Courant sigma model and L∞L_\infty-algebras

The Courant sigma model is a 3-dimensional topological sigma model of AKSZ type which has been used for the systematic description of closed strings in non-geometric flux backgrounds. In particular, the expression for the fluxes and their Bianchi identities coincide with the local form of the axioms of a Courant algebroid. On the other hand, the axioms of a Courant algebroid also coincide with the conditions for gauge invariance of the Courant sigma model. In this paper we embed this interplay between background fluxes of closed strings, gauge (or more precisely BRST) symmetries of the Courant sigma model and axioms of a Courant algebroid into an $L_\infty$-algebra structure. We show how the complete BV-BRST formulation of the Courant sigma model is described in terms of $L_\infty$-algebras. Moreover, the morphism between the $L_\infty$-algebra for a Courant algebroid and the one for the corresponding sigma model is constructed.Comment: 34 pages. v2: typos corrected, published versio

Initiation of DNA interstrand cross-link repair in humans: the nucleotide excision repair system makes dual incisions 5' to the cross-linked base and removes a 22- to 28-nucleotide-long damage-free strand.

Most DNA repair mechanisms rely on the redundant information inherent to the duplex to remove damaged nucleotides and replace them with normal ones, using the complementary strand as a template. Interstrand cross-links pose a unique challenge to the DNA repair machinery because both strands are damaged. To study the repair of interstrand cross-links by mammalian cells, we tested the activities of cell extracts of wild-type or excision repair-defective rodent cell lines and of purified human excision nuclease on a duplex with a site-specific cross-link. We found that in contrast to monoadducts, which are removed by dual incisions bracketing the lesion, the cross-link causes dual incisions, both 5' to the cross-link in one of the two strands. The net result is the generation of a 22- to 28-nucleotide-long gap immediately 5' to the cross-link. This gap may act as a recombinogenic signal to initiate cross-link removal

New high-speed induction motor driven by a commercial source

This paper described the structure and characteristics of a new high-speed induction motor. The motor has the magnetic combination of an induction motor and a magnetic frequency tripler and is called a “hybrid motor”. When the three-phase to two-phase type tripler we proposed is adopted, this rotating-field type hybrid motor can be constructed. The motor has remarkable starting torque and operates near synchronous speed (10800rpm) by only an application of a 60 Hz commercial source. It is noted that the motor has no semiconductor device and a brushless structure

Performance and analysis of an advanced type magnetic frequency tripler with three three-legged cores

A new magnetic frequency tripler employing three 3-legged transformers connected in delta is proposed. The device has very little Input current distortion and which only changes very little with the fluctuations of the input voltage and the load. In addition, the volume of iron and copper is about the same as in traditional star-connected circuit. Properties of a three-legged transformer and tripler are shown with and without filters. Fundamental analysis based on single-phase equivalent circuit is conducted. Results of experiments and and analysis show improved performance of the new tripler

High-speed ac motor including the function of a magnetic frequency tripler

The new electric motor is the magnetic combination of a magnetic frequency multiplier and a AC motor which share the common magnetic yoke. The motor operates near the synchronous speed (10,800 rpm) by applied the single-phase commercial source at 60 Hz. The new machine is called “high-speed hybrid AC motor” because the combination of a motor and a frequency converter. This paper describes the structure and the operating characteristics of the new motor

Purification and Characterization of the XPF-ERCC1 Complex of Human DNA Repair Excision Nuclease

A complex, which consists of ERCC1 (38 kDa) and a 112-kDa protein, was purified from HeLa cells to homogeneity. This complex complemented the nucleotide excision repair defects of rodent ERCC-1, ERCC-4, and human XP-F mutant cell-free extracts, indicating that the 112-kDa protein is XPF/ERCC4 and providing direct biochemical evidence that XPF and ERCC4 are identical. The XPF/ERCC4-ERCC1 complex has an endonuclease activity with preference for single-stranded DNA and a single-stranded region of duplex DNA with a "bubble" structure. This complex also nicks supercoiled DNA weakly, and this nicking activity is stimulated by human replication protein A when the DNA contains UV damage