Masking phenomenon

For the STFT case, the bandwidth of the filter-bank is inversely proportional to the duration of the short-time frame and it is shown in [Cappe and Laroche, 1995], using standard results concerning the simultaneous frequency masking phenomenon, that the processing can suppress audible signal components (ie. components that were not masked by the additive noise) if the short-time duration is well below 40 ms. 

Panehsts are trained to evaluate malodor intensity and the degree of modification. It is important that the paneflst be able to smell through any extraneous odor(s), such as the fragrance of the product, to evaluate the efficacy of products making elimination or neutralization claims, as opposed to the phenomenon of masking. 

Al-Shuaili (cited in Johnstone Al-Shuaih, 2001, p. 44) showed that the dominant stimulus may have to be played down if it is in danger of masking other important observations. This does not imply that the teacher should give all the answers before the laboratory, but rather prepare the observational faculties for what is to come . A further complication to observation is that apparatus often masks a phenomenon. Johnstone and Al-Shuaili (2001) recommended that teachers should explain apparatuses so that the class can focus attention on the phenomenon. 

Another interesting chiral chain end effect is exhibited by the helical polymer block co-polymer, poly(l,l-dimethyl-2,2-di-/z-hexylsilylene)- -poly(triphenylmethyl methacrylate), reported by Sanji and Sakurai (see Scheme 7) and prepared by the anionic polymerization of a masked disilene.333 The helical poly(triphenylmethyl methacrylate) block (PTrMA) is reported to induce a PSS of the same sign in the poly(di- -propylsilylene) block in THF below — 20 °C, and also in the solid state, by helicity transfer, as evidenced by the positive Cotton effect at 340 nm, coincident with a fairly narrow polysilane backbone UV absorption characteristic of an all-transoid-conformation. This phenomenon was termed helical programming. Above 20°C, the polysilane block loses its optical activity and the UV absorption shifts to 310 nm in a reversible, temperature-dependent effect, due to the disordering of the chain, as shown in Figure 45. 

An additional problem with some supporting media is the phenomenon of electroendosmosis, in which the buffer itself moves due to an electrophoretic effect and hence masks the movement of the solute to some extent. However, this feature is exploited in some situations to aid separation. Electroendosmosis is caused by the presence of negatively charged groups on... 

The masking of the normal reaetions of simple ligands, such as the nitro, cyano, and ammonia groups, by coordination to a metal is a phenomenon encountered early by a chemist. One of the first examples of masking in a chelate complex was reported, signifieantly, in biological journals. It involves the protection by copper ion of the a-amino group in ornithine and lysine ... 

Applying a mask function in real space is equivalent to combining many structure factors through a convolution in reciprocal space. This results in an improvement because the random error component of the structure factors will average out, whereas the true values of the structure factors will add up systematically. Fig. 10.4 gives a graphical example showing this phenomenon. 

Fig. 16. Influence of the ionic strength in the prevention of readhesion phenomenon in the case of a positive particle on a negative substrate (alumina slurries on silicon oxide layer) a high-ionic-strength limit the double layer thickness. Particle and substrate are therefore electrically masked at a closer particle-substrate distance. (The double layer of the substrate is not represented here.)...

A next attempt involved fitting the experimental results of Table I to Eq. (Al). This 80-point least-squares fit led to K—49.4, a= 1.031, b=0.113, c = 0.537, d = 1.998, and tr = 0.02129 (5.2%), which reflected about the right dependence of P cPti on N b, Qub, and pa, but failed to reflect the predicted dependence on b (thereby leading to large values of K). Since a disproportionate number of the data points (75 of 80) were for explosives wherein Mtxb varied over the relatively narrow range 27.2-31.3, we feel that the dependency of P on Mt,rb may have been masked by the systematic errors in the measurements. It should be noted that if, as the results seem to show, exponents near 1.0 and 0.5 for jVwb and Q b realistically reflect the influences of these properties of the explosive on P, an exponent near 0.5 for M rb in Eq. (1) is necessary to introduce the buffering phenomenon discussed in the present series of papers. 

As for the results mentioned previously concerning signal cancellation, the obtained audibility limit should only be considered as an order of magnitude estimate in real situations since it does not take into account the possible mutual masking between different signal components (a phenomenon which may prevail when the noise level is very low) [Cappe and Laroche, 1995], These results still support several earlier... 

One essential experimental feature is that pressure resistant closed crucibles are used. This is because, at heating, volatile compounds may evaporate that may mask an exothermal phenomenon occurring in the same temperature range, and so the sample mass is no longer defined (see Section 4.3.2.1). 

It should be emphasised that the simplest way of avoiding the formation of deep etch patterns, namely, by reducing the time of the solid-with-liquid interaction, does not seem to be the best one because it only masks the phenomenon, not eliminating its cause. Therefore, it appears to be much more reasonable to increase the disc diameter and to reduce the volume of the liquid phase (within acceptable limits and taking account of other re-strictions 5 5 ), so that during dissolution of a solid from zero up to... 

Theoretically odors that actually counteract a given off-odor in the sense of decreasing its intensity, if possible to zero, would be even more ideal masking agents. In practice such annihilating odors have never yet been found. A few rare instances have been recorded where the addition of a second component results in reduced total intensity. But this phenomenon always involves a rather precise ratio of the two components, and it has as yet not been possible to put it to practical use. 

The AMI SCF-MO method was applied to calculate properties of all possible diazinodiazines and their monocations in order to get information about the site of protonation in these 7r-deficient heterocycles. Since some of these polyazanaphthalenes, like pteridine, are masked by the covalent hydration phenomenon the pA) values belong in fact to their hydrates, solvates, and mixtures of the adducts with the unmodified forms. Pteridine was found to be the strongest base in this series due to the high proton affinity at N-l <88JOC3900>. 

The second effect can greatly increase evaporation of a moderately volatile, moderately water-soluble pesticide. The pesticide will tend to be lost along with the water in the ratio present in the undisturbed soil water, not because of any peculiarity in the evaporation process but because the bulk flow of the solution up the capillaries is too fast for diffusion in the soil water to compete. Surface concentrations are automatically adjusted until evaporation occurs in the ratio supplied. A mixture of water, alcohols, ketones, etc., allowed to evaporate only from the top of a wick 30 mm. or more long, does so without any change of bulk composition. The phenomenon is exploited in the odor-masking devices sold. If excessively involatile constituents are avoided, any mixture can be evaporated automatically at constant composition if allowed to do so only through a wick. 

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