Index to 1985 NASA Tech Briefs, volume 10, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1985 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

10441 Abstracts Collection -- Exact Complexity of NP-hard Problems

A decade before NP-completeness became the lens through which Computer Science views computationally hard problems, beautiful algorithms were discovered that are much better than exhaustive search, for example Bellman\u27s 1962 dynamic programming treatment of the Traveling Salesman problem and Ryser\u27s 1963 inclusion--exclusion formula for the permanent

Methods for the identification of common RNA motifs

Löwes B. Methods for the identification of common RNA motifs. Bielefeld: Universität Bielefeld; 2017.For a long time, non-coding RNAs were given less attention than messenger RNAs, even though their existence was proposed at a similar time in 1971, because the research focus was mostly on protein coding genes. With the discovery of catalytically active RNA molecules and micro RNAs, which are involved in the post-transcriptional regulation of gene expression, non-coding RNAs have gained widespread attention. It was revealed early on that non-coding RNAs are often more conserved in structure than in sequence. Since determining the function of non-coding RNAs includes costly and time consuming laboratory experiments, computational methods can help identifying further homologs of experimentally validated RNA families. But a question remains: can we identify potential RNAs with novel functions solely by using *in silico* methods? In this thesis, we perform an evaluation of 4,667 viral reference genomes in order to identify common RNA motifs shared by multiple taxonomically distant viruses. One potential mechanism that might explain similar motifs in taxonomically distant viruses that infect common hosts by interacting with their cellular components is convergent evolution. Convergent evolution is used to describe the phenomenon that two different species that are originated from two ancestors share related or similar traits. By looking for long stretches of exact RNA structure matches with low sequence conservation, we want to maximize the chance that the common motifs are the result of structural convergence due to similar selection criteria in common host organisms. Viruses are an excellent fit when it comes to the discovery of shared RNA motifs without the involvement of conserved sequence regions because of their high mutation rates. We were able to identify 69 RNA motifs, which could not be assigned to any of the existing RNA families, with a length of at least 50 nucleotides that are shared among at least three taxonomically distant viruses. The secondary structure of an RNA molecule can be represented as a string. Finding maximal repeats in strings can be done using well-known string matching techniques based on suffix trees and arrays. In contrast to normal RNA sequences, secondary structure strings represent base pairing interactions within a single molecule. Thus, not every substring of the secondary structure defines a well-formed RNA structure. Therefore, we describe a new data structure, the viable suffix tree, that takes the constraints on the RNA secondary structure into account and only returns maximal repeats that are well-formed structures. But this data structure is not limited to RNA structures, it can also be used for any other problem domain for which a set of allowed words can be defined, e.g. by using a grammar. However, the overall complexity of constructing the viable suffix tree cannot be lower than the complexity of the word problem for the language of such a grammar. A limitation of exact structure matching is the need for long common stretches of secondary structures that are not allowed to have a mismatch at any position. Therefore, we need to allow small mismatches to find more potential targets, but current state of the art techniques use computationally too expensive methods for sequence and structure comparisons and exhibit high false positive rates around 50%. We present a new approach that uses smaller RNA sequence and structure seed motifs that do not require long stretches of the secondary structure to be identical. The sequence and structure motifs can be hashed into integer values, which can be compared much faster. An evaluation using the three well understood hammerhead ribozyme families showed that our approach is able to detect 70% to 80% of the hammerhead motifs with a similar false positive rate as the other approaches. Whenever the performance of new and existing tools should be compared, there is a need for a benchmark data set with an underlying gold standard. BRaliBase is a widely used benchmark for assessing the accuracy of RNA secondary structure alignment methods. In most case studies based on the BRaliBase benchmark, one can observe a puzzling drop in accuracy in the 40% to 60% sequence identity range, the so-called “BRaliBase dent”. We show that this dent is due to a bias in the composition of the BRaliBase benchmark, namely the inclusion of a disproportionate number of tRNAs, which exhibit a very conserved secondary structure. Furthermore, we show that a simple sampling approach that restricts the presence of the most abundant RNA families can prevent such artifacts during the performance evaluation

Index to NASA Tech Briefs, 1972

Abstracts of 1972 NASA Tech Briefs are presented. Four indexes are included: subject, personal author, originating center, and Tech Brief number

Network Formation and Dynamics under Economic Constraints

Networks describe a broad range of systems across a wide variety of topics from social and economic interactions over technical infrastructures such as power grids and the internet to biological contexts such as food webs or neural networks. A number of large scale failures and events in these interconnected systems in recent years has shown that understanding the behavior of individual units of these networks is not necessarily sufficient to handle the increasing complexity of these systems. Many theoretical models have been studied to understand the fundamental mechanisms underlying the formation and function of networked systems and a general framework was developed to describe and understand networked systems. However, most of these models ignore a constraint that affects almost all realistic systems: limited resources. In this thesis I study the effects of economic constraints, such as a limited budget or cost minimization, both on the control of network formation and dynamics as well as on network formation itself. I introduce and analyze a new coupling scheme for coupled dynamical systems, showing that synchronization of chaotic units can be enhanced by restricting the interactions based on the states of the individual units, thus saving interactions costs. This new interaction scheme guarantees synchronizability of arbitrary networks of coupled chaotic oscillators, independent of the network topology even with strongly limited interactions. I then propose a new order parameter to measure the degree of phase coherence of networks of coupled phase oscillators. This new order parameter accurately describes the phase coherence in all stages of incoherent movement, partial and full phase locking up to full synchrony. Importantly, I analytically relate this order parameter directly to the stability of the phase locked state. In the second part, I consider the formation of networks under economic constraints from two different points of view. First I study the effects of explicitly limited resources on the control of random percolation, showing that optimal control can have undesired side effects. Specifically, maximal delay of percolation with a limited budget results in a discontinuous percolation transition, making the transition itself uncontrollable in the sense that a single link can have a macroscopic effect on the connectivity. Finally, I propose a model where network formation is driven by cost minimization of the individual nodes in the network. Based on a simple economically motivated supply problem, the resulting network structure is given as the solution of a large number of individual but interaction optimization problem. I show that these network states directly correspond to the final states of a local percolation algorithm and analyze the effects of local optimization on the network formation process. Overall, I reveal mechanisms and phenomena introduced by these economic constraints that are typically not considered in the standard models, showing that economic constraints can strongly alter the formation and function of networked systems. Thereby, I extend the theoretical understanding that we have of networked systems to economic considerations. I hope that this thesis enables better prediction and control networked systems in realistic settings

The experience of pain and pain management among culturally and linguistically diverse communities living in Australia

The studies presented in this thesis enlighten contemporary understandings of the experience of chronic pain for CALD (culturally and linguistically diverse) communities. Each study is an original piece of scientific work that contributes to the field of research in chronic pain and provides healthcare providers with tangible opportunities to culturally adapt their interventions.Taken together, the studies also provide a practical guide for future researchers seeking to engage CALD communities. Finally, this thesis argues that for healthcare to be responsive to the needs of multicultural Australia, change needs to be enacted more broadly. Educational institutions, professional organisations and healthcare accreditation agencies have a role to play to ensure that CALD patients and communities are part of initiatives seeking to address the multifaceted disparities in healthcare that exist for CALD communities

Cumulative index to NASA Tech Briefs, 1970-1975

Tech briefs of technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Abstracts and indexes of subject, personal author, originating center, and tech brief number for the 1970-1975 tech briefs are presented