9,219 research outputs found
The Moving Center of Mass of a Leaking Bob
The evaluation of variation in oscillation time period of a simple pendulum
as its mass varies proves a rich source of discussion in a physics class-room,
overcoming erroneous notions carried forward by students as to what constitutes
a pendulum's length due to picking up only the results of approximations and
ignoring the rigorous definition. The discussion also presents a exercise for
evaluating center of mass of geometrical shapes and system of bodies. In all,
the pedagogical value of the problem is worth both theoretical and experimental
efforts. This article discusses the theoretical considerations.Comment: Nine pages and three figure
Studying Three Phase Supply in School
The power distribution of nearly all major countries have accepted 3-phase
distribution as a standard. With increasing power requirements of
instrumentation today even a small physics laboratory requires 3-phase supply.
While physics students are given an introduction of this in passing, no
experiment work is done with 3-phase supply due to the sheer possibility of
accidents while working with such large powers. We believe a conceptual
understanding of 3-phase supply would be useful for physics students with hands
on experience using a simple circuit that can be assembled even in a high
school laboratorys
Occurrence of Hysteresis like behavior of resistance of film in heating-cooling cycle
Experimental observations of a peculiar behavior observed on heating and
cooling films at different heating and cooling rate are
detailed. The film regained its original resistance, forming a closed loop, on
the completion of the heating-cooling cycle which was reproducible for
identical conditions of heating and cooling. The area enclosed by the loop was
found to depend on (i) the thickness of the film, (ii) the heating rate, (iii)
the maximum temperature to which film was heated and (iv) the cooling rate. The
observations are explained on basis of model which considers the film to be a
resultant of parallel resistances. The film's finite thermal conductivity gives
rise to a temperature gradient along the thickness of the film, due to this and
the temperature coefficient of resistance, the parallel combination of
resistance changes with temperature. Difference in heating and cooling rates
give different temperature gradient, which explains the observed hysteresis.Comment: 21 pages and 10 figure
Clinical application of high throughput molecular screening techniques for pharmacogenomics.
Genetic analysis is one of the fastest-growing areas of clinical diagnostics. Fortunately, as our knowledge of clinically relevant genetic variants rapidly expands, so does our ability to detect these variants in patient samples. Increasing demand for genetic information may necessitate the use of high throughput diagnostic methods as part of clinically validated testing. Here we provide a general overview of our current and near-future abilities to perform large-scale genetic testing in the clinical laboratory. First we review in detail molecular methods used for high throughput mutation detection, including techniques able to monitor thousands of genetic variants for a single patient or to genotype a single genetic variant for thousands of patients simultaneously. These methods are analyzed in the context of pharmacogenomic testing in the clinical laboratories, with a focus on tests that are currently validated as well as those that hold strong promise for widespread clinical application in the near future. We further discuss the unique economic and clinical challenges posed by pharmacogenomic markers. Our ability to detect genetic variants frequently outstrips our ability to accurately interpret them in a clinical context, carrying implications both for test development and introduction into patient management algorithms. These complexities must be taken into account prior to the introduction of any pharmacogenomic biomarker into routine clinical testing
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