High-altitude gastrointestinal bleeding:An observation in Qinghai-Tibetan railroad construction workers on Mountain Tanggula

AIM: To investigate the gastrointestinal bleeding (GIB) in people from lowland to high altitude and in workers on Mountain Tanggula and its causes as well as treatment and prophylaxis.METHODS: From 2001 to October 2003, we studied GIB in 13 502 workers constructing the railroad on Mountain Tanggula which is 4905 m above the sea level. The incidence of GIB in workers at different altitudes was recorded. Endoscopy was performed when the workers evacuated to Golmud (2808 m) and Xining (2261 m). The available data on altitude GIB were analyzed.RESULTS: The overall incidence of GIB was 0.49% in 13 502 workers. The incidence increased with increasing altitude. The onset of symptoms in most patients was within three weeks after arrival at high altitude. Bleeding manifested as hematemesis, melaena or hematochezia, and might be occult. Endoscopic examination showed that the causes of altitude GIB included hemorrhage gastritis, gastric ulcer, duodenal ulcer, and gastric erosion. Experimental studies suggested that acute gastric mucosal lesion (AGML) could be induced by hypoxic and cold stress, which might be the pathogenesis of altitude GIB. Those who consumed large amount of alcohol, aspirin or dexamethasone were at a higher risk of developing GIB. Persons who previously suffered from peptic ulcer or high-altitude polycythemia were also at risk of developing GIB. Early diagnosis, evacuation, and treatment led to early recovery. CONCLUSION: GIB is a potentially life threatening disease, if it is not treated promptly and effectively. Early diagnosis, treatment and evacuation lead to an early recovery. Death due to altitude GIB can be avoided if early symptoms and signs are recognized.

Impacts of nitrogen deposition on terrestrial plant diversity: a meta-analysis in China

Aims With the global atmospheric nitrogen(N)deposition increasing,the effect of N deposition on terrestrial plant diversity has been widely studied.Some studies have reviewed the effects of N deposition on plant species diversity;however,all studies addressed the effects of N deposition on plant community focused on species richness in specific ecosystem.There is a need for a systematic meta-analysis covering multiple dimensions of plant diversity in multiple climate zones and ecosystems types.Our goal was to quantify changes in species richness,evenness and uncertainty in plant communities in response to N addition across different environmental and experimental contexts.Methods We performed a meta-analysis of 623 experimental records published in English and Chinese journals to evaluate the response of terrestrial plant diversity to the experimental N addition in China.Three metrics were used to quantify the change in plant diversity:species richness(SR),evenness(Pielou index)uncertainty(Shannon index).Important Findings Results showed that(i)N addition negatively affected SR in temperate,Plateau zones and subtropical zone,but had no significant effect on Shannon index in subtropical zones;(ii)N addition decreased SR,Shannon index and Pielou index in grassland,and the negative effect of N addition on SR was stronger in forest than in grassland;(iii)N addition negatively affected plant diversity(SR,Shannon index and Pielou index)in the long term,whereas it did not affect plant diversity in the short term.Furthermore,the increase in N addition levels strengthened the negative effect of N deposition on plant diversity with long experiment duration;and(iv)the negative effect of ammonium nitrate(NH_(4)NO_(3))addition on SR was stronger than that of urea(CO(NH_(2))_(2))addition,but the negative effect of NH_(4)NO_(3) addition on Pielou index was weaker than that of CO(NH2)2 addition.Our results indicated that the effects of N addition on plant diversity varied depending on climate zones,ecosystem types,N addition levels,N type and experiment duration.This underlines the importance of integrating multiple dimensions of plant diversity and multiple factors into assessments of plant diversity to global environmental change.

Reliable Control for Nonlinear Systems with Stochastic Actuators Fault and Random Delays Through a T-S Fuzzy Model Approach

This paper considers the reliable control design for T-S fuzzy systems with probabilistic actuators faults and random time-varying delays. The faults of each actuator occurs randomly and its failure rates are governed by a set of unrelated random variables satisfying certain probabilistic distribution. In terms of the probabilistic failures of each actuator and time-varying random delays, new fault model is proposed. Based on the new fuzzy model, reliable controller is designed and sufficient conditions for the exponentially mean square stability （EMSS） of T-S fuzzy systems are derived by using Lyapunov functional method and linear matrix inequality （LMI） technique. It should be noted that the obtained criteria depend on not only the size of the delay, but also the probability distribution of it. Finally, a numerical example is given to show the effectiveness of the proposed method.

Comparison and research on the GRAVEL and PRIP algorithms of neutron energy spectrum unfolding

Objective Neutron energy spectrum unfolding is a key technique for neutron detection.It is essentially an inversion problem.The GRAVEL algorithm has been widely used in this field,and the PRIP algorithm transforms neutron energy spectrum unfolding into a typical nonnegative linear complementarity problem and solves it by interior point algorithm for potential reduction.Methods These two algorithms are applied to unfold several different neutron energy test spectra and actual D-T fusion neutron energy spectrum.Results and Conclusion By comparison,it can be concluded that the PRIP algorithm is highly computationally efficient and fast converging,and the GRAVEL algorithm solution results match up more with the expected results.