Data from the seventh national census show that the mobility of rural population in Liaoning is relatively active.Rural revitalization,as a major deployment for development in the new era,will undoubtedly face a varie...Data from the seventh national census show that the mobility of rural population in Liaoning is relatively active.Rural revitalization,as a major deployment for development in the new era,will undoubtedly face a variety of problems in the implementation process.Through the study of the relationship between rural revitalization and population,it is found that the loss of rural population is one of the important reasons that hinder rural economic development and lead to the imbalance of urban and rural economic development.According to the "push and pull theory" by the demographer Bagne,the paper analyzes the causes of rural population loss in Liaoning Province.The rural population backflow and two-way flow of urban and rural population in Liaoning Province is achieved through industrial interaction between urban and rural areas,innovative development of agriculture,steady follow-up of service industry and other measures,thus revitalizing the rural economy.展开更多
Thirteen volatile compounds were identified from Flemingia macrophylla plants. Eight major components significantly attracted the tea green leafhoppers, Empoasca flavescens F. Based on their relative abundances, follo...Thirteen volatile compounds were identified from Flemingia macrophylla plants. Eight major components significantly attracted the tea green leafhoppers, Empoasca flavescens F. Based on their relative abundances, following synthetic blends were made for field experiments: 1) eight-component-attractant blend included Z-3-hexen-1-ol, Z-3-hexenyl acetate, Z-ocimene, Me SA, Z-3-hexenyl butyrate, dodecane, hexadecane and nonanal at 10, 10, 1, 11, 2, 6, 2 and 4 mg mL^-1 in n-hexane, respectively;2) four-component-attractant blend #1 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and nonanal at 2, 10, 10 and 4 mg mL^-1 in n-hexane, respectively;3) four-component-attractant blend #2 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and Me SA at 2, 10, 10 and 11 mg mL^-1 in n-hexane, respectively. Thymol and 1-methoxy-4-methyl-2-(1-methylethyl)-benzene, identified from Lavandula angustifolia aeration samples, significantly repelled the leafhopper as strong repellents when tested alone or in combination at 10 mg mL^-1. For field bioassays, each attractant lure was attached to a bud green sticky board hung from a bamboo stick at above tea plant level for catching the leafhoppers, whereas the repellent dispenser was tied to a tea branch inside tea clump for pushing the leafhoppers away from tea clumps. The results showed that the eight-component-attractant blend caught similar numbers of the leafhopper as did the four-component-attractant blend #1 at about 53–79 leafhoppers/trap/day, which were significantly higher than those on the hexane-control bud green sticky boards. Average leafhopper catches from un-baited sticky boards were about 51–73 leafhoppers/trap/day when pushed by the repellents placed inside tea plants, with the two-component-repellent blend being more effective than their single components. When the two-component-repellent blend was further tested with the three attractant blends in a push-pull fashion, average trap catches ranged from 62 to 92 leafhoppers/trap/day. Control efficacy on the leafhoppers within the push-pull zones increased progressively from day 1(43%) to day 5(73%). This push-pull approach might have a great potential as a green control strategy for combating the tea green leafhoppers.展开更多
Background: Test-retest strength reliability of the Electronic Push/Pull Dynamometer (EPPD) in the measurement of the extensor and flexor muscles on a new constructed chair. The objective of the study was to assess re...Background: Test-retest strength reliability of the Electronic Push/Pull Dynamometer (EPPD) in the measurement of the extensor and flexor muscles on a new constructed chair. The objective of the study was to assess reliability of Electronic Push/Pull Dynamometer in the measurement of the knee flexion and extension at 90° and 60° on a new constructed chair. The aims of the author: To assess reliability of Electronic Push/Pull Dynamometer in the measurement of the knee flexion and extension at 90° and 60° on a new constructed chair. Design: A test-retest reliability study. Subjects: One hundred healthy students male and female (mean age, 21y). Methods: Maximum isometric strength of the quadriceps and hamstring muscle groups was measured using the EPPD were recorded at 60° and 90° for 3 trials on 2 occasions. Reliability was assessed with the Intraclass correlation coefficient (ICC), mean and standard deviation (SD) of measurements, and smallest real differences were calculated for the maximum and for the mean and work of the 3 repetitions. Results: Mean strength ranged from 50.44 kg for knee flexion to 55.76 kg for knee extension 50.44 kg to 61.98 kg at 90° hip flexion. Test-retest reliability Intraclass correlation coefficients (ICCs) ranged from 0.85 to 0.99. ICCs for test-retest reliability ranged from 0.780 to 0.998. Conclusions: The results of the reliability study indicate that the EPPD in reliable dynamometer to use in determining lower limb muscle force production. It can be used to measure disease progression and to evaluate changes in knee extension and flexion strength at the individual patient level.展开更多
This paper provides the static and dynamic pullin behavior of nano-beams resting on the elastic foundation based on the nonlocal theory which is able to capture the size effects for structures in micron and sub-micron...This paper provides the static and dynamic pullin behavior of nano-beams resting on the elastic foundation based on the nonlocal theory which is able to capture the size effects for structures in micron and sub-micron scales. For this purpose, the governing equation of motion and the boundary conditions are driven using a variational approach. This formulation includes the influences of fringing field and intermolecular forces such as Casimir and van der Waals forces. The differential quadrature （DQ） method is employed as a high-order approximation to discretize the governing nonlinear differential equation, yielding more accurate results with a Considerably smaller number of grid points. In addition, a powerful analytical method called parameter expansion method （PEM） is utilized to compute the dynamic solution and frequency-amplitude relationship. It is illustrated that the first two terms in series expansions are sufficient to produce an acceptable solution of the mentioned structure. Finally, the effects of basic parameters on static and dynamic pull-in insta- bility and natural frequency are studied.展开更多
In China, farmers employed in non-farm work have become important socio-economic actors, but few studies have examined the farmers' perspective in making their work location choices. Based on "push-pull"...In China, farmers employed in non-farm work have become important socio-economic actors, but few studies have examined the farmers' perspective in making their work location choices. Based on "push-pull" migration theory, this paper utilizes sectional data from a 2013 survey of farmers in China's Three Gorges Reservoir area to empirically analyze the factors influencing migrant workers' choice of employment location. The results indicate that 60.46% of laborers have migrated from their home province, whereas 39.54% have remained in their home province. Focusing on personal, household, and community characteristics—in addition to the economic characteristics of the sample counties—multinomial logistic regression models reveal that farmer-laborers' employment location decisions are influenced by their personal capital endowment(age, years of education and social networks), family structure(the number of laborers, elders, children and students), home village characteristics(location, economic development level and the degree of relief of the land) and home county economic development level. Notably, male and female laborers' location decisions reveal a converging trend, and their differences are not pronounced. Per capita arable land area has little influence on location decisions, whereas the educational level of laborers has a significant impact. The results differ significantly from those found in previous studies.展开更多
An approximate analytical model for calculating the pull-in voltage of a stepped cantilever-type radio frequency （RF） micro electro-mechanical system （MEMS） switch is developed based on the Euler-Bernoulli beam an...An approximate analytical model for calculating the pull-in voltage of a stepped cantilever-type radio frequency （RF） micro electro-mechanical system （MEMS） switch is developed based on the Euler-Bernoulli beam and a modified couple stress theory, and is validated by comparison with the finite element results. The sensitivity functions of the pull-in voltage to the designed parameters are derived based on the proposed model. The sensitivity investigation shows that the pull-in voltage sensitivities increase/decrease nonlinearly with the increases in the designed parameters. For the stepped cantilever beam, there exists a nonzero optimal dimensionless length ratio, where the pull-in voltage is insensitive. The optimal value of the dimensionless length ratio only depends on the dimensionless width ratio, and can be obtained by solving a nonlinear equation. The determination of the designed parameters is discussed, and some recommendations are made for the RF MEMS switch optimization.展开更多
The push-pull framework provides a useful approach for examining the tourist motivation. This paper takes the world heritage-Huangshan Mountain as a sample. From the two different aspects of pull and push factors, the...The push-pull framework provides a useful approach for examining the tourist motivation. This paper takes the world heritage-Huangshan Mountain as a sample. From the two different aspects of pull and push factors, the underlying features of visitors′ motives to Huangshan Mountain are analyzed with the help of factor analysis. As a result, five push factors and four pull factors are identified. Further analyses investigate differences in the push and pull factors among different socio-demographic subgroups with one-way ANOVA analysis. The result of the study affords us useful references for development, protection and marketing expansion of mountain resorts.展开更多
In recent years,China's college English education has achieved a great success.However,at the same time,it also brings a lot of negative effects,and problems emerge endlessly.According to her own learning experien...In recent years,China's college English education has achieved a great success.However,at the same time,it also brings a lot of negative effects,and problems emerge endlessly.According to her own learning experience,as well as combining the experience of her own college English teaching,the writer is trying to combine the famous marketing theory"Push& Pull" with college English teaching methods,hoping to provide some suggestions to improve the current teaching situation.展开更多
AIM To evaluate the efficacy of endoscopic ultrasoundguided fine needle aspiration(EUS-FNA) of pancreatic head cancer when pushing(push method) or pulling the echoendoscope(pull method).METHODS Overall, 566 pancreatic...AIM To evaluate the efficacy of endoscopic ultrasoundguided fine needle aspiration(EUS-FNA) of pancreatic head cancer when pushing(push method) or pulling the echoendoscope(pull method).METHODS Overall, 566 pancreatic cancer patients had their first EUS-FNA between February 2001 and December 2017. Among them, 201 who underwent EUS-FNA for pancreatic head lesions were included in this study. EUS-FNA was performed by the push method in 85 patients, the pull method in 101 patients and both the push and pull methods in 15 patients. After propensity score matching(age, sex, tumor diameter, and FNA needle), 85 patients each were stratified into the push and pull groups. Patient characteristics and EUSFNA-related factors were compared between the two groups.RESULTS Patient characteristics were not significantly different between the two groups. The distance to lesion was significantly longer in the push group than in the pull group(13.9 ± 4.9 mm vs 7.0 ± 4.9 mm, P < 0.01). The push method was a significant factor influencing the distance to lesion(≥ median 10 mm)(P < 0.01). Additionally, tumor diameter ≥ 25 mm(OR = 1.91, 95%CI: 1.02-3.58, P = 0.043) and the push method(OR = 1.91, 95%CI: 1.03-3.55, P = 0.04) were significant factors contributing to the histological diagnosis of malignancy.CONCLUSION The pull method shortened the distance between the endoscope and the lesion and facilitated EUS-FNA of pancreatic head cancer. The push method contributed to the histological diagnosis of pancreatic head cancer using EUS-FNA specimens.展开更多
Understanding muscle hemodynamics using near-infrared spectroscopy is increasingly evident in the recent spinal disorders-related literature.However,none of these human studies addressed the issue of physiological lim...Understanding muscle hemodynamics using near-infrared spectroscopy is increasingly evident in the recent spinal disorders-related literature.However,none of these human studies addressed the issue of physiological limits for the lumbar muscle within the same participants during various exercise modes.The purpose of this study is to evaluate physiological limits for the lumbar muscle during dynamic and static endurance tests.On three separate days,22 healthy men and women performed three endurance protocols(static prone trunk extension,arm cranking,and pushingpulling)until volitional exhaustion.For each protocol,minimum and maximum oxygenation and blood volume responses from the right lumbar erector spinae were obtained using a continuous dual wavelength near-infrared spectroscopy(Micro-Runman,NIM Inc.,PA,USA).Statistical analysis showed that greatest reduction in oxygenation(minimum)were obtained during dynamic exercises:pushingpulling(2.1 times)and arm cranking(2.03 times)versus static test (P<0:05).Physiological change(calculated as the difference between maximum during recovery and minimum at the point of volitional exhaustion)during static test was lower[(66-75%for oxygenation)and(34-46%for blood volume)]than dynamic exercises (P<0:05).Contrary to the theory that sufficient occlusion of bloodflow to the lumbar muscle is possible with static trunk extension,it was concluded that a dynamic protocol until volitional exhaustion might be a good alternative in establishing near-infrared spectroscopy-derived physiological limits to the lumbar muscle.Further research is essential to identify an optimal calibration procedure for establishing true hypoxic values for the human lumbar muscle.展开更多
We show that the electromagnetic quantum vacuum derives directly from Maxwell’s theory and plays a primary role in quantum electrodynamics, particle physics, gravitation and cosmology. It corresponds to the electroma...We show that the electromagnetic quantum vacuum derives directly from Maxwell’s theory and plays a primary role in quantum electrodynamics, particle physics, gravitation and cosmology. It corresponds to the electromagnetic field ground state at zero frequency, a zero-energy cosmic field permeating all of space and it is composed of real states, called kenons (κενο = vacuum). Photons are local oscillations of kenons guided by a non-local vector potential wave function with quantized amplitude. They propagate at the speed imposed by the vacuum electric permittivity ε<sub>0</sub> and magnetic permeability μ<sub>0</sub>, which are intrinsic properties of the electromagnetic quantum vacuum. The electron-positron elementary charge derives naturally from the electromagnetic quantum vacuum and is related to the photon vector potential. We establish the masse-charge equivalence relation showing that the masses of all particles (leptons, mesons, baryons) and antiparticles are states of the elementary charges and their magnetic moments. The equivalence between Newton’s gravitational law and Coulomb’s electrostatic law results naturally. In addition, we show that the gravitational constant G is expressed explicitly through the electromagnetic quantum vacuum constants putting in evidence the electromagnetic nature of gravity. We draw that G is the same for matter and antimatter but gravitational forces should be repulsive between particles and antiparticles because their masses bear naturally opposite signs. The electromagnetic quantum vacuum appears to be the natural link between quantum electrodynamics, particle physics, gravitation and cosmology and constitutes a basic step towards a unified field theory. Dark Energy and Dark Matter might originate from the electromagnetic quantum vacuum fluctuations. The calculated electromagnetic vacuum energy density, related to the cosmological constant considered responsible for the cosmic acceleration, is in good agreement with the astrophysical observations. The cosmic acceleration may be due to both “quantum vacuum fluctuations” and “matter-antimatter gravitational repelling”. All the above results are established without stating any assumptions or postulates. Next, we advance two hypotheses with cosmological impact. The first is based on the possibility that gravitation is due to the electromagnetic quantum vacuum density of states fluctuations giving rise to a photon pressure at the characteristic collective oscillation frequencies of the charge densities composing the bodies (Electromagnetic Push Gravity). The second advances that energy, matter and antimatter in the universe emerge spontaneously from the quantum vacuum fluctuations as residues that remain stable in space and we present the main principles upon which a new cosmological model may be developed overcoming the well-known Big Bang issues.展开更多
基金Sponsored by Key Project of Liaoning Social Science Planning Fund in 2019(L19AJY007)。
文摘Data from the seventh national census show that the mobility of rural population in Liaoning is relatively active.Rural revitalization,as a major deployment for development in the new era,will undoubtedly face a variety of problems in the implementation process.Through the study of the relationship between rural revitalization and population,it is found that the loss of rural population is one of the important reasons that hinder rural economic development and lead to the imbalance of urban and rural economic development.According to the "push and pull theory" by the demographer Bagne,the paper analyzes the causes of rural population loss in Liaoning Province.The rural population backflow and two-way flow of urban and rural population in Liaoning Province is achieved through industrial interaction between urban and rural areas,innovative development of agriculture,steady follow-up of service industry and other measures,thus revitalizing the rural economy.
基金financially supported by the National Key Research and Development Program of China (2018YFC1604402)the Natural Science Foundation of Zhejiang Province, China (LY17C140002)+1 种基金the Fundamental and Public Welfare of Zhejiang Province, China (LGN18C160006)the College Student Innovation and Entrepreneurship of Zhejiang Province, China (2017R409055)
文摘Thirteen volatile compounds were identified from Flemingia macrophylla plants. Eight major components significantly attracted the tea green leafhoppers, Empoasca flavescens F. Based on their relative abundances, following synthetic blends were made for field experiments: 1) eight-component-attractant blend included Z-3-hexen-1-ol, Z-3-hexenyl acetate, Z-ocimene, Me SA, Z-3-hexenyl butyrate, dodecane, hexadecane and nonanal at 10, 10, 1, 11, 2, 6, 2 and 4 mg mL^-1 in n-hexane, respectively;2) four-component-attractant blend #1 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and nonanal at 2, 10, 10 and 4 mg mL^-1 in n-hexane, respectively;3) four-component-attractant blend #2 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and Me SA at 2, 10, 10 and 11 mg mL^-1 in n-hexane, respectively. Thymol and 1-methoxy-4-methyl-2-(1-methylethyl)-benzene, identified from Lavandula angustifolia aeration samples, significantly repelled the leafhopper as strong repellents when tested alone or in combination at 10 mg mL^-1. For field bioassays, each attractant lure was attached to a bud green sticky board hung from a bamboo stick at above tea plant level for catching the leafhoppers, whereas the repellent dispenser was tied to a tea branch inside tea clump for pushing the leafhoppers away from tea clumps. The results showed that the eight-component-attractant blend caught similar numbers of the leafhopper as did the four-component-attractant blend #1 at about 53–79 leafhoppers/trap/day, which were significantly higher than those on the hexane-control bud green sticky boards. Average leafhopper catches from un-baited sticky boards were about 51–73 leafhoppers/trap/day when pushed by the repellents placed inside tea plants, with the two-component-repellent blend being more effective than their single components. When the two-component-repellent blend was further tested with the three attractant blends in a push-pull fashion, average trap catches ranged from 62 to 92 leafhoppers/trap/day. Control efficacy on the leafhoppers within the push-pull zones increased progressively from day 1(43%) to day 5(73%). This push-pull approach might have a great potential as a green control strategy for combating the tea green leafhoppers.
文摘Background: Test-retest strength reliability of the Electronic Push/Pull Dynamometer (EPPD) in the measurement of the extensor and flexor muscles on a new constructed chair. The objective of the study was to assess reliability of Electronic Push/Pull Dynamometer in the measurement of the knee flexion and extension at 90° and 60° on a new constructed chair. The aims of the author: To assess reliability of Electronic Push/Pull Dynamometer in the measurement of the knee flexion and extension at 90° and 60° on a new constructed chair. Design: A test-retest reliability study. Subjects: One hundred healthy students male and female (mean age, 21y). Methods: Maximum isometric strength of the quadriceps and hamstring muscle groups was measured using the EPPD were recorded at 60° and 90° for 3 trials on 2 occasions. Reliability was assessed with the Intraclass correlation coefficient (ICC), mean and standard deviation (SD) of measurements, and smallest real differences were calculated for the maximum and for the mean and work of the 3 repetitions. Results: Mean strength ranged from 50.44 kg for knee flexion to 55.76 kg for knee extension 50.44 kg to 61.98 kg at 90° hip flexion. Test-retest reliability Intraclass correlation coefficients (ICCs) ranged from 0.85 to 0.99. ICCs for test-retest reliability ranged from 0.780 to 0.998. Conclusions: The results of the reliability study indicate that the EPPD in reliable dynamometer to use in determining lower limb muscle force production. It can be used to measure disease progression and to evaluate changes in knee extension and flexion strength at the individual patient level.
文摘This paper provides the static and dynamic pullin behavior of nano-beams resting on the elastic foundation based on the nonlocal theory which is able to capture the size effects for structures in micron and sub-micron scales. For this purpose, the governing equation of motion and the boundary conditions are driven using a variational approach. This formulation includes the influences of fringing field and intermolecular forces such as Casimir and van der Waals forces. The differential quadrature （DQ） method is employed as a high-order approximation to discretize the governing nonlinear differential equation, yielding more accurate results with a Considerably smaller number of grid points. In addition, a powerful analytical method called parameter expansion method （PEM） is utilized to compute the dynamic solution and frequency-amplitude relationship. It is illustrated that the first two terms in series expansions are sufficient to produce an acceptable solution of the mentioned structure. Finally, the effects of basic parameters on static and dynamic pull-in insta- bility and natural frequency are studied.
基金financial supports from the National Natural Science Foundation of China (Grant Nos. 41571527, 41301193, 41101552,41401198)Main Direction Program (KZCX2-EW317)West Light Foundation of the Chinese Academy of Sciences (2013Yuhui)
文摘In China, farmers employed in non-farm work have become important socio-economic actors, but few studies have examined the farmers' perspective in making their work location choices. Based on "push-pull" migration theory, this paper utilizes sectional data from a 2013 survey of farmers in China's Three Gorges Reservoir area to empirically analyze the factors influencing migrant workers' choice of employment location. The results indicate that 60.46% of laborers have migrated from their home province, whereas 39.54% have remained in their home province. Focusing on personal, household, and community characteristics—in addition to the economic characteristics of the sample counties—multinomial logistic regression models reveal that farmer-laborers' employment location decisions are influenced by their personal capital endowment(age, years of education and social networks), family structure(the number of laborers, elders, children and students), home village characteristics(location, economic development level and the degree of relief of the land) and home county economic development level. Notably, male and female laborers' location decisions reveal a converging trend, and their differences are not pronounced. Per capita arable land area has little influence on location decisions, whereas the educational level of laborers has a significant impact. The results differ significantly from those found in previous studies.
基金supported by the National Natural Science Foundation of China(Nos.51505089 and61204116)the Opening Project of the Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(Nos.ZHD201207 and 9140C030605140C03015)the Pearl River S&T Nova Program of Guangzhou(No.2014J2200086)
文摘An approximate analytical model for calculating the pull-in voltage of a stepped cantilever-type radio frequency （RF） micro electro-mechanical system （MEMS） switch is developed based on the Euler-Bernoulli beam and a modified couple stress theory, and is validated by comparison with the finite element results. The sensitivity functions of the pull-in voltage to the designed parameters are derived based on the proposed model. The sensitivity investigation shows that the pull-in voltage sensitivities increase/decrease nonlinearly with the increases in the designed parameters. For the stepped cantilever beam, there exists a nonzero optimal dimensionless length ratio, where the pull-in voltage is insensitive. The optimal value of the dimensionless length ratio only depends on the dimensionless width ratio, and can be obtained by solving a nonlinear equation. The determination of the designed parameters is discussed, and some recommendations are made for the RF MEMS switch optimization.
文摘The push-pull framework provides a useful approach for examining the tourist motivation. This paper takes the world heritage-Huangshan Mountain as a sample. From the two different aspects of pull and push factors, the underlying features of visitors′ motives to Huangshan Mountain are analyzed with the help of factor analysis. As a result, five push factors and four pull factors are identified. Further analyses investigate differences in the push and pull factors among different socio-demographic subgroups with one-way ANOVA analysis. The result of the study affords us useful references for development, protection and marketing expansion of mountain resorts.
文摘In recent years,China's college English education has achieved a great success.However,at the same time,it also brings a lot of negative effects,and problems emerge endlessly.According to her own learning experience,as well as combining the experience of her own college English teaching,the writer is trying to combine the famous marketing theory"Push& Pull" with college English teaching methods,hoping to provide some suggestions to improve the current teaching situation.
文摘AIM To evaluate the efficacy of endoscopic ultrasoundguided fine needle aspiration(EUS-FNA) of pancreatic head cancer when pushing(push method) or pulling the echoendoscope(pull method).METHODS Overall, 566 pancreatic cancer patients had their first EUS-FNA between February 2001 and December 2017. Among them, 201 who underwent EUS-FNA for pancreatic head lesions were included in this study. EUS-FNA was performed by the push method in 85 patients, the pull method in 101 patients and both the push and pull methods in 15 patients. After propensity score matching(age, sex, tumor diameter, and FNA needle), 85 patients each were stratified into the push and pull groups. Patient characteristics and EUSFNA-related factors were compared between the two groups.RESULTS Patient characteristics were not significantly different between the two groups. The distance to lesion was significantly longer in the push group than in the pull group(13.9 ± 4.9 mm vs 7.0 ± 4.9 mm, P < 0.01). The push method was a significant factor influencing the distance to lesion(≥ median 10 mm)(P < 0.01). Additionally, tumor diameter ≥ 25 mm(OR = 1.91, 95%CI: 1.02-3.58, P = 0.043) and the push method(OR = 1.91, 95%CI: 1.03-3.55, P = 0.04) were significant factors contributing to the histological diagnosis of malignancy.CONCLUSION The pull method shortened the distance between the endoscope and the lesion and facilitated EUS-FNA of pancreatic head cancer. The push method contributed to the histological diagnosis of pancreatic head cancer using EUS-FNA specimens.
文摘Understanding muscle hemodynamics using near-infrared spectroscopy is increasingly evident in the recent spinal disorders-related literature.However,none of these human studies addressed the issue of physiological limits for the lumbar muscle within the same participants during various exercise modes.The purpose of this study is to evaluate physiological limits for the lumbar muscle during dynamic and static endurance tests.On three separate days,22 healthy men and women performed three endurance protocols(static prone trunk extension,arm cranking,and pushingpulling)until volitional exhaustion.For each protocol,minimum and maximum oxygenation and blood volume responses from the right lumbar erector spinae were obtained using a continuous dual wavelength near-infrared spectroscopy(Micro-Runman,NIM Inc.,PA,USA).Statistical analysis showed that greatest reduction in oxygenation(minimum)were obtained during dynamic exercises:pushingpulling(2.1 times)and arm cranking(2.03 times)versus static test (P<0:05).Physiological change(calculated as the difference between maximum during recovery and minimum at the point of volitional exhaustion)during static test was lower[(66-75%for oxygenation)and(34-46%for blood volume)]than dynamic exercises (P<0:05).Contrary to the theory that sufficient occlusion of bloodflow to the lumbar muscle is possible with static trunk extension,it was concluded that a dynamic protocol until volitional exhaustion might be a good alternative in establishing near-infrared spectroscopy-derived physiological limits to the lumbar muscle.Further research is essential to identify an optimal calibration procedure for establishing true hypoxic values for the human lumbar muscle.
文摘We show that the electromagnetic quantum vacuum derives directly from Maxwell’s theory and plays a primary role in quantum electrodynamics, particle physics, gravitation and cosmology. It corresponds to the electromagnetic field ground state at zero frequency, a zero-energy cosmic field permeating all of space and it is composed of real states, called kenons (κενο = vacuum). Photons are local oscillations of kenons guided by a non-local vector potential wave function with quantized amplitude. They propagate at the speed imposed by the vacuum electric permittivity ε<sub>0</sub> and magnetic permeability μ<sub>0</sub>, which are intrinsic properties of the electromagnetic quantum vacuum. The electron-positron elementary charge derives naturally from the electromagnetic quantum vacuum and is related to the photon vector potential. We establish the masse-charge equivalence relation showing that the masses of all particles (leptons, mesons, baryons) and antiparticles are states of the elementary charges and their magnetic moments. The equivalence between Newton’s gravitational law and Coulomb’s electrostatic law results naturally. In addition, we show that the gravitational constant G is expressed explicitly through the electromagnetic quantum vacuum constants putting in evidence the electromagnetic nature of gravity. We draw that G is the same for matter and antimatter but gravitational forces should be repulsive between particles and antiparticles because their masses bear naturally opposite signs. The electromagnetic quantum vacuum appears to be the natural link between quantum electrodynamics, particle physics, gravitation and cosmology and constitutes a basic step towards a unified field theory. Dark Energy and Dark Matter might originate from the electromagnetic quantum vacuum fluctuations. The calculated electromagnetic vacuum energy density, related to the cosmological constant considered responsible for the cosmic acceleration, is in good agreement with the astrophysical observations. The cosmic acceleration may be due to both “quantum vacuum fluctuations” and “matter-antimatter gravitational repelling”. All the above results are established without stating any assumptions or postulates. Next, we advance two hypotheses with cosmological impact. The first is based on the possibility that gravitation is due to the electromagnetic quantum vacuum density of states fluctuations giving rise to a photon pressure at the characteristic collective oscillation frequencies of the charge densities composing the bodies (Electromagnetic Push Gravity). The second advances that energy, matter and antimatter in the universe emerge spontaneously from the quantum vacuum fluctuations as residues that remain stable in space and we present the main principles upon which a new cosmological model may be developed overcoming the well-known Big Bang issues.
