Pattern sensitivity

In the stochastic theory of branching processes the reactivity of the functional groups is assumed to be independent of the size of the copolymer. In addition, cyclization is postulated not to occur in the sol fraction, so that all reactions in the sol fraction are intermolecular. Bonds once formed are assumed to remain stable, so that no randomization reactions such as trans-esterification are incorporated. In our opinion this model is only approximate because of the necessary simplifying assumptions. The numbers obtained will be of limited value in an absolute sense, but very useful to show patterns, sensitivities and trends. 

Other transport limitations, such as diffusion-controlled reactions, can lead to localized depletion of etchant, which results in a number of observable etch effects. The size and density of features can influence the etch rate at different locations on a single wafer, thus producing "pattern sensitivity." Depletion across a wafer produces a "bulls eye" effect, while depletion across a reactor is indicated by the fact that the leading wafer edge etches faster than the trailing edge. Similar effects are noted when product removal is transport-limited. Most of these effects can be reduced... 

Arcuri, P. and Murray, J. D. (1986). Pattern sensitivity to boundary and initial conditions in reaction-diffusion models. J. Math. Biol., 24, 141-65. 

Fig. 10 Generation of the patterned, sensitive monolayers using microcontact printing. a An amino-terminated monolayer on a glass surface is brought into contact with a poly(dimethylsiloxane) stamp inked with a fluorophore, resulting in the covalent attachment of the fluorophore to the amino-terminated monolayer (b). c Functionalization of the remaining free amino groups with reactive molecules...

Fukui, M., Imamura, R., Umemura, M., Kawabe, T., Suda, T. Pathogen-associated molecular patterns sensitize macrophages to Fas ligand-induced apoptosis and IL-1 beta release. J Immunol 171 (2003) 1868-1874. 

However, electropolishing is pattern sensitive and this may limit its applications. The passivation film or diffusion layer thickness is minimal above narrow features as the diffusion layer profile is unaffected by the copper surface profile. Therefore, the diffusion flux that corresponds to the removal rate is large for these features and planarization of these features is possible. For wide features, the diffusion layer profile follows the copper surface profile, the removal rate is low, and this leads to a conformal copper removal and inadequate planarization. 

The copper removal rates can be varied from 200 to 1700 nm/min. The removal rate is varied by altering the rotational speed and the water concentration. However, as mentioned, pattern sensitivity limits its application to planarization of integrated circuits. 

Isotope pattern filter (IPF) [170,172] Predicted isotope pattern Sensitive detection of unexpected metabolites Not suited for metabolites that have no nnique isotope pattern... 

Pattern sensitivity the contents of a ceU become complemented due to read and write operations in eledricaUy adjacent ceUs (ceU disturbances, adjacent ceU disturbances, column disturbances, adjacent column disturbances, row disturbance, adjacent row disturbance). 

A third group of problems arises from hardware failure interactions with software. A pattern sensitive or transient hardware failure can corrupt software or data, without becoming apparent. The results appear as software errors. 

For the hardware feilure/software interaction problems, a very simple technique is to use parallel redundancy, with comparison of outputs. This approach will detect most transient hardware ilures, and many pattern sensitive failures. 

For conventional probes, acoustic verification aims at characterizing the beam pattern, beam crossing, beam angle, sensitivity, etc., which are key characteristics in the acoustic interaction between acoustic beam and defect. For array transducers, obviously, it is also a meaning to check the acoustic capabilities of the probe. That is to valid a domain (angle beam, focus, etc.) in which the probe can operate satisfactorily. 

As any conventional probe, acoustic beam pattern of ultrasound array probes can be characterized either in water tank with reflector tip, hydrophone receiver, or using steel blocks with side-drilled holes or spherical holes, etc. Nevertheless, in case of longitudinal waves probes, we prefer acoustic beam evaluation in water tank because of the great versatility of equipment. Also, the use of an hydrophone receiver, when it is possible, yields a great sensitivity and a large signal to noise ratio. 

Although the structure of the surface that produces the diffraction pattern must be periodic in two dimensions, it need not be the same substance as the bulk material. Thus LEED is a particularly sensitive tool for studying the structures and properties of thin layers adsorbed epitaxially on the surfaces of crystals. 

Powder diffraction studies with neutrons are perfonned both at nuclear reactors and at spallation sources. In both cases a cylindrical sample is observed by multiple detectors or, in some cases, by a curved, position-sensitive detector. In a powder diffractometer at a reactor, collimators and detectors at many different 20 angles are scaimed over small angular ranges to fill in the pattern. At a spallation source, pulses of neutrons of different wavelengdis strike the sample at different times and detectors at different angles see the entire powder pattern, also at different times. These slightly displaced patterns are then time focused , either by electronic hardware or by software in the subsequent data analysis. 

The absolute measurement of areas is not usually usefiil, because tlie sensitivity of the spectrometer depends on factors such as temperature, pulse length, amplifier settings and the exact tuning of the coil used to detect resonance. Peak intensities are also less usefiil, because linewidths vary, and because the resonance from a given chemical type of atom will often be split into a pattern called a multiplet. However, the relative overall areas of the peaks or multiplets still obey the simple rule given above, if appropriate conditions are met. Most samples have several chemically distinct types of (for example) hydrogen atoms within the molecules under study, so that a simple inspection of the number of peaks/multiplets and of their relative areas can help to identify the molecules, even in cases where no usefid infonnation is available from shifts or couplings. 

There are a few other surface-sensitive characterization techniques that also rely on the use of lasers. For instance surface-plasmon resonance (SPR) measurements have been used to follow changes in surface optical properties as a fiinction of time as the sample is modified by, for instance, adsorption processes [ ]. SPR has proven usefiil to image adsorption patterns on surfaces as well [59]. 

Different combinations of stable xenon isotopes have been sealed into each of the fuel elements in fission reactors as tags so that should one of the elements later develop a leak, it could be identified by analyzing the xenon isotope pattern in the reactor s cover gas (4). Historically, the sensitive helium mass spectrometer devices for leak detection were developed as a cmcial part of building the gas-diffusion plant for uranium isotope separation at Oak Ridge, Tennessee (129), and heHum leak detection equipment is stiU an essential tool ia auclear technology (see Diffusion separation methods). 

Computer Models, The actual residence time for waste destmction can be quite different from the superficial value calculated by dividing the chamber volume by the volumetric flow rate. The large activation energies for chemical reaction, and the sensitivity of reaction rates to oxidant concentration, mean that the presence of cold spots or oxidant deficient zones render such subvolumes ineffective. Poor flow patterns, ie, dead zones and bypassing, can also contribute to loss of effective volume. The tools of computational fluid dynamics (qv) are useful in assessing the extent to which the actual profiles of velocity, temperature, and oxidant concentration deviate from the ideal (40). 

The equiHbrium approach should not be used for species that are highly sensitive to variations in residence time, oxidant concentration, or temperature, or for species which clearly do not reach equiHbrium. There are at least three classes of compounds that cannot be estimated weU by assuming equiHbrium CO, products of incomplete combustion (PlCs), and NO. Under most incineration conditions, chemical equiHbrium results in virtually no CO or PlCs, as required by regulations. Thus success depends on achieving a nearly complete approach to equiHbrium. Calculations depend on detailed knowledge of the reaction network, its kinetics, the mixing patterns, and the temperature, oxidant, and velocity profiles. 

As the width and thickness of IC layers and patterns continue to shrink into the submicrometer range, Si02 layers need to be fabricated of 5—20 nm thickness. These thin oxides have properties that are very sensitive to the substrate cleanliness and uniformity, gas purity, and temperature control. 

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