Anti-phage islands force their target phage to directly mediate island excision and spread.

Vibrio cholerae, the causative agent of the diarrheal disease cholera, is antagonized by the lytic phage ICP1 in the aquatic environment and in human hosts. Mobile genetic elements called PLEs (phage-inducible chromosomal island-like elements) protect V. cholerae from ICP1 infection and initiate their anti-phage response by excising from the chromosome. Here, we show that PLE 1 encodes a large serine recombinase, Int, that exploits an ICP1-specific protein as a recombination directionality factor (RDF) to excise PLE 1 in response to phage infection. We show that this phage-encoded protein is sufficient to direct Int-mediated recombination in vitro and that it is highly conserved in all sequenced ICP1 genomes. Our results uncover an aspect of the molecular specificity underlying the conflict between a single predatory phage and V. cholerae PLE and contribute to our understanding of long-term evolution between phage and their bacterial hosts

Terahertz detection mechanism and contact capacitance of individual metallic single-walled carbon nanotubes

We characterize the terahertz detection mechanism in antenna-coupled metallic single-walled carbon nanotubes. At low temperature, 4.2 K, a peak in the low-frequency differential resistance is observed at zero bias current due to non-Ohmic contacts. This electrical contact nonlinearity gives rise to the measured terahertz response. By modeling each nanotube contact as a nonlinear resistor in parallel with a capacitor, we determine an upper bound for the value of the contact capacitance that is smaller than previous experimental estimates. The small magnitude of this contact capacitance has favorable implications for the use of carbon nanotubes in high-frequency device applications.Comment: 13 pages, 3 figures, 1 tabl

Acoustoelectric effects in quantum constrictions

A dc current induced in a quantum constriction by a traveling acoustic wave (or by non-equilibrium ballistic phonons) is considered. We show that in many important situations the effect is originated from acoustically-induced scattering between the propagating and reflecting states in the constriction. Two particular regimes corresponding to relatively high and low acoustic frequencies are discussed. In the first regime, the acoustoelectric effect in a smooth constriction can be understood by semi-classical considerations based on local conservation laws. For the low frequency regime, we show that the acousto-conductance is closely related to the zero field conductance. The qualitative considerations are confirmed by numerical calculations both for smooth and abrupt channels.Comment: 10 pages, RevTeX, 9 postscript figures, submitted to Phys. Rev.

Pope Leo IX: A reforming pope?

No abstract available

The industrious revolution, the industriousness discourse, and the development of modern economies

ABSTRACTThe idea of industriousness has been an ever-recurring issue since Max Weber launched it as a putative explanation of the advent of economic modernity. The notion of ‘industrious revolution’ has provoked a renewed flourishing of publications focusing on this issue. Although most historians agree on the emergence of industriousness in seventeenth-century Europe, there is no consensus regarding the chronology, hence the real causes, of this mental and discursive shift. This article emphasizes the problematic role played by literary evidences in these social and cultural models of diffusion of new consumer values and desires. It then establishes the timing of the emergence of the ‘industriousness discourse’ using an original approach to diffusion based both on the quantitative analysis of very large corpora and a close reading of seventeenth-century economic pamphlets and educational literature. It concludes first that there was not one but several competing discourses on industriousness. It then identifies two crucial hinges which closely match the chronology proposed by Allen and Muldrew, but refutes that championed by de Vries and McCloskey. The industrious revolution as described by these authors would have happened both too late to fit its intellectual roots and too early to signal the beginning of a ‘consumer revolution’.This work was supported by the Arts and Humanities Research CouncilThis is the author accepted manuscript. The final version is available from Cambridge University Press via https://doi.org/10.1017/S0018246X1300052

Fluids and barriers of the CNS: a historical viewpoint

Tracing the exact origins of modern science can be a difficult but rewarding pursuit. It is possible for the astute reader to follow the background of any subject through the many important surviving texts from the classical and ancient world. While empirical investigations have been described by many since the time of Aristotle and scientific methods have been employed since the Middle Ages, the beginnings of modern science are generally accepted to have originated during the 'scientific revolution' of the 16th and 17th centuries in Europe. The scientific method is so fundamental to modern science that some philosophers consider earlier investigations as 'pre-science'. Notwithstanding this, the insight that can be gained from the study of the beginnings of a subject can prove important in the understanding of work more recently completed. As this journal undergoes an expansion in focus and nomenclature from cerebrospinal fluid (CSF) into all barriers of the central nervous system (CNS), this review traces the history of both the blood-CSF and blood-brain barriers from as early as it was possible to find references, to the time when modern concepts were established at the beginning of the 20th century