Group II Intron-Anchored Gene Deletion in Clostridium

Clostridium plays an important role in commercial and medical use, for which targeted gene deletion is difficult. We proposed an intron-anchored gene deletion approach for Clostridium, which combines the advantage of the group II intron “ClosTron” system and homologous recombination. In this approach, an intron carrying a fragment homologous to upstream or downstream of the target site was first inserted into the genome by retrotransposition, followed by homologous recombination, resulting in gene deletion. A functional unknown operon CAC1493–1494 located in the chromosome, and an operon ctfAB located in the megaplasmid of C. acetobutylicum DSM1731 were successfully deleted by using this approach, without leaving antibiotic marker in the genome. We therefore propose this approach can be used for targeted gene deletion in Clostridium. This approach might also be applicable for gene deletion in other bacterial species if group II intron retrotransposition system is established

Systemic and local antibiotic prophylaxis in the prevention of Staphylococcus epidermidis graft infection

BACKGROUND: The aim of the study was to investigate the in vivo efficacy of local and systemic antibiotic prophylaxis in the prevention of Staphylococcus (S.) epidermidis graft infection in a rat model and to evaluate the bacterial adherence to frequently used prosthetic graft materials. METHODS: Graft infections were established in the subcutaneous tissue of 120 male Wistar rats by implantation of Dacron/ePTFE grafts followed by topical inoculation with 2 × 10(7 )CFUs of clinical isolate of methicillin-resistant S. epidermidis. Each of the graft series included a control group, one contaminated group that did not receive any antibiotic prophylaxis, two contaminated groups that received systemic prophylaxis with teicoplanin or levofloxacin and two contaminated groups that received teicoplanin-soaked or levofloxacin-soaked grafts. The grafts were removed 7 days after implantation and evaluated by quantitative culture. RESULTS: There was significant bacterial growth inhibition in the groups given systemic or local prophylaxis (P < 0.05). Methicillin-resistant S. epidermidis had greater affinity to Dacron graft when compared with ePTFE graft in the untreated contaminated groups (P < 0.05). CONCLUSION: The study demonstrated that the usage of systemic or local prophylaxis and preference of ePTFE graft can be useful in reducing the risk of vascular graft infections caused by staphylococcal strains with high levels of resistance

A tiny and fully integrated differential VCO for LMDS application

A fully integrated GaAs HBT dual frequency VCO providing a high frequency 18 GHz signal but also a half-frequency 9 GHz signal to a PLL is described. The key advance is achieving good phase noise performance, over a wide frequency band, with very good temperature behaviour and harmonics suppression, at a low cost and small size. More than 3 GHz tuning range is achieved at the 18 GHz port, with 25 dB suppression of fundamental frequency (9 GHz).The 18 GHz VCO yields 5 dBm output power, while on the 9 GHz port it shows more than –10 dBm output power. The chip was assembled in a test jig, then a phase noise of –95 dBc/Hz @ 100 kHz offset was obtained at 9 GHz

Fully MMIC-Based Front End for FMCW Automotive Radar at 77GHz

This paper gives the last UMS developments in the field of automotive radar at 77GHz. A complete front-end based on four MMICs is described, it is dedicated to FMCW radar for Collision Warning/Avoidance systems. A detailed characterization results are given for a single channel front-end. These designs already demonstrate high level of performance on industrial MMIC technologies

A measurement based model of HEMT teking into account the non linear, non uniform transmission line nature of the channel its associated low frequency noise sources

For the first time, a fully measurement based extraction procedure of non linear and non uniform transmission line model of FET devices is proposed. This model describes accurately the distributed nature under the device gate which allows a good distortion prediction (IM3) and promises good perspectives for simulation of noise characteristics in non linear circuits

Mm-wave front-end developed within the on-going AWARE/LOCOMOTIVE projects for automotive applications at 77GHz

This paper describes the development of a millimetre-wave front-end for a 76.5GHz Collision Warning Avoidance (CW/A) car radar. This CW/A sensor is based on a FMCW concept. The main development steps are described and have led to the definition of a fully MMIC-based front-end. Based on a demonstrator done in AWARE a new chip-set has been defined, fabricated and characterised within LOCOMOTIVE. Using a total chip-set area of 13.7 mm2, the first obtained results show a high level of performance

Standard multifunction MMIC chip for phase locked microwave oscillators

This paper presents the design and realization of a new fully integrated multifunction circuit which is of great interest for all applications that need low cost phase locked microwave oscillators. The realization described here is in X band, but the design can be easily extrapolated up to millimeter frequencies. Experimental results are presented about all the MMIC's functions. A low cost package, also extrapolable up to higher frequencies is described

Linear and nonlinear stability analysis of MMICs

Stability analysis of MMICs becomes a preoccupation of engineers for the design of power amplifiers as well as of oscillators. In this paper it is shown that the classical approach of linear stability analysis fails in the case of unstable unloaded circuits. Nyquist based methods are proposed to circumvent this problem. A method relying on the general Harmonic Balance formulation is proposed, which enables the linear and non linear stability analysis. Examples of global stability analysis based on the resolution of the bifurcation equations are given. Finally an open loop method is proposed which allows to design analog frequency dividers with the aid of standard CAD packages

Graphical-method spots power-FET operating points

International audienc

Conception de transitions très large bande pour circuits MMIC en bande E pour des applications bas coût télécom et RADAR automobile à 77 GHz

National audienc