无症状中国年轻人颈椎矢状位曲度正常值及其与全脊柱平衡的关系

目的:探讨无症状中国年轻人颈椎矢状位曲度的正常值及其与全脊柱平衡的关系。方法:2011年11月—2014年12月招募并选择年龄18~30岁的志愿者行全脊柱侧位X线检查,在X线片上测量指标包括C_(0)-C_(2)角、从C_(2)-C_(3)到C_(6)-C_(7)的间盘角、从C_(3)到C_(7)的椎体角、T_(1)倾斜角、胸椎后凸角(thoracic kyphosis,TK)、腰椎前凸角(lumbar lordosis,LL)、骨盆入射角(pelvic incidence,PI)、骶骨倾斜角(sacral slope,SS)、C_(2)-C_(7)矢状轴向垂线(C_(2)-C_(7)sagittal vertical axis,C_(2)-C_(7)SVA)、头重心至C_(7)的矢状位轴向垂线(center of gravity of head to C_(7)SVA,CGH-C_(7)SVA)、C_(7)到S 1的矢状位轴向垂线(C_(7)-S 1SVA)。依据脊柱骨盆矢状位形态进行Roussouly分型,比较不同Roussouly分型下的颈椎曲度及形态。结果:共纳入126名志愿者参与研究,其中男性67名,女性59名,平均年龄(21.4±2.3)岁。C_(0)-C_(7)前凸角平均为26.0°±12.8°,其中C_(0)-C_(2)前凸角平均为15.2°±6.7°,C_(2)-C_(3)到C_(6)-C_(7)间盘前凸角总和平均为9.1°±12.1°,C_(3)到C_(7)的椎体前凸角总和平均仅为1.4°±10.2°。C_(2)-C_(7)SVA(18.6±7.9)mm和CGH-C_(7)SVA[(22.9±12.3)mm]由C_(7)-S 1SVA[(-21.6±31.0)mm]完美代偿。不同的Roussouly分型间颈椎曲度差异有统计学意义(P<0.01)。颈椎曲度与T_(1)倾斜角(P<0.01)、胸椎后凸角(P<0.01)有显着相关性。从T_(1)倾斜角到C_(0)-C_(2)角,相邻节段间盘角之间存在显著相关性(P<0.05)。结论:测量并计算了无症状中国年轻人颈椎椎体角和间盘角的正常值,发现颈椎前凸主要发生在C_(0)-C_(2)和椎间盘水平,这些角度受到其他脊柱部位形态(T_(1)倾斜角、胸椎后凸角和Roussouly分型)的影响,且相邻间盘角之间存在显著的相关性。

太阳能吸附式制冷机强化传质运行策略的优化

提出并搭建了自然解吸与强化解吸协同工作的太阳能吸附式制冷实验平台.测试结果表明,采用自然和强化协同运行方式的制冷量和性能系数(COP),比单独自然传质提高了30.28%和31.58%,比单独强化传质提高了8.82%和7.53%.

Time-series analysis of the relationship between air quality, temperature, and sudden unexplained death in Beijing during 2005-2008

Background There is a yearly increase in the rate of sudden unexplained death （SUD）, even through extensive physical examination and the testing of a large number of biomarkers, the cause of sudden death in patients previously in good health cannot be fully determined. During clinical practice, a spatial aggregation phenomenon has been observed in the incidence of sudden unexplained death. Previous research has shown that environmental factors, such as air pollution, weather conditions, etc., have a significant impact on human health. In the wake of the continuous environmental damage, the relationship between environmental factors and sudden unexplained death still needs to be studied. To study the relationship between sudden unexplained death and air quality and temperature, commonly used markers such as particulate matter of aerodynamic diameter 〈10 μm （PM10）, daily average concentration of the gaseous pollutants sulfur dioxide （SO2） and nitrogen dioxide （NO2）, and the daily average temperature were investigated. Methods The methods include collecting the data of sudden unexplained death; air quality monitoring; meteorological monitoring from January 1, 2005 to December 31, 2008; utilizing generalized additive models （GAM）; controlling the influential factors such as secular trend, seasonal trend, and Sunday dummy variable; and analyzing the correlation between daily inhalable particle concentration, daily average temperature, and the number of daily SUD. Results There was no statistical significance between the daily inhalable particle and daily incidence of sudden unexplained death. Incidence rate of sudden unexplained death had nonlinear positive correlation with daily temperature. When the temperature was 5℃ above the daily average temperature, the daily incidence of sudden unexplained death went up with the rising temperature. Conclusion Temperature may be one of the key risk factor or precipitating factor of SUD.

Common underlying diseases do not contribute in determining the causes of sudden unexplained death

Background Underlying diseases have a statistically significant positive correlation to sudden death. However, sudden unexplained death （SUD） is different from sudden death, as there is no clinical evidence to support the sudden death due to the original underlying disease, nor a lethal pathological basis to be found during autopsy. In addition, SUD are more common in young, previously healthy individuals, usually without any signs of disease, with no positive lesions found after autopsy. Therefore, a causal relationship between SUD and the underlying disease needs to be further explored. This study aimed to explore the role that common underlying diseases play in patients with SUD and to reveal the correlation between them. Methods The medical records, history and case information of 208 patients with SUD were collected for the survey. All these SUD occurred in the emergency room of Peking University Third Hospital from January 2006 to December 2009. The patients were stratified by with and without common underlying diseases. To examine possible associations between the underlying diseases and the cause of unexplained sudden death, the chi-squared and Fisher＇s exact tests were used. Results Among the 208 patients, 65 were diagnosed with common underlying diseases while 143 were not. Within these two groups, there were 45 patients for whom the clear cause of death was determined. However, there were no statistically significant differences or strong associations （x2=1.238, P 〉0.05） between the 11 patients with （16.90%） and 34 without （23.78%） common underlying disease among these 45 patients. We also found that occurrence of the common underlying diseases, such as neurological system, cardiovascular and pulmonary system diseases, are not statistically significant （P 〉0.05） in the diagnosis of the SUD. Conclusion Common underlying diseases make no obvious contributions to SUD and are not useful in diagnosing the underlying reasons for death.

Analysis of the prodromal symptoms of unexplained sudden death in patients with or without underlying diseases

Background In recent years, the incidence of unexplained sudden death has risen significantly across the world. However, it occurred suddenly, often in young apparently healthy individuals and almost 50% of the patients did not have any warning signals or symptoms. Therefore, the prodromal symptoms before the incident are extremely important for early prediction of sudden death. In this article, we aimed to explore the value of prodromal symptoms for unexplained sudden death and whether the prodromal symptoms have a predictive function to unexplained sudden death （USD） without underlying diseases. Methods A total of 208 sudden death cases were selected for the survey in the Emergency Department of Peking University Third Hospital from January 2006 to December 2009 and their medical records were reviewed. The patients were divided into two groups, 65 patients had underlying diseases while 143 had not underlying diseases. In the meantime, their prodromal symptoms were collected and compared, prodromal symptoms including chest distress, dyspnea, syncope, fever, headache, vomiting, etc. Results Patients with underlying diseases were compared to those without underlying diseases associated with sudden death; there was no significant difference in gender and age distribution. Among the 208 cases, 39 cases （18.75%） had prodromal symptoms, patients with underlying diseases had prodromal symptoms in 12 cases （18.46%）, while patients without underlying diseases had prodromal symptoms in 27 cases （18.88%）. The difference between the two groups with prodromal symptoms was not statistically significant （P 〉0.05）. Conclusions Prodromal symptoms are extremely important warning signals in the occurrence of USD. It has equally important predictive value for patients both with and without underlying diseases, especially in predicting sudden death caused by cardiopulmonary and neurological diseases.