Influence of High-Velocity Blood Flow on Right-to-Left Shunt in Patients with Patent Foramen Ovale during the Valsalva Maneuver

In this study, we investigated the changes in the right-to-left shunt (RLS) of the patent foramen ovale (PFO) at different phases of the Valsalva maneuver and analyzed the possible mechanisms. The study population consisted of 57 patients with symptoms highly suggestive of a PFO. These patients had been diagnosed with apsychia, migraine with aura, cerebral infarction, transient ischemic attack (TIA), and cerebral ischemia with unknown cause. Routine echocardiography was performed in all patients to rule out a cardiac malformation. Contrast-transcranial Doppler (c-TCD) and contrast-enhanced transthoracic echocardiography (c-TTE) were used to visualize and quantify the RLS. The standard apical four chamber view was used to observe the changes of E peak, A peak, and velocity-time integral (VTI) ratio of tricuspid blood flow during the strain phase and release phase of the Valsalva maneuver. Paired t-test was used to compare E peak, A peak, and VTI ratio of tricuspid blood flow during the different phases. The right-to-left shunt across the PFO (PFO-RLS) was graded in the two phases and compared by Kruskal-Wallis test. Compared with the strain phase of the Valsalva maneuver, the parameters of E, A, and VTI in diastolic period in patients with PFO-RLS at the release phase were significantly increased [54.30 ± 13.65 cm/s vs 100.35 ± 21.11 cm/s, 42.21 ± 12.32 cm/s vs 57.30 ± 18.88 cm/s, 10.34 ± 3.27 cm/s vs 19.58 ± 4.56 cm/s, respectively], and the difference was statistically significant. The positive consequence of PFO-RLS, as diagnosed by c-TTE with the Valsalva maneuver at the release phase of the Valsalva maneuver, was significantly higher than that at the strain phase of the Valsalva maneuver. At the beginning of release phase of the Valsalva maneuver, decreased intrathoracic pressure led to increased venous backflow into the right atrium. Thus, high-velocity blood flow rapidly pushed the PFO open, which resulted in a significant increase in the PFO-RLS. Therefore, the increase of the PFO-RLS during the Valsalva maneuver is caused by the impact of high-velocity blood flow the PFO.

Empirical Study of E-logistics System Based on Tibet Logistics Industry

With the rapid growth of E-logistics in the global logistics industry,it is important to get insight into E-logistics system in Chinese logistics industry.Regarding the current situation of E-logistics of Chinese logistics industry,there are still many problems to be concerned and resolved.This paper will review the concepts and theoretical background of E-logistics System from previous researches.After acknowledging the essential issues on E-logistics System,a research model is designed and tested based on the Theory Acceptance Model.This research aims to provide theoretical and practical contributions for Chinese logistics companies to enhance understanding on E-logistics System.It also provides some useful theoretical implication and practical guidelines for the development of E-logistics System in Chinese logistics industry.

Object-based Analysis for Extraction of Dominant Tree Species

As forest is of great significance for our whole development and the sustainable plan is so focus on it. It is very urgent for us to have the whole distribution,stock volume and other related information about that. So the forest inventory program is on our schedule. Aiming at dealing with the problem in extraction of dominant tree species,we tested the highly hot method-object-based analysis. Based on the ALOS image data,we combined multi-resolution in e Cognition software and fuzzy classification algorithm. Through analyzing the segmentation results,we basically extract the spruce,the pine,the birch and the oak of the study area. Both the spectral and spatial characteristics were derived from those objects,and with the help of GLCM,we got the differences of each species. We use confusion matrix to do the Classification accuracy assessment compared with the actual ground data and this method showed a comparatively good precision as 87% with the kappa coefficient 0. 837.

nfluence and mechanism of Xindakang on cardiac functions of isolated frog heart

OBJECTIVE To evaluate the effects of flavonoids from Xindakang(Hippophae Fructus flavone)on myocardial systolic and diastolic functions of isolated frog hearts and explore the possible mechanism,and provide experimental basis for improving the effect and efficacy of Xindakang on cardiac function.METHODS The isolated frog heart perfusion specimens were prepared by Yagi′s method,and the effects of different concentrations of Xindakang on myocardial contractility(0.0125,0.025,0.05,0.1 and 0.2 g·L^(-1)),heart rate and cardiac output of isolated frog heart were studied.Acetylcholine,atropine and epinephrine were administered successively to analyze the effects of Xindakang on cardiac systolic function of isolated frogs under the action of different drugs,and compared with propranolol.The effect of extracellular calcium ion concentration on the action of Xindakang was studied by using low calcium concentration,high calcium concentration and normal Ren′s solution.To study the effect and possible mechanism of Xindakang on cardiac systolic function of frog.RESULTS The concentration of Xindakang in the range of 0.0125-0.1 g·L^(-1)could weaken the contractility of isolated frog heart and increase the concentration of Xindakang.The inhibitory effect of Xindakang on contractility of isolated frog heart was enhanced,and showed obvious dose-effect relationship.Cardiac output was significantly decreased by Xindakang(P<0.01),slow heart rate(P<0.05);M receptor blocker atropine could not antagonize the contractile effect of Xindakang,and Xindakang could not completely antagonize the contractile effect of adrenalin.Xindakang could inhibit the isolated frog heart in low calcium concentration,high calcium concentration and normal Ren′s solution,and increased with the increase of extracellular calcium concentration(P<0.01).CONCLUSION Xindakang has inhibitory effect on isolated frog heart,which may be achieved by blocking the calcium channel on myocardial cell membrane and reducing the calcium concentration in myocardial cells.

Strain effects on valence bands of wurtzite ZnO

Based on the k.p theory of Luttinger-Kohn and Bir-Pikus,analytical E-k solutions for the valence band of strained wurtzite ZnO materials are obtained.Strain effects on valence band edges and hole effective masses in strained wurtzite ZnO materials are also discussed.In comparison with unstrained ZnO materials,apparent movement of valence band edges such as "light hole band","heavy hole band" and "crystal splitting band" at Γ point is found in strained wurtzite ZnO materials.Moreover,effective masses of "light hole band","heavy hole band" and "crystal splitting band" for strained wurtzite ZnO materials as the function of stress are given.The analytical results can provide a theoretical foundation for the understanding of physics of strained ZnO materials and its applications with the framework for an effective mass theory.

Strain effects on band structure of wurtzite ZnO: a GGA+U study

Band structures in wurtzite bulk ZnO/Zn1-xMgxO are calculated using first-principles based on the framework of generalized gradient approximation to density functional theory with the introduction of the on-site Coulomb interaction. Strain effects on band gap, splitting energies of valence bands, electron and hole effective masses in strained bulk ZnO are discussed. According to the results, the band gap increases gradually with increasing stress in strained ZnO as an Mg content of Znl-xMgxO substrate less than 0.3, which is consistent with the experimental results. It is further demonstrated that electron mass of conduction band （CB） under stress increases slightly. There are almost no changes in effective masses of light hole band （LHB） and heavy hole band （HHB） along [00k] and [k00] directions under stress, and stress leads to an obvious decrease in effective masses of crystal splitting band （CSB） along the same directions.

Inter valley phonon scattering mechanism in strained Si/(101)Si_(1-x)Ge_x

Inter valley scattering has a great impact on carrier mobility of strained Si materials,so based on Fermi＇s golden rule and the theory of Boltzmann collision term approximation,inter valley phonon scattering mechanism of electrons in nano scale strained Si（101） materials is established under the influence of both energy and stress. It shows that inter valley phonon f_2,f_3,g_3 scattering rates decrease markedly in nano scale strained Si（101） materials with increasing stress.The quantized models can provide valuable references to the understanding of strained Si materials and the research on electron carrier mobility.