Known Identities

Phase stability of nanostructures has been one of the central issues in nanoscience and technology. For a given specimen of a fixed size, phase transition takes place when the temperature is raised to a certain degree. The value of the critical temperature (Tc) varies with the actual process of phase transition. The Tq values are different for the magnetic-paramagnetic, ferroelectric-non-ferroelectric, solid-solid, solid-liquid, and liquid-vapor phase transitions of the same specimen. Generally, solid-size reduction depresses the Tc of a nanosolid because atomic undercoordination lowers cohesive energy of atomics in the skin. 

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DNA microarrays, or DNA chips consist of thousands of individual DNA sequences arrayed at a high density on a single matrix, usually glass slides or quartz wafers, but sometimes on nylon substrates. Probes with known identity are used to determine complementary binding, thus allowing the analysis of gene expression, DNA sequence variation or protein levels in a highly parallel format. 

As first practiced by Geysen and Houghton, the preparation of combinatorial libraries produced discrete compounds of known identity through a technique known as "spatial separation," which simply means that individual compounds in the library are produced discretely and are not mixtures. Such spatially addressable compound sets are produced in such a way as to keep separate the reaction flasks or resin beads containing the individual components of the library and perform bioassays on the discrete compounds, one at a time. Thus, if the "history" of the reaction conditions performed in each flask or on each solid support, the identity of the compounds produced is known, without resort to structure elucidation techniques. Initially, this technique, after typically an extensive reaction development stage, allowed the preparation of between 10 and 1000 discrete combinatorial products. 

Soxhlet, sonication, supercritical fluid, subcritical or accelerated solvent, and purge-and-trap extraction have been introduced into a variety of methods for the extraction of contaminated soil. Headspace is recommended as a screening method. Shaking/vortexing is adequate for the extraction of petroleum hydrocarbons in most environmental samples. For these extraction methods, the ability to extract petroleum hydrocarbons from soil and water samples depends on the solvent and the sample matrix. Surrogates (compounds of known identity and quantity) are frequently added to monitor extraction efficiency. Environmental laboratories also generally perform matrix spikes (addition of target analytes) to determine if the soil or water matrix retains analytes. 

Recording the NIR spectra. For a set of samples of known identity, either certified by the supplier or confirmed using alternative identification tests, the NIR spectra are recorded in a defined manner. 

DNA microarrays are produced using high-speed robotics on glass or nylon substrates to form probes with known identity. According to Phimister, probe stands... 

Determination of the DNA type to be used for probes in this experiment Generally, cDNA/oligo with known identity is used. 

The purity of the reference standard used to prepare spiked samples can affect the study data. For this reason, an analytical reference standard of known identity and purity should be used to prepare solutions of known concentrations. If possible, the reference standard should be identical to the analyte. When this is not possible, an established chemical form (free base or acid, salt, or ester) of known purity can be used. Three types of reference standards are generally used ... 

Calibrate the chemical measuring instrument using standards prepared from pure substance reference materials of known identity and purity Calibrate physical measurement processes with traceable physical standards... 

An explicit representation of Eq. (6.36) is obtained by using the well-known identity (obtained by a similar contour integration to that depicted in Fig. 2.1),... 

These are samples of known identity and concentration which are used to determine that the chromatographic system and detector are functioning correctly. This is achieved through examination of the retention time and, sometimes, a specific chromatographic property, for example, peak asymmetry, area or height. If the system is performing correctly, then the results obtained from such check standards should be the same every time. 

In the 1990s the validity of this approach was demonstrated with numerous examples published in the literature and presented at international conferences. It now forms a routine part of any field development operation. A number of modifications have been introduced, such as those described by Halpern (1995). In the typical fingerprinting approach described above, the peaks are selected pretty much at random since their identity is not crucial as long as we know the same peaks are being utilized for each analyses. In the Halpern approach, peaks of known identity were selected and two sets of parameters developed. The first set consists of correlation... 

Using the well-known identity V (l/r) = -47T(5(r), we can reduce equation... 

Because of the well-known identity Equation (32) the semi-minor axis can be described using the scattering angle, the tilt and the detector to sample distance, as given in Equation (33) ... 

Now a and c can be inserted into the well-known identity e = cja to denote the eccentricity in calibration parameters ... 

The most important distinction is that between initialization for a previously known identity and initialization for a newly created identity. Formally, this distinction defines which events have the identity of the signer as a parameter. For compactness, only the more common initialization for a previously known identity has been worked out in detail and is used in all subsequent sections. 

Initialization for a previously known identity means that the identity that the signer will use in authentications and disputes has been defined outside the signature scheme. For instance, it may be a name and address, but also a previously known pseudonym. This type of identity has been assumed in the examples so far. 

The following properties characterize initialization for a previously known identity ... 

However, in practice, the identity is present in the entity under an access point in the form of access to a broadcast channel under this previously known identity (for the time of initialization). For instance, with an ordinary digital signature scheme, the public key is broadcast on this channel inside the system during such an initialization. Similarly, if the system contained an authority that issues key certificates, the entity would need access to a secure channel to the authority under this identity, e.g., via the user who makes a handwritten signature. Note that the entities of all signers still use the same program e.g., they use a particular port for broadcast outputs. 

In contrast to previously known identities, one could now alternatively define that the signer inputs her own new identity. Her entity would generate a public key or whatever as before and additionally broadcast the identity. If someone chose an identity that any entity participating in this initialization knew to be already in use, all the entities would reject it. 

A broadcast port, which is mainly used for broadcast under the previously known identities in initialization, see Section 5.2.4. 

The metal salts of the phosphorodithioate esters are among the most intensively studied of the lubricant additives. But the reader should be aware that in purity the preparations used have ranged from carefully synthesized, single-component, crystalline substances of known identity to heterogeneous commercial mixtures prepared in a mineral oil medium from which they were never separated. In the commercial process the diester of phosphorodithioic acid is prepared by treating the appropriate... 

Batch-type experimental techniques employed to search out a new venture in industry are essentially similar to those employed in academic studies (Chapter 2), but the flexibility is less. In academic studies, the purpose of which is to increase our store of general knowledge, the investigator works with substances of known identity and concentration, moreover he has much freedom in the choice of experimental conditions. 

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