Twilight zone

SY Chung, S Subbiah. A structural explanation for the twilight zone of protein sequence homology. Structure 4 1123-1127, 1996. 

B Rost. Twilight zone of protein sequence alignments. Protein Eng 12 85-94, 1999. 

Jones B (1995) Processes associated with microbial biofilms in the twilight zone of caves examples from the Cayman Islands. J Sediment Res A65 552-560... 

That summer of 1989, from May until October, was the most miserable, unbelievable experience of my life. I didn t know what was going on. I couldn t believe something so horrible could be happening to me, and that my life had turned to this. It was like being in a strange episode of The Twilight Zone. 

The Annex, where physicians had offices and conducted volunteer studies, also had very little visible security. One could often enter it freely through unlocked doors. I remember coming in at night and feeling a spooky Twilight Zone sensation, when walking alone through its deserted halls. 

Seife, Charles, Physics Enters the Twilight Zone, Science, 305(5683) 464-466, July 23, 2004. Researchers suggest that if the matter and energy in the universe are created by random quantum fluctua-... 

Ooh, Sally, I thought you were supposed to be the skeptic. You begin to hum the eerie, repetitive theme of the Twilight Zone. Sally, I m beginning to like you. ... 

In classifying synthetic fibers, there is also a narrow, twilight zone between fibers and elastomers. There are elastomers with liber-like qualifies and vice versa. For example, spandex is a fiber with rubber-like qualities. See also Elastomers. 

In a laboratory-based study of sleepiness using the Multiple Sleep Latency Test (MSLT), hospital residents were found to be near the twilight zone following postcall (mean time to sleep of 5.5 min) (46). Perhaps most provocative was that their baseline (not on-call) level of sleepiness was not significantly different at 6.5 min. This demonstrated both the level of chronic sleep deprivation experienced (as reflected in the baseline condition) and the physiological level of sleepiness that can be expressed postcall. When the residents had the opportunity... 

A second goal of these new methods is the detection of structural homologies in the twilight zone" of sequence similarity (less than 25% identity), e.g., the structural similarity between carboxypeptidases A and N (sequence identity 18%). None of the sequence-structuie-aligmnent methods has been proven to conristentlv and eenerallv detect remote structural homoloeies with a hi eh score... 

Everybody is different in one way or another and that is the way it should be. A few months ago, I saw an old Twilight Zone episodethat was supposed to take place in the future. In it, everyone looked the same. If you happened to look different, you were forced to have surgery. It madeyou look like the others. That was their definition of beauty. It was really interesting. I do not think that it was too impossible either. It s not a far-fetched idea for our culture at all. 

The first two types of interaction are certainly physical adsorption the fourth is certainly chemisorption the third, which is a postulated mechanism whose actual occurrence has not yet been adequately demonstrated, exists in a twilight zone that defies classification as either physical or chemical adsorption. Previous papers of this series have not been concerned with the source of the adsorptive potential, but have postulated only that the adsorbed film be mobile their considerations could apply, therefore, to all adsorption situations other than No. 4. The present paper is devoted to a consideration of the adsorptive potential arising from 1 and 2—that is, physical adsorption properly so called. This general topic has been discussed by de Boer (5) for a number of specific cases the theory and techniques that we have developed enable us to derive from experimental data a quantity, Pads, the depth of the adsorptive potential well, which can also be calculated a priori from physical properties of the system. We are therefore able to compare theory and observation and so have an independent test of conclusions reached in previous papers. 

In this chapter we identify functional indicators of PDB-reported soluble proteins with clusters of dehydrons. Such regions, rich in structural vulnerabilities, may be characterized as belonging to a twilight zone between order and native disorder [4], This characterization is already suggested by a strong correlation between wrapping of intramolecular hydrogen bonds (p) and propensity for structural disorder (/d), as shown in Fig. 5.1. The correlation reveals that the inability to exclude... 

Figure 12.2. Sketch of the maximal number of contacts that a short, compact tube can make as a function of X, the dimensionless ratio of the tube thickness to the range of the attractive interaction. When X is large compared with 1, one obtains a swollen phase. At the other extreme, when X 1, one finds a highly degenerate compact phase. The twilight zone between these two phases occurs in the vicinity of X 1 and is characterized by marginally compact structures. The figure shows typical tube conformations in each of the phases.

In the twilight zone, a tube is barely able to avail itself of the attractive interactions promoting compaction. In this region of parameter space, the forces promoting compaction just set in, and one would expect to obtain marginally compact structures that have the ability to expel the water from the interior. In addition, because the scale of the interaction strength is relatively small, one would expect a... 

If significant similarities between uncharacterized and annotated sequences are found, the transfer of annotation is straightforward at high identity levels (> 40%). Below that sequence-identity level, the establishment of firm sequence-function relationships can start to present some problems. The signal starts to become blurred at 20 to 30% identity, the so-called Twilight Zone [12,13]. If identity levels are even lower, the region is called the Midnight Zone (fig. 3.2). For identity levels over 30%,... 

Jaroszewski, L., L. Rychlewski, and A. Godzik. 2000. Improving the quality of twilight-zone alignments. Protein Sci 9 1487-96. 

---