler is the folded structure that can be developed on a plane. This feature makes it possible to produce the filler by isometric t ransformation of thin sheet through local bending without material stretching.Th e main difficulty is that the bending must be carried out along all lines of com plex-shaped marking-out at a time. The problem of shaping can be solved by use of the original shaping device that can be transformed in operation. The herein -presented technology of production makes it possible to fabricate parts with d eep relief using a wide gamut of different materials even as the thin-sheet met al alloys and paper.展开更多
This article presents a novel method to prove that： let E be an AM-space and if dim E ≥ 3, then there does not exist any odd subtractive.isometric mapping from the unit sphere S（E） into S[L（Ω, μ）]. In particul...This article presents a novel method to prove that： let E be an AM-space and if dim E ≥ 3, then there does not exist any odd subtractive.isometric mapping from the unit sphere S（E） into S[L（Ω, μ）]. In particular, there does not exist any real linear isometry from E into L（Ω, μ）.展开更多
This is such a article to consider an ＂into＂ isometric mapping between two unit spheres of two infinite dimensional spaces of different types. In this article, we find a useful condition （using the Krein-Milman pro...This is such a article to consider an ＂into＂ isometric mapping between two unit spheres of two infinite dimensional spaces of different types. In this article, we find a useful condition （using the Krein-Milman property） under which an into-isometric mapping from the unit sphere of e（Γ） to the unit sphere of a normed space E can be linearly isometric extended.展开更多
Osteoarthritis of knee is a common problem in the elderly population worldwide. Physical therapy has been shown to be useful in decreasing pain and increasing mobility in this population. The aim of this study was to ...Osteoarthritis of knee is a common problem in the elderly population worldwide. Physical therapy has been shown to be useful in decreasing pain and increasing mobility in this population. The aim of this study was to study the effectiveness of slow reversal hold and isometric exercise techniques in reducing pain, increasing muscle strength, and increasing range of motion for knee flexion in patients with osteoarthritis of knee. The other aim of this study was to compare the relative effectiveness of these two interventions. 60 subjects participated in this study and were randomly assigned either to the slow reversal hold group (n = 30) or, to the isometrics exercise group (n = 30). All subjects performed their respective exercises for 3 weeks. Pain scores using the visual analog scale, muscle strength using manual muscle testing of quadriceps and hamstrings, and range of motion (ROM) for knee flexion using a goniometer were recorded both pre-treatment and post-treatment for both left and right knees. Both the interventions showed a significant decrease in pain scores, an increase in muscle strength, as well as an increase in the ROM. However, ROM was significantly increased in the slow reversal hold group as compared to the isometrics group in both knees. It was concluded that both exercise techniques could be useful in patients with osteoarthritis of knee for decreasing pain and increasing muscle strength. Slow reversal hold technique might be a better technique than isometrics for increasing ROM for knee flexion.展开更多
Background:Females are typically less fatigable than males during sustained isometric contractions at lower isometric contraction intensities.This sex difference in fatigability becomes more variable during higher int...Background:Females are typically less fatigable than males during sustained isometric contractions at lower isometric contraction intensities.This sex difference in fatigability becomes more variable during higher intensity isometric and dynamic contractions.While less fatiguing than isometric or concentric contractions,eccentric contractions induce greater and longer lasting impairments in force production.However,it is not clear how muscle weakness influences fatigability in males and females during sustained isometric contractions.Methods:We investigated the effects of eccentric exercise-induced muscle weakness on time to task failure(TTF)during a sustained submaximal isometric contraction in young(18-30 years)healthy males(n=9)and females(n=10).Participants performed a sustained isometric contraction of the dorsiflexors at 35°plantar flexion by matching a 30%maximal voluntary contraction(MVC)torque target until task failure(i.e.,falling below 5%of their target torque for>2 s).The same sustained isometric contraction was repeated 30 min after 150 maximal eccentric contractions.Agonist and antagonist activation were assessed using surface electromyography over the tibialis anterior and soleus muscles,respectively.Results:Males were~41%stronger than females.Following eccentric exercise both males and females experienced an~20%decline in maximal voliuntary contraction torque.TTF was-34%longer in females than males prior to eccentic exercise-induced muscle weakness.However,following eccentric exercise-induced muscle weakness,this sex-related difference was abolished,with both groups having an"45%shorter TTF.Notably,there was~100%greater antagonist activation in the female group during the sustained isometric contraction following exercise-induced weakness as compared to the males.Conclusion:This increase in antagonist activation disadvantaged females by decreasing their TTF,resulting in a blunting of their typical fatigability advantage over males.展开更多
In this paper, we consider the infinitesimal I- and Il-isometry deformations of submanifolds immersed in a space form N of constant curvature. We obtain some results which are new even in the case of N being the Eucli...In this paper, we consider the infinitesimal I- and Il-isometry deformations of submanifolds immersed in a space form N of constant curvature. We obtain some results which are new even in the case of N being the Euclidean space. At the same time, we generalize some classical results in E-3 Go the submanifolds immersed in a space form of constant curvature.展开更多
Isometric exercise(IE)is a promising intervention of noninvasive revascularization in patients with acute myocardial infarction(AMI).This study aimed to investigate the impact and mechanisms of IE training on arteriog...Isometric exercise(IE)is a promising intervention of noninvasive revascularization in patients with acute myocardial infarction(AMI).This study aimed to investigate the impact and mechanisms of IE training on arteriogenesis in AMI.Male Sprague-Dawley rats were randomly assigned into the sham-operation group(SO),myocardial infarction(MI)group,and 13 IE subgroups treated according to training intensity,frequency,duration,or monocyte chemoattractant protein-1(MCP-1),or/and fibroblast growth factor-2(FGF-2)inhibitors for eight weeks.Our results demonstrated that the IE group achieved superior improvement compared with the MI group in terms of left ventricular ejection fraction(LVEF),myocardial infarction size(MIS),arterial density(AD),monocytes(MNCs),smooth muscle cells(SMCs),endothelial cells(ECs),relative collateral blood flow(RCBF),MCP-1,and FGF-2 at the endpoint.Positive correlations between MCP-1 and MNCs,MNCs and FGF-2,FGF-2 and SMCs,SMCs and AD,as well as AD and RCBF were observed.This study demonstrated that with MI of 100%load 20 times daily for eight weeks,the arteriogenesis was improved,which may be attributed to the recruitment of MNCs and SMCs in remote ischemic myocardium caused by increases in MCP-1 and FGF-2 expression.展开更多
There are two kinds of isometric isomorphism in probabilistic metric space theory. The first is that a PM space (E, F) is isometrically isomorphic to another PM space (E', F'), and the second is that a PM spac...There are two kinds of isometric isomorphism in probabilistic metric space theory. The first is that a PM space (E, F) is isometrically isomorphic to another PM space (E', F'), and the second is that a PM space (E, F) is isometrically isomorphic to a generating space of quasi-metric family (E', d(r), r is an element of (0, 1)). This paper establishes the connection between the two kinds of isometric isomorphism.展开更多
In this paper, we show that if Vo is a 1-Lipschitz mapping between unit spheres of Lp （μ, H） and Lp（v, g）（p 〉 2, H is a Hilbert space）, and -Vo（ S（ np（μ, H） ） ） Vo（ S（ Lp（μ, H） ） ） then Vo can ...In this paper, we show that if Vo is a 1-Lipschitz mapping between unit spheres of Lp （μ, H） and Lp（v, g）（p 〉 2, H is a Hilbert space）, and -Vo（ S（ np（μ, H） ） ） Vo（ S（ Lp（μ, H） ） ） then Vo can be extended to a linear isometry defined on the whole space. If 1 〈 p 〈 2 and Vo is an ＂anti-l-Lipschitz＂ mapping, then Vo can also be linearly and isometrically extended.展开更多
Background: Patellofemoral Pain Syndrome (PFPS) is one of the most common conditions among athletes. Although there are various causes for this condition, reduced balance is the problem most frequently expressed by th...Background: Patellofemoral Pain Syndrome (PFPS) is one of the most common conditions among athletes. Although there are various causes for this condition, reduced balance is the problem most frequently expressed by these patients. The aim of the present study was to examine the effect of Extensor Muscle Sling Isometric and Isotonic (EMSII) exercises of lower limbs on female basketball players suffering from PFPS. Method: A total of 30 participants, all female basketball players suffering from PFPS, with an average age of 20 - 30 years, were divided into two isometric/isotonic and control experimental groups. Eight weeks of isometric and isotonic exercises were recommended to the participants with a focus on EMSII exercises of lower limbs in two four-week phases. The control group received no specific exercise program. Pre-test and post-test included the use of Stork balance test (SBT) and Y Balance tests (YBT) to assess the static and dynamic balance, respectively. Results: After eight weeks of performing separate isometric and isotonic exercises on the mentioned muscles, and according to the results of the pre-test, a significant increase was observed in the results of both static and dynamic balance tests (P Conclusion: EMSII exercises of lower limbs showed a significant effect on the increased balance. Recommended exercises can be suggested according to the type of exercises as a factor for increasing static and dynamic balance.展开更多
The most prevalent group of disorders of human shoulder is related to the muscles of the rotator cuff. In order to develop a mechanical method for rotator cuff muscles’ evaluation, we hypothesized that measurement of...The most prevalent group of disorders of human shoulder is related to the muscles of the rotator cuff. In order to develop a mechanical method for rotator cuff muscles’ evaluation, we hypothesized that measurement of the isometric force generated by the individual muscle of the rotator cuff might detect the variations, which are characteristic to the different disorders of rotator cuff muscles in adults. The isometric force of supraspinatus, infraspinatus and subscapularis muscles were measured in patients with rotator cuff tears, calcific tendinitis and subacromial impingement syndrome, 30 patients with each disorder, and compared to the normal values from our previous study. Torque of the force was calculated and normalized to lean body mass. The profiles of the mean torque-time curves of each group were compared statistically. We found the expected significantly lower profiles of the torque-time curves of all the tested rotator cuff muscles in comparison to the normal values. The best resolution between the curves of different study groups was found in the testing of the infraspinatus muscles. Therefore the previously unrecognized variations of rotator cuff muscles’ isometric strength build up patterns in the common disorders involving the rotator cuff muscles were revealed. The presented data might be a basis for the future development of a simple mechanical diagnostic method for identification of the abnormal patterns of muscle isometric strength in patients with rotator cuff muscles’ pathology.展开更多
Background: Studies on physical activity during pregnancy and its impact on mother and fetus are still limited. International protocols consider only aerobic exercise and fail to provide information about other modali...Background: Studies on physical activity during pregnancy and its impact on mother and fetus are still limited. International protocols consider only aerobic exercise and fail to provide information about other modalities such as isometric exercise. Isometric exercise promotes cardiorespiratory resistance and muscle strengthening, but it is rarely tested on pregnant women because it increases maternal blood pressure and can subsequently affect placental circulation. Objective: To evaluate maternal and fetal response of low-risk pregnant women undergoing isometric testing through a Doppler velocimetry study. Methodology: A cross-sectional, experimental study was performed on 46 healthy pregnant women (gestational age between 26 and 36 weeks) who underwent isometric testing. This testing was performed using a handgrip dynamometer to measure maternal and fetal hemodynamic parameters before, during, and after isometric testing. Results: There was a significant increase in systolic blood pressure (BP;pre-isometrics 113.13 ± 9.92 mmHg, during isometrics 117.13 ± 10.24 mmHg, and post-isometrics 112.43 ± 9.87 mmHg, p 0.001) and heart rate (HR;pre-isometrics 87.52 ± 14.10 bpm, during isometrics 97.61 ± 14.83 bpm, and post-isometrics 85.13 ± 13.24 bpm, p 0.001). There were significant decreases in the pulsatility index (PI;pre-isometrics 0.63 ± 0.15, during isometrics 0.56 ± 0.15, and post-isometrics 0.65 ± 0.17, p = 0.001), resistance index (RI;pre-isometrics 0.44 ± 0.08, during isometrics 0.40 ± 0.07, and post-isometrics 0.45 ± 0.08, p = 0.001), and systolic/diastolic (S/D) ratio (pre-isometrics 1.81 ± 0.26, during isometrics 1.69 ± 0.24, and post-isometrics 1.85 ± 0.29, p 0.001) of the left uterine artery (UA). These results showed significant changes only during the isometric exercise, and not between the pre- and post-isometric exercises. There were no significant differences in fetal parameters when the results before, during, and after the isometric test were compared. Conclusion: Isometric testing had no repercussions for fetal hemodynamics in healthy low-risk pregnant women.展开更多
The aim of this study was to determine the within-day and between-days reliability of surface electromyographic (EMG) power spectral analysis in assessing fatigability of the vastus medialis (VM) muscle during knee an...The aim of this study was to determine the within-day and between-days reliability of surface electromyographic (EMG) power spectral analysis in assessing fatigability of the vastus medialis (VM) muscle during knee and hip flexion under constant load application. The subjects were 13 healthy adult men free of knee abnormalities. Surface EMG was recorded from vastus medialis obliquus (VMO) and vastus medialis longus (VML) during sustained isometric contractions at 60% of maximal voluntary contraction until exhaustion on the leg press machine (static leg press test). Linear regression analysis was applied to median frequency (MF) time series to calculate initial MF and MF slope. For VMO and VML, the initial MF showed moderate to high reliability, while the MF slope showed high reliability (Intraclass correlation coefficient (ICC) = initial MF: 0.63 - 0.92, MF slope: 0.70 - 0.86). The results demonstrated that spectral analysis of surface EMG recording during isometric VM muscle contraction has high within-day and between-days reliability in the assessment of fatigability of the VMO and VML.展开更多
文摘Low back pain(LPB)is a common and impactful health concern globally,affecting individuals across various demographics and imposing a significant burden on the health care system.Nonspecific chronic LBP(NCLBP),charac-terized as pain lasting over 12 weeks without an identifiable cause,leads to notable functional limitations and reduced quality of life.Traditional rehabil-itation programs,often focusing on dynamic exercises for lumbar strengthening,typically do not target the deep stabilizing muscles crucial for lumbar support and effective recovery.Multi-angular isometric lumbar exercise(MAILE)offers a low-impact method for strengthening lumbar stabilizers through multi-angular isometric contractions,reducing risks from dynamic movements.This article examines MAILE’s potential in addressing motor control dysfunctions in NCLBP,highlighting studies on lumbar muscle activation,core stability,and isometric exercises.The article explores the prevalence and socioeconomic impact of NCLBP in the Middle East,highlighting the need for affordable treatment options in areas like Qatar and Saudi Arabia.This article aims to validate the efficacy of MAILE in reducing pain,enhancing mobility,and improving lumbar stability,offering a valuable option for NCLBP management.Future research should focus on large-scale clinical trials to substantiate these findings and guide clinical practice.
文摘The short communication discusses the interrelationships of loxodromes,isometric latitudes and the normal aspect of Mercator projection.It is shown that by applying the isometric latitude,a very simple equation of the loxodrome on the sphere is reached.The consequence of this is that the isometric latitude can be defined using the generalized longitude,and not only using the latitude,as was common until now.Generalized longitude is the longitude defined for every real number;modulo 2πof generalized and usual longitude are congruent.Since the image of the loxodrome in the plane of the Mercator projection is a straight line,the isometric latitude can also be defined using this projection.Finally,a new definition of theMercator projection is given,according to which it is a normal aspect cylindrical projection in which the images of the loxodromes on the sphere are straight lines in the plane of the projection that,together with the images of the meridians in the projection,form equal angles,as do the loxodromes with the meridians on the sphere.The short communication provides additional knowledge to all those who are interested in the theory of maps in navigation and have a piece of requisite mathematical knowledge,as well as an interest in map projections.It will be useful for teachers and students studying cartography and GIS,navigation or applied mathematics.
文摘In this paper, we deal with isommetric immersions of globally null warped product manifolds into Lorentzian manifolds with constant curvature c in codimension k≥3. Under the assumptions that the globally null warped product manifold has no points with the same constant sectional curvature c as the Lorentzian ambient, we show that such isometric immersion splits into warped product of isometric immersions.
文摘In this paper, some characterizations of isometric operators and ε-isometric opertors from 2-dim Banach Space E2 into L1[0, 1] are given, where E2 denotes a Banach Spacewhose unit ball is the union of a polygon C and the region enclosd by C in the plane. Also,the answer for IAP(Isometric Approximation Problem) on B(E2,L1 [0, 1]) is obtained.
文摘The formed principle and CNC grinding machining method of isometric polygonal profile are studied deeply and systematically. Equation about section curve of isometric polygon profile is set up by means of geometric principle. With the use of differential geometry theory, the curve is proved to be with geometric feature of convex curve. It is referred to as Isometric Polygonal Curve (IPC), because that is a kind of convex curve on which the distance between any parallel tangent lines is equal. Isometric Polygonal Profile (IPP) or Isometric Polygonal Cone Profile (IPCP) or Isometric Polygonal Topless Cone (IPTC) is formed with the IPC and straight line as generating curve. But the machining and measuring of the IPCP are so inconvenient that it has little value. Keeping in mind the characteristic of the IPP and IPTC, this paper puts forward the program method of CNC grinding machining. Isometric polygonal profile connection is a kind of polygonal profile connection. It has the superiority over keys (prismatic key & spline etc), and can be suit for the situations such as high rotative velocity, large torque, high precision, and small fixed room and vibration. Nowadays, some countries such as America, Russia, German and Switzerland applied CNC machining to the machining of polygon surface coupling parts, which makes their applications in machine productions such as motor engine, heavy machine increase day by day. But reports about concrete machining technology of isometric polygonal profile and programming of CNC machining program are very few. CNC grinding of the IPP and IPTC is one kind of the precision machining technology. It is of great importance to the popularization of the IPP and IPTC connection. From the forming mechanism, we can see that the machining and measuring of the IPP and IPTC are convenient, and therefore they have the value of the popularization. But the machining and measuring of the IPCP are so inconvenient that it has little value. In the programming the CNC grinding of the IPP and IPTC, it is more reasonable to calculate the coordinate of node according to the approaching method of equal error arc. According to the method of CNC grinding mentioned above to design the grinding machine, the structure is simple and of economical and practical.
基金Supported by NSFC(10271060)NSFC(10171014) the Doctoral Programme Foundation of Institution of Higher Education(20010055013).
文摘Let X be a Banach space. If there exists a quotient space of X which is asymptotically isometric to l^1, then X contains complemented asymptotically isometric copies of l^1. Every infinite dimensional closed subspace of l1. contains a complemented subspace of l1 which is asymptotically isometric to l1. Let X be a separable Banach space such that X^＊ contains asymptotically isometric copies of lp （1 〈 p 〈∞）. Then there exists a quotient space of X which is asymptotically isometric to lq （1/p ＋ 1/q=1）. Complemented asymptotically isometric copies of co in K（X, Y） and W（X, Y） are discussed. Let X be a Gelfand-Phillips space. If X contains asymptotically isometric copies of co, it has to contain complemented asymptotically isometric copies of co.
基金Supported by the National Natural Science Foundation of China(No.81222021 and No.31011130042)the National Key Technology R&D Program of the Ministry of Science and Technology of China(No.2012BAI34B02)
文摘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.
文摘Some problems connect ed with production of new light-weight filler type are considered for sandwich layers. Constructively, the filler is the folded structure that can be developed on a plane. This feature makes it possible to produce the filler by isometric t ransformation of thin sheet through local bending without material stretching.Th e main difficulty is that the bending must be carried out along all lines of com plex-shaped marking-out at a time. The problem of shaping can be solved by use of the original shaping device that can be transformed in operation. The herein -presented technology of production makes it possible to fabricate parts with d eep relief using a wide gamut of different materials even as the thin-sheet met al alloys and paper.
基金This study is supported by the National Natural Science Foundation of China (10571090)the Research Fund for the Doctoral Program of Higher Education (20060055010)
文摘This article presents a novel method to prove that： let E be an AM-space and if dim E ≥ 3, then there does not exist any odd subtractive.isometric mapping from the unit sphere S（E） into S[L（Ω, μ）]. In particular, there does not exist any real linear isometry from E into L（Ω, μ）.
基金supported by the National Natural Science Foundation of China(10871101)the Research Fund for the Doctoral Program of Higher Education (20060055010)
文摘This is such a article to consider an ＂into＂ isometric mapping between two unit spheres of two infinite dimensional spaces of different types. In this article, we find a useful condition （using the Krein-Milman property） under which an into-isometric mapping from the unit sphere of e（Γ） to the unit sphere of a normed space E can be linearly isometric extended.
文摘Osteoarthritis of knee is a common problem in the elderly population worldwide. Physical therapy has been shown to be useful in decreasing pain and increasing mobility in this population. The aim of this study was to study the effectiveness of slow reversal hold and isometric exercise techniques in reducing pain, increasing muscle strength, and increasing range of motion for knee flexion in patients with osteoarthritis of knee. The other aim of this study was to compare the relative effectiveness of these two interventions. 60 subjects participated in this study and were randomly assigned either to the slow reversal hold group (n = 30) or, to the isometrics exercise group (n = 30). All subjects performed their respective exercises for 3 weeks. Pain scores using the visual analog scale, muscle strength using manual muscle testing of quadriceps and hamstrings, and range of motion (ROM) for knee flexion using a goniometer were recorded both pre-treatment and post-treatment for both left and right knees. Both the interventions showed a significant decrease in pain scores, an increase in muscle strength, as well as an increase in the ROM. However, ROM was significantly increased in the slow reversal hold group as compared to the isometrics group in both knees. It was concluded that both exercise techniques could be useful in patients with osteoarthritis of knee for decreasing pain and increasing muscle strength. Slow reversal hold technique might be a better technique than isometrics for increasing ROM for knee flexion.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)。
文摘Background:Females are typically less fatigable than males during sustained isometric contractions at lower isometric contraction intensities.This sex difference in fatigability becomes more variable during higher intensity isometric and dynamic contractions.While less fatiguing than isometric or concentric contractions,eccentric contractions induce greater and longer lasting impairments in force production.However,it is not clear how muscle weakness influences fatigability in males and females during sustained isometric contractions.Methods:We investigated the effects of eccentric exercise-induced muscle weakness on time to task failure(TTF)during a sustained submaximal isometric contraction in young(18-30 years)healthy males(n=9)and females(n=10).Participants performed a sustained isometric contraction of the dorsiflexors at 35°plantar flexion by matching a 30%maximal voluntary contraction(MVC)torque target until task failure(i.e.,falling below 5%of their target torque for>2 s).The same sustained isometric contraction was repeated 30 min after 150 maximal eccentric contractions.Agonist and antagonist activation were assessed using surface electromyography over the tibialis anterior and soleus muscles,respectively.Results:Males were~41%stronger than females.Following eccentric exercise both males and females experienced an~20%decline in maximal voliuntary contraction torque.TTF was-34%longer in females than males prior to eccentic exercise-induced muscle weakness.However,following eccentric exercise-induced muscle weakness,this sex-related difference was abolished,with both groups having an"45%shorter TTF.Notably,there was~100%greater antagonist activation in the female group during the sustained isometric contraction following exercise-induced weakness as compared to the males.Conclusion:This increase in antagonist activation disadvantaged females by decreasing their TTF,resulting in a blunting of their typical fatigability advantage over males.
文摘In this paper, we consider the infinitesimal I- and Il-isometry deformations of submanifolds immersed in a space form N of constant curvature. We obtain some results which are new even in the case of N being the Euclidean space. At the same time, we generalize some classical results in E-3 Go the submanifolds immersed in a space form of constant curvature.
基金supported by the research grants from the National Natural Science Foundation of China(Grant No.8177244,No.81902288,and No.82072546)Nanjing Municipal Science and Technology Bureau(Grant No.2019060002).
文摘Isometric exercise(IE)is a promising intervention of noninvasive revascularization in patients with acute myocardial infarction(AMI).This study aimed to investigate the impact and mechanisms of IE training on arteriogenesis in AMI.Male Sprague-Dawley rats were randomly assigned into the sham-operation group(SO),myocardial infarction(MI)group,and 13 IE subgroups treated according to training intensity,frequency,duration,or monocyte chemoattractant protein-1(MCP-1),or/and fibroblast growth factor-2(FGF-2)inhibitors for eight weeks.Our results demonstrated that the IE group achieved superior improvement compared with the MI group in terms of left ventricular ejection fraction(LVEF),myocardial infarction size(MIS),arterial density(AD),monocytes(MNCs),smooth muscle cells(SMCs),endothelial cells(ECs),relative collateral blood flow(RCBF),MCP-1,and FGF-2 at the endpoint.Positive correlations between MCP-1 and MNCs,MNCs and FGF-2,FGF-2 and SMCs,SMCs and AD,as well as AD and RCBF were observed.This study demonstrated that with MI of 100%load 20 times daily for eight weeks,the arteriogenesis was improved,which may be attributed to the recruitment of MNCs and SMCs in remote ischemic myocardium caused by increases in MCP-1 and FGF-2 expression.
文摘There are two kinds of isometric isomorphism in probabilistic metric space theory. The first is that a PM space (E, F) is isometrically isomorphic to another PM space (E', F'), and the second is that a PM space (E, F) is isometrically isomorphic to a generating space of quasi-metric family (E', d(r), r is an element of (0, 1)). This paper establishes the connection between the two kinds of isometric isomorphism.
基金Supported by the National Natural Science Foundation of China(Grant No.11271248)Specific Academic Discipline Project of Shanghai Municipal Education Commission(Grant No.11xk11)
文摘In this paper, we show that if Vo is a 1-Lipschitz mapping between unit spheres of Lp （μ, H） and Lp（v, g）（p 〉 2, H is a Hilbert space）, and -Vo（ S（ np（μ, H） ） ） Vo（ S（ Lp（μ, H） ） ） then Vo can be extended to a linear isometry defined on the whole space. If 1 〈 p 〈 2 and Vo is an ＂anti-l-Lipschitz＂ mapping, then Vo can also be linearly and isometrically extended.
文摘Background: Patellofemoral Pain Syndrome (PFPS) is one of the most common conditions among athletes. Although there are various causes for this condition, reduced balance is the problem most frequently expressed by these patients. The aim of the present study was to examine the effect of Extensor Muscle Sling Isometric and Isotonic (EMSII) exercises of lower limbs on female basketball players suffering from PFPS. Method: A total of 30 participants, all female basketball players suffering from PFPS, with an average age of 20 - 30 years, were divided into two isometric/isotonic and control experimental groups. Eight weeks of isometric and isotonic exercises were recommended to the participants with a focus on EMSII exercises of lower limbs in two four-week phases. The control group received no specific exercise program. Pre-test and post-test included the use of Stork balance test (SBT) and Y Balance tests (YBT) to assess the static and dynamic balance, respectively. Results: After eight weeks of performing separate isometric and isotonic exercises on the mentioned muscles, and according to the results of the pre-test, a significant increase was observed in the results of both static and dynamic balance tests (P Conclusion: EMSII exercises of lower limbs showed a significant effect on the increased balance. Recommended exercises can be suggested according to the type of exercises as a factor for increasing static and dynamic balance.
文摘The most prevalent group of disorders of human shoulder is related to the muscles of the rotator cuff. In order to develop a mechanical method for rotator cuff muscles’ evaluation, we hypothesized that measurement of the isometric force generated by the individual muscle of the rotator cuff might detect the variations, which are characteristic to the different disorders of rotator cuff muscles in adults. The isometric force of supraspinatus, infraspinatus and subscapularis muscles were measured in patients with rotator cuff tears, calcific tendinitis and subacromial impingement syndrome, 30 patients with each disorder, and compared to the normal values from our previous study. Torque of the force was calculated and normalized to lean body mass. The profiles of the mean torque-time curves of each group were compared statistically. We found the expected significantly lower profiles of the torque-time curves of all the tested rotator cuff muscles in comparison to the normal values. The best resolution between the curves of different study groups was found in the testing of the infraspinatus muscles. Therefore the previously unrecognized variations of rotator cuff muscles’ isometric strength build up patterns in the common disorders involving the rotator cuff muscles were revealed. The presented data might be a basis for the future development of a simple mechanical diagnostic method for identification of the abnormal patterns of muscle isometric strength in patients with rotator cuff muscles’ pathology.
文摘Background: Studies on physical activity during pregnancy and its impact on mother and fetus are still limited. International protocols consider only aerobic exercise and fail to provide information about other modalities such as isometric exercise. Isometric exercise promotes cardiorespiratory resistance and muscle strengthening, but it is rarely tested on pregnant women because it increases maternal blood pressure and can subsequently affect placental circulation. Objective: To evaluate maternal and fetal response of low-risk pregnant women undergoing isometric testing through a Doppler velocimetry study. Methodology: A cross-sectional, experimental study was performed on 46 healthy pregnant women (gestational age between 26 and 36 weeks) who underwent isometric testing. This testing was performed using a handgrip dynamometer to measure maternal and fetal hemodynamic parameters before, during, and after isometric testing. Results: There was a significant increase in systolic blood pressure (BP;pre-isometrics 113.13 ± 9.92 mmHg, during isometrics 117.13 ± 10.24 mmHg, and post-isometrics 112.43 ± 9.87 mmHg, p 0.001) and heart rate (HR;pre-isometrics 87.52 ± 14.10 bpm, during isometrics 97.61 ± 14.83 bpm, and post-isometrics 85.13 ± 13.24 bpm, p 0.001). There were significant decreases in the pulsatility index (PI;pre-isometrics 0.63 ± 0.15, during isometrics 0.56 ± 0.15, and post-isometrics 0.65 ± 0.17, p = 0.001), resistance index (RI;pre-isometrics 0.44 ± 0.08, during isometrics 0.40 ± 0.07, and post-isometrics 0.45 ± 0.08, p = 0.001), and systolic/diastolic (S/D) ratio (pre-isometrics 1.81 ± 0.26, during isometrics 1.69 ± 0.24, and post-isometrics 1.85 ± 0.29, p 0.001) of the left uterine artery (UA). These results showed significant changes only during the isometric exercise, and not between the pre- and post-isometric exercises. There were no significant differences in fetal parameters when the results before, during, and after the isometric test were compared. Conclusion: Isometric testing had no repercussions for fetal hemodynamics in healthy low-risk pregnant women.
文摘The aim of this study was to determine the within-day and between-days reliability of surface electromyographic (EMG) power spectral analysis in assessing fatigability of the vastus medialis (VM) muscle during knee and hip flexion under constant load application. The subjects were 13 healthy adult men free of knee abnormalities. Surface EMG was recorded from vastus medialis obliquus (VMO) and vastus medialis longus (VML) during sustained isometric contractions at 60% of maximal voluntary contraction until exhaustion on the leg press machine (static leg press test). Linear regression analysis was applied to median frequency (MF) time series to calculate initial MF and MF slope. For VMO and VML, the initial MF showed moderate to high reliability, while the MF slope showed high reliability (Intraclass correlation coefficient (ICC) = initial MF: 0.63 - 0.92, MF slope: 0.70 - 0.86). The results demonstrated that spectral analysis of surface EMG recording during isometric VM muscle contraction has high within-day and between-days reliability in the assessment of fatigability of the VMO and VML.
