5,110 research outputs found
Design and test of a prototype scale ejector wing
A two dimensional momentum integral analysis was used to examine the effect of changing inlet area ratio, diffuser area ratio, and the ratio of ejector length to width. A relatively wide range of these parameters was considered. It was found that for constant inlet area ratio the augmentation increases with the ejector length, and for constant length: width ratio the augmentation increases with inlet area ratio. Scale model tests were used to verify these trends and to examine th effect of aspect ratio. On the basis of these results, an ejector configuration was selected for fabrication and testing at a scale representative of an ejector wing aircraft. The test ejector was powered by a Pratt-Whitney F401 engine developing approximately 12,000 pounds of thrust. The results of preliminary tests indicate that the ejector develops a thrust augmentation ratio better than 1.65
Probabilistic enhancement of the Failure Forecast Method using a stochastic differential equation and application to volcanic eruption forecasts
We introduce a doubly stochastic method for performing material failure
theory based forecasts of volcanic eruptions. The method enhances the well
known Failure Forecast Method equation, introducing a new formulation similar
to the Hull-White model in financial mathematics. In particular, we incorporate
a stochastic noise term in the original equation, and systematically
characterize the uncertainty. The model is a stochastic differential equation
with mean reverting paths, where the traditional ordinary differential equation
defines the mean solution. Our implementation allows the model to make
excursions from the classical solutions, by including uncertainty in the
estimation. The doubly stochastic formulation is particularly powerful, in that
it provides a complete posterior probability distribution, allowing users to
determine a worst case scenario with a specified level of confidence. We apply
the new method on historical datasets of precursory signals, across a wide
range of possible values of convexity in the solutions and amounts of
scattering in the observations. The results show the increased forecasting
skill of the doubly stochastic formulation of the equations if compared to
statistical regression.Comment: 27 pages, 13 figure
Performance of screening for aneuploidies by cell-free DNA analysis of maternal blood in twin pregnancies
Objectives
To report clinical implementation of cell‐free DNA (cfDNA) analysis of maternal blood in screening for trisomies 21, 18 and 13 in twin pregnancies and examine variables that could influence the failure rate of the test.
Methods
cfDNA testing was performed in 515 twin pregnancies at 10–28 weeks' gestation. The failure rate of the test to provide results was compared with that in 1847 singleton pregnancies, and logistic regression analysis was used to determine which factors among maternal and pregnancy characteristics were significant predictors of test failure.
Results
Failure rate of the cfDNA test at first sampling was 1.7% in singletons and 5.6% in twins. Of those with a test result, the median fetal fraction in twins was 8.7% (range, 4.1–30.0%), which was lower than that in singletons (11.7% (range, 4.0–38.9%)). Multivariable regression analysis demonstrated that twin pregnancy, higher maternal weight and conception by in‐vitro fertilization provided significant independent prediction of test failure. Follow‐up was available in 351 (68.2%) of the twin pregnancies and comprised 334 with euploid fetuses, 12 discordant for trisomy 21 and five discordant for trisomy 18. In all 323 euploid cases with a result, the risk score for each trisomy was < 1:10 000. In 11 of the 12 cases with trisomy 21 and in the five with trisomy 18, the cfDNA test gave a high‐risk result, but in one case of trisomy 21, the score was < 1:10 000.
Conclusion
In twin pregnancies screening by cfDNA testing is feasible, but the failure rate is higher and detection rate may be lower than in singletons
Genotypic and Phenotypic Heterogeneity in Alicyclobacillus acidoterrestris: A Contribution to Species Characterization.
Alicyclobacillus acidoterrestris is the main cause of most spoilage problems in fruit juices
and acidic products. Since soil borne species often contaminate fruit juices and do not need
strict extreme requirements for survival, it is a great concern to investigate whether and how
soil species could evolve from their ecological niches in microbial community to new environments as fruit juices. In this study, 23 isolates of thermo-acidophilic, spore-forming bacteria from soil were characterized by cultural and molecular methods. In addition, 2 strains
isolated from a spoilage incident in pear juice were typed. Strains phenotyping showed that
they could be grouped into 3 different clusters, and some isolates showed identical or quite
similar patterns. Analyzing pH and temperature ranges for growth, the majority of strains
were able to grow at values described for many species of Alicyclobacillus. Qualitative utilization of lysine, arginine and indole production from tryptophan revealed, for the first time,
deamination of lysine and decarboxylation of arginine. Resistance to 5% NaCl as well as
the ability to hydrolyze starch and gelatin, nitrate reduction, catalase and oxidase activities
confirmed literature evidences. Examining of 16S rRNA, showed that isolates were divided
into three blocks represented by effectively soil species and strains that are moving from
soil to other possible growing source characterized by parameters that could strongly influence bacterial survival. RAPD PCR technique evidenced a great variability in banding patterns and, although it was not possible to obtain genotypically well-distinguished groups, it
was feasible to appreciate genetic similarity between some strains. In conclusion, the investigation of a microbial community entails a combination of metagenomic and classic culturedependent approaches to expand our knowledge about Alicyclobacillus and to look for new
subspecies
Hybrid core-shell (HyCoS) nanoparticles produced by complex coacervation for multimodal applications
Multimodal imaging probes can provide diagnostic information combining different imaging modalities. Nanoparticles (NPs) can contain two or more imaging tracers that allow several diagnostic techniques to be used simultaneously. In this work, a complex coacervation process to produce core-shell completely biocompatible polymeric nanoparticles (HyCoS) for multimodal imaging applications is described. Innovations on the traditional coacervation process are found in the control of the reaction temperature, allowing a speeding up of the reaction itself, and the production of a double-crosslinked system to improve the stability of the nanostructures in the presence of a clinically relevant contrast agent for MRI (Gd-DTPA). Through the control of the crosslinking behavior, an increase up to 6 times of the relaxometric properties of the Gd-DTPA is achieved. Furthermore, HyCoS can be loaded with a high amount of dye such as ATTO 633 or conjugated with a model dye such as FITC for in vivo optical imaging. The results show stable core-shell polymeric nanoparticles that can be used both for MRI and for optical applications allowing detection free from harmful radiation. Additionally, preliminary results about the possibility to trigger the release of a drug through a pH effect are reported
How well can the LHC distinguish between the SM light Higgs scenario, a composite Higgs and the Higgsless case using VV scattering channels?
A complete parton level analysis of ll + four jets l = e,mu and 3lv + two
jets production at the LHC is presented, including all processes at order
\ordEW, \ordQCD and \ordQCDsq when appropriate. The infinite Higgs mass
scenario, which is considered as a benchmark for strong scattering theories and
is the limiting case for composite Higgs models, and one example of a model
incorporating a Strongly Interacting Light Higgs are confronted with the
Standard Model light Higgs predictions. This analysis is combined with the
results in the lv + four jets channel presented in a previous paper, in order
to determine whether a composite Higgs signal can be detected as an excess of
events in boson--boson scattering.Comment: Introduced some representative Feynman diagrams. Rearranged section
4. Typos fixed. Published in JHE
Plasmacytoid dendritic cells migrate in afferent skin lymph (Correction: vol 180, pg 5963, 2008)
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