The measurements of the similarity of dynamic brain functional network / 生物医学工程学杂志

Brain functional network changes over time along with the process of brain development, disease, and aging. However, most of the available measurements for evaluation of the difference (or similarity) between the individual brain functional networks are for charactering static networks, which do not work with the dynamic characteristics of the brain networks that typically involve a long-span and large-scale evolution over the time. The current study proposes an index for measuring the similarity of dynamic brain networks, named as dynamic network similarity (DNS). It measures the similarity by combining the "evolutional" and "structural" properties of the dynamic network. Four sets of simulated dynamic networks with different evolutional and structural properties (varying amplitude of changes, trend of changes, distribution of connectivity strength, range of connectivity strength) were generated to validate the performance of DNS. In addition, real world imaging datasets, acquired from 13 stroke patients who were treated by transcranial direct current stimulation (tDCS), were used to further validate the proposed method and compared with the traditional similarity measurements that were developed for static network similarity. The results showed that DNS was significantly correlated with the varying amplitude of changes, trend of changes, distribution of connectivity strength and range of connectivity strength of the dynamic networks. DNS was able to appropriately measure the significant similarity of the dynamics of network changes over the time for the patients before and after the tDCS treatments. However, the traditional methods failed, which showed significantly differences between the data before and after the tDCS treatments. The experiment results demonstrate that DNS may robustly measure the similarity of evolutional and structural properties of dynamic networks. The new method appears to be superior to the traditional methods in that the new one is capable of assessing the temporal similarity of dynamic functional imaging data.

Prevalence of acute coronary heart disease among farmers in Panyu, Guangzhou: a 20-year population-based study / 中华心血管病杂志

<p><b>OBJECTIVE</b>To monitor the incidence change of acute coronary heart events in the all-ages farmers in Panyu District, Guangzhou City during 1991-2001 and 2010-2011.</p><p><b>METHODS</b>The surveillance on the same defined population as that from the PRC-USA cooperative epidemiologic project on the cardiovascular and pulmonary diseases 30-year ago was carried out in Panyu, Guangzhou in 1991-2001 and 2010-2011. The crude incidence of acute coronary events and the age-standardized incidence rate were calculated by the year, gender and age, and standardized with the world standard population age distribution. Incidences at the two different periods were compared. The annual average changing rate of the incidence was obtained by the regression analysis methods.</p><p><b>RESULTS</b>In the 11 consecutive years of 1991-2001, a upward trend on the incidence of acute coronary events among the farmers in women in Panyu District was found (P < 0.05). The incidence of the acute coronary events in the year of 2010-2011 was significantly higher than that in the year of 1991 to 2001 [34.06 per 100 000 (age-adjusted rate as 28.50 per 100 000) versus 16.14 per 100 000 (age-adjusted rate as 16.57 per 100 000), P < 0.05]. The age-adjusted rate increased by 83.04%. Peak incidence of acute coronary events in males was noticed in 75-79 age group, and in 80-84 age group in females. Comparing to the period of 1991-2001, the largest incidence increases appeared in the age groups of 35-39 and 75-79 years in males, while in the age groups of 50-54 and 65-69 years in females. Up to 47.37% (36/76) events occurred on the age group older than 75 years, raised by 40.44% comparing to that in 1991-2001 (33.73%, 56/166).</p><p><b>CONCLUSIONS</b>The incidence of acute coronary events among farmers in Panyu District is at middle or low level of China but there is an increasing trend in acute coronary incidence from 1991 to 2011. Our results suggest that the prevention and treatment on acute coronary syndrome should be strengthened, and especially on the age group with the largest increase of disease incidence.</p>