Documentation of the Analyses of the Benefits and Costs of Aeronautical Research and Technology models (ABC-ART). Volume 2: Appendices

Fleet variables are defined, and source codes for each module are presented

Documentation of the analysis of the benefits and costs of aeronautical research and technology models, volume 1

The analysis of the benefits and costs of aeronautical research and technology (ABC-ART) models are documented. These models were developed by NASA for use in analyzing the economic feasibility of applying advanced aeronautical technology to future civil aircraft. The methodology is composed of three major modules: fleet accounting module, airframe manufacturing module, and air carrier module. The fleet accounting module is used to estimate the number of new aircraft required as a function of time to meet demand. This estimation is based primarily upon the expected retirement age of existing aircraft and the expected change in revenue passenger miles demanded. Fuel consumption estimates are also generated by this module. The airframe manufacturer module is used to analyze the feasibility of the manufacturing the new aircraft demanded. The module includes logic for production scheduling and estimating manufacturing costs. For a series of aircraft selling prices, a cash flow analysis is performed and a rate of return on investment is calculated. The air carrier module provides a tool for analyzing the financial feasibility of an airline purchasing and operating the new aircraft. This module includes a methodology for computing the air carrier direct and indirect operating costs, performing a cash flow analysis, and estimating the internal rate of return on investment for a set of aircraft purchase prices

Counting Complex Disordered States by Efficient Pattern Matching: Chromatic Polynomials and Potts Partition Functions

Counting problems, determining the number of possible states of a large system under certain constraints, play an important role in many areas of science. They naturally arise for complex disordered systems in physics and chemistry, in mathematical graph theory, and in computer science. Counting problems, however, are among the hardest problems to access computationally. Here, we suggest a novel method to access a benchmark counting problem, finding chromatic polynomials of graphs. We develop a vertex-oriented symbolic pattern matching algorithm that exploits the equivalence between the chromatic polynomial and the zero-temperature partition function of the Potts antiferromagnet on the same graph. Implementing this bottom-up algorithm using appropriate computer algebra, the new method outperforms standard top-down methods by several orders of magnitude, already for moderately sized graphs. As a first application, we compute chromatic polynomials of samples of the simple cubic lattice, for the first time computationally accessing three-dimensional lattices of physical relevance. The method offers straightforward generalizations to several other counting problems.Comment: 7 pages, 4 figure

Clemastine/tamoxifen hybrids as easily accessible antileishmanial drug leads

A library of hybrid molecules is developed based on the common chemical features shared by clemastine and tamoxifen both of which are well known for their antileishmanial activities. In the initial screening against Leishmania major and L. amazonensis promastigotes, as well as cytotoxicity assays using HepG2 cells, several hybrids showed submicromolar activity against the parasite and no toxicity against human cells. The compounds with an EC50 10 were further characterized against intracellular amastigotes as well as promastigotes of species that cause both visceral and cutaneous leishmaniasis, such as L. infantum and L. braziliensis, respectively. These sequential screenings revealed the high pan-activity of this class of molecules against these species, with several compounds displaying an EC50 ≤ 2 μM against both promastigotes and intracellular amastigotes. Two of them were identified as the potential templates for lead optimization of this series having shown the highest activities against all species in both stages of parasite. The present findings can serve as a good starting point in the search for novel antileishmanial compounds that are easy to access and highly active

South African women’s perspectives on self-sampling for cervical cancer screening: A mixed-methods study

Background. Self-sampling as a method of screening for cervical cancer and its precursors is an attractive option for low-resource settings. However, to allow successful integration of self-sampling into national screening programmes, it is necessary to understand women’s perceptions and beliefs surrounding this method of sampling the cervix.Objectives. To explore women’s attitudes to self-collection of samples for cervical screening in a low-resource setting in South Africa (SA).Methods. Mixed methods were used to meet the study objectives. We recruited women aged 30 - 65 years into a study in Cape Town, SA, to participate in a cross-sectional survey. All women collected a vaginal self-sample, and underwent visual inspection with acetic acid, colposcopy, and collection of cervical samples and appropriate histology specimens by a doctor. Women had a quantitative questionnairebased exit interview. A subset of these women participated in focus group discussions (FGDs).Results. A total of 822 women answered the exit survey questionnaire and 41 women participated in the FGDs. Most women from the survey had a positive perception of self-sampling, with 93.6% of the women reporting not feeling embarrassed and 89.4% reporting experiencing no discomfort at all when taking a self-sample. This was  corroborated by the FGD participants, who found self-sampling easier, more comfortable and less embarrassing than clinician sampling. However, many women (64.7%) felt more confident when the sample was taken by a clinician, despite having a positive attitude towards self-sampling. In most cases this was because they thought that the clinician would take a better sample, as explained by the FGD  participants. Although 93.9% of the women were  willing to collect a selfsample, the women in the FGDs expressed a preference for doing so at the health facility  rather than at home. There were many reasons for this, including the cost of returning to the clinic with the sample.Conclusions. Attitudes regarding self-sample collection were positive in this study population. Participants were willing to perform selfsampling, but expressed concerns regarding the quality of the specimen and the financial implications of returning to the clinic with it. Pilot implementation studies will be useful before this method of sampling is adopted and integrated into screening programmes

Supporting User-Defined Functions on Uncertain Data

Uncertain data management has become crucial in many sensing and scientific applications. As user-defined functions (UDFs) become widely used in these applications, an important task is to capture result uncertainty for queries that evaluate UDFs on uncertain data. In this work, we provide a general framework for supporting UDFs on uncertain data. Specifically, we propose a learning approach based on Gaussian processes (GPs) to compute approximate output distributions of a UDF when evaluated on uncertain input, with guaranteed error bounds. We also devise an online algorithm to compute such output distributions, which employs a suite of optimizations to improve accuracy and performance. Our evaluation using both real-world and synthetic functions shows that our proposed GP approach can outperform the state-of-the-art sampling approach with up to two orders of magnitude improvement for a variety of UDFs. 1

Multiple-Point and Multiple-Time Correlations Functions in a Hard-Sphere Fluid

A recent mode coupling theory of higher-order correlation functions is tested on a simple hard-sphere fluid system at intermediate densities. Multi-point and multi-time correlation functions of the densities of conserved variables are calculated in the hydrodynamic limit and compared to results obtained from event-based molecular dynamics simulations. It is demonstrated that the mode coupling theory results are in excellent agreement with the simulation results provided that dissipative couplings are included in the vertices appearing in the theory. In contrast, simplified mode coupling theories in which the densities obey Gaussian statistics neglect important contributions to both the multi-point and multi-time correlation functions on all time scales.Comment: Second one in a sequence of two (in the first, the formalism was developed). 12 pages REVTeX. 5 figures (eps). Submitted to Phys.Rev.