On-board aircraft oxygen generating system

Onboard oxygen generation equipment with minimal ground support equipment and applicable to spacecraft and submarine us

Structural dynamics verification facility study

The need for a structural dynamics verification facility to support structures programs was studied. Most of the industry operated facilities are used for highly focused research, component development, and problem solving, and are not used for the generic understanding of the coupled dynamic response of major engine subsystems. Capabilities for the proposed facility include: the ability to both excite and measure coupled structural dynamic response of elastic blades on elastic shafting, the mechanical simulation of various dynamical loadings representative of those seen in operating engines, and the measurement of engine dynamic deflections and interface forces caused by alternative engine mounting configurations and compliances

Inflammation-Induced Cell Proliferation Potentiates DNA Damage-Induced Mutations In Vivo

Mutations are a critical driver of cancer initiation. While extensive studies have focused on exposure-induced mutations, few studies have explored the importance of tissue physiology as a modulator of mutation susceptibility in vivo. Of particular interest is inflammation, a known cancer risk factor relevant to chronic inflammatory diseases and pathogen-induced inflammation. Here, we used the fluorescent yellow direct repeat (FYDR) mice that harbor a reporter to detect misalignments during homologous recombination (HR), an important class of mutations. FYDR mice were exposed to cerulein, a potent inducer of pancreatic inflammation. We show that inflammation induces DSBs (γH2AX foci) and that several days later there is an increase in cell proliferation. While isolated bouts of inflammation did not induce HR, overlap between inflammation-induced DNA damage and inflammation-induced cell proliferation induced HR significantly. To study exogenously-induced DNA damage, animals were exposed to methylnitrosourea, a model alkylating agent that creates DNA lesions relevant to both environmental exposures and cancer chemotherapy. We found that exposure to alkylation damage induces HR, and importantly, that inflammation-induced cell proliferation and alkylation induce HR in a synergistic fashion. Taken together, these results show that, during an acute bout of inflammation, there is a kinetic barrier separating DNA damage from cell proliferation that protects against mutations, and that inflammation-induced cell proliferation greatly potentiates exposure-induced mutations. These studies demonstrate a fundamental mechanism by which inflammation can act synergistically with DNA damage to induce mutations that drive cancer and cancer recurrence.Austrian Academy of Sciences (APART Fellowship)Singapore-MIT Alliance for Research and TechnologySingapore. National Research FoundationNational Institutes of Health (U.S.) (NIH R33-CA112151)National Institutes of Health (U.S.) (grant R01-CA079827

Active contour approach for accurate quantitative airway analysis

Chronic airway disease causes structural changes in the lungs including peribronchial thickening and airway dilatation. Multi-detector computed tomography (CT) yields detailed near-isotropic images of the lungs, and thus the potential to obtain quantitative measurements of lumen diameter and airway wall thickness. Such measurements would allow standardized assessment, and physicians to diagnose and locate airway abnormalities, adapt treatment, and monitor progress over time. However, due to the sheer number of airways per patient, systematic analysis is infeasible in routine clinical practice without automation. We have developed an automated and real-time method based on active contours to estimate both airway lumen and wall dimensions; the method does not require manual contour initialization but only a starting point on the targeted airway. While the lumen contour segmentation is purely region-based, the estimation of the outer diameter considers the inner wall segmentation as well as local intensity variation, in order anticipate the presence of nearby arteries and exclude them. These properties make the method more robust than the Full-Width Half Maximum (FWHM) approach. Results are demonstrated on a phantom dataset with known dimensions and on a human dataset where the automated measurements are compared against two human operators. The average error on the phantom measurements was 0.10mm and 0.14mm for inner and outer diameters, showing sub-voxel accuracy. Similarly, the mean variation from the average manual measurement was 0.14mm and 0.18mm for inner and outer diameters respectively

DOTASA revisited : 1H NMR and potentiometric studies of a highly asymmetrical ligand and its lanthanide(III) complexes

Poster apresentado no 8th FIGIPAS Meeting in Inorganic Chemistry, Atenas, Grécia, 6 - 9 Jul. 2005.DOTASA (1,4,7,10-tetraazacyclodo-decane-1-(R,S)-succinic acid-4,7,10-triacetic acid) is a DOTA-like macrocyclic ligand showing a carboxymethyl -CH2COOH substituent moiety at a C carbon of one of the four acetate pendant arms, present as a racemic mixture of R and S configurations.The protonation constants of the ligand were determined by potentiometry, giving values close to DOTA except for the extra pK3 value of 5.35 assigned to protonation of the extra carboxylate group in the succinyl arm. The 1H NMR spectra of DOTASA at different pH values are too complex to allow the determination of its microscopic protonation scheme, due to the presence of multiple isomeric structures in solution. The thermodynamic stability constant of its Gd3+ chelate was determined by a potentiometric method, and the value obtained, log KML = 27.2 (0.2), is higher than for the [Gd(DOTA)(H2O)]- complex. The solution structure of the asymmetrical Ln3+ chelates of DOTASA was studied by 1H NMR spectroscopy, indicating the presence of four isomers, corresponding to the combination of the antiprismatic (M) and twisted antiprismatic (m) helicities of the pendant arms and to the R and S configurations of the substituted pendant arm C atom. The m/M isomer ratio decreases along the lanthanide series, with the m isomer decreasing from 90% at La to about 50% from Eu-Lu. This shows that the expected m isomer population of the Gd3+ complex with DOTASA is higher than for the unsubstituted Gd3+-DOTA (~15%) but lower than for a Gd3+ chelate of a RRRR tetrasubstituted DOTA (~70%). Thus the stabilisation of the m isomer by C monosubstitution at the DOTA acetate pendant arms in [Gd(DOTASA)(H2O)]2- is responsible for its increased water exchange rate and higher relaxivity

Quiet time fluxes and radial gradients of low-energy protons in the inner and outer heliosphere

Radial variations of low-energy (~1-8 MeV) quiet-time fluxes of protons are examined at distances of 20-85 AU during low solar activity periods using Voyager 1-2 data and compared with Ulysses fluxes at 1-5 AU as well as IMP-8 and SOHO at Earth and Helios between 0.3 and 1 AU. To obtain nearly background-free fluxes, the data are based on a careful pulse-height analysis. Except for high solar activity periods, contaminated with solar particles, all fluxes are very low, of the order of, and below 10^(-5) /(cm^2 s sr MeV). The Ulysses fluxes seem to be the lowest, whereas Helios and Voyager fluxes are nearly at the same level. The radial variation in 1-8 MeV suggests a negative gradient from 0.5 to about 2 AU that gradually turns positive beyond 2 AU. Whereas the true variation is difficult to infer between 5 and 17 AU due to solar contribution, from 30 to about 60 AU it exhibits a wide plateau, beyond which a slight increasing tendency is observed. At energies above ~6 MeV a clear contribution of anomalous hydrogen is observed

Analysis of arterial sub-trees affected by Pulmonary Emboli

©2004 SPIE--The International Society for Optical Engineering. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. The electronic version of this article is the complete one and can be found online at: http://dx.doi.org/10.1117/12.535993DOI: 10.1117/12.535993Presented at Medical imaging 2004. Image processing : 16-19 February 2004, San Diego, California, USA.Although Pulmonary Embolism (PE) is one of the most common causes of unexpected death in the U.S., it may also be one of the most preventable. Images acquired from 16-slice Computed Tomography (CT) machines of contrast-injected patients provide sufficient resolution for the localization and analysis of emboli located in segmental and sub-segmental arteries. After a PE is found, it is difficult to assess the local characteristics of the affected arterial tree without automation. We propose a method to compute characteristics of the local arterial tree given the location of a PE. The computed information localizes the portion of the arterial tree that is affected by the embolism. Our method is based on the segmentation of the arteries and veins followed by a localized tree computation at the given site. The method determines bifurcation points and the remaining arterial tree. A preliminary segmentation method is also demonstrated to locally eliminate over-segmentation of the arterial tree. The final result can then be used assess the affected lung volume and arterial supply. Initial tests revealed a good ability to compute local tree characteristics of selected sites

Mathematical modeling of thermal power plant's boiler air-gas flow path regulation modes

В работе предлагаются математические модели газовоздушного тракта котла и механизмов собственных нужд ТЭС. С использованием табличных и графических представлений напорных характеристик серийных вентиляторов и дымососов получены эквивалентные соотношения для сети механизмов. Исследована задача нахождения оптимальных параметров управления для группы центробежных механизмов, обеспечивающих работу газовоздушного тракта котла. Исследовано влияние разрежения в топке котла на режим работы его вспомогательных механизмов. Приводятся результаты моделирования для типичных последовательно-параллельных соединений механизмов в гидравлических сетях ТЭС.The paper presents a mathematical model for thermal power plant's boiler air-gas flow paths and auxiliaries. With application of production fans' and flue gas extractor fans' head-capacity curves and tables, equivalent relations for the net of the mechanisms are obtained. A problem of determining the optimal control parameters for a group of centrifugal mechanisms in the air-gas path is studied. The effect of the boiler furnace draft on its auxiliaries operation is analyzed. The results of mathematical modeling for typical serial and parallel connections of the mechanisms in the thermal power plant hydraulic network are given