The Senses

Flavour is made up of the aroma and trigeminal perceptions when tasting (such as haptic aspects and/or homess, strong spiciness as an aspect of the sense of pain). 

As far as olfaction is concerned, it is essential for the purposes of quality testing that a strict distinction is made between two types of smelling  

Nasal smelling is normal smelling through the nose. The active substances producing the smell pass through the nostrils on their way to the olfactory epithelium in the roof of the nasal cavity and from there through the nasopharynx to the oral / pulmonary cavity from where they are then exhaled. The process corresponds to breathing with the mouth closed. 

The olfactory perception can be reinforced by sniffing i.e. by swirling the air intermittently over the ethmoid bone below the olfactory epithelium. The swirling effect causes the active components producing the smell to flow past the olfactory epithelium several times (instead of just once), thereby reinforcing the effect (particularly important in quality testing in the case of weak samples or samples with only very minor differences between them). 

Retronasal smelling occurs when an aromatic product is placed in the mouth, the mouth is then closed and the product is eaten , causing the active components producing the smell to rise through he nasopharynx to the olfactory epithelium (this can be demonstrated quite simply by holding the nose closed, thus creating a counterpressure which prevents the active components from rising from the mouth to the nose). 

If assemblages of neurons cannot be viewed as the building blocks of consciousness, then consciousness must be a primary principle. 

The basics of control systems have been explained in Section 4.4. As explained there, all control systems start with the ability to sense an environmental attribute. If it can t be sensed, it can t be 

Taste and smell are both chanical senses (Tables 6.20.1 and 6.20.2), touch and hearing are mechanical, and vision is electromagnetic in nature. To this list, we could perhaps add the senses of balance, somatic condition, blood chanical composition, and temperature. Some other animals also sense heat (mosquito, pit viper), magnetic fields (many birds), and electrostatic fields (sharks). 

Many specialized receptors are actually sensitive to several different kinds of primary signals. The hot, burning sensation we sometimes get from intense mechanical pain is because cutaneous thermoreceptors (those that sense skin temperature) are also somewhat sensitive to mechanical 

Iodoform Butyric acid Propyl mercaptan Artificial musk Methyl mercaptan 

---

A completely updated edition of the well-known book by the author of The Mind. The clear and comprehensive text deals with everything from sex to the skeleton, sleep to the senses. 

Having set up the ultrasonic instrument (according to test specifications), the inspector scans the weld volume. Any indications subject to recording are interpreted and documented in a handwritten on-site report. The test report only describes the indications detected by the inspector, but not the completeness of the lest in the sense of a documented 100% volume testing as is the case with X-ray testing. 

The scope of the directive covers the design, manufacture and conformity assessment of pressure equipment and assemblies with a maximum allowable pressure greater than 0,5 bar. A pressure equipment in the sense of the directive is any vessel, piping, safety accessory or pressure accessory. An assembly means several pieces of pressure equipment assembled by a manufacturer to constitute an integrated and functional whole. It is important to be aware that the directive relates exclusively to the pressure risk and that therefore other directives, such as for machinery, low voltage may be applicable to the equipment concerned. 

Various kinds of potentials have been referred to in the course of this and the preceding chapter, and their interrelation is the subject of the present section. The chief problem is that certain types of potential differences are physically meaningful in the sense that they are operationally defined, whereas others that may be spoken of more vaguely are really conceptual in nature and may not be definable experimentally. 

Dislocation theory as a portion of the subject of solid-state physics is somewhat beyond the scope of this book, but it is desirable to examine the subject briefly in terms of its implications in surface chemistry. Perhaps the most elementary type of defect is that of an extra or interstitial atom—Frenkel defect [110]—or a missing atom or vacancy—Schottky defect [111]. Such point defects play an important role in the treatment of diffusion and electrical conductivities in solids and the solubility of a salt in the host lattice of another or different valence type [112]. Point defects have a thermodynamic basis for their existence in terms of the energy and entropy of their formation, the situation is similar to the formation of isolated holes and erratic atoms on a surface. Dislocations, on the other hand, may be viewed as an organized concentration of point defects they are lattice defects and play an important role in the mechanism of the plastic deformation of solids. Lattice defects or dislocations are not thermodynamic in the sense of the point defects their formation is intimately connected with the mechanism of nucleation and crystal growth (see Section IX-4), and they constitute an important source of surface imperfection. 

As is made evident in the next section, there is no sharp dividing line between these two types of adsorption, although the extremes are easily distinguishable. It is true that most of the experimental work has tended to cluster at these extremes, but this is more a reflection of practical interests and of human nature than of anything else. At any rate, although this chapter is ostensibly devoted to physical adsorption, much of the material can be applied to chemisorption as well. For the moment, we do assume that the adsorption process is reversible in the sense that equilibrium is reached and that on desorption the adsorbate is recovered unchanged. 

Physically, why does a temi like the Darling-Dennison couplmg arise We have said that the spectroscopic Hamiltonian is an abstract representation of the more concrete, physical Hamiltonian fomied by letting the nuclei in the molecule move with specified initial conditions of displacement and momentum on the PES, with a given total kinetic plus potential energy. This is the sense in which the spectroscopic Hamiltonian is an effective Hamiltonian, in the nomenclature used above. The concrete Hamiltonian that it mimics is expressed in temis of particle momenta and displacements, in the representation given by the nomial coordinates. Then, in general, it may contain temis proportional to all the powers of the products of the... 

Wlien first proposed, density llinctional theory was not widely accepted in the chemistry conununity. The theory is not rigorous in the sense that it is not clear how to improve the estimates for the ground-state energies. For wavefiinction-based methods, one can include more Slater detenuinants as in a configuration interaction approach. As the wavellmctions improve via the variational theorem, the energy is lowered. In density fiinctional theory, there is no... 

Unlike the solid state, the liquid state cannot be characterized by a static description. In a liquid, bonds break and refomi continuously as a fiinction of time. The quantum states in the liquid are similar to those in amorphous solids in the sense that the system is also disordered. The liquid state can be quantified only by considering some ensemble averaging and using statistical measures. For example, consider an elemental liquid. Just as for amorphous solids, one can ask what is the distribution of atoms at a given distance from a reference atom on average, i.e. the radial distribution function or the pair correlation function can also be defined for a liquid. In scattering experiments on liquids, a structure factor is measured. The radial distribution fiinction, g r), is related to the stnicture factor, S q), by... 

The quantity 1 + x is known as the dielectric constant, it is constant only in the sense of being independent of E, but is generally dependent on the frequency of E. Since x is generally complex so is the wavevector k. It is customary to write... 

The -frmction excitation is not only the simplest case to consider it is the frmdamental building block, m the sense thatv the more complicated pulse sequences can be interpreted as superpositions of 5-frmctions, giving rise to superpositions of M avepackets which can in principle interfere. 

As described at the end of section Al.6.1. in nonlinear spectroscopy a polarization is created in the material which depends in a nonlinear way on the strength of the electric field. As we shall now see, the microscopic description of this nonlinear polarization involves multiple interactions of the material with the electric field. The multiple interactions in principle contain infomiation on both the ground electronic state and excited electronic state dynamics, and for a molecule in the presence of solvent, infomiation on the molecule-solvent interactions. Excellent general introductions to nonlinear spectroscopy may be found in [35, 36 and 37]. Raman spectroscopy, described at the end of the previous section, is also a nonlinear spectroscopy, in the sense that it involves more than one interaction of light with the material, but it is a pathological example since the second interaction is tlirough spontaneous emission and therefore not proportional to a driving field... 

The equation of state detemiined by Z N, V, T ) is not known in the sense that it cannot be written down as a simple expression. However, the critical parameters depend on e and a, and a test of the law of corresponding states is to use the reduced variables T, and as the scaled variables in the equation of state. Figure A2.3.5 bl illustrates this for the liquid-gas coexistence curves of several substances. As first shown by Guggenlieim [19], the curvature near the critical pomt is consistent with a critical exponent (3 closer to 1/3 rather than the 1/2 predicted by van der Waals equation. This provides additional evidence that the law of corresponding states obeyed is not the fomi associated with van der Waals equation. Figure A2.3.5 (b) shows tliat PIpkT is approximately the same fiinction of the reduced variables and... 

Iiifomiation about the behaviour of the 3D Ising ferromagnet near the critical point was first obtained from high- and low-temperatnre expansions. The expansion parameter in the high-temperatnre series is tanli K, and the corresponding parameter in the low-temperatnre expansion is exp(-2A ). A 2D square lattice is self-dual in the sense that the bisectors of the line joining the lattice points also fomi a square lattice and the coefficients of the two expansions, for the 2D square lattice system, are identical to within a factor of two. The singularity occurs when... 

All the theory developed up to this point has been limited in the sense that translational motion (the continuum degree of freedom) has been restricted to one dimension. In this section we discuss the generalization of this to three dimensions for collision processes where space is isotropic (i.e., collisions in homogeneous phases, such as in a... 

Table 81.21.1. Surface stmctural detemiination methods. The second colunni indicates whether a technique can be considered a diffraction method, in the sense of relying on wave interference. Also shown are statistics of surface stmctural detemiinations, extracted from the Surface Stmcture Database [14], up to 1997. Counted here are only detailed and complete stmctural determinations, in which typically the experiment is simulated computationally and atomic positions are fitted to experiment. (Some stmctural detemiinations are perfomied by combining two or more methods those are counted more than once in this table, so that the colunnis add up to more than the actual 1113 stmctural detemiinations included in the database.)...

Figure Bl.21.1 shows a number of other clean umeconstnicted low-Miller-index surfaces. Most surfaces studied in surface science have low Miller indices, like (111), (110) and (100). These planes correspond to relatively close-packed surfaces that are atomically rather smooth. With fee materials, the (111) surface is the densest and smoothest, followed by the (100) surface the (110) surface is somewhat more open , in the sense that an additional atom with the same or smaller diameter can bond directly to an atom in the second substrate layer. For the hexagonal close-packed (licp) materials, the (0001) surface is very similar to the fee (111) surface the difference only occurs deeper into the surface, namely in the fashion of stacking of the hexagonal close-packed monolayers onto each other (ABABAB.. . versus ABCABC.. ., in the convenient layerstacking notation). The hep (1010) surface resembles the fee (110) surface to some extent, in that it also...

Computer simulations act as a bridge between microscopic length and time scales and tlie macroscopic world of the laboratory (see figure B3.3.1. We provide a guess at the interactions between molecules, and obtain exact predictions of bulk properties. The predictions are exact in the sense that they can be made as accurate as we like, subject to the limitations imposed by our computer budget. At the same time, the hidden detail behind bulk measurements can be revealed. Examples are the link between the diffiision coefficient and... 

As in previous sections, the zeros of l (x, t) in the complex t plane at fixed x are of interest. This appears a hopeless task, but the situation is not that bleak. Thus, let us consider a wavepacket initially localized in the ground state in the sense that in Eq. (50), for some given x. 

This analysis is heuristic in the sense that the Hilbert spaces in question are in general of large, if not infinite, dimension while we have focused on spaces of dimension four or two. A form of degenerate perturbation theory [3] can be used to demonstrate that the preceding analysis is essentially correct and, to provide the means for locating and characterizing conical intersections. 

All Np states belonging to the Pth sub-space interact strongly with each other in the sense that each pair of consecutive states have at least one point where they form a Landau-Zener type interaction. In other words, all j = I,... At/> — I form at least at one point in configuration space, a conical (parabolical) intersection. 

In this appendix, we discuss the case where two components of Xm, namely, x p and XMg (p and q are Cartesian coordinates) are singular in the sense that at least one element in each of them is singular at the point B p = a,q = b) located on the plane formed by p and q. We shall show that in such a case the adiabatic-to-diabatic transformation matrix may become multivalued. 

Although sulphur dioxide, as a gas, is a reducing agent in the sense that it unites with oxygen, free or combined (for example in dioxides or peroxides) most of its reducing reactions in aqueous solution are better regarded as reactions of sulphurous acid (in acid solution), or the sulphite ion (in alkaline solution). 

---