The effect of system load on the existence of bit errors in CDMA with and without parallel interference cancelation

In this correspondence, we study a lightly loaded code-division multiple-access (CDMA) system with and without multistage hard- and soft-decision parallel interference cancelation (HD-PIC and SD-PIC). Throughout this paper we will only consider the situation of a noiseless channel, equal powers and random spreading codes. For the system with no or a fixed number of steps of interference cancelation, we give a lower bound on the maximum number of users such that the probability for the system to have no bit-errors converges to one. Moreover, we investigate when the matched filter system, where parallel interference cancelation is absent, has bit errors with probability converging to one. This implies that the use of HD-PIC and SD-PIC significantly enhances the number of users the system can serv

Thermodynamic Formalism Of Neural Computing

Neural networks are systems of interconnected processors mimicking some of the brain functions. After a rapid overview of neural computing, the thermodynamic formalism of the learning procedure is introduced. Besides its use in introducing efficient stochastic learning algorithms, it gives an insight in terms of information theory. Main emphasis is given in the information restitution process; stochastic evolution is used as the starting point for introducing statistical mechanics of associative memory. Instead of formulating problems in their most general setting, it is preferred stating precise results on specific models. In this report are mainly presented those features that are relevant when the neural net becomes very large. A survey of the most recent results is given and the main open problems are pointed out

The Inosine Monophosphate Dehydrogenase, GuaB2, Is a Vulnerable New Bactericidal Drug Target for Tuberculosis

VCC234718, a molecule with growth inhibitory activity against Mycobacterium tuberculosis (<i>Mtb</i>), was identified by phenotypic screening of a 15344-compound library. Sequencing of a VCC234718-resistant mutant identified a Y487C substitution in the inosine monophosphate dehydrogenase, GuaB2, which was subsequently validated to be the primary molecular target of VCC234718 in <i>Mtb</i>. VCC234718 inhibits <i>Mtb</i> GuaB2 with a <i>K</i>_i of 100 nM and is uncompetitive with respect to IMP and NAD⁺. This compound binds at the NAD⁺ site, after IMP has bound, and makes direct interactions with IMP; therefore, the inhibitor is by definition uncompetitive. VCC234718 forms strong pi interactions with the Y487 residue side chain from the adjacent protomer in the tetramer, explaining the resistance-conferring mutation. In addition to sensitizing <i>Mtb</i> to VCC234718, depletion of GuaB2 was bactericidal in <i>Mtb</i> in vitro and in macrophages. When supplied at a high concentration (≥125 μM), guanine alleviated the toxicity of VCC234718 treatment or GuaB2 depletion via purine salvage. However, transcriptional silencing of <i>guaB2</i> prevented <i>Mtb</i> from establishing an infection in mice, confirming that <i>Mtb</i> has limited access to guanine in this animal model. Together, these data provide compelling validation of GuaB2 as a new tuberculosis drug target

History of Cyclodextrins

Cyclodextrins are cyclic oligosaccharides obtained by enzymatic degradation of starch. They are remarkable macrocyclic molecules that have led major theoretical and practical advances in chemistry, biology, biochemistry, health science, and agriculture. Their molecular structure is composed of a hydrophobic cavity that can encapsulate other substances to form inclusion complexes through host-guest interactions. This unique feature is at the origin of many applications. Cyclodextrins and their derivatives have a wide variety of practical applications in almost all sectors of the industry, including pharmacy, medicine, foods, cosmetics, chromatography, catalysis, biotechnology, and the textile industry.Villiers published the first reference to cyclodextrins in 1891. Since the beginning of the twentieth century, major researchers, such as Schardinger, Pringsheim, Karrer, Freudenberg, French, Cramer, Casu, Bender, Saenger, Nagai, Szejtli, and Pitha, have paved the history of the cyclodextrins. Several time periods have marked their history. After their discovery and characterization from 1891 to 1911, there has been a period of doubt and disagreement from 1911 to 1935. Then, the 1935–1950 exploration period was marked by structural results on the “Schardinger dextrins.” In 1949, Cramer introduced the cyclodextrin-based nomenclature. Research between 1950 and 1970, the period of maturation, focused on conformations and spectroscopic data of cyclodextrins and their inclusion complexes, with applications in catalysis and as enzyme models. Finally, the period of use has been ongoing since 1970 and has seen cyclodextrins find many industrial applications. Cyclodextrins have then found many industrial applications, initially in the pharmaceutical and food sectors. In 1984, the first chromatographic columns were commercialized. At that time, many cyclodextrin-based catalysts were developed for biomimetic chemistry and other applications such as artificial enzymes. Currently, more than 2000 publications on cyclodextrins are published each year.In this chapter, we present a historical overview of the discovery, development, and applications of cyclodextrins