1,721,082 research outputs found
Iterated combination-based paired permutation tests to determine shape effects of chemotherapy in patients with esophageal cancer
No full textThe nonparametric combination of dependent permutation tests method is a useful general tool when a
testing problem can be broken down into a set of different k>1 partial tests. These partial tests, after
adjustment of p-values to control for multiplicity, can be marginally analyzed, but jointly considered they
can provide information on an overall hypothesis, which might represent the true goal of the testing
problem. On the one hand, independence among the partial tests is usually an unrealistic assumption; on
the other, even when the underlying dependence relations are known quite often they are difficult to cope
with properly. Therefore this combination must be achieved nonparametrically, by implicitly taking into
account the dependence structure of tests without explicitly describing it. An important property of the
tests based on nonparametric combination methodology, when the number of response variables is high
compared to the sample sizes, consists in the finite sample consistency. A practical problem involves
choosing the most suitable combining function for each specific testing problem given that the final result
can be affected by this crucial choice. The purpose of this article is to present an nonparametric
combination solution based on the iterated combination of partial tests, evaluate its power behavior
using a Monte Carlo simulation study and apply it to a real medical problem, namely the evaluation of the
effects of chemotherapy on the shape of esophageal tumors. R code has been implemented to carry out
the analyses
Presenting a New Wireless Strain Method for Structural Monitoring: Experimental Validation
No full textThe structural health monitoring (SHM) of large and complex infrastructures as well as laboratory tests of new structures and materials resorts to strain gauge measurements to check mechanical stress. A wireless measurement of the strain gauge response is desirable in many practical applications to avoid the cost and the difficulty of wiring, particularly in large structures requiring several sensors and in complex objects where the measurement points are difficult to access. In this paper, a wireless strain gauge which is a hybrid between an RFID tag and a usual thin-film resistive strain gauge is experimented. Installation and maintenance problems of the wireless sensor networks are overcome allowing a high level of measurement accuracy, comparable to that of wired strain sensors, together with a long measurement distance. A large set of measurements has been performed using reference specimens and readings in order to validate the sensor and to develop a calibration procedure that makes the sensor suitable for a large number of different applications in civil engineering. © 2019 Amedeo Gregori et al.The structural health monitoring (SHM) of large and complex infrastructures as well as laboratory tests of new structures and materials resorts to strain gauge measurements to check mechanical stress. A wireless measurement of the strain gauge response is desirable in many practical applications to avoid the cost and the difficulty of wiring, particularly in large structures requiring several sensors and in complex objects where the measurement points are difficult to access. In this paper, a wireless strain gauge which is a hybrid between an RFID tag and a usual thin-film resistive strain gauge is experimented. Installation and maintenance problems of the wireless sensor networks are overcome allowing a high level of measurement accuracy, comparable to that of wired strain sensors, together with a long measurement distance. A large set of measurements has been performed using reference specimens and readings in order to validate the sensor and to develop a calibration procedure that makes the sensor suitable for a large number of different applications in civil engineering
Strength reduction factor of concrete with recycled rubber aggregates from tires
No full textRecycling of waste tire rubber is a significant environmental problem due to the huge number of waste tires needing disposal. A promising alternative to methodologies usually used for this aim is the use of tire rubber in the construction industry as artificial aggregate in concrete. This paper investigated the effects on the concrete compressive strength of the partial replacement of natural aggregates with waste tire rubber. Different types and amounts of natural aggregate substitutions were considered, with percentages of rubber ranging from 0% to 100% and including only fine aggregates (F), only coarse aggregates (C), and fine and coarse aggregates simultaneously (C&F). A literature review and new experimental data were considered, presenting about 1,500 tests from dozens of different authors in more than 20 independent studies, included the present one. Based on this large data set, new analytical relationships were developed and proposed to analyze the concrete strength reduction factor (SRF) expected as a consequence of natural aggregate substitution with rubber, and the relationship with the equivalent degree of compaction (EDC) of the mixture was considered
Combined granular cell tumour of the oesophagus and stomach: a case report and review of the literature.
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