208 research outputs found
Cryogenic Hydrogen Radiation Shield for Human Spaceflight
The disclosed subject matter relates to a radiation shielding apparatus including a cryogenic vessel and a cryogenic hydrogen radiation shielding material capable of providing a radiation shield, the cryogenic hydrogen radiation shielding material including cryogenic hydrogen
ESD Control in the NASA STD-8739.6
This presentation covers the history of NASA using the industry ESD standard ANSI/ESD S20.20, the rationale for adding ESD control requirments to NASA STD-8739.6, and what many of those changes will look like
Orientation computation of an inclined textured plane: accuracy and performances
The aim of this paper is to present one method for computing the orientation of an inclined textured plane with
only one view of this plane. Two steps are used for this computation. First we build a local scales map by a wavelets
decomposition of the image of the plane. Then we have to do an interpolation of this map by use the theoretical
equation of the local scales variation. So we obtain features values which allow us to compute the tilt and the
slant angles. After developing the computation technique, we do a theoretical study in order to know the precision
of the method. For the tilt angle, the precision is about one degree, but for the slant angle the precision is
only about five degrees, if the slant angle is over forty degrees. But, we have to know the camera parameters for
computing the slant angle. If there is some errors about these parameters, so the slant angle will be bad. After this study, we build a data base of one hundred images of real textures with different tilt and slant angles. The camera
which has been used for acquiring the images has been calibrated. Results on this data base are agree with the
theoretical study.Le but de cet article est de présenter une méthode de calcul de l'orientation d'un plan texturé incliné à partir d'une seule vue de ce plan. Cette méthode est constituée de deux étapes. Dans un premier temps on calcule, à partir de l'image initiale, une carte des échelles locales. Ces échelles sont obtenues au moyen d'une décomposition en ondelettes de l'image d'origine. Puis on interpole cette carte des échelles locales par l'équation théorique de leurs variations. On obtient ainsi des paramètres qui permettent de calculer les angles de tilt et de slant, décrivant l'orientation du plan. Pour valider cette démarche, nous avons mené une étude théorique sur la précision qui pouvait être atteinte par une telle méthode. Nous avons pu mettre en évidence que, si la précision sur l'angle de tilt était assez bonne (de l'ordre de 1°), celle sur l'angle de slant n'excédait pas 5°, à condition que cet angle soit suffisamment important (supérieur à 40°). Mais la précision sur l'angle de slant est conditionnée par la connaissance des paramètres de prise de vue. En effet, nous avons mis en évidence que l'utilisation de valeurs erronées des paramètres de la caméra entraînerait une erreur maximum pour un slant entre 40° et 50°, c'est à dire, a priori, là où la méthode est la meilleure. Cette étude théorique a été validée par des expérimentations sur des images de synthèse et sur des images de textures réelles. Une base de données d'une centaine d'images a été constituée, au moyen d'une caméra préalablement calibrée, pour évaluer la qualité des résultats fournis par notre méthode
Prior tonsillectomy is associated with an increased risk of esophageal adenocarcinoma.
BACKGROUND: Esophageal cancer is a deadly cancer with 5-year survival
METHODS: Cases included 452 esophagectomy cases, including 396 with EAC and 56 who underwent esophagectomy for Barrett\u27s esophagus (BE) with high grade dysplasia (HGD). 1,102 thoracic surgery patients with surgical indications other than dysplastic BE or esophageal cancer represented the controls for our analysis. The association of tonsillectomy and HGD/EAC were primarily evaluated by using univariate tests and then verified by logistic regression analysis. Baseline demographics, medical history, and thoracic surgery controls were compared by using χ2 tests or 95% CIs. Significant risk factors were considered as covariates in the multivariate models while evaluating the association between tonsillectomy and HGD/EAC. P-values or odds ratios were estimated with 95% confidence limits to identify significances which was more appropriate.
RESULTS: Tonsillectomy was more common in cases than controls and was found to have a significant association with esophageal cancer (19.9% vs. 12.7%; p-value = 0.0003). This significant association persisted after controlling for other known risk factors/covariates.
CONCLUSION: A prior history of tonsillectomy was significantly associated with HGD/EAC and may represent an independent risk factor for the development of EAC. However, the underlying biology driving this association remains unclear
A Comparison of High-Energy Electron and Cobalt-60 Gamma-Ray Radiation Testing
In this paper, a comparison between the effects of irradiating microelectronics with high energy electrons and Cobalt-60 gamma-rays is examined. Additionally, the effect of electron energy is also discussed. A variety of part types are investigated, including discrete bipolar transistors, hybrids, and junction field effect transistor
Posttraumatic Stress Disorder Biomarker — p11
Post-traumatic stress disorder (PTSD) is a chronic and disabling anxiety disorder associated with a traumatic event [1]. It is linked to increased risk of suicide and deficits in social functioning [2, 3]. Despite extensive study in psychiatry, the underlying mechanisms of PTSD are still poorly understood [4, 5]. Currently, the diagnosis for PTSD is based on clinical observation and symptom checklist [4, 6-8] and no laboratory blood-based tests. Although biomarker discovery for PTSD is not easy [8], a reliable biomarker would significantly impact the diagnosis and therapeutic monitoring of PTSD. Developing interventions to identify and treat PTSD requires objective approaches to determining the presence of PTSD [8]. Substantial data indicate several potential biomarkers for PTSD. Of these candidate markers, p11 (S100A10) has been studied in PTSD animal models [7] and in human subjects with PTSD [6]. We found that p11 is over-expressed in both animal models and post-mortem brains of subjects with PTSD [7]. Incorporating testing of p11, a novel biomarker for PTSD, into clinical practice, along with more subjective measures, such as participants’ medical history, mental status, duration of symptoms, and symptom checklist or self-report, would provide additional power to predict impending PTSD. In this chapter, we discuss the biomarker concept and the potential clinical utility of PTSD biomarkers. We further discuss the potential of p11 as a PTSD biomarker and as a tool that may enhance PTSD diagnosis and intervention in health care practice
Alignment between PIN1 Polarity and Microtubule Orientation in the Shoot Apical Meristem Reveals a Tight Coupling between Morphogenesis and Auxin Transport
Morphogenesis during multicellular development is regulated by intercellular signaling molecules as well as by the mechanical properties of individual cells. In particular, normal patterns of organogenesis in plants require coordination between growth direction and growth magnitude. How this is achieved remains unclear. Here we show that in Arabidopsis thaliana, auxin patterning and cellular growth are linked through a correlated pattern of auxin efflux carrier localization and cortical microtubule orientation. Our experiments reveal that both PIN1 localization and microtubule array orientation are likely to respond to a shared upstream regulator that appears to be biomechanical in nature. Lastly, through mathematical modeling we show that such a biophysical coupling could mediate the feedback loop between auxin and its transport that underlies plant phyllotaxis
Compendium of Total Ionizing Dose and Displacement Damage for Candidate Spacecraft Electronics for NASA
Vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage is studied. Devices tested include optoelectronics, digital, analog, linear, and hybrid devices
Compendium of Current Total Ionizing Dose and Displacement Damage for Candidate Spacecraft Electronics for NASA
Total ionizing dose and displacement damage testing is performed to characterize and determine the feasibility of candidate electronics for NASA spacecraft and program use. AEROSPACE ENVIRONMENT
Compendium of Current Total Ionizing Dose and Displacement Damage for Candidate Spacecraft Electronics for NASA
Total ionizing dose and displacement damage testing is performed to characterize and determine the suitability of candidate electronics for NASA spacecraft and program use
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