Common misconceptions

Note The discussion above assumes that the hybrids are ideal—that is, nothing is being reflected. For a discussion where the hybrid is reflecting a small signal, see reference 59. 

The examples above are only typical. Endless variations are possible. For example, the hybrids are not restricted to be merely of the 3-dB type. An example is shown in Fig. 2.21 with a power split of 2.3/4.0dB. A former Ph.D. student Clayton Larson (now a successful Big Shot ) and the author needed such a hybrid for a very special antenna. Not being an off-the-shelf item, we had to either order one custom-made or make one ourselves. Clay those the latter approach (he was never too keen on telephone negotiations). Overnight he designed, cut the design with an exacto knife and assembled such a hybrid. The next morning we checked it out on the special antenna. It worked flawlessly. Thank you Clay. 

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Example A common misconception is that the conjugate base of a weak acid is strong This is sometimes but not always true It is true for example for ammo nia which is a very weak acid (pK 36) Its conjugate base amide ion (H2N ) is a much stronger base than HO It is not true however for acetic acid both acetic acid and its conjugate base acetate ion are weak The conjugate base of a weak acid will be strong only when the acid is a weaker acid than water... 

A common misconception is that a stereospecific reaction is simply one that is 100% stereoselective The two terms are not synonymous however A stereospecific reac tion IS one which when carried out with stereoisomeric starting materials gives a prod uct from one reactant that is a stereoisomer of the product from the other A stereo selective reaction is one m which a single starting material gives a predominance of a... 

There are many common misconceptions about vinyl. Eor example, the idea that vinyl is not recycled is untme. Industrial scrap vinyl has been recycled for years, but in more recent years, post-consumer vinyl recycling is growing, too, with about 3.25 x 10 tons (6.5 x 10 lb) of post-consumer vinyl (primarily botdes) being recycled in the 1990s. When the Council for SoHd Waste Solutions (now the American Plastics Council) conducted a nationwide survey in 1991, it found that there were an estimated 1100 municipal recycling programs in place or plaimed in the United States that include vinyl. 

Table 1 shows prevalent examples of misconceptions about QRA. Many are actually generalizations that are too broadly applied. Two of the most common misconceptions concern (1) the lack of adequate equipment failure data and (2) the cost of performing QRA. 

Fitzpatrick, M., Common Misconceptions About the RCRA Subtitle C Exemption from Crude Oil and Natural Gas Exploration, Development and Production, Proceedings from the First International Symposium on Oil and Gas Exploration Waste Management Practices, pp. 169-179, 1990. 

A contract is made when the essential elements have been fulfilled and the offer and acceptance communicated, and, apart from contracts involving land, can be verbal. A common misconception is that a party signs a contract. In reality, a party signs a document, which contains the terms of the contract being entered into. Almost all contract documents omit many matters, which are important, and the reason for this is that the law says that certain matters are implied to be contained within a contract. An example is that if X buys an item of plant from y it is implied that X will receive it within a reasonable time, and that it will be of merchantable quality when he receives it. 

Thermal insulation does not generate heat. It is a common misconception that such insulation automatically warms the building in which it is installed. If no heat is supplied to that building it will remain cold. Any temperature rise that may occur will be the result of better utilization of internal fortuitous or incidental heat gains. 

Mineral wool is perhaps the best known of the whole range of insulation types. It is widely used in all sectors of industry, transport and building for thermal, acoustic and fire-protection purposes. There is a common misconception that mineral wool is a specific product type - it is not. Mineral wool is a generic name for a range of man-made non-metallic inorganic fibers. The following definitions should help to clarify the situation ... 

It remains a common misconception that radical-radical termination is suppressed in processes such as NMP or ATRP. Another issue, in many people s minds, is whether processes that involve an irreversible termination step, even as a minor side reaction, should be called living. Living radical polymerization appears to be an oxymoron and the heading to this section a contradiction in terms (Section 9.1.1). In any processes that involve propagating radicals, there will be a finite rate of termination commensurate with the concentration of propagating radicals and the reaction conditions. The processes that fall under the heading of living or controlled radical polymerization (e.g. NMP, ATRP, RAFT) provide no exceptions. 

Many or most of the results from data mining in industry went unpublished. More recently, when a few academic researchers gained access to data mining software, the weakly active compounds they found were excitedly published. This difference between industry and academia in handling similar kinds of results is a matter of priorities. In industry, the hrst priority is to hnd marketable products and get them out the door. In academia, the priority is to publish (especially in high-impact journals). Contrary to a common misconception, scientists in industry do publish, a point we return to below. 

Elucidation of the activities of individual COX isoforms led to the development of drugs that selectively inhibit the inducible form of the enzyme, COX-2. Thus COX-2 inhibitors were expected to minimize NSAID gastrointestinal toxicity and antiplatelet effects (see Fig. 55-3).19 A common misconception is that COX-2 inhibitors are more effective than nonselective NSAIDs in relieving pain and inflammation. In clinical trials, patients experienced similar levels of pain relief with COX-2 inhibitors and nonselective NSAIDs. 

It is a common misconception that opinions and interpretations are only offered by forensic scientists and Public Analysts. Analysts from many areas are required to provide this service, e.g. those dealing with consumer safety, geology/geochemistry, oil exploration and food science, to mention but a few. Some examples are given below. 

Metal chelate affinity chromatography finds most prominent application in the affinity purification of recombinant proteins to which a histidine tag has been attached (described later). As protein binding occurs via the histidine residues, this technique is no more inherently useful for the purification of metalloproteins than for the purification of non-metalloproteins (a common misconception, given its name). 

GC is one of the most widely applied instrumental techniques. The basis requirement is that the analyte(s) be volatile under conditions within the gas chromatograph and that they be separated from nonvolatile matrix components. Misunderstanding of volatility and vapor pressure is the most common misconception about GC many users... 

There is a common misconception that the absence of hazardous constituents in a waste makes it nonhazardous. In fact, any... 

This may be a good place to correct some common misconceptions about the effects of BZ and related belladonnoids. Those unfamiliar with the delirious state have often referred to BZ as hallucinogenic or psychotomimetic. It is undeniably hallucinogenic, but the term is hopelessly contaminated by its inexact use in reference to drugs like LSD and psilocybin. Such drugs produce striking illusions, but subjects generally know they are unreal. 

Before we begin, it is important to point out a common misconception that involves the definition of a linear model (Deming and Morgan (1979)]. Many individuals understand the term linear model to mean (and to be limited to) straight line relationships of the form... 

Perhaps the most common problem is that of thermal decomposition of the sample, either in the batch inlet, for which the cure is a lower inlet temperature or use of the direct probe, or in the source itself. A common misconception among mass spectroscopists, often promulgated by manufacturers, is that if the source is kept hot, the decomposition of contaminants is minimized. The ion source should routinely be run no hotter than 180°-200°C. A source at the common temperature of 250°C is much more likely to result in decomposition of sample and contamination of the source, and should be used only rarely. On our AEI MS-30 we run 200 samples per month, many of which are organometallic or inorganic, and we are seldom forced to exceed 200°C more than once a month. If some sample condenses into the source it is far better to sublime it away slowly by carefully raising the temperature than to pyrolyze it. 

As an approximation to the solar distribution at the earth s surface, we will take Boer s (T/S) distribution for AM 1.2 which is for a bright sunny summer day near noon ( ). (AM stands for air mass. AM 0 would correspond to incident solar power outside the earth s atmosphere. AM 1 would correspond to incident solar power at sea level with the sun at the zenith.) If we make the ideal assimption that a(X) = 1 for X Xg and a(X) = 0 for X then we can calculate an ideal value of rig as a function of This is shown as curve E in Fig. 2. ri has a maximiam value at 1110 nm for AM 1.2 but the maximum is very broad in that rig is > 45% between 800 nm and 1300 nm. It is a common misconception among photochemists that r g represents the fraction of solar power that can be converted to electricity or chemical energy. The next section will attairpt to show the fallacy of this view. 

For equivalence and non-inferiority trials, therefore, the regulators like to see analyses undertaken on both the full analysis set and the per-protocol set with positive conclusions being drawn from both. In this sense these two analyses are considered co-primary. There is a common misconception here that for equivalence/non-inferiority trials the per-protocol set is primary. This is not the case. The per protocol set is still potentially subject to bias because of the exclusion of randomised patients and so cannot supply the complete answer both analysis sets need to be supporting equivalence/non-inferiority in order to have a robust conclusion. 

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