Camera a miroir giratoire muni d'une optique interchangeable

A rotating mirror camera constructed from simple components is described, which can be adapted to the dimensions of the process to be filmed by interchanging the optical equipment in front of the rotating mirror. Frequeney range; 20,000-300,000 i/s., image scale between 1 : 10 and 5 : 1.On decrit ici une camera a miroir giratoire, construite a partir d'e1ements simples, et susceptible de s'adapter a l'ordre de grandeur du phenomene a photographier; il suffit de changer la partie de l' optique placee devant le miroir giratoire. Domaine de frequences; de 20000 a 300000 i/s; echelle de reproduction situee entre 1 : 10 et 5 : 1

Characterization of a Biosynthetic Pathway Yielding Anticancer Natural Products from a Marine Bacterium

Natural products are bioactive secondary metabolites produced by living organisms and are prevalently utilized as pharmaceutical drugs. Marine adapted organisms are a promising source of new natural products possessing unique chemical structures and biological activities. By studying the biosynthetic pathways employed by living organisms to produce natural products, insights into new strategies to generate molecules to combat disease and overcome drug resistance may be gained. This thesis study aimed to uncover the biosynthetic pathway employed by a marine actinomycete, Nocardiopsis sp. CMB-M0232, to catalyze the assembly of the nocardioazines. These molecules are a group of 2,5-diketopiperazine natural products that feature structurally unique functional groups. Nocardioazine A, the hypothesized end product of the nocardioazine biosynthetic pathway, exhibits anticancer activity. Bioinformatics analyses revealed three biosynthetic gene clusters from Nocardiopsis encoding proteins with hypothesized roles in nocardioazine A biosynthesis. Two cyclodipeptide synthases (CDPSs), NozA and NcdA, were biochemically characterized in vivo and in vitro to reveal that both are substrate specific enzymes that utilize tryptophan-charged tRNA substrates to catalyze assembly of cyclo(L-Trp-L-Trp), a proposed precursor of nocardioazines. Fidelity is uncommon amongst characterized CDPSs, making NozA and NcdA important CDPS family additions. This study also aimed to characterize NozD and NozE, two cytochrome P450 homologs with predicted roles as diketopiperazine-tailoring enzymes. Heterologous expression of these enzymes in Streptomyces strains was not able to confirm the functions of NozD and NozE but set the stage for future studies to optimize conditions for probing their roles in nocardioazine A biosynthesis. The results gathered from this study, along with future work to better understand the engineering of unique functional groups from Nocardiopsis may provide opportunities to produce new bioactive molecules

Comparing the cost-per-QALYs gained and cost-per-DALYs averted literatures [version 1; referees: 3 approved]

Background: We examined the similarities and differences between studies using two common metrics used in cost-effectiveness analyses (CEAs): cost per quality-adjusted life years (QALYs) gained and cost per disability-adjusted life year (DALY) averted. Methods: We used the Tufts Medical Center CEA Registry, which contains English-language cost-per-QALY gained studies, and  Global Cost-Effectiveness Analysis (GHCEA) Registry, which contains cost-per-DALY averted studies. We examined study characteristics including intervention type, sponsor, country, and primary disease, and also analysed the number of CEAs versus disease burden estimates for major diseases and conditions across three geographic regions. Results: We identified 6,438 cost-per-QALY and 543 cost-per-DALY studies published through 2016 and observed rapid growth in publication rates for both literatures. Cost-per-QALY studies were most likely to examine pharmaceuticals and interventions in high-income countries. Cost-per-DALY studies predominantly focused on infectious disease interventions and interventions in low and lower-middle income countries. We found discrepancies in the number of published CEAs for certain diseases and conditions in certain regions, suggesting “under-studied” areas (e.g., cardiovascular disease in Southeast Asia, East Asia, and Oceania and “overstudied” areas (e.g., HIV in Sub Saharan Africa) relative to disease burden in those regions. Conclusions: The number of cost-per QALY and cost-per-DALY analyses has grown rapidly with applications to diverse interventions and diseases.  Discrepancies between the number of published studies and disease burden suggest funding opportunities for future cost-effectiveness research

Comparing the cost-per-QALYs gained and cost-per-DALYs averted literatures [version 2; referees: 3 approved]

Background: We examined the similarities and differences between studies using two common metrics used in cost-effectiveness analyses (CEAs): cost per quality-adjusted life year (QALY) gained and cost per disability-adjusted life year (DALY) averted. Methods: We used the Tufts Medical Center CEA Registry, which contains English-language cost-per-QALY gained studies, and the Global Cost-Effectiveness Analysis (GHCEA) Registry, which contains cost-per-DALY averted studies. We examined study characteristics, including intervention type, sponsor, country, and primary disease, and also compared the number of published CEAs to disease burden for major diseases and conditions across geographic regions. Results: We identified 6,438 cost-per-QALY and 543 cost-per-DALY studies published through 2016 and observed rapid growth for both literatures. Cost-per-QALY studies most often examined pharmaceuticals and interventions in high-income countries. Cost-per-DALY studies predominantly focused on infectious disease interventions and interventions in low and lower-middle income countries. We found that while diseases imposing a larger burden tend to receive more attention in the cost-effectiveness analysis literature, the number of publications for some diseases and conditions deviates from this pattern, suggesting “under-studied” conditions (e.g., neonatal disorders) and “over-studied” conditions (e.g., HIV and TB). Conclusions: The CEA literature has grown rapidly, with applications to diverse interventions and diseases.  The publication of fewer studies than expected for some diseases given their imposed burden suggests funding opportunities for future cost-effectiveness research

Dual-gated bilayer graphene hot electron bolometer

Detection of infrared light is central to diverse applications in security, medicine, astronomy, materials science, and biology. Often different materials and detection mechanisms are employed to optimize performance in different spectral ranges. Graphene is a unique material with strong, nearly frequency-independent light-matter interaction from far infrared to ultraviolet, with potential for broadband photonics applications. Moreover, graphene's small electron-phonon coupling suggests that hot-electron effects may be exploited at relatively high temperatures for fast and highly sensitive detectors in which light energy heats only the small-specific-heat electronic system. Here we demonstrate such a hot-electron bolometer using bilayer graphene that is dual-gated to create a tunable bandgap and electron-temperature-dependent conductivity. The measured large electron-phonon heat resistance is in good agreement with theoretical estimates in magnitude and temperature dependence, and enables our graphene bolometer operating at a temperature of 5 K to have a low noise equivalent power (33 fW/Hz1/2). We employ a pump-probe technique to directly measure the intrinsic speed of our device, >1 GHz at 10 K.Comment: 5 figure

Global biogeography of mating system variation in seed plants

Latitudinal gradients in biotic interactions have been suggested as causes of global patterns of biodiversity and phenotypic variation. Plant biologists have long speculated that outcrossing mating systems are more common at low than high latitudes owing to a greater predictability of plant–pollinator interactions in the tropics; however, these ideas have not previously been tested. Here, we present the first global biogeographic analysis of plant mating systems based on 624 published studies from 492 taxa. We found a weak decline in outcrossing rate towards higher latitudes and among some biomes, but no biogeographic patterns in the frequency of self-incompatibility. Incorporating life history and growth form into biogeographic analyses reduced or eliminated the importance of latitude and biome in predicting outcrossing or self-incompatibility. Our results suggest that biogeographic patterns in mating system are more likely a reflection of the frequency of life forms across latitudes rather than the strength of plant–pollinator interactions