ACID loops

ACID is a loop-based music composition tool, which raises the more basic question What are loops Loops are typically short segments of music that are combined to form larger works. 

Modern electronics and computers have eliminated the magnetic audiotape from the equation. Loops are now created on computers and sold on CD-ROMs. While loops are most obviously used in repetitive electronic dance music, widely available acoustic and even orchestral loops mean that loop-based composition has invaded just about every genre of music. A three-piece guitar/bass/drum band might want a tabla percussion line in a song and use a commercial loop 

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All phosphoms oxides are obtained by direct oxidation of phosphoms, but only phosphoms(V) oxide is produced commercially. This is in part because of the stabiUty of phosphoms pentoxide and the tendency for the intermediate oxidation states to undergo disproportionation to mixtures. Besides the oxides mentioned above, other lower oxides of phosphoms can be formed but which are poorly understood. These are commonly termed lower oxides of phosphoms (LOOPs) and are mixtures of usually water-insoluble, yeUow-to-orange, and poorly characteri2ed polymers (58). LOOPs are often formed as a disproportionation by-product in a number of reactions, eg, in combustion of phosphoms with an inadequate air supply, in hydrolysis of a phosphoms trihahde with less than a stoichiometric amount of water, and in various reactions of phosphoms haUdes or phosphonic acid. LOOPs appear to have a backbone of phosphoms atoms having —OH, =0, and —H pendent groups and is often represented by an approximate formula, (P OH). LOOPs may either hydroly2e slowly, be pyrophoric, or pyroly2e rapidly and yield diphosphine-contaminated phosphine. LOOP can also decompose explosively in the presence of moisture and air near 150° C. 

Structurally, the three NPs are alike in that they contain a 17-amino acid loop with a conserved sequence (see also Figure 8.8). 

Finally, a recent paper by Gunther et aL shows that SEK uniquely binds to the T-cell receptor (human V/35.1) through a 15 amino-acid loop (q 3-/38) not evident in other superantigens, except for those in the same toxin grouping (e.g., SET). Surface plasmon resonance studies reveal a 6 (tmol binding affinity of SEK for V/35.1, which fits the range for other SEs when used in this technique. 

The A domains of all mammalian and some other GH13 a-amylases have a chloridebinding site that is essential for activity together with a short, inserted downstream amino acid loop (residues 304 through 311 in salivary amylase). This loop is flexible and interacts with substrate after binding so that the catalytic residues are correctly positioned for hydrolysis. It is absent from enzymes that do not require chloride ions for activity. The C domain has no known function, but it may facilitate solubility, in part, because of glycan attached to asparagine-413 in this domain. 

Reisfeld et al. (1987) described a hydrazide biotin labeling method (Table 7.20D) by which they could detect 1 pg of target DNA. Hydrazide compounds can be used similarly for a large number of other labels (enzymes, chromo- or fluorophores, electron-dense markers, etc.). Since the reaction is specific for ss nucleic acid, loops in duplices can be specifically labeled. 

Prior to use as a nanoparticle template, the p subunits were genetically modified by adding cysteine residues at different solvent exposed sites to yield two mutant variations of the P subunits. The two variations consisted of p subunits with exposed 28 amino acid loops and p subunits with these amino acid loops deleted. These p subunits were then assembled into chaperonin proteins upon Mg +/ATP binding and crystallized into a reactive protein template with a ring of thiol groups that protruded into the protein pore to different extents (3 nm and 9 nm pore diameters). ... 

Shah J (2003) The salicylic acid loop in plant defense. Curr Opin Plant Biol 6(4) 365-371. doi S136952660300058X [pii]... 

Loops are specially recorded audio files that are usually fairly short in duration. Loops are standard audio files that can be played back using just about any Windows-compatible media player (even the Windows Media Player). What makes a loop a loop is that it is recorded and structured so that when it is played back twice in a row, the end of the loop immediately and seamlessly leads back into the beginning of the loop. This means that most loops can be played over and over again infinitely, sounding as if it were a much longer continuous recording. Loops are normal. wav audio files and are commercially available from multimedia companies for use in loop-based music tools. ACID loops from Sonic Foundry contain a little more information than a typical. wav file (such as key and tempo information) that make them particularly easy to use in ACID. Sonic Foundry loop libraries can be used with many other multimedia applications (for example, video editing applications or Flash animation tools) and loops from other companies loop libraries can also be used in ACID. 

While all of the methods for changing the pitch are fundamentally the same, changing the root note of a loop as it occurs in a project is probably the last method you should use. The default root note information saved with an ACIDized loop was saved there by the artist who recorded the loop and provides important information both to you, the composer, and to AQD itself about the inherent key of the audio file. In most cases, it is probably better to change the key of the track that contains the loop instead of changing the root note of the loop in the properties dialog box, even though the results are identical. See Chapter 10 for more information about the root notes of loops. 

Up until this point, the word loop has heen used in a very general way, referring to any audio file on your computer that is used in ACID. Loop originally meant a physical loop of audiotape that had the two ends spliced together to create an infinitely repeating audio clip. In much the same way, the archetypical loop file on a computer is a short file that will play hack seamlessly end to end— and perhaps most commercial loop files are designed to work that way. But the definition has definitely expanded to include material that will not endlessly and seamlessly loop, and there are a large number of loops that don t actually loop. 

So what makes an ACID loop an ACID Loop ACID loops are simply audio files available from Sonic Foundry that have had beat, pitch, and tempo information added to them. As mentioned previously, this information is useful only to ACID (and perhaps some other Sonic Foundry projects in the future). At this time, only loops from Sonic Foundry have this additional information, but this is not some carefully guarded secret. Anyone can create ACIDized loops. Information about a media file as it pertains to ACID can be found in the Explorer window and in the Track Properties window for files that have already been inserted into ACID, as shown in Figure 9.2. See the section later in this chapter about ACIDizing your own loops. 

The other way is to find a few simple loops with clear tonal qualities that have key information saved with them. Simple solo parts without complex harmonies work best. Insert an ACIDized loop— most likely a loop finm Sonic Foundry— into a project. Change the project s key to be the same as the media file s key. The media file s key can be seen in the Summary region at the bottom of the Explorer window or as the root note in the Track Properties window. The number after the key (for example, A3) should represent the octave of the note—but it always seems to be either octave 3 or 4 in ACID— firom the lowest sub-bass to the highest piccolo. Figure 9.12 shows the various octaves. (A3 might be called A4 if the first octave is numbered Octave 1, as it sometimes is numbered.)... 

Wavetable samples are similar to ACID loops and fall very near one another on a musical continuum. Samples typically used for MIDI applications are shorter in duration than most ACID loops and are most frequently only a single note. With the right software—say, Sound Forge and Creative Labs Vienna— you can edit. wav files to be used as loops in ACID from SoundFont samples or convert ACID loops into SoundFont samples. 

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