Effects of sawtooth heat pulses on edge flows and turbulence in a tokamak plasma

Enhancements of edge zonal flows,radial electric fields,and turbulence are observed in electron cyclotron resonance heating-heated plasmas(Zhao et al 2013 Nucl.Fusion 53083011).In this paper,the effects of sawtooth heat pulses on flows and turbulence are presented.These experiments are performed using multiple Langmuir probe arrays in the edge plasmas of the HL-2A tokamak.The edge zonal flows,radial electric fields,and turbulence are all enhanced by sawteeth.Propagation of the zonal flow and turbulence intensities is also observed.The delay time of the maximal intensity of the electric fields,zonal flows,and turbulence with respect to the sawtooth crashes is estimated as~1 ms and comparable to that of the sawtooth-triggered intermediate phases.Not only the zonal flows but also the radial electric fields lag behind the turbulence.Furthermore,the intensities of both the zonal flows and electric fields nearly linearly increase/decrease with the increase/decrease of the turbulence intensity.A double-source predator-prey model analysis suggests that a relatively strong turbulence source may contribute to the dominant zonal flow formation during sawtooth cycles.

Prevalence and intensity of soil-transmitted helminth infections among school-age children in the Cagayan Valley, the Philippines

Objective:To identify the prevalence of soil-transmitted helminthiasis(STH)among school-age children in the Cagayan Valley,the Philippines,assess their level of awareness on the disease,and determine predisposing factors of the disease.Methods:A total of 478 GradesⅢ-Ⅴschool-age children in Pamplona and Sanchez-Mira School Districts in the Cagayan Valley answered the questionnaire assessing their knowledge,attitude,and practices on STH,subjected to anthropometric measurements,and provided faecal samples for parasitologic assessment(direct smear,Kato-Katz,and formol-ether concentration techniques).Results:The participants of the study,with 55.86%females,were 8 to 14 years old.Their nutritional status was assessed‘normal’(84.31%),‘severely wasted’(6.49%),‘wasted’(5.23%),‘overweight’(2.72%),and‘obese’(1.26%).The prevalence of infection with at least 1 STH species was 25.99%in Pamplona and 19.40%in SanchezMira.Overall,the prevalence of heavy intensity was 7.11%for Ascaris lumbricoides and 1.67%for Trichuris trichiura.All hookworm infections had light intensities.The majority of the school-age children had a low score in the KAP test.In knowledge of STH,‘stunted growth as a symptom of infection’was associated with a lower risk of Ascaris lumbricoides infection(OR 0.448;95%CI 0.212,0.945;P=0.035)while‘playing with soil as a mode of transmission’was associated with an increased risk of Ascaris lumbricoides infection(OR 2.067;95%CI 1.014,4.212;P=0.046).In attitude towards STH,‘I think I have intestinal worm now’was associated with a higher risk of Ascaris lumbricoides infection(OR 1.681;95%CI 1.061,2.662;P=0.027).Conclusions:The prevalence rate of Ascaris lumbricoides among the school-age children in the Cagayan Valley shows the need to further intensify intervention in the area to meet the threshold set by the World Health Organization.The identified predictors of infection,which concerns the school-age children’s knowledge and attitude toward STH,can be used in augmenting intervention programs in the future.

Radio-protective effect of vitamin E on spermatogenesis in mice exposed to γ-irradiation: a flow cytometric study

Aim: To investigate the effect of vitamin E on the radioprotection of spermatogenesis and chromatin condensation of spermatozoa during passage through the epididymis in mice exposed to irradiation. Methods: Adult outbred male ICR mice were orally administered natural vitamin E (VE, D-α-tocopheryl acetate) at 400 IU/kg for 7 days before exposure to 1 Gy of γ-irradiation. The animals were sacrificed at day 1, 7, 14, 21, 28, 35 and 70 post-irradiation (IR) and the percentage of testicular germ cells and epididymal sperm chromatin condensation was analyzed using flow cytometry. Results: Serum D-α-tocopheryl acetate levels were 47.4 ± 3.2 μg/dL in the treated group, yet it could not be detected in the control group. The testicular weight of irradiated mice pretreated with VE+IR was significantly (P<0.05) higher than that of those without VE treatment (IR) at day 14 and 21 post-irradiation. The percentage of primary spermatocytes (4C) in the VE+IR group was comparable to the controls but significantly (P<0.05) higher than those in the IR group from day 7 to 35 post-irradiation. The percentage of round spermatids (1C) in the VE+IR group was also significantly (P<0.05) higher than those in the IR group at day 28 post-irradiation. The primary spermatocytes : spermatogonia ratio in the IR group was significantly (P<0.05) declined at day 7 to 35 post-irradiation when compared to the VE+IR and control groups. The round spermatid : spermatogonia ratio in the VE+IR group was significantly (P<0.05) higher than that of the IR group at day 14 and 28 post-irradiation. The chromatin condensation of epididymal spermatozoa measured by propidium iodide uptake was not affected by 1 Gy of γ-irradiation. Conclusion: The administration of VE prior to irradiation protects spermatogenic cells from radiation.