Numerical simulation of helicopter engine plume in forward flight

Flowfields around helicopters contain complex flow features such as large separated flow regions, vortices, shear layers, blown and suction surfaces and an inherently unsteady flow imposed by the rotor system. Another complicated feature of helicopters is their infrared signature. Typically, the aircraft's exhaust plume interacts with the rotor downwash, the fuselage's complicated flowfield, and the fuselage itself giving each aircraft a unique IR signature at given flight conditions. The goal of this project was to compute the flow about a realistic helicopter fuselage including the interaction of the engine air intakes and exhaust plume. The computations solve the Think-Layer Navier Stokes equations using overset type grids and in particular use the OVERFLOW code by Buning of NASA Ames. During this three month effort, an existing grid system of the Comanche Helicopter was to be modified to include the engine inlet and the hot engine exhaust. The engine exhaust was to be modeled as hot air exhaust. However, considerable changes in the fuselage geometry required a complete regriding of the surface and volume grids. The engine plume computations have been delayed to future efforts. The results of the current work consists of a complete regeneration of the surface and volume grids of the most recent Comanche fuselage along with a flowfield computation

Lampreys, the jawless vertebrates, contain three Pax6 genes with distinct expression in eye, brain and pancreas

10.1038/s41598-019-56085-8Scientific Reports911955

Expression of zebrafish pax6b in pancreas is regulated by two enhancers containing highly conserved cis-elements bound by PDX1, PBX and PREP factors

BACKGROUND: PAX6 is a transcription factor playing a crucial role in the development of the eye and in the differentiation of the pancreatic endocrine cells as well as of enteroendocrine cells. Studies on the mouse Pax6 gene have shown that sequences upstream from the P0 promoter are required for expression in the lens and the pancreas; but there remain discrepancies regarding the precise location of the pancreatic regulatory elements. RESULTS: Due to genome duplication in the evolution of ray-finned fishes, zebrafish has two pax6 genes, pax6a and pax6b. While both zebrafish pax6 genes are expressed in the developing eye and nervous system, only pax6b is expressed in the endocrine cells of the pancreas. To investigate the cause of this differential expression, we used a combination of in silico, in vivo and in vitro approaches. We show that the pax6b P0 promoter targets expression to endocrine pancreatic cells and also to enteroendocrine cells, retinal neurons and the telencephalon of transgenic zebrafish. Deletion analyses indicate that strong pancreatic expression of the pax6b gene relies on the combined action of two conserved regulatory enhancers, called regions A and C. By means of gel shift assays, we detected binding of the homeoproteins PDX1, PBX and PREP to several cis-elements of these regions. In constrast, regions A and C of the zebrafish pax6a gene are not active in the pancreas, this difference being attributable to sequence divergences within two cis-elements binding the pancreatic homeoprotein PDX1. CONCLUSION: Our data indicate a conserved role of enhancers A and C in the pancreatic expression of pax6b and emphasize the importance of the homeoproteins PBX and PREP cooperating with PDX1, in activating pax6b expression in endocrine pancreatic cells. This study also provides a striking example of how adaptative evolution of gene regulatory sequences upon gene duplication progressively leads to subfunctionalization of the paralogous gene pair

Risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy: population based retrospective cohort study.

OBJECTIVE: To assess the risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy. DESIGN: Population based retrospective cohort study. SETTING: Ontario, Canada, 1 May to 31 December 2021. PARTICIPANTS: All liveborn and stillborn infants from pregnancies conceived at least 42 weeks before the end of the study period and with gestational age ≥20 weeks or birth weight ≥500 g. MAIN OUTCOME MEASURES: Using Cox regression, hazard ratios and 95% confidence intervals were estimated for preterm birth before 37 weeks (overall and spontaneous preterm birth), very preterm birth (<32 weeks), small for gestational age at birth (<10th centile), and stillbirth. Vaccination against covid-19 was treated as a time varying exposure in the outcome specific risk window, and propensity score weighting was used to adjust hazard ratios for potential confounding. RESULTS: Among 85 162 births, 43 099 (50.6%) occurred in individuals who received one dose or more of a covid-19 vaccine during pregnancy-42 979 (99.7%) received an mRNA vaccine. Vaccination during pregnancy was not associated with any increased risk of overall preterm birth (6.5% among vaccinated v 6.9% among unvaccinated; adjusted hazard ratio 1.02, 95% confidence interval 0.96 to 1.08), spontaneous preterm birth (3.7% v 4.4%; 0.96, 0.90 to 1.03), or very preterm birth (0.59% v 0.89%; 0.80, 0.67 to 0.95). No increase was found in risk of small for gestational age at birth (9.1% v 9.2%; 0.98, 0.93 to 1.03) or stillbirth (0.25% v 0.44%; 0.65, 0.51 to 0.84). Findings were similar by trimester of vaccination, mRNA vaccine product, and number of doses received during pregnancy. CONCLUSION: The findings suggest that vaccination against covid-19 during pregnancy is not associated with a higher risk of preterm birth, small for gestational age at birth, or stillbirth

Long-range downstream enhancers are essential for Pax6 expression

AbstractPax6 is a developmental control gene with an essential role in development of the eye, brain and pancreas. Pax6, as many other developmental regulators, depends on a substantial number of cis-regulatory elements in addition to its promoters for correct spatiotemporal and quantitative expression. Here we report on our analysis of a set of mice transgenic for a modified yeast artificial chromosome carrying the human PAX6 locus. In this 420 kb YAC a tauGFP-IRES-Neomycin reporter cassette has been inserted into the PAX6 translational start site in exon 4. The YAC has been further engineered to insert LoxP sites flanking a 35 kb long, distant downstream regulatory region (DRR) containing previously described DNaseI hypersensitive sites, to allow direct comparison between the presence or absence of this region in the same genomic context. Five independent transgenic lines were obtained that vary in the extent of downstream PAX6 locus that has integrated. Analysis of transgenic embryos carrying full-length and truncated versions of the YAC indicates the location and putative function of several novel tissue-specific enhancers. Absence of these distal regulatory elements abolishes expression in specific tissues despite the presence of more proximal enhancers with overlapping specificity, strongly suggesting interaction between these control elements. Using plasmid-based reporter transgenic analysis we provide detailed characterization of one of these enhancers in isolation. Furthermore, we show that overexpression of a short PAX6 isoform derived from an internal promoter in a multicopy YAC transgenic line results in a microphthalmia phenotype. Finally, direct comparison of a single-copy line with the floxed DRR before and after Cre-mediated deletion demonstrates unequivocally the essential role of these long-range control elements for PAX6 expression

Tolerance of Penaeus monodon eggs and larvae to fungicides against Lagenidium sp. and Haliphthoros philippinensis

Contribution No. 163 of the SEAFDEC Aquaculture Department, Southeast Asian Fisheries Development Center.The in vivo effect of mycostatic levels of fungicides against the fungi Lagenidium sp. and Haliphthoros philippinensis was tested on Penaeus monodon eggs and larvae. Hatching rate and survival of nauplii, zoeae, myses and postlarvae exposed to 10 mg/l benzalkonium chloride, 1 mg/l Clotrimazole, 1 mg/l crystal violet, 10 mg/l 2,4-D, 10 mg/l Daconil, 20 mg/l laundry detergent, 1 mg/l Econazole nitrate, 10 mg/l Resiguard, 0.2 mg/l and 10 mg/l Treflan-R, and 0.01 mg/l and 0.2 mg/l trifluralin were monitored daily for 96 h in a static bioassay in glass aquaria. Test chemicals did not have an inhibitory effect on hatching rate but survival rate of hatched nauplii was significantly reduced in most treatments except those with 0.2 mg/l Treflan-R and 0.2 mg/l trifluralin. Tests with zoeae, myses and postlarvae indicated that 0.2 mg/l Treflan-R as well as 0.01 mg/l and 0.2 mg/l trifluralin did not adversely affect survival. In addition, application of 10 mg/l benzalkonium chloride caused no significant mortalities among exposed myses

RITMO TROPICAL - 3 / Xavier CUGAT et son orchestre ; vocal : V. AVILES

Comprend : GAY MERNGUE - LAS CHISMOSAS - RITMO TROPICAL - EL MERENGUEBnF-Partenariats, Collection sonore - BelieveContient une table des matière