System lexicon

Given this large offline lexicon, we see then that the real debate about rules vs lexicons is not one of quality, but rather one of balance between run-time and off-line resources. If we take the case where we include the entire off-line lexicon in the system lexicon, we will have a system which uses a considerable amount of memory, but where the processing speed is minimal (simply the small amount of time taken to look up a word). If on the other hand we create a system lexicon that is only a small subset of the offline lexicon, this will result in a smaller footprint, but as the pronunciation of absent words will have to generate at run-time, the processing costs... 

Some properties of the interactions between antibodies or T-cell receptors and the molecules they bind are unique to the immune system, and a specialized lexicon is used to describe them. Any molecule or pathogen capable of eliciting an immune response is called an antigen. An antigen may be a virus, a bacterial cell wall, or an individual protein or other macromolecule. A complex antigen may be bound by a number of different antibodies. An individual antibody or T-cell receptor binds only a particular molecular structure within the antigen, called its antigenic determinant or epitope. 

Despite the fact that only 20 amino acids (plus selenocys-teine and formylmethionine in prokaryotic systems) are known to be directly specified by the genetic code, chemical analysis of mature proteins has revealed hundreds of different amino acids, all of them structural variants on the original 20. This structural diversity, which greatly expands the chemical lexicon of proteins, results from posttranslational modification of the primary products of translation. Our knowledge of the nature and significance of enzymatic reactions that bring about these important alterations is still very incomplete. 

The FDA does not recognize the term revalidation. In their lexicon, the protocol testing for any system is validation whether or not a system has been previously validated. 

As a general notation, it is common to enclose within square brackets the number of functions of various types. For example, [6s5p2d/4s2p] indicates that first-row atoms are represented by 6s functions, 5 sets of 3 (p, p, and p ) p-functions, and two separate sets of five d-functions. The basis set for hydrogen is indicated after the slash 4s and 2 sets of p-functions. Because the order is always the same s, followed by p, d, etc. it is not uncommon to leave out the letters entirely [652/42]. In this lexicon, the 6-31G basis set could be represented as [321/21]. If the system were to contain atoms beyond the first row of the periodic table, they would be indicated to the left of the first set of numbers, as in [second-row/first-row/H]. 

Many of the compartments in Kong s tables contain several molecules indeed, the paper that introduces his diatomic-molecular system comes with a lexicon listing the molecules contained in each compartment. The hst is two-dimensional (arranged according to the differences of the atoms period and group numbers), which suggests that Kong s table is in fact a projection onto two-dimensional space of a four-dimensional architecture. 

Many molecules can exist in one compartment, even if the restriction to row-two atoms is maintained for instance, CO and BF are in the same compartment as N2, and FNO2, O4, and N2F2 are in the same compartment as BF3. The schematic does not show the additional axes necessary to distinguish between these horizontally isoelectronic molecules such axes are shown explicitly in the lexicon for Kong s periodic system for diatomics. The schematic also does not indicate the additional... 

Ultraviolet photoelectron spectroscopy (UPS) has established its place in the lexicon of chemical spectroscopies as the technique which uniquely reveals the valence electronic structure of the isolated molecule. It has been particularly successful for organic systems... 

It is not hard to find this legislative lexicon of safety - the legalese -on construction sites, often within safety documentation and induction materials. The safe systems of work and working environment found in Clauses 2(a) and 2(d) of the Health and Safety at Work etc. Act 1974, respectively can be easily found throughout our safety documentation. They are often either associated with general management practices or focused on specific work tasks such as falls/ fall prevention or excavations, where guidance often makes explicit reference to a safe system of work. ... 

It is therefore unsurprising that away from the formal manifestations of legal requirements in safety management systems and documents, safety becomes much more fluid and flexible. When those who work on sites everyday try to adopt the polarised lexicon of safety with their own understandings of construction site life, it doesn t quite work. Evidence of this can be readily found in site-produced safety documentation (as opposed to formal corporate documents distributed by contractor head offices), such as induction slides, where the site team often try to reposition safe/ unsafe within a wider context examples of practice are given as they were in the earliest legislation, the acknowledgement of variation... 

The polarised safe/unsafe of the legislative lexicon has unsurprisingly become embedded in organisational safety management practices and safety management systems. Binary evaluations of safety are therefore also found at the heart of various safety management activities, such as risk assessments and site inspections, and so have considerable influence on the construction of safety in practice. 

In all modem TTS systems we make extensive use of a lexicon. The issue of lexicons is in fact quite complicated, and we discuss this in full in Chapter 8 when we start to talk about pronunciation in detail. For our current purpose, its main use is that it lists the words that are known to the system, and that it defines their written form. A word may have more than one written form (labour and labor) and two words may share the same written form polish etc. It is by using a lexicon as a place to define what is a possible word and what its written forms may be, that we can use the decoding model we are adopting in this book. 

One simple rule based systems works as follows. Firstly, we require a lexicon which gives the orthography for each word. With this, we can easily determine cheek whether two words in the lexicon have the same orthography, and from this compile a list of tokens which have two or more word forms. Next we write by hand a set of rules which fire (i.e. the activate) on the presence of the trigger token, for example ... 

Most words have a single canonical pronunciation it is this that we think of as being stored in the lexicon it is this which is the definition of how that word sounds. Hence a canonical transcription aims to transcribe the speech in terms of the canonical pronunciations which are given for each word in the lexicon. In such a system, the task can be described as one where we first identify the words, and then transcribe the speech with the phonemes for each word and finally mark the boundaries between the phonemes. Complications lie in the fact that the speaker may say a filled pause (i.e. an um or err ), or that they may mispronounce a word (i.e. they might say /n uw k y uw 1 er/ instead of /n uw k 1 iy er/ for nuclear). In such cases, one must decide whether to take account of these effects and label them, or whether to stick to the canonical pronunciation. A second type of broad transcription, known as phonemic transcription takes a slightly more literal approach, whereby the transcriber marks the sounds as he or she thinks they occur, but in doing so only draws from the inventory of defined phonemes. Thus in such a system, the transcriber would be able to describe the differences between the two renditions of NUCLEAR. 

Perhaps unsurprisingly, the consensus as to where this point should be has shifted over the years. When more traditional systems were developed, memory was very tight and hence the number of base types had to be kept low regardless of any errors. In more recent years technological developments have eased the pressure on memory making more abstract representations possible. Given this, there is more choice over where exaetly the ideal representation should lie. In fact, as we shall see in Chapter 16, the most successfiil systems adopt a quite phonemic representation and avoid any rewriting to a phonetic space if at all possible. Because of this, the pronunciation component in modem systems is in fact much simpler than was perhaps the case in older systems, and quite often the input to the synthesiser is simply canonical forms themselves, direct from the lexicon. 

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