Global exact tracking for uncertain MIMO linear systems by output feedback sliding mode control

This paper presents a solution to the problem of global exact output tracking for uncertain MIMO (multiple-input–multiple-output) linear plants with non-uniform arbitrary relative degree using output feedback sliding mode control. The key idea to overcome the relative degree obstacle is to generalize our previous hybrid estimation scheme to a multivariable version by combining, through switching, a standard linear lead filter with a non-linear one based on robust exact differentiators, achieving uniform global exponential practical stability and exact tracking.     

Metastasis of gastric carcinoma to the thyroid and lung: a case report and review of literature

Cancer metastasis to the thyroid is extremely rare. The more commonly reported primary sites for metastasis to the thyroid are the kidney, breast, lung, colon, esophagus, and uterus. Thyroid metastasis from the stomach has only been reported in three cases. Herein, we report a 71-year-old man presenting with bilateral thyroid multinodular lesions. Bilateral near-total thyroidectomy was performed due to airway compression with related symptoms. Wedge resection of a suspicious pulmonary nodule, detected on CT, was performed for diagnosis. Polypoid lesions in the stomach were examined by trans-scopic biopsy. Poorly differentiated adenocarcinomas with the same histological profiles were noted at these three sites. The immunohistochemical staining for thyroglobulin of these specimens was negative. We conclude that a new thyroid mass appearing in a patient with present or prior malignancies should raise the concern of metastatic disease.     

Where is the “theory” within the field of educational technology research?

Critics often characterise the study of educational technology as under-theorised. To test this assertion and to determine the extent of this criticism, the present paper reports an in-depth analysis of the 503 most recent empirical articles published in three selected education-technology-related journals (Computers & Education; Learning, Media and Technology; and British Journal of Educational Technology). These journals were selected because they publish studies related to all education settings rather than focusing on only a certain segment such as higher education; they have broad geographical catchment; and they were the most highly ranked journals in terms of their 2017 journal citation impact factor. The present paper examines how explicitly existing theory was identified in previous research, how theories were applied and how often these theories were advanced in education technology research. In the majority of cases, explicit engagement with theory was absent. Many studies either were wholly bereft of theories or made vague use of theory. Where theory was explicit, the articles were more likely to use theory to conceptualise the research, to inform the data collection or analysis process and to discuss the results. Very few articles reported findings that help us to learn something new about a particular theory (ie, little evidence of theory advancement).     

The impact of national research funds: A regression discontinuity approach to the Chilean FONDECYT

This paper analyses the role of national research funds in promoting scientific production in emerging economies. The study focuses on the impact of the Chilean National Science and Technology Research Fund (FONDECYT). The analysis uses data drawn from international sources of bibliometric information combined with the administrative records of the program's executing unit. To measure the program's impact, we implement a regression discontinuity (RD) design on principal researchers who applied for funding between 1988 and 1997 considering as outcomes both quantity (publications up to 2002) and quality (citations up to 2005) of their scientific production. Our results show significant and positive impact in terms of publications, but no impact in terms of quality of scientific production in the proximity of the program's threshold ranking.     

西门塔尔牛的限制酶显带

本文采用限制酶HinI、AluI分别处理西门塔尔牛的中期染色体18小时。AluI产生部分C带和部分G带;Hinf产生G带和部分C带。