ObjectiveWith the increased population mobility and the transition in population policy, scholars are quite concerned about family planning/sexual and reproductive health (SRH) and related factors among internal migrant population of reproductive age. Therefore, the proposed study was designed to explore the association between factors related to family planning/SRH and contraceptive use as well as consistent condom use among the above-described population in China.DesignCross-sectional study.SettingThree municipalities in China, namely Beijing, Shanghai and Chongqing.ParticipantsAmong the 6545 participants, 2099, 2414 and 2031 subjects came from Beijing, Shanghai and Chongqing, respectively.ResultsA total of 6545 eligible participants were included as the full sample, 6188 of whom who had intercourse in the last 3 months were selected as the subsample. Among the subsample, 80.88% (5005/6188) adopted any form of contraceptive methods and 49.14% (3041/6188) consistently used condom in the last three sexual intercourses. Meanwhile, the involved participants had a better mastery of knowledge on SRH than on contraception (p<0.0001). The results of the Heckprobit models revealed that the factors associated with both contraceptive use and consistent condom use were relationship with the first intercourse partner, communication frequency with spouse/sexual partners on sex, actual number of children and knowledge on SRH, while knowledge on contraception and age at first intercourse were associated with contraceptive use and consistent condom use, respectively (p<0.05).ConclusionsIn the current study, we revealed a high-level contraceptive prevalence, a relatively low-level consistent condom use and a poor mastery of knowledge on contraception and SRH. The Heckprobit selection model specified the existence of selection bias, providing evidence on the association between the factors on family planning/SRH and contraceptive use as well as consistent condom use, respectively. Our findings indicated that health institutions should offer appropriate technology and high-quality family planning/SRH services for the internal migrant population in China.

BackgroundEpiretinal prosthesis is one device for the treatment of blindness, which target retinal ganglion cells (RGCs) by electrodes on retinal surface. The stimulating current of epiretinal prosthesis is an important factor that influences the safety threshold and visual perception. Stochastic resonance (SR) can be used to enhance the detection and transmission of subthreshold stimuli in neurons. Here, it was assumed that SR was a potential way to improve the performance of epiretinal prosthesis. The effect of noises on the response of RGCs to electrical stimulation and the energy of stimulating current was studied based on a RGC model.MethodsThe RGC was modeled as a multi-compartment model consisting of dendrites and its branches, soma and axon. To evoke SR, a subthreshold signal, a series of bipolar rectangular pulse sequences, plus stochastic biphasic pulse sequences as noises, were used as a stimulus to the model. The SR-type behavior in the model was characterized by a “power norm” measure. To decrease energy consumption of the stimulation waveform, the stochastic biphasic pulse sequences were only added to the cathode and anode phase of the subthreshold pulse and the noise parameters were optimized by using a genetic algorithm (GA).ResultsWhen certain intensity of noise is added to the subthreshold signal, RGC model can fire. With the noise’s RMS amplitudes increased, more spikes were elicited and the curve of power norm presents the inverted U-like graph. The larger pulse width of stochastic biphasic pulse sequences resulted in higher power norm. The energy consumption and charges of the single bipolar rectangular pulse without noise in threshold level are 468.18 pJ, 15.30 nC, and after adding optimized parameters’s noise to the subthreshold signal, they became 314.8174 pJ, 11.9281 nC and were reduced by 32.8 and 22.0%, respectively.ConclusionsThe SR exists in the RGC model and can enhance the representation of RGC model to the subthreshold signal. Adding the stochastic biphasic pulse sequences to the cathode and anode phase of the subthreshold signal helps to reduce stimulation threshold, energy consumption and charge of RGC stimulation. These may be helpful for improving the performance of epiretinal prosthesis.