Problems conceptual

Aside from merely calculational difficulties, the existence of a low-temperature rate-constant limit poses a conceptual problem. In fact, one may question the actual meaning of the rate constant at r = 0, when the TST conditions listed above are not fulfilled. If the potential has a double-well shape, then quantum mechanics predicts coherent oscillations of probability between the wells, rather than the exponential decay towards equilibrium. These oscillations are associated with tunneling splitting measured spectroscopically, not with a chemical conversion. Therefore, a simple one-dimensional system has no rate constant at T = 0, unless it is a metastable potential without a bound final state. In practice, however, there are exchange chemical reactions, characterized by symmetric, or nearly symmetric double-well potentials, in which the rate constant is measured. To account for this, one has to admit the existence of some external mechanism whose role is to destroy the phase coherence. It is here that the need to introduce a heat bath arises. 

The speed and capability of the modem computer are revolutionizing the practice of chemical engineering. Advances in speed and memory size and improvements in complex problem-solving ability are more than doubling the effective speed of the computer each year. This umelenting pace of advance has reached the stage where it profoundly alters the way in which chemical engineers can conceptualize problems and approach solutions. For example ... 

An excellent overview of the problems that students experience in learning the notions underlying chemical equilibrium is available (van Driel Graber, 2002). Research shows that conceptual problems arose when students, who had been introduced to chemical reactions through examples that evidently go to completion , first met examples of incomplete reactions . In this situation, they... 

Neve, KA and Neve, RL (Eds) (1996) The Dopamine Receptor, Humana Press, New York. Salamone, JD, Cousins, MS and Snyder, BJ (1997) Behavioural functions of nucleus acumbens dopamine empirical and conceptual problems with the anhedonia h5 pothesis. Neurosci. Behav. Rev. 21 341-359. 

Dobbs, Betty Jo Teeter. "Conceptual problems in Newton s early chemistry a preliminary study." In Religion, science and worldview, eds. Margaret J. Osier and Paul Lawrence Farber, 3-32. Cambridge Cambridge Univ P, 1985. 

A major conceptual problem associated with the idea of a photon is how to reconcile its corpuscular nature with a wave expanding in three dimensions. One way to address the problem starts from the wave function of a photon in an arbitrary state, expanded in terms of the general wave function (59) as... 

The conceptual problems start when considering materials such as plutonium, which is a by-product of the nuclear electricity industry. Plutonium is one of the most chemically toxic materials known to humanity, and it is also radioactive. The half-life of 238Pu is so long at 4.5 x 108 years (see Table 8.2) that we say with some certainty that effectively none of it will disappear from the environment by radioactive decay and if none of it decays, then it cannot have emitted ionizing a and f) particles, etc. and, therefore, cannot really be said to be a radioactive hazard. Unfortunately, the long half-life also means that the 238Pu remains more-or-less for ever to pollute the environment with its lethal chemistry. 

Some previous and some new participants continued to explore the characterization of RDMs, related conceptual problems, as well as practical problems to incorporate correlations. 

Despite the success of the disorder model concerning the interpretation of data on the temperature and field dependence of the mobility, one has to recognize that the temperature regime available for data analysis is quite restricted. Therefore it is often difficult to decide if a In p vs or rather a In p vs representation is more appropriate. This ambiguity is an inherent conceptual problem because in organic semiconductors there is, inevitably, a superposition of disorder and polaron effects whose mutual contributions depend on the kind of material. A few representative studies may suffice to illustrate the intricacies involved when analyzing experimental results. They deal with polyfluorene copolymers, arylamine-containing polyfluorene copolymers, and c-bonded polysilanes. 

Berrios GE Conceptual problems in diagnosing schizophrenic disorders, in Advances in the Neurobiology of Schizophrenia. Edited by Den Boer JA, Westenberg HGM, Van Praag HM. New York, Wiley, 1995... 

Moreover, chemical reaction in or near the shock front can cause additional complications. Nevertheless, the data in Table 1 can be very useful as will be shown below, even though, aside from conceptual problems, there is some inconsistency in the data for some of the explosives. 

Then, we focused on conceptual problems such as the definition of local spins that do hardly emerge naturally in holistic quantum theory. The local spin concept was rigorously introduced in quantum chemistry about 10 years ago by Clark and Davidson. We reviewed the most important contributions in this field and... 

In some instances, the root in question is dominated by a single CSF, allowing one to describe the state conveniently by reference to the ground state. In other instances, however, that will not be the case, and simple relationships between the excited state and the ground state cannot be easily formulated. This is, of course, purely a conceptual problem - the wave functions themselves are perfectly well defined and useful. 

Political philosophers have traditionally conceived of justice as a relationship among people living within the same nation or state. Plato (1974), for example, held that a just state is rationally ordered. Hobbes (1982) held that principles of justice are rules that people adopt in order to attain the benefits of social cooperation and avoid the dangers of the state of nature. Conceptual problems arise when one extends this standard account of justice to the international domain, because people around the globe are not living in the same nation. The world s five billion people live in more than 150 nations. How can there be justice among people in different nations ... 

In order to clarify the central arguments and to minimize conceptual problems in this initial development, we assume that the model universe is stationary in the sense that the overall statistical properties of the material distribution do not evolve in any way. Whilst this was intended merely as a simplifying assumption, it has the fundamental effect of making the development inherently nonrelativistic (in the sense that the system evolves within a curved metric 3-space, rather than being a geodesic structure within a spacetime continuum). 

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