Characteristic class

Perhaps the simplest examination done is the physical match. A small fragment of wood, plastic, or other material is recovered and fitted into a large piece found on the suspect or at the scene of the crime (39). Other examinations result ordy in demonstrating class characteristics (40). Such information may be used in a prosecution as circumstantial evidence in a trial. However, it is important that the forensic scientist neither inflate nor minimize (41,42) its importance. 

The identification of ivory and ivory substitutes is based on the (55) physical and chemical class characteristics of these materials. A common approach to identification is to use the macroscopic and microscopic physical characteristics of ivory in combination with a simple chemical test using ultraviolet light. 

General Mechanism Class Characteristics and Specific Mechanisms Examples" Remarks... 

Examination of physical evidence provides two subtle and different types of conclusion. All members of a class or group have identical characteristics. Types of physical evidence which exhibit class characteristics are paint, glass, fibers, fabric, building material, etc. This type of physical evidence is said to be identified. The best that chemical and physical examinations can ever do is to place items into groups of similarly manufactured ilems. It is not possible to differentiate one item of evidence as being uniquely distinguishable from another. 

Trace evidence in criminal investigations typically consists of hairs both natural and synthetic fibers, fabrics glass plastics soil plant material building material such as cement, paint, stucco, wood, etc, flammable fluid residues, e.g., in arson investigations explosive residues, e.g.. from bombings, and so on. Perhaps the simplest examination done is the physical match. Other examinations result only in demonstrating class characteristics. 

Class characteristic fragment ions of chlorophylls and related chlorins are summarized for both positive and negative ion APCI. Detailed instrument parameters for LC/MS using APCI are described. 

Symbolic. From the redefinition of the problem, carried out in the making the familiar strange phase, it is possible to look at attributes or keywords in the description to see if class-characteristics can be identified. The task is then to see if these characteristics suggest any new answers to the problem. 

If the agreement is satisfactory, the classification procedure can be used on a routine bias. If not, some of the classification algorithm parameters, the composition of the training population, the class characteristics or the selection of the shape descriptors should be modified. 

In considering the aromatic aldehydes and ketones and later the aromatic acids it should be emphasized that the relationships discussed in Part I (p. 129) between alcohols, aldehydes, ketones and acids are general and apply just as truly to the aromatic compounds as to the aliphatic. The class characteristics of alcohols, aldehydes, ketones and acids are the same in both series. Thus the primary alcohols, on oxidation, always yield first aldehydes and then acids, while the secondary alcohols yield ketones. 

The last FAB spectrum. Figure 12, is that of hydroxyhexamethyl melamine glucuronide measured with a thioglycerol matrix. The protonated molecular ion is observed, as well as the class characteristic ion (M+H-194) of mass 20. When this analysis was run from a glyceroi matrix, (M-H) ions were desorbed in greater abundance than (M+H) ions. 

The module provides a search interface as well as directories for chemical classes, characteristics, and use of substances. Particularly interesting is an expert system for designing safer substances based on chemical classes. Selecting, for instance, the chemical class polymers gives access to the designing safer polymers entry, which leads to a series of questions (answers are marked in bold case) ... 

ACCS = Activity Class Characteristic Substructures —> substructure descriptors ( structural keys)... 

Activity Class-Characteristic Substructures (ACCS) are those molecular fragments that occur in the randomly generated fragment populations of at least two active molecules but not in the population of the compounds of other activity classes [Lounkine, Batista et al, 2007]. These are specific unique combinations of fragments, whose presence depends on eacii other, and seem to define the core structures in compound activity classes. 

Once ACCS subset is assigned to a specific activity class, characteristic substructures are mapped back on each molecule by performing a subgraph search for each fragment and whenever a fragment matches an atom of the molecule, a counter for that atom is increased by 1. For each atom, division of its final counter state by the total number of matched substructures gives its match rate. Then, for each active molecule, core structures are defined as the set of all atoms of the molecule that have an ACCS match rate greater than a threshold value. 

An abstracted system differs from an abstraction, which is a concept Gike those that make up coneeptual systems) representing a class of phenomena all of which are considered to have some similar class characteristic. The members of such a class are not thought to interact or be interrelated, as are the relationships in an abstracted System. 

For practical selectivity searching, 69 inhibitors with at least 50-fold selectivity for cathepsin K over S and L were selected as reference molecules. The search protocol involved two different in-house-developed LEVS approaches, as shown in Figure 11.9 a compound mapping algorithm termed DynaMAD [38] and a specialized type of molecular fingerprint consisting of compound class characteristic substructures, ACCS-FP [61]. 

Program-Related Factors Laboratory Class Characteristics... 

Note that this sum does not take into account the probability of a compound being active in the first place (the prior), rather, it reflects if the molecule contains more class-characteristic features or more features that are not present in the class. An ensuing limitation is bias toward high-molecular weight compounds. For example, polyhydroxylated natural products tend to receive too high scores if features encoding for hydroxyl groups in different chemical contexts are enriched in an activity class. 

In addition, alternate virtual screening methods can incorporate activity-class-characteristic features. For example, by counting the number of activity-characteristic features in test compounds, active molecules were identified that possessed new combinations of activity-characteristic features that were not observed in reference compounds, resulting in chemotypes that were distinct from any of the reference compounds [13]. Similarly, virtual fragment linking [7] used features enriched... 

The observation that features enriched in sets of active compounds irrespective of potency enables retrieval of highly potent compounds also supports the usage of feature weights extracted from NBM to identify compound-class characteristic molecular features. So far, we have discussed only activity classes, but any way to group molecules can be used to identify features that preferentially occur in desired groups of compounds. Other examples of compound class definition include ADME characteristics [24], toxicity [21 ], clinical ADRs [35], or chemical... 

A broad definition of the term forensic, according to Webster s New World Dictionary, is suitable for a law court or public debate. With the application of forensic science, one must demonstrate in court that the evidence analyzed has relevance to the case in question. The significance of evidence related to a case is often determined by whether the physical evidence has individual or class characteristic properties. Individual characteristics are properties of evidence that can be attributed to a common source with an extremely high degree of certainty. Class characteristics are properties of evidence that can only be associated with a group and never with a single source. (3)... 

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