ABSTRACT
Objective@#To compare the effects on glucose tolerance and insulin sensitivity between equal isocaloric consumption moderate intensity continuous exercise and high-intensity intermittent exercise in healthy male adolescents, and to provide a reference for a reasonable exercise intervention program to maintain and improve the health level of adolescents.@*Methods@#The 13 subjects from middle schools in Nantong were divided into control group, moderate intensity continuous exercise group (MICE) and high-intensity intermittent exercise group HIIE. The oral glucose tolerance tests were carried out on 13 healthy subjects in all conditions. Meanwhile, the insulin sensitivity index (ISI), total area under the curve (tAUC) and incremental area under the curve (iAUC) of glucose as well as insulin were calculated.@*Results@#The tAUC of plasma glucose of MICE and HIIE group decreased by 5.99% (ES=-0.75) and 9.32% (ES=-0.86)(P<0.05) compared to C group, respectively. The tAUC of plasma glucose in HIIE group decreased by 3.54% (ES=-0.30, P<0.01) compared to MICE group. The tAUC of plasma insulin in MICE and HIIE group was attenuated 4.49% (ES=-0.64, P<0.01) and 6.79% (ES=-0.80, P<0.01) compared to C group, respectively. The tAUC of plasma glucose in HIIE group decreased by 2.42% (ES=-0.30，P<0.01) compared to MICE group. The iAUC of plasma glucose in MICE and HIIE group decreased by 25.52% (ES=-0.57, P<0.01) and 35.82% (ES=-0.73, P<0.01) compared to C group, respectively. The iAUC of plasma glucose in HIIE group decreased by 13.83% (ES=-0.16, P<0.05) compared to MICE group. The iAUC of plasma insulin in MICE and HIIE group descended by 7.14% (ES=-0.67, P<0.01) and 10.18%(ES=-0.75, P<0.01) compared to C group, respectively. The iAUC of plasma insulin in HIIE group decreased by 3.27% (ES=0.21, P<0.05) compared to MICE group. The ISI of MICE and HIIE group increased by 1.65% (ES=0.15, P>0.05) and 4.72% (ES=0.25, P<0.01) compared to C group, respectively. There was no significantly difference in ISI between MICE and HIIE group.@*Conclusion@#The intervention effects on the level of glucose, insulin and insulin sensitivity of high intensity intermittent exercise is better than moderate intensity continuous exercise among adolescents.
ABSTRACT
Multiband high index of refraction can be realized by thin ring-type terahertz metamaterials composed of multilayer coupled unit cells. We have focused on the numerical investigation of this type of a metamaterial. By drastically decreasing the diamagnetic effect with a thin metallic structure in the unit cell and by increasing the effective permittivity through strong capacitive coupling, a bandwidth of 1.5 THz with an index of more than 24 can be achieved using a single-layer thin brick-type metamaterial. The refractive index peak is 35. Then, we design a ring-type metamaterial structure, achieving a refractive index of 91 at about 0.45 THz, which is due to a decrease in the diamagnetic effect with smaller area surrounded by toroidal currents. Based on the coupling effects of double layer ring-type metamaterials or single-layer double ring-type structures, the refractive index peaks reach 43.2 and 18.68 at 0.43 THz and 0.92 THz, respectively. A three-layer ring-type metamaterial structure is proposed to obtain three band high index metamaterials.
ABSTRACT
A self-referenced method for extracting the complex refractive index of material was proposed. The method utilized signals reflected from the front and rear surfaces of a slice sample as reference and sample signals, respectively. Before using the self-referenced method, a hybrid filtering technique for eliminating systematic and random noises of time-domain terahertz reflection spectroscopy was used. A terahertz reflection spectrum of crystalline glucose was measured and three feature absorption peaks were obtained from 0.2 to 2.0 THz. We suggest that intermolecular vibrational modes may contribute to the observed absorption spectra in the THz frequency range.
ABSTRACT
The measurement speed is an important parameter of terahertz time-domain spectroscopy (THz-TDS) instruments. To improve the measurement speed of the spectrometer we need to increase the scanning speed of the delay line. In this paper, we study the influence of the scanning speed, the time constant of lock-in amplifier and the sampling rate on the signal quality. The results show that, when the time constant equal to 10 ms, increasing the scanning speed does not cause significant changes in the amplitude of the signal. But when the time constant equal to 30, 100 and 300 ms, with the increasing of the scanning speed the signal amplitude decreases rapidly. Therefore, the time constant should be set as small as possible to avoid deterioration of signal quality. On the other hand, higher the scanning speed is, fewer data points are collected with a same time-domain length. Therefore, when the scanning speed increase, not only the time constant should be reduced, but also the sampling rate should be increased to avoid the distortion of signal waveform caused by the number reduction of data points. The conclusions can provide a reference for improving the measurement speed of THz-TDS instrument.
ABSTRACT
Measurement errors in frequency domain always appear when testing samples' terahertz (THz) absorption spectrum using terahertz time-domain spectroscopy (THz-TDS) system, which is supposed to be attributed to the sampling accuracy of the high speed electro-optic sampling system In order to make the measurement have a high accuracy, the method of error correction was studied in the present article. Carbon monoxide in gas phase was employed as our standard sample, and its absorption spectrum at the pressure of 2.0 x 10(5) Pa was measured experimentally. Comparing the obtained absorption frequencies with the corresponding standard data in JPL database, we got the error values, and their distribution law shows that the values have a linear correlation with the standard absorption frequency. Based on this, the error correction model was built. Using the model to correct the experimental data, the result shows the maximum error after correction is reduced to 3.36 GHz, which is two orders of magnitude lower than the error before correction. This states that the model can be used to correct the error of the THz spectrum caused by high speed electro-optic sampling system. At last, the authors draw a conclusion that the THz-TDS system is supposed to be corrected by the terahertz spectrum of carbon monoxide before measurement, in this way, the terahertz spectrum of sample can have a high accuracy. The study contributes to the material identification and the construction of molecular spectroscopy database in THz region.
ABSTRACT
We report a simple, broadband and high-absorbance coating for terahertz radiometry. The spectral properties of this coating in THz region were characterized with a home-made terahertz time-domain spectrometer. The measured spectral reflectance is less than 0.3% ranging from 0.2 THz to 0.5 THz and less than 0.1% ranging from 0.5 THz to 2.0 THz. We assembled a terahertz radiometer with this coating as absorber, and discussed its heat transfer in comparison with that of a carbon nanotube array radiometer. This coating is highly absorptive both in terahertz region and in visible light; therefore, the responsivity of this radiometer is easily traceable to National Laser Power Standards. This coating is easily fabricated. It is useful in traceability of terahertz sources and detectors to the SI units.
ABSTRACT
Conventional Fourier-transform mixes the frequency components of the entire temporal terahertz waveform in one frequency domain; therefore, it cannot distinguish the terahertz frequency in the main pulse from the noise frequency in the pulse tail. Thus traditional Fourier-transform produces inconsistent spectra from different scanning lengths of terahertz pulse. And the interference spectrum appears when the THz echo pulse is recorded. The authors applied wavelet-transform and removed the inconsistent spectra and the interference spectra. Wavelet-transform technique exhibited the local frequency of THz in different time locations. This technique would find applications in THz time-resolved spectroscopy.
ABSTRACT
We proposed a simple and straightforward technique, wavelet-transform analysis, for group delay extraction from the white light spectral interferograms. In this paper, we demonstrated that the extracted group delay dispersion by wavelet-transform was insensitive to the path length balancing of the interferometer. This promises a flexible and robust technique for chirped mirror characterization.
Subject(s)
Algorithms , Interferometry/methods , Models, Theoretical , Refractometry/methods , Computer Simulation , Light , Scattering, RadiationABSTRACT
We propose and demonstrate an analysis method to directly extract the group delay rather than the phase from the white-light spectral interferogram. By the joint time-frequency analysis technique, group delay is directly read from the ridge of wavelet transform, and group-delay dispersion is easily obtained by additional differentiation. The technique shows reasonable potential for the characterization of ultra-broadband chirped mirrors.
ABSTRACT
We introduce a novel method for retrieving the phase from a spectral shearing interferogram, based on wavelet-transform technique. We demonstrate with both theoretical and experimental data that this technique provides an alternative and reliable technique for phase retrieval, particularly for highly structured pulse spectra.
