Search

Habitat selection by animals is conventionally linked with nature selection pressures. However, niche construction as a potent evolutionary agent palys a crucial role for many types of evolutionary habitat selection by species and this modifies nature selection pressures. We used data obtained from an 11-year period to observe the evolutionary habitat selection by the plateau pika (Ochotona curzoniae) in relation to the niche construction of livestock management. We hypothesized that the niche construction of local nomads affects the evolutionary habitat selection of the plateau pika, and furthermore that the plateau pika does not fit niche conservatism in the Kobresia ecosystem of the Qinghai Tibetan Plateau (QTP). In order to verify the above hypotheses, we used the distance to the nearest yak-bedding areas and dung management as the variables that most strongly explain variation in pika occupancy (probability) and detection probability based on free-ranging livestock. Both pika occupancy and detection probability decrease sharply with increasing distance to the nearest yak-bedding area, suggesting that pika population densities are highest closest to yak-bedding areas. There is a strong correlation between dung cover and occupancy of the plateau pika; the more dung drying on the ground, the more plateau pikas occupy the area. Consequently, the plateau pika is frequently detected in damaged grass. Rangeland dominated by Kobresia sedges on the QTP is modified by livestock grazing and management, especially by dung management. This is the first research suggesting that local nomads may cause expansion of the habitat of the plateau pika. In sum, the habitat of the plateau pika is expanding and there is strong evidence that it retains its biodiversity on the Qinghai-Tibetan Plateau in spite of exposure to poison as control measure. Still, the current control management of the plateau pika may result in diminished diversity of both fauna and flora species and a collapse of the food web on the QTP.

At present, the colonoscopy rate of colorectal cancer in urban residents is low. In order to acknowledge colonoscopy screening compliance of colorectal cancer high-risk of urban community residents and its influencing factors is for the purpose of targeted nursing intervention to improve compliance, to provide basis for colorectal cancer screening. The authors take colorectal cancer screening high-risk groups sample from community in Tianjin as the research object, according to whether be willing to accept endoscopic check, put them into the case group and the control group. Designed the general questionnaire colorectal cancer screening and colonoscopy cognitive questionnaire and refusing colonoscopy questionnaire for patients at high risk of colorectal cancer, using Delphi method to get final questionnaire, to get the influence factors of colorectal cancer high-risk patients receiving endoscopic check. Through the data analysis, we draw that only whether of health care between groups in all of the characteristics has statistically significant difference (P 0. 05).Two groups has significant statistical difference in the colonoscopy cognitive (P

This paper reports a continuous-wave (CW) mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate (PPLN) pumped by a diode-end-pumped CW Nd:YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN's grating period of 28.5μm and the temperature of 140°C, the maximum idler output power of 155mW at 3.86μm has been achieved when the 808nm pump power is 8.5W, leading to an optical-to-optical conversion efficiency of 1.82%.

This paper investigates the effects of spontaneously induced coherence on absorption properties in a nearly equispaced three-level ladder-type system driven by two coherent fields. It find that the absorption properties of this system with the probe field applied on the lower transition can be significantly modified if this coherence is optimized. In the case of small spontaneous decay rate in the upper excited state, it finds that such coherence does not destroy the electromagnetically induced transparency (EIT). Nevertheless, the absorption peak on both sides of zero detuning and the linewidth of absorption line become larger and narrower than those in the case corresponding to the effects of spontaneously induced coherence; while in the case of large decay rate, it finds that, instead of EIT with low resonant absorption, a sharp absorption peak at resonance appears. That is, electromagnetically induced absorption in the nearly equispaced ladder-type system can occur due to such coherent effects.