Optical sideband generation up to room temperature with mid-infrared quantum cascade lasers.

Mid-infrared (MIR) sideband generation on a near infrared (NIR) optical carrier is demonstrated within a quantum cascade laser (QCL). By employing an externally injected NIR beam, E(NIR), that is resonant with the interband transitions of the quantum wells in the QCL, the nonlinear susceptibility is enhanced, leading to both frequency mixing and sideband generation. A GaAs-based MIR QCL (E(QCL) = 135 meV) with an aluminum-reinforced waveguide was utilized to overlap the NIR and MIR modes with the optical nonlinearity of the active region. The resulting difference sideband (E(NIR) - E(QCL)) shows a resonant behavior as a function of NIR pump wavelength and a maximum second order nonlinear susceptibility, χ((2)), of ~1 nm/V was obtained. Further, the sideband intensity showed little dependence with the operating temperature of the QCL, allowing sideband generation to be realized at room temperature.

Mode-locking of a terahertz laser by direct phase synchronization.

A novel scheme to achieve mode-locking of a multimode laser is demonstrated. Traditional methods to produce ultrashort laser pulses are based on modulating the cavity gain or losses at the cavity roundtrip frequency, favoring the pulsed emission. Here, we rather directly act on the phases of the modes, resulting in constructive interference for the appropriated phase relationship. This was performed on a terahertz quantum cascade laser by multimode injection seeding with an external terahertz pulse, resulting in phase mode-locked terahertz laser pulses of 9 ps duration, characterized unambiguously in the time domain.

Integrated injection seeded terahertz source and amplifier for time-domain spectroscopy.

We used a terahertz (THz) quantum cascade laser (QCL) as an integrated injection seeded source and amplifier for THz time-domain spectroscopy. A THz input pulse is generated inside a QCL by illuminating the laser facet with a near-IR pulse from a femtosecond laser and amplified using gain switching. The THz output from the QCL is found to saturate upon increasing the amplitude of the THz input power, which indicates that the QCL is operating in an injection seeded regime.

Generic drug prescriptions following hospital discharge: a prospective study in France.

AIMS: Systematic generic prescription at discharge could reduce confusion on drug-name usage, decrease commercial influence on medicine, and reduce drug-related expenditures. This study aimed to analyze generic drug prescriptions at discharge from hospital and to estimate the potential savings associated with a total substitution policy (substitution of every substitutable drug for its cheapest generic counterpart). METHODS: Drug prescriptions before admission and at discharge of all patients from three medical units of a university hospital were prospectively collected for five weeks without informing prescribers. RESULTS: Prescriptions from 85 patients were analyzed. On admission, 68 patients (80%) received 413 drugs; 141 were substitutable brand-name drugs and 23 (16%), which were directly prescribed as generics. At discharge, 488 drugs were prescribed to the 85 patients; 180 were substitutable drugs but only 5 (2.8%) were written as generics on prescription pads, a decrease of 78% (p<0.0001) compared to admission. In average, generics were 18% less expensive than brand-name drugs. Some common therapeutic classes offered even greater price difference, such as proton-pump inhibitors (42%), statins (32%), or antihypertensive agents (28%). Potential savings from a total substitution policy at discharge were estimated to €1512 per 1000 patients per week; for lifetime drugs, savings amounted to €18,960 per 1000 patients per year. CONCLUSIONS: Very few drugs are written as generics on medical forms at discharge in France. Hospital practitioners should be encouraged to prescribe generics, particularly in chronic diseases. A broad generic prescription policy at hospital discharge would result in substantial savings for health insurance.

[Antimicrobial consumption reported through standardized reports on infection control activities, relationship with the ICATB public reporting indicator]. / Consommation des antibiotiques rapportée via les bilans standardisés de lutte contre les infections nosocomiales et relation avec l'ICATB.

OBJECTIVE: The study's objective was to describe the evolution of antibiotic consumption between 2006 and 2008 in French health care facilities (HCF) its relations with the national policy of good antibiotics use using the ICATB score. METHOD: Data from standardized reports on infection control activities collected from 2006 to 2008 by the Ministry of Health (antibiotic consumptions and elements of antibiotic stewardship of every HCF) were analyzed with linear regression models to multilevel random intercept adjusted on HCF characteristics (public or private) and activity. RESULTS: The analysis was performed on 4062 (48,2%) observations after exclusion of HCF not concerned by the ICATB public reporting indicator (7.2% of observations), invalid or missing data (21,2% of observations) and irrelevant values (23.4%). The global antibiotic consumption was 343 defined daily doses (DDD) per 1000 patient-days (PD) and varied little between 2006 and 2008. However, the linear regression model showed an increase of 5.7 DDD per 1000 PDs per year (P<0.001). There was a positive association between antibiotic consumption and ICATB score, mainly concerning sub-scores ICATB-action and ICATB-organization. CONCLUSION: The recent lack of decrease in antibiotic consumption in French HCF between 2006 and 2008 is coherent with other available national data, but exclusion of more than 50% of observations limits the impact of this analysis. The relationship between policy of good use and consumption of antibiotics remain difficult to specify, because of the short (three years) study length and because of the nature of ICATB, a composite indicator assessing only partly antibiotic policies.