Introduction: The aim of this study was to compare digital and conventional radiography in determining the working length of dilacerated canals.Methods: Thirty nine human extracted single-rooted teeth with root curvature more than 35 degrees were included in this study. After access preparation, a file was inserted into the canal and advanced until the file tip was visualized at the foramen. Wi...

In his recent article on "Quantum theory without observers" [1], Sheldon Goldstein raised a number of important questions about quantum theory. Even though I cannot quite understand what a universal physical theory without any concept of observers could mean, I agree with many of his critical remarks. Bell, who once objected "against measurement," also pointed out that Bohm's quantum theory dep...

We establish the conditions that must be satisfied for the mathematical operations of linear algebra and calculus to be applicable. The mathematical foundations of decision theory and related theories depend on these conditions which have not been correctly identified in the classical literature. Operations Research and Decision Analysis Societies should act to correct fundamental errors in the...

We construct a rigourous model of quantum measurement. A two-state model of a negative temperature amplifier, such as a laser, is taken to a classical thermodynamic limit. In the limit, it becomes a classical measurement apparatus obeying the stochastic axioms of quantum mechanics. Thus we derive the probabilities from a deterministic Schroedinger's equation by procedures analogous to those of ...

This study found mixed support for the hypothesis that the difference in criterion-related validity between unstructured and structured employment interviews is due solely to the greater reliability of structured interviews. Using data from prior meta-analyses, this hypothesis was tested in 4 data sets by using standard psychometric procedures to remove the effects of measurement error in inter...

We present a quantum information theory that allows for the consistent description of quantum entanglement. It parallels classical (Shannon) information theory but is based entirely on matrices, rather than probability distributions, for the description of quantum ensembles. We find that conditional quantum entropies can be negative for quantum entangled systems, which leads to a violation of w...

A consistent description of interactions between classical and quantum systems is relevant to quantum measurement theory, and to calculations in quantum chemistry and quantum gravity. A solution is offered here to this longstanding problem, based on a universally-applicable formalism for ensembles on configuration space. This approach overcomes difficulties arising in previous attempts, and in ...

The quantum theory of measurement has been a matter of debate for over eighty years. Most of the discussion has focused on theoretical issues with the consequence that other aspects (such as the operational prescriptions that are an integral part of experimental physics) have been largely ignored. This has undoubtedly exacerbated attempts to find a solution to the “measurement problem”. How the...

The degree distribution of the internet, that is, the fraction of routers with k links for any k, is its most studied property. It has a crucial influence on network robustness, spreading phenomena and protocol design. In practice, however, this distribution is observed on partial, biased and erroneous maps. This raises serious concerns about the true knowledge we actually have of this key prop...