Historical notes on the determination of distance by timed radio waves

The foregoing notes trace the history of the measurement of the propagation times of radio waves as a means for determining distance. While the reader may feel that undue emphasis has been placed upon the KHL height measurements, a survey of the literature will show that only a small proportion of the reported observations have been cited here. Out of the hundreds of published articles on KHL height measurements, the writer has endeavored to select those which present the step-by-step improvements in the methods and apparatus. In the period just prior to the War, the United States Patents offered the principal means for tracing the development of the art. In the war period the notes are necessarily incomplete because of the scarcity of publications; this is no doubt due to secrecy conditions.     

Hypocalcemia in an 11 Year Old Child: <Emphasis Type="Italic">A Difficult Case to Treat</Emphasis>

Hypocalcemia is a laboratory and clinical abnormality that is observed especially in neonates and paediatric patients. Laboratory hypocalcaemia is often asymptomatic but it can manifest as central nervous system irritability, paraesthesia, tetany (i.e. contraction of hands, arms, feet, larynx, bronchioles), seizures, and even psychiatric changes in children. Cardiac function may also be impaired because of poor muscle contractility. We report a unique case of an eleven year old male child who presented with chronic kidney disease associated with severe hypocalcemia, tonic-clonic seizures, hypovitaminosis D but normal electroencephalogram and electrocardiography. The child required prolonged intravenous calcium gluconate therapy to correct his ionised calcium levels.     

大学的收益:留学生教育中的经济学意义

留学生教育的经济收益是国际教育服务贸易中的重要部分,国外有关学者、政府机构和国际组织都非常关注,但在国内,人们对留学生教育的认识还主要集中在政治和文化层面。通过建构的经济收益测算模型(包括图式模型和数学模型),并以上海一所大学的留学生样本进行试测,研究显现出我国高校留学生教育的经济学意义:留学生教育促进了教育服务贸易,增加了我国经济总量;能够缩减我国在国际教育服务贸易中的巨大逆差;增加了高校的"预算外收入";改变了高校的教育资源结构,提高了教育管理效率。     

审美游戏与中学课程教学

审美游戏是人类特有的一种融创造性、娱乐性和教育性为一体的活动,由于学校教育和审美游戏在本质上具有同一性,因而在实践活动中可以将二者有机地结合起来。以中学课程教学为例:语文和哲学是关于语言和解释的游戏,音乐和数学是关于符号和序列的游戏,美术和历史是关于时间和变化的游戏,地理和物理是关于空间和运动的游戏,生物和化学是关于模拟与复制的游戏。搞好课程教学的关键在于充分发掘身体、器物和符号这三者之间的内在联系并不断地促使其相互转化。     

Circulating Cell-Free DNA Level in Prediction of COVID-19 Severity and Mortality: Correlation of with Haematology and Serum Biochemical Parameters

Lymphocyte dysregulation in coronavirus disease-19 (COVID-19) is a major contributing factor linked to disease severity and mortality. Apoptosis results in the accumulation of cell-free DNA (cfDNA) in circulation. COVID-19 has a heterogeneous clinical course. The role of cfDNA levels was studied to assess the severity and outcome of COVID-19 patients and correlated with other laboratory parameters. The current case series included 100 patients with mild COVID-19 (MCOV-19) and 106 patients with severe COVID-19 (SCOV-19). Plasma cfDNA levels were quantified using SYBR green quantitative real-time PCR through amplification of the β-actin gene. CfDNA level was significantly higher in SCOV-19 at 706.7 ng/ml (522.6–1258) as compared to MCOV-19 at 219.8 ng/ml (167.7–299.6). The cfDNA levels were significantly higher in non-survivor than in survivors (p = 0.0001). CfDNA showed a significant correlation with NLR, ferritin, LDH, procalcitonin, and IL-6. The diagnostic sensitivity and specificity of cfDNA in the discrimination of SCOV-19 from MCOV-19 were 90.57% & 80%, respectively. CfDNA showed a sensitivity of 94.74% in the differentiation of non-survivors from survivors. CfDNA levels showed a significant positive correlation with other laboratory and inflammatory markers of COVID-19. CfDNA levels, NLR, and other parameters may be used to stratify and monitor COVID-19 patients and predict mortality. CfDNA may be used to predict COVID-19 severity with higher diagnostic sensitivity.