4 research outputs found
Passive Laser Power Stabilization via an Optical Spring
Metrology experiments can be limited by the noise produced by the laser
involved via small fluctuations in the laser's power or frequency. Typically,
active power stabilization schemes consisting of an in-loop sensor and a
feedback control loop are employed. Those schemes are fundamentally limited by
shot noise coupling at the in-loop sensor. In this letter we propose to use the
optical spring effect to passively stabilize the classical power fluctuations
of a laser beam. In a proof of principle experiment, we show that the relative
power noise of the laser is stabilized from approximately
Hz to a minimum value of Hz,
corresponding to the power noise reduction by a factor of . The bandwidth
at which stabilization occurs ranges from Hz to kHz. The work
reported in this letter further paves the way for high power laser stability
techniques which could be implemented in optomechanical experiments and in
gravitational wave detectors
16S rRNA Gene Pyrosequencing Reveals Bacterial Dysbiosis in the Duodenum of Dogs with Idiopathic Inflammatory Bowel Disease
BACKGROUND: Canine idiopathic inflammatory bowel disease (IBD) is believed to be caused by a complex interaction of genetic, immunologic, and microbial factors. While mucosa-associated bacteria have been implicated in the pathogenesis of canine IBD, detailed studies investigating the enteric microbiota using deep sequencing techniques are lacking. The objective of this study was to evaluate mucosa-adherent microbiota in the duodenum of dogs with spontaneous idiopathic IBD using 16 S rRNA gene pyrosequencing. METHODOLOGY/PRINCIPAL FINDINGS: Biopsy samples of small intestinal mucosa were collected endoscopically from healthy dogs (n = 6) and dogs with moderate IBD (n = 7) or severe IBD (n = 7) as assessed by a clinical disease activity index. Total RNA was extracted from biopsy specimens and 454-pyrosequencing of the 16 S rRNA gene was performed on aliquots of cDNA from each dog. Intestinal inflammation was associated with significant differences in the composition of the intestinal microbiota when compared to healthy dogs. PCoA plots based on the unweighted UniFrac distance metric indicated clustering of samples between healthy dogs and dogs with IBD (ANOSIM, p<0.001). Proportions of Fusobacteria (p = 0.010), Bacteroidaceae (p = 0.015), Prevotellaceae (p = 0.022), and Clostridiales (p = 0.019) were significantly more abundant in healthy dogs. In contrast, specific bacterial genera within Proteobacteria, including Diaphorobacter (p = 0.044) and Acinetobacter (p = 0.040), were either more abundant or more frequently identified in IBD dogs. CONCLUSIONS/SIGNIFICANCE: In conclusion, dogs with spontaneous IBD exhibit alterations in microbial groups, which bear resemblance to dysbiosis reported in humans with chronic intestinal inflammation. These bacterial groups may serve as useful targets for monitoring intestinal inflammation