InGaAsSb/GaSb lasers and photodetectors integrated on a silicon-on-insulator waveguide circuit for spectroscopic applications

International audienc

GaSb-based integrated lasers and photodetectors on a silicon-on-insulator waveguide circuit for sensing applications in the shortwave infrared

We report our results on GaSb photodiodes and lasers integrated on a Silicon-On-Insulator waveguide circuit. The photodiodes operate at room temperature with 0.4A/W responsivity for grating-assisted coupling and >1 A/W for an evanescent design. On the other hand, integrated Fabry-Perot lasers operate in continuous wave at room temperature with a threshold current of 49.7mA

Dimensionality, secondary flows and helicity in low-Rm MHD vortices

In this paper, we examine the dimensionality of a single electrically driven vortex bounded by two no-slip and perfectly insulating horizontal walls distant by $h$. The study was performed in the weakly inertial limit by means of an asymptotic expansion, which is valid for any Hartmann number. We show that the dimensionality of the leading order can be fully described using the single parameter $l_z^\nu / h$, where $l_z^\nu$ represents the distance over which the Lorentz force is able to act before being balanced by viscous dissipation. The base flow happens to introduce inertial recirculations in the meridional plane at the first order, which are shown to follow two radically different mechanisms: inverse Ekman pumping driven by a vertical pressure gradient along the axis of the vortex, or direct Ekman pumping driven by a radial pressure gradient in the Hartman boundary layers. We demonstrate that when the base flow is quasi-2D, the relative importance of direct and inverse pumping is solely determined by the aspect ratio $\eta / h$, where $\eta$ refers to the width of the vortex. Of both mechanisms, only inverse pumping appears to act as a significant source of helicity

Vaccination against Actinobacillus pleuropneumoniae as an alternative strategy to antimicrobial use in Danish pig herds

In this study the objective was to determine whether use of vaccination against Actinobacillus pleuropneumoniae (APP) had an effect on the antimicrobial consumption in finisher pigs, when compared to herds without vaccination. Based on observational data, we found that the change in antimicrobial consumption after vaccination was initiated was significant associated with the baseline antimicrobial use before vaccination. The decrease in antimicrobial used was more pronounced in vaccinated herds (N=101) when compared to herds without vaccination (N=320), indicating an effect of vaccination against APP on the antimicrobial consumption level

Associations between vaccination and antimicrobial consumption in Danish pig herds, 2013

Antimicrobial agents are being used in modern swine production worldwide, generating concern in regards to the development of antimicrobial resistance. Identifying efficient alternatives has therefore become a subject of interest. The aim of this study was to explore the impact of routinely used vaccination as an alternative to antimicrobial consumption in weaner pig herds. The hypothesis was that herds with increased use of vaccination would have a lower antimicrobial consumption. Data were obtained from the Danish VetStat database in which prescriptions of medication for livestock are recorded as well as the Danish Central Husbandry Register. All Danish one-site pig herds, active in year 2013, with \u3e50 sows and \u3e200 weaners were selected for the study. Initially, data were analysed using a univariable model, and secondly a multivariable linear regression model was applied. The analyses included use of three different vaccines against Porcine Circovirus Type 2 (PCV2), Mycoplasma hyopneumoniae (M_HYO) and Lawsonia intracellularis (LAW), respectively, as well as annual production measured as number of weaners produced in a year. The outcome was the average antimicrobial consumption measured in animal daily does (ADD) per weaner pig. Out of the 1,513 herds selected for the study, 1,415 herds had antimicrobials prescribed for gastrointestinal disorders, and 836 for respiratory disorders. PCV2 vaccine was used in 880 herds, M_HYO vaccine in 787 and LAW vaccine was the least used, with 115 herds using it. The results suggested that antimicrobials to some extent were being used for other disease categories than those officially prescribed by the veterinarians. On average, herds using the different combinations of vaccines had higher use of antimicrobials than herds not using the vaccines – probably as a result of health problems in the herds existing prior to the initiation of vaccine use. Information about vaccination protocols, health status, biosecurity, and management practices was not available limiting the ability to assess causality

Risk assessment for Toxoplasma gondii in the Danish pig industry

The parasite Toxoplasma gondii is capable of infecting most mammals including man. In humans, toxoplasmosis is usually asymptomatic but may have serious consequences for pregnant women or immuno-compromised patients. Contact with infected cats and cat litter, contaminated soil and Infected meat are risk factors for toxoplasmosis. Although the prevalence of Toxoplasma in pig production has declined significantly dunng the past 30 years, it has recently been suggested that a large part of human cases of toxoplasmosis may be ascribed to meat, mcluding pork and pork products. Moreover, perinatal screening of pregnant women and infants for Toxoplasma has proven to be of limited value. This has raised the question of how to survey for Toxoplasma· in humans or meat? Therefore, the role of meat, including pigs and pork, as a risk factor for human toxoplasmosis was assessed by the Danish Meat Association . The release assessment showed that outdoor-reared pigs as well as sows and boars were at higher risk of infection with Toxoplasma. With respect to exposure, consumption of mildly cured pork products and inadequately heat-treated pork were associated with increased risk. Knowledge on elimination or survival of Toxoplasma in cured pork products is sparse, which is unsatisfactory given current trends toward lower salt content and lower cooking temperatures. It was concluded that, aside from consumption of raw pork, which is rare in Denmark and not recommended for other reasons, certain mildly cured ready-to-eat pork products, that have not been heat-treated, may constitute a risk for toxoplasmosis, if not frozen prior to manufacturing. Information on the effects of cunng on survival of Toxoplasma in meat is sparse and therefore deserves further research. However, most of the pork used for manufacturing in Denmark onginates from pigs raised indoors and for logistic reasons it is frozen prior to processing, thereby reducing the risk for human toxoplasmosis

Exposure assessment of extended-spectrum beta-lactamases/AmpC beta-lactamases-producing in meat in Denmark

Extended-Spectrum Beta-Lactamases (ESBL) and AmpC Beta-Lactamases (AmpC) are of great concern because of their ability to cause antimicrobial resistance in Enterobacteriaceae hampering the effect of treatment with beta-lactam antibiotics. The main objective of this study was to assess the relative importance of different types of meat for the exposure of consumers to ESBL/AmpC and their potential relevance for human cases in Denmark