A型、D型人格影响冠心病预后的心理生理机制

Coronary heart disease （CHD）is a common cardiovascular disease in the elderly, is also a typical psychosomatic disease. Personality factors are very important in many psychological factors impacting on the prognosis of patients with CHD. The most influential personality factors to CHD are Type A and Type D personality. The previous research has shown that although Type A personality increased the prevalence of CHD, it cannot predict the development and prognosis after diagnosis. In contradict, Type D personality can predict prognosis. There is still no clinic-based or theory-based answer to the question: Why Type A personality cannot predict the outcome while Type D personality could predict the prognosis independently. The current research conducted a systematic investigation to the above question, which included one comparison study between CHD patients and control group, and four studies on reaction experiment and answered the question: why Type A personality cannot predict whereas Type D personality could effectively predict prognosis of CHD. The findings of the current research were: Type A and Type D personality influence CHD prognosis through different psychological mechanisms: both dimensions of Type D personality have direct influence on social support, whereas neither dimensions of Type A personality related to social support, directly of indirectly. Negative affection component of Type D personality significantly related to anxiety and depression, Social repression significantly related to anxiety but not depression. Both dimensions of Type A personality significantly related to anxiety but not depression. Neither under rest or diaphragmatic breathing conditions, Type A personality had no significant influence on vestibular autonomic reaction among healthy young males. Neither Type A nor Type D personality had significant influence on vestibular autonomic reaction among old CHD patients under rest condition. Type D personality predicted lower sympathetic excitation under rest condition, and lower cardiac vagal tone under diaphragmatic breathing condition among healthy young males. When actively reacted to stimuli (math calculation) under rest condition, Type A personality increased sympathetic excitation among healthy young males. When actively reacted to stimuli (math calculation) under diaphragmatic breathing condition, Type A personality increased cardiac vagal tone among the same group of subjects. When actively reacted to stimuli under neither condition, Type D personality showed no significant influence on vestibular autonomic reaction among young males. When passively reacted to stimuli under neither condition, Type A personality showed no significant influence on vestibular autonomic reaction among young males. When passively stimulated followed rest, Type D personality increased sympathetic excitation and decreased cardiac vagal tone among young males. When passively stimulated followed diaphragmatic breathing, Typed showed no significant influence on vestibular autonomic reaction among young males. The above results indicated that Type A and Type D personalities had different psychological mechanisms to the outcome of CHD treatment: neither dimensions of Type A personality had direct or indirect effects on social support; both dimensions of Type D personality had direct and indirect effects on social support. Negative affection component of Type D personality significantly related to anxiety and depression, Social repression significantly related to anxiety but not depression. Both dimensions of Type A personality significantly related to anxiety but not depression. Social support positively related to the outcome after CHD treatment. The biological mechanisms of Type A and Type B personality to CHD prognosis differed in the following ways: Type A personality increased sympathetic excitation when actively stimulated, but had no influence when passively stimulated among young male subjects. When passively stimulated after rest, Type D personality predicted high sympathetic excitation and low cardiac vagal tone among young males, but not vestibular autonomic reaction among young males. Key words: Type A personality, Type D personality, Coronary Heart Disease (CHD), Prognosis, Psychobiological Mechanisms

Effect Of A Negative Poisson Ratio In The Tension Of Ceramics

The effect of a negative Poisson ratio is experimentally revealed in the tension deformation of a natural layered ceramic. This effect can increase the volume strain energy per unit volume by 1100% and, simultaneously, decrease the deformation strain energy per unit volume by about 44%, so that it effectively enhances the deformation capacity by about 1 order of magnitude in the tension of the material. The present study also shows that the physical mechanisms producing the effect are attributed to the climbing on one another of the nanostructures in the natural material, which provides a guide to the design of synthetic toughening composites.

Negative refractive index in a four-level atomic system

We propose a scheme for realizing negative refractive index in a four-level atomic system. It is shown that such a system can simultaneously exhibit negative permittivity and negative permeability in an optical frequency range. Furthermore, by analysing the dispersion property of the left-handed material, we find that the probe beam can be controlled from superluminal to subluminal or vice versa via choosing appropriate parameters.

Phase control of switching from positive to negative index material in a four-level atomic system

Electric and magnetic responses of the medium to the probe field are analysed in a four-level loop atomic system by taking into account the relative phase of the applied fields. An interesting phenomenon is found: under suitable conditions, a change of the refractive index from positive to negative can occur by modulating the relative phase of the applied fields. Then the medium can be switched from a positive index material to a negative index material in our scheme. In addition, a negative index material can be realized in different frequency regions by adjusting the relative phase. It may give us a convenient way to obtain the desired material with positive or negative index.

Electromagnetically induced negative refractive index in a V-type four-level atomic system

We propose a scheme for realizing negative refractive index in a V-type four-level atomic system. It is shown that the negative refractive index can be achieved in a wide frequency band based on the effect of quantum coherence. It is also found that the frequency band of negative refractive index and the absorption property of left-handed material are manipulated by the pump and control fields. Furthermore, left-handed material with reduced absorption is possible by choosing appropriate parameters. (c) 2006 Elsevier B.V. All rights reserved.

Anomalous behaviour of photorefractive grating erasure owing to existence of both negative and positive carriers

In LiNbO3:Fe, anomalous behaviour of grating erasure is observed with different wavelenghts, i.e. rapid grating erasure in the short wavelength range, which deviates from the results predicted by the electron transport band model. The deviation is related to the coexistance of electrons and holes in photorefraction, and charge-transfer process including electrons and hole has been proposed. The electron and hole contributions to photo-excitation coefficient S of the Fe centre on the wavelength.

Negative refraction in a honeycomb-lattice photonic crystal

In this paper we theoretically investigate a photonic crystal with dielectric rods in a honeycomb lattice. Two left-handed frequency regions are found in the second and third photonic band by using the plane wave expansion method to analyze the photonic band structure and equifrequency contours. Subwavelength imaging by the photonic crystal flat lens are systematically studied by numerical simulations using the multiple scattering method. Different from the photonic crystals with noncircular dielectric rods in air, this structure is almost isotropic at the optimal frequency for superlensing. As a comparison, flat slab focusing is also demonstrated at other frequencies in the two left-handed regions. (c) 2006 Elsevier Ltd. All rights reserved.

The tunable negative refractive index in granular composite

The effective refractive index of a kind of granular composite, which consists of granular metallic and magnetic inclusions with different radius embedded in a host medium, is theoretically investigated. Results show that for certain volume fractions of these two inclusions, the negative permittivity peak shifts to low frequency and the peak value increases with increasing radius ratio of the radius of magnetic granulae to that of metallic granulae. Simultaneously, peak value of permeability decreases with the radius ratio, and value peak shifts to high frequency with increasing volume fraction of magnetic inclusion. Therefore, the radius ratio can affect the effective refractive index considerably, and it is found that by adjusting the radius ratio, the refractive index may change between negative and positive values for certain volume fractions of the two inclusions. (c) 2005 Elsevier B.V. All rights reserved.

Negative refraction via domain wall resonances in a homogeneous mixture of ferro- and nonmagnetic substances

We deliver the general conditions on the synthetic proportions for a homogeneous mixture of ferro- and nonmagnetic substances to become left-handed. As an alternative for left-handed metamaterials, we consider mixing ferromagnetic materials with nonmagnetic microscopic particles. In the mixture, the ferromagnetic material provides the needed permeability via domain wall resonances at high frequencies, whereas the nonmagnetic material gives the required permittivity. Using the effective medium theory, we have found that when the concentration of the nonmagnetic particles falls into a certain range, the refractive index of the mixture is negative, n < 0, which includes the double negative ( epsilon < 0 and mu < 0) and other cases ( e. g. epsilon < 0 and mu > 0). We finally give the requirements on the microscopic material properties for the ferromagnetic materials to reach the domain wall resonances at high frequencies.

Influence of negative ion element impurities on laser induced damage threshold of HfO2 thin film

Negative ion element impurities breakdown model in HfO2 thin film was reported in this paper. The content of negative ion elements were detected by glow discharge mass spectrum analysis (GDMS); HfO2 thin films were deposited by the electron-beam evaporation method. The weak absorption and laser induced damage threshold (LIDT) of HfO2 thin films were measured to testify the negative ion element impurity breakdown model. It was found that the LIDT would decrease and the absorption would increase with increasing the content of negative ion element. These results indicated that negative ion elements were harmful impurities and would speed up the damage of thin film. (c) 2006 Elsevier B.V. All rights reserved.

Negative dispersion mirrors in Ta2O5/: SiO2 for femtosecond Ti : Sapphire lasers by using gires-tournois interferometers

We design and experimentally demonstrate some negative dispersion mirrors with optimized Gires-Tournois interferometers. The mirror structure is composed of 38 alternating Ta2O5 and SiO2 layers and could be regarded as two sections: high-reflectivity section consisting of a series of quarter-wavelength optical thickness stacks and negative-dispersion section consisting of only 13 layers. The designed mirrors exhibit the expected performance. These mirrors were fabricated by using ion beam sputtering. By adopting such mirrors, dispersion of a mode-locked femtosecond Ti:sapphire laser has been compensated for mostly. With two series of the mirrors, 32 fs and 15 fs pulses have been obtained respectively.