Development of a Portfolio Management Approach with Case Study of the NASA Airspace Systems Program

A portfolio management approach was developed for the National Aeronautics and Space Administration s (NASA s) Airspace Systems Program (ASP). The purpose was to help inform ASP leadership regarding future investment decisions related to its existing portfolio of advanced technology concepts and capabilities (C/Cs) currently under development and to potentially identify new opportunities. The portfolio management approach is general in form and is extensible to other advanced technology development programs. It focuses on individual C/Cs and consists of three parts: 1) concept of operations (con-ops) development, 2) safety impact assessment, and 3) benefit-cost-risk (B-C-R) assessment. The first two parts are recommendations to ASP leaders and will be discussed only briefly, while the B-C-R part relates to the development of an assessment capability and will be discussed in greater detail. The B-C-R assessment capability enables estimation of the relative value of each C/C as compared with all other C/Cs in the ASP portfolio. Value is expressed in terms of a composite weighted utility function (WUF) rating, based on estimated benefits, costs, and risks. Benefit utility is estimated relative to achieving key NAS performance objectives, which are outlined in the ASP Strategic Plan.1 Risk utility focuses on C/C development and implementation risk, while cost utility focuses on the development and implementation portions of overall C/C life-cycle costs. Initial composite ratings of the ASP C/Cs were successfully generated; however, the limited availability of B-C-R information, which is used as inputs to the WUF model, reduced the meaningfulness of these initial investment ratings. Development of this approach, however, defined specific information-generation requirements for ASP C/C developers that will increase the meaningfulness of future B-C-R ratings

Chave para a identificação das espécies de abóboras (Cucurbita, Cucurbitaceae) cultivadas no Brasil.

Metodologia para identificação taxonômica de espécies de abóboras cultivadas (Cucurbita maxima, Cucurbita moschata, Cucurbita pepo, Cucurbita ficifolia e Cucurbita argyrosperma) - As abóboras cultivadas pertencem a cinco diferentes espécies, as quais são conhecidas por uma grande diversidade de nomes populares, particulares ou em comum, que confundem a correta identificação taxonômica da espécie. A carência de chaves taxonômicas no Brasil para a identificação das espécies cultivadas de abóboras, e o fato de que a maioria das chaves disponíveis em outros idiomas permite apenas a determinação taxonômica das três espécies mais comumente cultivadas (C. maxima, C. moschata e C. pepo), dificultam o correto reconhecimento e aproveitamento do potencial que estas culturas podem oferecer. A identificação adequada das espécies é essencial para atividades rotineiras de coleta, conservação, caracterização e multiplicação de acessos em um banco de germoplasma, e crucial para o sucesso de cruzamentos em programas de melhoramento. Além disso, sem uma correta identificação das espécies é difícil obter informações relevantes sobre estes cultivos. Para auxiliar na determinação taxonômica, esta publicação apresenta três chaves complementares de identificação, amplamente ilustradas com fotografias dos acessos do Banco Ativo de Germoplasma de Cucurbitaceae da Embrapa Clima Temperado. A primeira chave foi elaborada para identificação com base em caracteres vegetativos, a segunda em características dos frutos e a terceira para a identificação através de sementes. A diversidade morfológica entre as espécies cultivadas de Cucurbita é notável e, por isso, sempre que possível, mais de uma destas chaves deve ser considerada para confirmar a determinação de uma espécie. As informações das chaves são complementadas pelas fotografias que mostram características importantes para a identificação das espécies.bitstream/item/33837/1/documento-197.pd

A clinical investigation between two different rigid gas permeable contact lens materials based on oxygen permeability (Dk)

The varying oxygen permeability of rigid gas permeable materials continues to be a primary concern among contact lens manufacturers. Manufacturers promote that more oxygen permeability leads to greater comfort, and less corneal edema. In this study, Paraperm EW, a moderatly high Dk lens, and Polycon II, a relatively low Dk lens were clinically evaluated for patient comfort, corneal edema, related changes in corneal curvature, and any refractive changes. Both objective clinical data and subjective patient responses were used to determine whether the current low Dk lenses are as effective as the higher Dk lenses for daily wear. Fourteen subjects were fit with a pair of Paraperm EW lenses and a pair of · Polycon II lenses, of which ten subjects completed the study. One lens from each pair was worn on each eye. Following a period of two months the lens types were reversed so that each eye had worn each type of lens for two months. No significant difference was seen between either of the lens materials with respect to objective clinical data and subjective preference. The results, therefore, indicate very little difference between the low Dk material and the higher Dk materials with respect to corneal thickness changes, corneal curvature or refractive changes, or patient preferences over the four months of the study

A Performance Assessment of a Tactical Airborne Separation Assistance System using Realistic, Complex Traffic Flows

This paper presents the results from a study that investigates the performance of aspects of an Airborne Separation Assistance System (ASAS) under varying demand levels using realistic traffic patterns. This study only addresses the tactical aspects of an ASAS using aircraft state data (latitude, longitude, altitude, heading and speed) to detect and resolve projected conflicts. The main focus of this paper is to determine the extent to which sole reliance on the proposed tactical ASAS can maintain aircraft separation at demand levels up to three times current traffic. The effect of mixing ASAS equipped aircraft with non-equipped aircraft that do not have the capability to self-separate is also investigated

From the Hitchin section to opers through nonabelian Hodge

For a complex simple simply connected Lie group $G$, and a compact Riemann surface $C$, we consider two sorts of families of flat $G$-connections over $C$. Each family is determined by a point ${\mathbf u}$ of the base of Hitchin's integrable system for $(G,C)$. One family $\nabla_{\hbar,{\mathbf u}}$ consists of $G$-opers, and depends on $\hbar \in {\mathbb C}^\times$. The other family $\nabla_{R,\zeta,{\mathbf u}}$ is built from solutions of Hitchin's equations, and depends on $\zeta \in {\mathbb C}^\times, R \in {\mathbb R}^+$. We show that in the scaling limit $R \to 0$, $\zeta = \hbar R$, we have $\nabla_{R,\zeta,{\mathbf u}} \to \nabla_{\hbar,{\mathbf u}}$. This establishes and generalizes a conjecture formulated by Gaiotto

Quantum Attractor Flows

Motivated by the interpretation of the Ooguri-Strominger-Vafa conjecture as a holographic correspondence in the mini-superspace approximation, we study the radial quantization of stationary, spherically symmetric black holes in four dimensions. A key ingredient is the classical equivalence between the radial evolution equation and geodesic motion of a fiducial particle on the moduli space M^*_3 of the three-dimensional theory after reduction along the time direction. In the case of N=2 supergravity, M^*_3 is a para-quaternionic-Kahler manifold; in this case, we show that BPS black holes correspond to a particular class of geodesics which lift holomorphically to the twistor space Z of M^*_3, and identify Z as the BPS phase space. We give a natural quantization of the BPS phase space in terms of the sheaf cohomology of Z, and compute the exact wave function of a BPS black hole with fixed electric and magnetic charges in this framework. We comment on the relation to the topological string amplitude, extensions to N>2 supergravity theories, and applications to automorphic black hole partition functions.Comment: 43 pages, 6 figures; v2: typos and references added; v3: published version, minor change

Higher Derivative Corrections, Dimensional Reduction and Ehlers Duality

Motivated by applications to black hole physics and duality, we study the effect of higher derivative corrections on the dimensional reduction of four-dimensional Einstein, Einstein Liouville and Einstein-Maxwell gravity to one direction, as appropriate for stationary, spherically symmetric solutions. We construct a field redefinition scheme such that the one-dimensional Lagrangian is corrected only by powers of first derivatives of the fields, eliminating spurious modes and providing a suitable starting point for quantization. We show that the Ehlers symmetry, broken by the leading $R^2$ corrections in Einstein-Liouville gravity, can be restored by including contributions of Taub-NUT instantons. Finally, we give a preliminary discussion of the duality between higher-derivative F-term corrections on the vector and hypermultiplet branches in N=2 supergravity in four dimensions.Comment: 21 pages, uses JHEP3.cls; v3: minor corrections, final version published in JHE