Tuberculosis vaccine strain _Mycobacterium bovis_ BCG Russia is a natural _recA_ mutant

The current tuberculosis vaccine is a live vaccine derived from _Mycobacterium bovis_ and attenuated by serial _in vitro_ passaging. All vaccine substrains in use stem from one source, strain Bacille Calmette-Guérin. However, they differ in regions of genomic deletions, antigen expression levels, immunogenicity, and protective efficacy. As a RecA phenotype increases genetic stability and may contribute restricting the ongoing evolution of the various BCG substrains, we aimed to inactivate _recA_ by allelic replacement in BCG vaccine strains representing different phylogenetic lineages (Pasteur, Frappier, Denmark, Russia). Homologous gene replacement was successful in three out of four strains. However, only illegitimate recombination was observed in BCG substrain Russia. Sequence analyses of _recA_ revealed that a single nucleotide insertion in the 5' part of _recA_ led to a translational frameshift with an early stop codon making BCG Russia a natural _recA_ mutant. At the protein level BCG Russia failed to express RecA. According to phylogenetic analyses BCG Russia is an ancient vaccine strain most closely related to the parental _M. bovis_. Our data suggest that _recA_ inactivation in BCG Russia occurred early and is in part responsible for its high degree of genomic stability, resulting in a substrain that has less genetic alterations than other vaccine substrains with respect to _M. bovis_ AF2122/97 wild type

Inference Optimization using Relational Algebra

Exact inference procedures in Bayesian networks can be expressed using relational algebra; this provides a common ground for optimizations from the AI and database communities. Specifically, the ability to accomodate sparse representations of probability distributions opens up the way to optimize for their cardinality instead of the dimensionality; we apply this in a sensor data model.\u

A low-offset low-voltage CMOS Op Amp with rail-to-rail input and output ranges

A low voltage CMOS op amp is presented. The circuit uses complementary input pairs to achieve a rail-to-rail common mode input voltage range. Special attention has been given to the reduction of the op amp's systematic offset voltage. Gain boost amplifiers are connected in a special way to provide not only an increase of the low-frequency open-loop gain but also a significant reduction of the systematic offset voltag

Social security arrangements and early-stage entrepreneurial activity; an empirical analysis

This exploratory study focuses on the relation between social security arrangements and the rate of early-stage entrepreneurial activity at the country level. Using a sample of countries participating in the Global Entrepreneurship Monitor, we explore how various measures of entrepreneurial activity are related to various measures of social security arrangements. On the one hand we look at aggregate indicators such as the social security contributions or premiums paid by employers and employees. On the other hand we look at micro level based indicators such as 'replacement rates', measuring the benefits an individual is entitled to in case of unemployment or illness/disability. Our analysis using aggregate indicators shows that the height of employer premiums negatively influences entrepreneurial activity at the macro level, but that the height of employee premiums has no impact. The results of our analysis using micro level based indicators suggest that the replacement rate of employees has a significantly negative influence on the level of early-stage entrepreneurship at the macro level.

Social security etitlements and early-stage entrepreneurial activity; an empirical analysis

This exploratory study focuses on the relation between social security entitlements and the rate of early-stage entrepreneurial activity at the country level. Using a sample of countries participating in the Global Entrepreneurship Monitor, we explore how various measures of entrepreneurial activity are related to 'replacement rates' in case of unemployment and illness/disability. The results of our empirical study indicate that social security entitlements of employees have a significant negative influence on the level of early-stage entrepreneurship at the macro level. However, the results of our study do not support the hypothesis that the relative level of social security benefits for self-employed, compared to that for employees, has an additional impact on entrepreneurial activity.

Social security arrangements and early-stage entrepreneurial activity

This exploratory study defines a number of propositions regarding the relation between social security arrangements and the rate of early-stage entrepreneurial activity at the country level. We state that in investigating this relation it may be relevant to distinguish between social security contributions paid by employers and employees, and to look at micro-based indicators (replacement rates) for the benefits an individual is entitled to in case of unemployment and illness. Furthermore, we state that it may be especially relevant to focus on the social security position of self-employed relative to the social security position of employees. Using a sample of countries participating in the Global Entrepreneurship Monitor, we explore how various measures of entrepreneurial activity are related to various measures of social security arrangements. Our analysis using aggregate indicators shows that the height of employer social security contributions negatively influences entrepreneurial activity at the macro level, but that the height of employee contributions has no impact. The results of our analysis using micro-level based indicators suggest that the replacement rate of employees has a significantly negative influence on the level of early-stage entrepreneurship at the macro level.