Debates over

In this formulation, the electron density is expressed as a linear combination of basis functions similar in mathematical form to HF orbitals. A determinant is then formed from these functions, called Kohn-Sham orbitals. It is the electron density from this determinant of orbitals that is used to compute the energy. This procedure is necessary because Fermion systems can only have electron densities that arise from an antisymmetric wave function. There has been some debate over the interpretation of Kohn-Sham orbitals. It is certain that they are not mathematically equivalent to either HF orbitals or natural orbitals from correlated calculations. However, Kohn-Sham orbitals do describe the behavior of electrons in a molecule, just as the other orbitals mentioned do. DFT orbital eigenvalues do not match the energies obtained from photoelectron spectroscopy experiments as well as HF orbital energies do. The questions still being debated are how to assign similarities and how to physically interpret the differences. 

Saccharin. Sacchatin [81-07-2] C H NO S, which is approximately 300 times as sweet as sucrose ia coaceatratioas up to the equivaleat of a 10% sucrose solutioa, has beea used commercially as a nonnutritive sweeteaer siace before 1900, predomiaanfly ia carboaated soft drioks, tabletop sweeteaers, and dietetic foods marketed primarily to diabetics. In 1977, the FDA proposed a ban on sacchatin because of its association with bladder cancer ia laboratory animals. At the time, it was the only commercially available nonnutritive sweetener, and pubflc outcry led to a delay of the ban, which was officially withdrawn ia 1991. Instead, the FDA required that warning labels be placed on all foods that contained the iagredient. Although sacchatin is heat stable, the pubflc debate over its safety, as well as the fact that approximately one-third of the population perceives it to have a bitter aftertaste, has limited its use. 

Although in the early days of resin finishing there was continued debate over the mechanism by which these agents achieved smooth-dry performance, by the 1950s most textile chemists beHeved that cross-linking was primarily responsible for achieving smooth-dry performance. 

Uranium hexafluoride [7783-81-5], UF, is an extremely corrosive, colorless, crystalline soHd, which sublimes with ease at room temperature and atmospheric pressure. The complex can be obtained by multiple routes, ie, fluorination of UF [10049-14-6] with F2, oxidation of UF with O2, or fluorination of UO [1344-58-7] by F2. The hexafluoride is monomeric in nature having an octahedral geometry. UF is soluble in H2O, CCl and other chlorinated hydrocarbons, is insoluble in CS2, and decomposes in alcohols and ethers. The importance of UF in isotopic enrichment and the subsequent apphcations of uranium metal cannot be overstated. The U.S. government has approximately 500,000 t of UF stockpiled for enrichment or quick conversion into nuclear weapons had the need arisen (57). With the change in pohtical tides and the downsizing of the nation s nuclear arsenal, debates over releasing the stockpiles for use in the production of fuel for civiUan nuclear reactors continue. 

The current debate over controversial global warming theories will continue. The impact of carbon dioxide levels in the atmosphere, whether they are increasing or not over time, and the effect on climate and economics will continue to he discussed. A solution, if it is needed, may evolve—or not. 

Although the electrochemistry of conducting polymers is now a quite mature subject, there is still considerable debate over most of the basic processes. In part, the issues have been clouded by the diversity of different polymers that have been studied. It is often assumed that conclusions drawn from data on a certain polypyrrole, for example, can be extended... 

One of the most problematic issues, still to be fully resolved, is the dependence of the degree of oxidation on potential, as measured most commonly by cyclic voltammetry at low scan rates. There is currently no accepted model to describe the shape of the curve and the hysteresis between anodic and cathodic scans. The debate over whether the charge has a significant component due to a polymer/solution double layer is still not fully resolved. 

Debates over the validity of the Gaia hypothesis have focused on two very different issues. One concerns the degree to which the composition of the atmosphere and, hence, Earth s... 

However, most of the debate over the possibility of 1,3 migrations has concerned not methyl or bromine but 1,3 hydride shifts.There is no doubt that apparent 1,3 hydride shifts take place (many instances have been found), but the question is whether they are truly direct hydride shifts or whether they occur by another... 

There are several models that depend on monitoring changes in animals behaviour when they are exposed to conditioned threatening cues. One of these, the fear-potentiated startle reflex, rests on the development of an exaggerated startle on presentation of the conditioned cue. Although this response is prevented by anti-anxiety drugs, there is considerable debate over whether fear is the same as anxiety . 

Dietary fibre, which comprises all the non-digestible structural carbohydrates of plant cell walls and any associate lignin, provides a further example of a complex food-borne factor which cannot be classified as a nutrient, and which continues to generate debate over such issues as definition and analytical techniques. However, whatever the unresolved complexities, dietary fibre has a lengthy history and had proved itself eminently suitable as a component of functional food products long before the term was even coined. 

In Malaysia, interference from the outside, political or otherwise, regarding decisions of the regulatory authority is rare. A recent exception was the debate over the registration of sildenafil (Viagra ), for the treatment of erectile dysfianction. 

Chronology is not the only contentious issue debates over the interpretation of morphological and genetic data are as contentious as that of dating. While the anatomical classification of hominids is often problematic and can take a subjective slant, the dating is in theory objective and absolute. The following examples, which have been selected to illustrate these issues are exemplars of the current debate, and cover the major issues noted above specifically from the perspective of U-series dating. 

It is unfortunate that the debate over narrow therapeutic index (ratio) or critical care drugs has been... 

Muller s invention launched both the synthetic pesticide industry that exploited his discovery and the environmental movement that opposed its use. Yet Paul Muller, a shy and determined nature lover, shared many of the same reservations about using DDT in the environment that Rachel Carson popularized in her best seller, Silent Spring, 14 years later. In the 1990s, three decades after DDT was banned in most of the industrialized world, international health workers revived the debate over its use. DDT is a cheap and effective insecticide against malaria, which kills nearly three million people annually, most of them young children and pregnant women in sub-Saharan Africa. 

An electrospray is generally produced by the application of an electric field to a small flow of liquid from a capillary tube toward a counter electrode. The principles of electrospray as applicable to mass spectrometry and the mechanisms involved have been a subject of intense debate over the last decade and have been addressed even before that. This is evident from the discussions in the 2000 issue of the Journal of Mass Spectrometry (e.g., Mora11), the book by Cole,12 and several reviews.8,10 13 14 Here we present a summary encapsulating the relevant observations and direct the readers to the above articles for a more elaborate account. 

Neurodegeneration Localised or widespread death of neurons, a feature of a number of brain disorders, such as Alzheimer s disease, Parkinson s disease and cerebrovascular stroke. It can also be caused by neurotoxic drugs like MDMA/Ecstasy, although there is debate over whether this occurs in humans as well as laboratory animals. 

---