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 $2 \times 10^{-5}$ Hz$^{-1/2}$ to a minimum value of $1.6 \times 10^{-7}$ Hz$^{-1/2}$, corresponding to the power noise reduction by a factor of $125$. The bandwidth at which stabilization occurs ranges from $400$ Hz to $100$ 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

Perspectives of Portuguese People with Physical Disabilities Regarding Their Sexual Health: A Focus Group Study

The World Health Organization has considered sexual health as a major dimension of global health and a sexual right. However, the sexual health of people with physical disabilities is still poorly addressed by health and social care professionals, and it is very stigmatized by society. This study aimed to assess the perspectives of Portuguese people living with physical disabilities regarding issues affecting their sexual health. Nine women and 17 men with different physical disabilities participated in the study. Participants were recruited from a professional rehabilitation facility located in the North of Portugal and were assigned to four groups in one-hour sessions. Three main categories emerged from the content analysis: (1) meanings and beliefs regarding sexuality; (2) experiences of sexuality; (3) necessary changes. Despite the positive social changes towards sexuality, participants expressed that their sexual rights are still unfulfilled, as they live in a context that perpetuates their dependency. They pointed out low self-esteem, prejudice and social isolation, poor architectural accessibility and scarcity of financial support as some of the barriers to their lives and their sexual health. Finally, participants identified the main needs regarding their sexual health, such as: access to specialized information; training for health professionals. This study gives voice to people with physical disabilities and sheds light into both individual and contextual factors affecting their sexual health. Of utmost importance, this study draws attention to the need for reinforcing sexuality of people with disabilities in the social agenda and brings implications for future research and practice.This study was supported by a Grant attributed to the first author by the Portuguese Foundation for Science and Technology (SFRH/BD/112168/2015)info:eu-repo/semantics/publishedVersio

Predicting Prokaryotic Ecological Niches Using Genome Sequence Analysis

Automated DNA sequencing technology is so rapid that analysis has become the rate-limiting step. Hundreds of prokaryotic genome sequences are publicly available, with new genomes uploaded at the rate of approximately 20 per month. As a result, this growing body of genome sequences will include microorganisms not previously identified, isolated, or observed. We hypothesize that evolutionary pressure exerted by an ecological niche selects for a similar genetic repertoire in those prokaryotes that occupy the same niche, and that this is due to both vertical and horizontal transmission. To test this, we have developed a novel method to classify prokaryotes, by calculating their Pfam protein domain distributions and clustering them with all other sequenced prokaryotic species. Clusters of organisms are visualized in two dimensions as ‘mountains’ on a topological map. When compared to a phylogenetic map constructed using 16S rRNA, this map more accurately clusters prokaryotes according to functional and environmental attributes. We demonstrate the ability of this map, which we term a “niche map”, to cluster according to ecological niche both quantitatively and qualitatively, and propose that this method be used to associate uncharacterized prokaryotes with their ecological niche as a means of predicting their functional role directly from their genome sequence

An Insect Herbivore Microbiome with High Plant Biomass-Degrading Capacity

Herbivores can gain indirect access to recalcitrant carbon present in plant cell walls through symbiotic associations with lignocellulolytic microbes. A paradigmatic example is the leaf-cutter ant (Tribe: Attini), which uses fresh leaves to cultivate a fungus for food in specialized gardens. Using a combination of sugar composition analyses, metagenomics, and whole-genome sequencing, we reveal that the fungus garden microbiome of leaf-cutter ants is composed of a diverse community of bacteria with high plant biomass-degrading capacity. Comparison of this microbiome's predicted carbohydrate-degrading enzyme profile with other metagenomes shows closest similarity to the bovine rumen, indicating evolutionary convergence of plant biomass degrading potential between two important herbivorous animals. Genomic and physiological characterization of two dominant bacteria in the fungus garden microbiome provides evidence of their capacity to degrade cellulose. Given the recent interest in cellulosic biofuels, understanding how large-scale and rapid plant biomass degradation occurs in a highly evolved insect herbivore is of particular relevance for bioenergy

Nonpeptidic ligands for peptide-activated G protein-coupled receptors

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