Survey of attitude and knowledge of reproductive health among middle school students in Luoyang, China.

The aim of this study was to assess the knowledge and attitude of AIDS and sexual behavior of middle school students. Structural questionnaires were designed to interview 1980 junior and senior middle school students about their basic knowledge, attitude, and behavior with respect to AIDS and sexual behavior. Students were recruited from the six most common middle schools of the six regions in Luoyang City of the Henan Province of China by cluster sampling from September to December of 2004. Results showed that 54.5% of students had not learned about the prevention of HIV/AIDS in school, and 38.3% of students did not have any knowledge about the route of transmission of HIV/AIDS. Furthermore, 91.2% of students were reluctant to share a classroom with HIV/AIDS patients. Approximately 21.7% of students had read books, watched videos, and consulted other media related to sex, 1.1% of students had had sexual intercourse during high school, and 80.5% believed that health education on HIV/AIDS and sex was necessary. The results of this survey showed that middle school students have little knowledge about HIV/AIDS and sex. Therefore, health education programs for HIV/AIDS prevention and sexual health should be developed as soon as possible to help students peacefully get through a sexually puzzling period of life.

Cardiac MRI for clinical dilated cardiomyopathy: Improved diagnostic power via combined T1, T2, and ECV.

INTRODUCTION: Early diagnosis of patients with dilated cardiomyopathy (DCM) remains challenging. Cardiac MR can correlate myocardial changes with their pathological basis. There have been some previous studies on the effect of T1 mapping in DCM, but there is limited data on the incremental value of T2 mapping for DCM in routine clinical practice. This study will examine whether the combination of MRI T1 and T2 mapping offers greater advantages in the diagnosis of DCM. METHODS: The study included 28 patients with DCM and 21 healthy controls. CMR evaluation included late gadolinium enhancement (LGE), T1 mapping, extracellular volume (ECV) fraction and T2 mapping. The DCM group was divided into LGE (+) and LGE (-) subgroups. The main modes of LGE are subendocardial, midwall, subepicardial, or transmural. T1 values, T2 values, and ECV in the 16 segments myocardial levels were measured by post-processing software. Student's t-tests or Mann-Whitney U test was used to compare between two groups, and one-way ANOVA or Kruskal-Wallis H test was used to compare between multiple groups, with p values corrected by Bonferroni. The difference was considered statistically significant at P < 0.05. ROC curve analysis was used to compare the area under the curve (AUC) of each index and its combined value, and the cut-off value, sensitivity and specificity were determined by Jordan's index. RESULTS: Mean native myocardial T1, ECV and T2 were significantly higher in the DCM group compared to controls (p ≤ 0.001, respectively). The best cut-off values for T1, T2 and ECV to discriminate DCM from controls were 1184 ms, 40.9 ms and 29.2%, respectively. The AUC of T1, ECV and T2 were 0.87, 0.89, and 0.83, respectively. The combined AUC of the three values was 0.96. CONCLUSION: Native T1 value and ECV overcome some of the limitations of LGE, and the T2 helps to understand the extent of myocardial damage. The combination of T1 and T2 mapping techniques can reveal fibrotic and oedematous changes in the early stages of DCM, providing a more comprehensive assessment of DCM and better guidance for individualised clinical management of patients. IMPLICATIONS FOR PRACTICE: We suggest that the addition of T2 mapping to the routine CMR examination of patients with suspected DCM, and the combined assessment of T1mapping and T2 mapping can provide complementary information about the disease and improve the early diagnosis of DCM.

Kinetic model and Vlasov simulation verification of two-ion decay instability.

A kinetic theory is developed to describe the longitudinal decay of two-ion decay (TID): The pump ion-acoustic wave (IAW) decays into two daughter IAWs with a longer wavelength. The instability growth rate and threshold are given by the theory. Both the simulations of full kinetic Vlasov and hybrid Vlasov (kinetic ions and Boltzmann electrons) are employed to verify the theory and have a high quantitative agreement with the theory for 8≤ZT_{e}/T_{i}≤15, where Z is the ion charge number and T_{i}(T_{e}) is the ion (electron) temperature. The kinetic model developed here solves a long-standing problem that the simple fluid theory underestimates growth rate by a factor of 2∼3. Also, a reasonable explanation is given to the typical characteristics of TID that the dependence curves of subharmonic growth rate γ and wave number k.

Anomalous staged hot-electron acceleration by two-plasmon decay instability in magnetized plasmas.

We present a staged hot-electron acceleration mechanism of the two-plasmon decay (TPD) instability in the transverse magnetic field under the parameters relevant to inertial confinement fusion experiments. After being accelerated by the forward electron plasma wave (FEPW) of TPD, the hot-electrons can be anomalously accelerated again by the backward electron plasma wave (BEPW) of TPD and then obtain higher energy. Moreover, the surfatron acceleration mechanism of TPD in the magnetic field is also confirmed, the electrons trapped by the TPD daughter EPWs are accelerated in the direction along the wave front. Interestingly, the velocity of electrons accelerated by surfing from the FEPW is quite easily close to the BEPW phase velocity, which markedly enhances the efficiency of the staged acceleration. The coexistence of these two acceleration mechanisms leads to a significant increase of energetic electrons generated by TPD in the magnetic field. Meanwhile the EPWs are dissipated, TPD instability is effectively suppressed, and the laser transmission increases.

Prevalence of the metabolic syndrome in the Yan-an region of northwest China.

OBJECTIVES: To evaluate the prevalence of the metabolic syndrome in a sample population from northwest China, and to determine the optimal cut-off point for waist circumference for diagnosing the metabolic syndrome in this population. METHODS: A total of 1290 residents of the Yan-an region of China completed a cross-sectional survey, physical examination and laboratory tests. The International Diabetes Federation (IDF), Chinese Diabetes Society (CDS), and the National Cholesterol Education Program Adults Treatment Panel-III (NCEP-ATPIII) criteria were used to assess the prevalence of the metabolic syndrome and its relationship with age and gender. RESULTS: According to the NCEP-ATPIII, CDS and IDF diagnostic criteria, the prevalence of the metabolic syndrome was 15.8%, 20.4% and 26.4%, respectively. The optimal cut-off point for waist circumference was ≥ 86.5 cm for men and ≥ 80.5 cm for women. CONCLUSIONS: The prevalence of the metabolic syndrome in the Yan-an region was significantly higher than that in other regions of China, and participants with the metabolic syndrome were much younger than those in other Chinese regions.

Decreased gray matter concentration and local synchronization of spontaneous activity in the motor cortex in Duchenne muscular dystrophy.

BACKGROUND AND PURPOSE: Patients with DMD have demonstrated functional abnormalities in the motor-related brain areas in previous PET, MRS, and TMS studies. We applied structural MR imaging and RS-fMRI in patients with DMD for the first time, and aimed to investigate the GMC and ReHo or local synchronization of spontaneous activity in the motor cortex. MATERIALS AND METHODS: Ten boys with DMD (6.4-14.0 years of age) and 15 healthy controls (7.9-15.1 years of age) underwent brain structural MR imaging and RS-fMRI scanning. GMC and local synchronization of spontaneous activity in the motor cortex were analyzed by using VBM and ReHo approaches, respectively. RESULTS: Compared with healthy controls, boys with DMD showed decreased GMC in the left PSMC and decreased ReHo in the bilateral PMSC as well as in the supplementary motor area (P < .05, corrected). CONCLUSIONS: The current results indicate that boys with DMD have both GMC loss and decreased local synchronization of spontaneous activity in the motor cortex, which might be due to the deficiency of dystrophin in the brain.