The set of the second-order elastic constants and their hydrostatic-pressure derivatives have been obtained for the rhombohedral single-crystal berlinite (AlPO4) using the ultrasonic pulse echo overlap technique. To quantify the vibrational anharmonicity, the acoustic-mode Gruneisen parameters in the long-wavelength limit have been derived in the quasiharmonic approximation.The results extend previous observations that the elastic and physical behavior of berlinite is quite similar to that of quartz. The hydrostatic-pressure derivative BC«/BP has a negative value indicating that the corresponding transverse-acoustic mode softens under pressure; this is in accord with the anomalous positive temperature dependence of C«. The anomalous behavior of C« indicates that there may be even at room-temperature inhuence of the zone-center optic phonon, whose softening is associated with the a-P structural transformation, on long-wavelength transverse-acoustic phonons propagating in the same crystallographic direction.
This study aimed to examine the specific means and internal processes through which mathematical understanding is achieved by focusing on the process of understanding three new mathematical concepts. For this purpose interviews were conducted with 54 junior high school students. The results revealed that mathematical understanding can be achieved when new concepts are connected to at least two existing concepts within a student’s cognitive structure of. One of these two concepts should be the superordinate concept of the new concept or, more accurately, the superordinate concept that is closest to the new concept. The other concept should be convertible, so that a specific example can be derived by changing or transforming its examples. Moreover, the process of understanding a new concept was found to involve two processes, namely, “going” and “coming.” “Going” refers to the process by which a connection is established between a new concept and its closest superordinate concept. In contrast, “coming” is a process by which a connection is established between an existing convertible concept and a new concept. Therefore the connection leading to understanding should include two types of connections: belonging and transforming. These new findings enrich the literature on mathematical understanding and encourage further exploration. The findings suggest that, in order to help students fully understand new mathematical concepts, teachers should first explain the definition of a given concept to students and subsequently teach them how to create a specific example based on examples of an existing concept.
Introduction
Penile incarceration for erotic or autoerotic purposes has been reported in a wide range of age groups, and often presents a significant challenge to urologic surgeons. No ready method has been reported for removing a polyvinylchloride (PVC) pipe entrapped on the penis.
Aim
To present our experience in using hot-melt method to remove a constricted PVC pipe on the penis.
Methods
A long melting split was made on the PVC pipe entrapped on the penis by using the long narrow branch of forceps heated on a gas stove.
Results
The heated forceps was able to make a melt split on the PVC pipe. Consequently, the PVC pipe was removed by pulling the edges of the pipe apart without much difficulty. The total operation time was 20 minutes.
Conclusion
Penile incarceration is a urologic emergency, for which resourcefulness is required in some unexpected cases. Hot-melting has proved to be an easy and effective method for removing penile strangulation by a PVC pipe. To our knowledge, it is the first report about the removal of PVC pipe entrapped on a penis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.