Conundrum

As can be seen from these examples, even talking about ethical responsibilities to future people can raise conundrums. Some critics claim that talk of ethical responsibilities to distant people is nonsense and that present energy policy should be governed solely... 

The relationship between structure and anticoagulant activity of heparin was a conundrum that puzzled Stacey. He did not solve the problem, but demonstrated that certain structural features of heparin (for example, extensive release of amino groups) alone were not responsible for the biological activity. 

The last big problem facing early twentieth century physics was Ernest Rutherford s atomic structure. Physicists knew that Rutherford s atom could not exist, but no one could come up with anything better. The man who would resolve this conundrum showed up at Manchester, England, in 1912 to work for Rutherford. Rutherford himself had worked for J.J. Thomson and had disproved Thomson s plum pudding structure of the atom. Now, the new man in Manchester, Niels Bohr, was about to do the same thing to Rutherford. By the end of his career, Bohr would have contributed as much as anyone to understanding Feynman s little particles. Science is a meritocracy. Poor kids can excel and get ahead in the world of science just as easily as the well-heeled. For example. 

Chase and Long (1997) propose that this conundrum can be eliminated by the use of Zero Reference Materials (ZRMs) in analytical methods development to fully evaluate the method. A ZRM is a product matrix that lacks those nutrient components that are to be assayed, i.e. a blank matrix. The use of a ZRM in method development can and will give a true indication as to how the method will perform as the spiked nutrient levels approach zero. For example, two products. Corn Starch (NIST RM 8432) and Microcrystalline Cellulose (NIST RM 8416), contain very low elemental concentrations and could conceivably serve as real sample blanks or ZRMs in some analytical procedures. 

Before the first indication of the existence of cannabinoid receptors, the prevailing theory on the mechanism of cannabinoid activity was that cannabinoids exert their effects by nonspecific interactions with cell membrane lipids (Makriyannis, 1990). Such interactions can increase the membrane fluidity, perturb the lipid bilayer and concomitantly alter the function of membrane-associated proteins (Loh, 1980). A plethora of experimental evidence suggests that cannabinoids interact with membrane lipids and modify the properties of membranes. However, the relevance of these phenomena to biological activities is still only, at best, correlative. An important conundrum associated with the membrane theories of cannabinoid activity is uncertainty over whether cannabinoids can achieve in vivo membrane concentrations comparable to the relatively high concentrations used in in vitro biophysical studies (Makriyannis, 1995). It may be possible that local high concentrations are attainable under certain physiological circumstances, and, if so, some of the cannabinoid activities may indeed be mediated through membrane perturbation. 

Since the Nineteenth century, these philosophers have struggled to rescue time from a dimension on a simple, linear scale and install time as a multidimensional variable in a complex way of thinking about life. The biophilosophers have been drawn to evolution as a place to resolve the fundamental conundrum of time - How does it affect life The biophilosopher Georges Canguilhem, for one, tells his reader ... 

The dilemmas raised by the genetics of the work are also considerable and are discussed elsewhere [4], A major difficulty is the choice of the appropriate genetic polymorphisms to associate to drug response. A statistical conundrum is created by the need to assess multiple variables that are partially related to one another (without a priori knowledge of the exact nature of such interactions) and that contribute to small effects in clinical trials that are highly costly and often cannot be as large as desired. 

A route to the resolution of this conundrum is provided by the photoactivation of the donor-acceptor complex to the ion-radical pair, as described in equation (98). In this case, the close interrelationship between the photochemi-cally-produced or vertical (nonadiabatic) ion pair formed in equation (98) and the thermally accessed or contact (adiabatic) ion pair in equation (99) is illustrated in Scheme 28, where the asterisk identifies the contact ion-pair in the gas phase and s represents the solvation of ion-radical pair. According to... 

Note, from Table 4, that kH for PI1CH2CCI is 6 x 107 s 1, about 3 times greater than kH for PI12CHCCI. This underscores the previously noted nonadditivity of bystander effects on rate constants in going from 10a to 66, the second Ph bystander actually slows the 1,2-H shift. The KGH analysis provides a solution to this conundrum. Steric effects in 66 cause the second Ph to adopt... 

The mechanistic conundrum presented by such a dichotomy between electron-transfer and electrophilic processes can only be rigorously resolved by the experimental proof of whether the cation radical (or the electrophilic adduct) is, or is not, the vital reactive intermediate. However, in a thermal (adiabatic) reaction between arene donors and the nitrosonium cation, such reactive intermediates cannot be formed in sufficient concentrations to be observed directly by conventional experimental methods since their rates of follow-up reactions must perforce always be faster than their rates of formation, except when they are formed in a reversible equilibrium like the... 

Since the latter conditions pertain to aromatic nitration solely via the homolytic annihilation of the cation radical in Scheme 16, it follows from the isomeric distributions in (81) that the electrophilic nitrations of the less reactive aromatic donors (toluene, mesitylene, anisole, etc.) also proceed via Scheme 19. If so, why do the electrophilic and charge-transfer pathways diverge when the less reactive aromatic donors are treated with other /V-nitropyridinium reagents, particularly those derived from the electron-rich MeOPy and MePy The conundrum is cleanly resolved in Fig. 17, which shows the rate of homolytic annihilation of aromatic cation radicals by NO, (k2) to be singularly insensitive to cation-radical stability, as evaluated by x. By contrast, the rate of nucleophilic annihilation of ArH+- by pyridine (k2) shows a distinctive downward trend decreasing monotonically from toluene cation radical to anthracene cation radical. Indeed, the... 

Of the Bom-Oppenheimer paper, David Dennison commented to Thomas Kuhn that it validated things that people were doing anyway and that he "took this for granted." In interview of David Dennison with Thomas Kuhn, January 28, 1964, Ann Arbor, Michigan, no. 2 of 3 sessions, 19. SHQP, Berkeley. Also see, Stephen J. Weininger, "The Molecular Structure Conundrum Can Classical Chemistry be Reduced to Quantum Chemistry " JChem.Ed. 61 (1984) 939944, on 940. 

Weininger, Stephen J. "The Molecular Structure Conundrum Can Classical Chemistry be Reduced to Quantum... 

Following on from the previous discussion, if current has been allowed to pass through a reference electrode, its internal composition will change and thus its potential will be unknown, which explains the conundrum when is a reference electrode not a reference electrode - when charge is passed through it ... 

In order to resolve this conundrum, we draw a Koutecky-Levich plot of l/(current) (as y ) against lw (as x ). (Plots using these axes are also sometimes called inverse-Levich plots .)... 

Hoping to resolve this conundrum, I searched the Internet and (as mentioned earlier) spoke by telephone with Dr. Theodore Stanley, Professor and Chairman of Anesthesiology at the University of Utah. Dr. Stanley is an authority on morphine and Fentanyl-hke compounds. Although very helpful, some of his answers seemed to conflict with other authorities. 

Maurizio Calves addresses this conundrum. He was accused of being a Jungian, but he claims that he was simply interested in the visual images he found in Jung s Psychology and Alchemy (Calvesi 1993, xxi). 

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