Analogous Examples Research Articles

Examples of large closo boron hydride analogs of carbon fullerenes

Examples of large closo boron hydride analogs of carbon fullerenes

Synthesis of phosphonate derivatives of myo-inositol for use in biochemical studies of inositol-binding proteins

Phospholipids containing the inositol headgroup (phosphoinositides) serve as membrane storage forms of a family of messenger molecules that transmit signals in cells. In this study a general synthesis of myo-inositol phosphate derivatives in which the posphorus oxygen bond is replaced with a phosphorus carbon bond (i.e. phosphonates) is presented. Four specific examples of phosphonate analogs of phosphatidylinositol (PI) are prepared which have a single alkyl chain in place of the diacylglycerol. These derivatives are stable in neutral and alkaline solutions and are designed for use in biochemical studies of PI-specific phospholipases C and other enzymes involved in the phosphoinositide signal transduction pathway.

White Swans, Black Ravens, and Lame Ducks: Necessary and Sufficient Causes in Epidemiology

Several authors have used Popper's "white swan" example to support arguments for a falsificationist approach to epidemiology. The statement "all swans are white" cannot be verified by finding even a large number of white swans, but can be falsified by finding a single black swan. An analogous epidemiologic example that has been proposed is the hypothesis that a particular virus is a necessary cause of acquired immunodeficiency syndrome (AIDS). Such examples, however, have little relevance to science since scientific theories are not generalizations of facts; rather, they involve an understanding of the underlying processes that cause certain facts to occur. Furthermore, the "white swan" example is particularly inapplicable to epidemiology, since most factors of scientific or public health importance are neither necessary nor sufficient causes of disease. Nevertheless, epidemiologic research has achieved success in the understanding and prevention of disease. These points are exemplified by applying Rothman's model of causal constellations, which provides a conceptual basis for the development of epidemiologic theories.

Modular representations as a possible basis of finite physics

The approach in which physical systems are described by the elements of a linear space over a finite field, and operators of physical quantities by linear operators in this space, is discussed. The mathematical formulation of the correspondence between such a description and the conventional one is given for a case when the characteristic of the finite field is sufficiently large. The above correspondence is considered in the examples of finite analogs of representations of so(2,3), so(1,4), and osp(1,4) algebras. Finite analogs of representations of infinite-dimensional algebras are briefly discussed.

New layered phases achieved with centered zirconium chloride clusters. The stoichiometry Zr6Cl16

The phase Na{sub 4}Zr{sub 6}Cl{sub 16}Be is obtained in quantitative yield from the reaction of Zr powder, ZrCl{sub 4}, NaCl, and Be flakes in a sealed Ta container at 800{degree}C. A different, isostructural group of phases Cs{sub 3}Zr{sub 6}Cl{sub 16}C, Cs{sub 3}Zr{sub 6}Cl{sub 16}B, and Cs{sub 4}Zr{sub 6}Cl{sub 16}Be were similarly obtained in {approx}90% yield from analogous reactions with CsCl, graphite, amorphous boron, etc.; reasonable yields of the first two occurred only when somewhat overreduced conditions were employed. The two structure types were established by single-crystal x-ray diffraction means for the following refined compositions: Na{sub 3.9(1)}Zr{sub 6}Cl{sub 16}Be, space group Pcmm, Z = 4, a = 13.251 (1) {angstrom}, b = 14.319 (1) {angstrom}, c = 14.092 (2) {angstrom} R = 4.3%, R{sub w} = 3.8%, Cs{sub 3.04(3)}Zr{sub 6}Cl{sub 16}C, space group P2{sub 1}/n, Z = 4, a = 11.032 (2) {angstrom}, b = 11.851 (3) {angstrom}, c = 12.473 (3) {angstrom}, {beta} = 108.01 (2){degree}, R = 6.2%, R{sub w} = 6.8%. Both structures contain puckered layers formed from Zr{sub 6}Cl{sub 12}-type clusters with Cl{sup a-a} atoms bridging four vertices into sheets plus two terminal Cl{sup a} occupying single trans positions, viz, {infinity}{sup 2}(Zr{sub 6}Cl{sub 12}Z)Cl{sup a-a}{sub 4/2}Cl{sup a}{submore » 2}, where the interstitial Z = Be, B, or C occupies all cluster centers. The cluster layers are separated and puckered to different degrees in order to provide suitable chlorine polyhedra between them to accommodate the cations. The latter fractionally occupy irregular sites that are minimally six- (Na{sup +}) or seven-coordinate (Cs{sup +}). The 15-electron cluster in the cesium salt exhibits shorter Zr-Zr and Zr-Zr distances than analogous 14-electron examples. 24 refs., 7 figs., 5 tabs.« less

Cyclic, disulfide- and dithioether-containing opioid tetrapeptides: Development of a ligard with high delta opioid receptor selectivity and affinity

Tetrapeptides of primary sequence Tyr-X-Phe-YNH 2, where X is D-Cys or D-Pen (penicillamine) and where Y is D-Pen or L-Pen, were prepared and were cyclized via the side chain sulfurs of residues 2 and 4 to disulfide or dithioether-containing analogs. These peptides are related to previously reported penicillamine-containing pentapeptide enkephalin analogs but lack the central glycine residue of the latter and were designed to assess the effect of decreased ring size on opioid activity. Binding affinities of the tetrapeptides were determined to both μ and δ opioid receptors. Binding affinity and selectivity in the tetrapeptide series were observed to be highly dependent on primary sequence. For example, L-Pen 4 analogs displayed low affinity and were nonselective, while the corresponding D-Pen 4 diastereomers were of variable affinity and higher selectivity. Among the latter compounds were examples of potent analogs in which selectivity shifted from δ selective to μ selective as the ring size was increased. The relatively high binding affinity and δ receptor selectivity observed with one of the carboxamide terminal disulfide analogs led to the synthesis of the corresponding carboxylic acid terminal, Tyr-D-Cys-Phe-D-PenOH. This analog displayed δ receptor binding selectivity similar to that of the standard δ ligand, [D-Pen 2, D-Pen 5] enkephalin (DPDPE), and was found to have a 3.5-fold higher binding affinity than DPDPE. All the tetrapeptides were further evaluated in the isolated mouse vas deferens (mvd) assay and all displayed opioid agonist activity. In general, tetrapeptide potencies in the mouse vas deferens correlated well with binding affinities but were somewhat lower. Receptor selectivity in the mvd, assessed by examining the effect of opioid antagonists on the tetrapeptide concentration-effect curves, was similar to that determined in the binding studies.

Peptides and proteins as drugs.

Relatively small modifications of clinically useful endogenous compounds have been shown to have therapeutically beneficial effects on their pharmacodynamic and pharmacokinetic properties. These effects include increased potency and effect selectivity, and prolonged duration of action. In addition, these modifications have resulted in compounds that can be administered orally where only parenteral administration was previously possible. One type of modification resulting in distinctive properties is exemplified by the hybrid interferons produced by the recombination of segments of genes coding for different molecular species. Chemical modification has also resulted in many examples of analogs of natural peptides that are more potent, more selective and more stable than the endogenous compounds. Conjugation to peptide or protein carriers is a third method used to selectively modify the properties of an endogenous compound. The carriers that have been used include synthetic polypeptides, endogenous proteins, toxins and monoclonal antibodies. The effect that covalent attachment to a carrier has on the properties of a ligand is highly dependent upon the carrier, the ligand and the linkage between them.

Analogy and axiomatics

The concept of an analogy can be viewed from two perspectives. One active, being the process of drawing an analogy. The other passive, being the relationship of one thing being an analogy for another. The focus in this paper is on the latter meaning, or the static view of analogy. To be investigated are the types of analogies there are, not where they come from. Examples of analogies abound: LISP is analogous to SLIP; logic is analogous to Boolean algebra; electricity is analogous to hydraulics; home brewing is analogous to bread baking. The scope of this paper is further restricted to a consideration of analogies between subject matters. The subject matter may be logic, Boolean algebra, electricity, brewing, baking or some other. It need not be the complete subject matter but only some sub-part.

The geophysical implications of minimal Tertiary motion along Nares Strait

In the light of the geological evidence indicating less than 25 km of left-lateral offset along the Wegener Fault in Nares Strait, we examined three models for the formation of Baffin Bay which do not involve sea-floor spreading in that region. Our purpose was to investigate whether these models present realistic alternatives to sea-floor spreading and simultaneously remove the requirement for extensive lateral separation between Greenland and North America. These models are crustal extension, mantle upwelling and magmatic intrusion. Each model is constrained to match the observed subsidence and present width of the basin and, where possible, the observed crustal thickness. The crustal extension and magmatic intrusion models require extensive left-lateral motion between Greenland and North America, and thus they appear to be at odds with the geological observations. Furthermore, neither the mantle upwelling model nor the magmatic intrusion model can produce the required crustal thinning (85% of continental crust must be eliminated), and there are no analogous examples of such an extreme case of 'oceanization' elsewhere in the world. Thus none of the models can account for both the thin crust in central Baffin Bay and the apparent lack of offset along the Wegener Fault.
 We suggest two possible solutions to the conflict between the available observations: 1) Tertiary left-lateral motion has reversed earlier right-lateral motion; or 2) left-lateral motion between Greenland and North America was accommodated elsewhere than along the Nares Strait waterway. The first is shown to be in conflict with geological evidence from the margins of Baffin Bay. There is at present no evidence to support the second, but we suggest that this possibility be critically evaluated in future studies of the geological history of the region. In this context, we suggest that minimal offset across the Nares Strait waterway need not be incompatible with major Tertiary left-lateral motion on the Wegener Fault if one accepts the concept of a fault zone rather than a single discrete offset. Future studies of the extent of horizontal deformation immediately north of Baffin Bay and within the Sverdrup Basin are also required.
 A tectonic model, which includes elements of mantle upwelling and crustal extension at the margins and sea-floor spreading in central Baffin Bay, accounts for the observed subsidence and crustal thickness in the centre of the basin, and explains the uplift of eastern Baffin Island and western Greenland. It also satisfies the geometrical requirements of plate tectonic reconstructions for the North Atlantic and Arctic Oceans. However, it requires that an acceptable means of accommodating the opening of Baffin Bay be found before it can be considered valid.

A Comment on Curren's “Potential Interpretations of ‘Stone Gorget’ Function”

Curren (1977) presents an interesting and provocative hypothesis regarding the “potential” function of “stone gorgets.” Nevertheless, there are some serious problems with his thesis that require comment.Initially, there is a danger in the rather simplistic association drawn between form and function. To claim a functional similarity because there is a morphological similarity between stone gorgets and contemporary ceramic tools called “ribs” is a risky procedure. One does not need to go very far to demonstrate analogous examples. For instance, if I were to show a surveyor a stone “plummet,” I would most likely elicit the response, “ a surveyor’s plummet in stone?” If I were to present an unsuspecting archaeologist with a surveyor’s plummet, I might hear, “plummets (net sinkers or bolas] in brass?” In contrast to the paper under disucssion, Ahler’s (1971) important study is a sophisticated treatment of the problems involved in equating form with function.

Quasi-identities of certain finite algebras

In this note an example of a finite lattice not having a finite basis of quasiidentities and an analogous example for algebras of the type are indicated.

The application of renormalization group techniques to quarks and strings

Recent work by K. G. Wilson, A. A. Migdal and others has led to a statistical mechanical treatment of systems of interaction quarks and strings. This work is summarized here. The major topics discussed include boson and fermion variables in statistical mechanics; descriptions of local and gauge symmetries; exact solutions of one-dimensional problems with nearest-neighbor interactions; exact solutions of two dimensional problems with plaquette interactions; Wilson's model of quarks and strings; asymptotic freedom and trapping for this model; the effect of a phase transition in this system; approximate recursion relations of the Migdal form. Finally, all this is put together to give a partial argument for the simultaneous existence of asymptotic freedom and trapping ${\mathrm{O}}_{2}$ in the quark-string case. Arguments are developed which distinguish this case from the superficially analogous example of quantum electrodynamics.

ON SUMMABILITY AND CONVERGENCE OF EIGENFUNCTION EXPANSIONS OF A DIFFERENTIAL OPERATOR

Let be a positive elliptic operator with constant coefficients, and let be a region in . We consider the operator on , and we let be an extension of this operator with a positive lower bound. Let denote the spectral family of the operator . The operator or its Riesz mean will be considered on functions , , such that , where is a region with compact closure in . We will study the norm of the operator . We obtain definitive results when the point lies in one of the three regions: (l-1)\left(\frac{1}{p}-\frac{1}{2}\right) \right\}.$ SRC=http://ej.iop.org/images/0025-5734/20/2/A01/tex_sm_1868_img17.gif/> For , we construct an example of a function for which the Riesz mean of order of its spectral expansion diverges almost everywhere. For , we construct an analogous example for multiple Fourier series expansions.Bibliography: 26 items.

Nitroxide and anion radicals derived from isatogen and related indole derivatives

Neutral indolic nitroxides were obtained by oxidation of 1-hydroxyindoles with lead dioxide. Anion indolic nitroxides were obtained by reduction of indoline-N-oxides in DMSO/t-BuOK (reducing agent being the CH 3SOCH 2 − anion). In both cases an a N of about 6 gauss was found. This value, which differs from values previously reported, is justified in the course of the work. Some other anion radicals derived from bi-indolic derivatives are also reported and their structures discussed on the basis of MO calculations or by comparison with analogous examples.

In vivo stimulation of peripheral lymphocytes to proliferation after oral challenge of children allergic to foods.

During culture of peripheral lymphocytes of children suspected of allergy to foods, the lymphocytes of 6 children were found on more than one occasion to exhibit exceptionally active proliferation without <i>in vitro</i> addition of food protein to the culture, that is in the control culture. For reasons given this was not considered artifactual. The phenomenon was observed only after oral challenge with a suspected food, and never in children sensitive to inhalant allergens alone. Exceptionally active proliferation of the lymphocytes without addition of antigen <i>in vitro</i> suggests that antigenic stimulation of circulating sensitized lymphocytes occurred <i>in vivo.</i> This is credible in children allergic to foods, as antigenic substances may be absorbed from the gut during digestion of food. Analogous examples of <i>in vivo</i> stimulation of sensitized peripheral lymphocytes are reported in the literature.

Selection rules for mass spectrometry. Example of photochemical analogy

Selection rules for mass spectrometry. Example of photochemical analogy

Acoustic amplification and acoustoelectric effect in piezoelectric semiconductors: Hervouet, C., Rope, J.P., Onde Electronique, Vol 48, No 496–497 (July 1968) pp 647–655 (In French) (1492)

Story picture books with examples can be used to teach young children science concepts. Learners can abstract relational information by comparing the analogical examples in the books, leading to a more abstract transferrable understanding of the concept. The purpose of this study was to determine whether manipulating the content or arrangement of the examples included in a picture book would support children’s generalization and transfer of a relational concept, namely color camouflage. In total, 81 3-year-olds and 80 4-year-olds were read one of four books at two visits spaced approximately 1 week apart. Examples were manipulated in a 2 (Object Similarity: high or low) × 2 (Arrangement: interleaved or blocked) design. At each visit, children were asked forced-choice questions with photographs (generalization) and real animals (transfer) and needed to explain their choices. At the first visit, only 3-year-olds who had been read a book with high object similarity displayed generalization and transfer. After they were read the same book again at the second visit, 3-year-olds in all conditions performed above chance on generalization questions but made more correct selections if they had been read the books with blocked examples. The 4-year-olds showed no book-related differences on forced-choice questions at either visit but gave better explanations at the second visit if they had been read interleaved books. Our study provides evidence that picture books with analogical examples can be used to teach children about science but that different types and arrangements of examples may better support children at different ages and with different amounts of prior experience.

EXAMPLE OF NONUNIQUENESS IN THE HOPF CLASS OF WEAK SOLUTIONS FOR THE NAVIER-STOKES EQUATIONS

An example of nonuniqueness in the class of weak Hopf solutions is constructed for an initial-boundary value problem for the Navier-Stokes equations. An analogous example is also constructed for quasilinear parabolic equations.

Reaction of perfluoronitrosoalkanes with esters of phosphorous acid

1. Depending on the structure of the perfluoronitrosoalkanes, their reaction with triethyl phosphite leads to obtaining fluorine-containing phosphazo compounds, the ethyl ethers of oximes of perfluoro ketones, and the oxides of perfluoronitriles. 2. Some new examples of a chemical analogy between the perfluoronitrosoalkanes and perfluoro ketones were discovered. 3. The obtained results are in agreement with the concept that the phosphite initially attacks the nitrogen atom of the nitroso group.

Secondary Flows in an Incompressible Fluid of Varying Density in a Rotating Reference Frame

This paper presents the theory of secondary flow generation for an incompressible fluid of spatially varying density due to rotation of the frame of reference. It is pointed out that, while Coriolis forces may deflect the relative streamlines, the generation of secondary vorticity and secondary circulation generally requires an appropriately oriented momentum gradient. In particular, secondary vorticity will not be generated by rotation of the frame of reference in the absence of momentum gradients perpendicular to the flow direction when the streamlines are plane curves. Consideration is given to the rotating dishpan experiment and to the apparently analogous physical examples of the vortex formation when water drains very slowly from a large tank, and the generation of circulation in a hurricane.