Assessment of oxidative stress and effect of antioxidant supplementation during radiotherapy in carcinoma of upper digestive tract

Oxidative stress was studied by estimating plasma levels of malondialdehyde (MDA), beta carotene, vitamin E and erythrocytic superoxide dismutase(E-SOD) activity in 50 cases of carcinoma of upper digestive tract which included carcinoma of oral cavity, pharynx and oesophagus. While plasma MDA level was found to be increased (3.5±1.0 nmole/ml), a significant decrease in beta carotene (81.2±14.5mg%), vitamin E (8.5±1.1 mg/L) level and E-SOD activity (657.0±80.6 U/G Hb) were observed in carcinoma of upper digestive tract. Patients were treated with radiotherapy which itself was toxic enough and produced its deleterious effects by generation of reactive oxygen species (ROS). As antioxdiants can detoxify ROS, beneficial effect if any, of antioxidant administration during radiotherapy was studied in two groups of patients, group A (n=5, supplemented with antioxidants) and group B (n=5, without antioxidant supplementation). Plasma MDA level was found to be elevated in both the groups but the increase in group B was significant, compared to pretreatment level. Further, body weight was found to be significantly decreased in group B patients, which was maintained in group A patients. Moreover, group A patients showed significant elevation in beta carotene concentration, thus showing beneficial effect of administration of antioxidants during radiotherapy without disturbing the desirable therapeutic effect of radiotherapy.     

几种蒸散模型在玉米农田蒸散量计算中的应用比较

模拟蒸散的物理过程,计算农田蒸散量是进行生态系统水资源评价和管理的重要手段,同时也是气象部门进行土壤湿度预报的首要条件.本研究以玉米农田为研究对象,基于涡度相关法观测的蒸散实测资料,比较分析了基于常规气象数据的蒸散模型(Hargreaves法、Priestlev-Taylor法、FAO-Penman-Monteith法)和基于气象梯度数据的蒸散模型(波文比法、梯度法、生态系统过程模型模拟)的模拟精度.结果表明:①Hargreaves法、Priestley-Taylor法和FAO-Penman-Monteith法日蒸散的模拟结果较为一致,总体上高估20%～26%,其中Priestley-Taylor法模拟结果最优;②生态系统过程模型模拟的农田日蒸散精度较高,但模型中涉及的物理过程和参数较多,在实际应用中难于获取;③波文比法在波文比小于0.4且仪器精度较高时可以得到较准确的估算值.研究同时还指出,仪器的安装高度及高差设计对梯度法估算蒸散十分重要.     

Intersample optimization in a sampled-data control system using the redundancy of a dual-rate system

The present study discusses the design method for controlling a single-input/single-output linear time-invariant dual-rate system, where the sampling interval of the plant output is longer than the holding interval of the control input. In such a dual-rate system, the intersample output might oscillate even when the sampled output converges to the reference input in the steady state. In a conventional ripple-free method, an existing control law is extended by introducing an exogenous variable, which is independent of the discrete-time sampled response, and the exogenous variable is designed for eliminating the steady-state intersample ripples without changing the existing sampled response. In another method, since a control law is designed such that the intersample performance is optimized, the intersample ripples are eliminated in the transient as well as steady states. However, the preservation of an existing sampled response is not taken into account. The present study proposes a new design method for eliminating the intersample ripples subject to the existing sampled response. In the proposed method, the continuous-time index is optimized subject to the existing discrete-time response. As a result, the intersample ripples are eliminated in the transient as well as steady states, and the existing discrete-time sampled response is maintained. The proposed method is compared to the conventional dual-rate design methods in numerical examples, and the effectiveness of the method is demonstrated.     

A comparative study on oxidative stress and antioxidant status in ischemic stroke patients with and without diabetes

The study was conducted to find out the extent of lipid peroxidation and antioxidant status in ischemic stroke patients (ISPs) with and without diabetes. Malondialdehyde (MDA) was studied as a marker of lipid peroxidation. Glutathione (GSH), uric acid and ceruloplasmin were estimated to study the antioxidant potential of ISPs. Significantly higher levels of MDA were found in both the groups of ISPs and the increase in MDA was more in ISPs without diabetes. GSH levels were decreased significantly in both the groups of ISPs and maximum decline was found in ISPs with diabetes. Uric acid levels were significantly increased in both the groups of ISPs. Ceruloplasmin levels were increased significantly in ISPs without diabetes, whereas its levels were slightly decreased in ISPs with diabetes. A negative correlation was found between MDA and the antioxidants GSH, uric acid and ceruloplasmin in ISPs with diabetes. This study suggests that there is an association between ischemic stroke and increased oxidative stress and the antioxidant potential is impaired in both the groups of ISPs with and without diabetes.     

Explaining the substantial inter-domain and over-time correlations in student achievement: the importance of stable student attributes

Multi-domain and longitudinal studies of student achievement routinely find moderate to strong correlations across achievement domains and even stronger within-domain correlations over time. The purpose of this study is to examine the sources of these patterns analysing student achievement in 5 domains across Years 3, 5 and 7. The analysis is of longitudinal population data of over 22,000 students and utilizes fixed-effects models to incorporate stable general and domain-specific latent factors. These latent factors correspond to a general cognitive-ability-like factor and specific aptitudes in particular, or types of, subject areas. The preferred model incorporates both general and domain-specific latent factors with stronger effects for the general factor, although the domain-specific factors are particularly strong for spelling and numeracy. When taking into account general and domain-specific latent factors, the effects of student’s socioeconomic status (SES) and school SES are trivial.     

Are Canadian adolescents happy？ A gender-based analysis of a nationally representative survey

In this study, the authors analyzed data from a nationally representative survey of youth to study happiness amongst Canadian adolescents aged 12-17. Testing for differences in the level of happiness between female and male adolescents was conducted. Following this, multivariate analysis was employed to determine which factors were associated with adolescent happiness. The authors determined that the level of happiness appeared to vary between the genders, as the males reported a higher level of happiness than the females. However, the difference between the genders in terms of reported happiness was modest. The authors detected some gender differences in regards to determinants of happiness. The study＇s theoretical and practical implications are also considered.     

Re-Examining the Similarities Between Teacher and Student Conceptions About Physical Science

There is a large body of research that has explored students’ misconceptions about science phenomena. Less research, however, has been devoted to identifying teachers’ misconceptions, but the results of the few existing studies demonstrate that teachers and students possess similar misconceptions. This study explored the physical science conceptions of 103 elementary science teachers to determine whether, after three decades of misconception research, teachers still possess conceptions similar to those held by students. We found that our teachers expressed misconceptions regarding gravity, magnetism, gases, and temperature that were similar to common student misconceptions. Suggestions for improving science professional development programs are discussed.