Independent Orbiter Assessment (IOA): Assessment of the manned maneuvering unit

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Manned Maneuvering Unit (MMU) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contain within the NASA FMEA/CIL documentation. The IOA results were then compared to the proposed Martin Marietta FMEA/CIL Post 51-L updates. A discussion of each discrepancy from the comparison is provided through additional analysis as required. These discrepancies were flagged as issues, and recommendations were made based on the FMEA data available at the time. The results of this comparison for the Orbiter MMU hardware are documented. The IOA product for the MMU analysis consisted of 204 failure mode worksheets that resulted in 95 potential critical items being identified. Comparison was made to the NASA baseline which consisted of 179 FMEAs and 110 CIL items. This comparison produced agreement on all 121 FMEAs which caused differences in 92 CIL items

Theoretical Design and Analysis of Multivolume Digital Assays with Wide Dynamic Range Validated Experimentally with Microfluidic Digital PCR

This paper presents a protocol using theoretical methods and free software to design and analyze multivolume digital PCR (MV digital PCR) devices; the theory and software are also applicable to design and analysis of dilution series in digital PCR. MV digital PCR minimizes the total number of wells required for “digital” (single molecule) measurements while maintaining high dynamic range and high resolution. In some examples, multivolume designs with fewer than 200 total wells are predicted to provide dynamic range with 5-fold resolution similar to that of single-volume designs requiring 12 000 wells. Mathematical techniques were utilized and expanded to maximize the information obtained from each experiment and to quantify performance of devices and were experimentally validated using the SlipChip platform. MV digital PCR was demonstrated to perform reliably, and results from wells of different volumes agreed with one another. No artifacts due to different surface-to-volume ratios were observed, and single molecule amplification in volumes ranging from 1 to 125 nL was self-consistent. The device presented here was designed to meet the testing requirements for measuring clinically relevant levels of HIV viral load at the point-of-care (in plasma, 1 000 000 molecules/mL), and the predicted resolution and dynamic range was experimentally validated using a control sequence of DNA. This approach simplifies digital PCR experiments, saves space, and thus enables multiplexing using separate areas for each sample on one chip, and facilitates the development of new high-performance diagnostic tools for resource-limited applications. The theory and software presented here are general and are applicable to designing and analyzing other digital analytical platforms including digital immunoassays and digital bacterial analysis. It is not limited to SlipChip and could also be useful for the design of systems on platforms including valve-based and droplet-based platforms. In a separate publication by Shen et al. (J. Am. Chem. Soc., 2011, DOI: 10.1021/ja2060116), this approach is used to design and test digital RT-PCR devices for quantifying RNA

Evaluating residents’ preferences for remediation technologies: A choice experiment approach

© 2017 Elsevier B.V. The choice of technologies used to remediate contaminated environments is increasingly made through engagement with a multitude of stakeholders including affected residents. Despite this, little is known about how residents perceive remediation technology applications. In this study a choice experiment is designed to explore ways of understanding and measuring residents’ preferences for different remediation technologies approaches using a sample of 944 residents in New South Wales, Australia. Analysis reveals that the residents’ acceptability of remediation technologies can be explained by both the efficacy of the technology in improving the environmental quality of the community, and the reputational value of the technology. In particular it is found that residents prefer Monitor Natural Attenuation and Bioremediation to other remediation technologies. In particular they are willing to pay an increase in yearly taxes of $44.60 and$41.15 respectively for implementing such technologies instead of alternative remediation technologies like Chemical remediation

Analog of Astrophysical Magnetorotational Instability in a Couette-Taylor Flow of Polymer Fluids

We report experimental observation of an instability in a Couette-Taylor flow of a polymer fluid in a thin gap between two coaxially rotating cylinders in a regime where their angular velocity decreases with the radius while the specific angular momentum increases with the radius. In the considered regime, neither the inertial Rayleigh instability nor the purely elastic instability are possible. We propose that the observed "elasto-rotational" instability is an analog of the magnetorotational instability which plays a fundamental role in astrophysical Keplerian accretion disks.Comment: 4 pages, 1 figur

Integer Vector Addition Systems with States

This paper studies reachability, coverability and inclusion problems for Integer Vector Addition Systems with States (ZVASS) and extensions and restrictions thereof. A ZVASS comprises a finite-state controller with a finite number of counters ranging over the integers. Although it is folklore that reachability in ZVASS is NP-complete, it turns out that despite their naturalness, from a complexity point of view this class has received little attention in the literature. We fill this gap by providing an in-depth analysis of the computational complexity of the aforementioned decision problems. Most interestingly, it turns out that while the addition of reset operations to ordinary VASS leads to undecidability and Ackermann-hardness of reachability and coverability, respectively, they can be added to ZVASS while retaining NP-completness of both coverability and reachability.Comment: 17 pages, 2 figure

Pik3r1 Is Required for Glucocorticoid-Induced Perilipin 1 Phosphorylation in Lipid Droplet for Adipocyte Lipolysis.

Glucocorticoids promote lipolysis in white adipose tissue (WAT) to adapt to energy demands under stress, whereas superfluous lipolysis causes metabolic disorders, including dyslipidemia and hepatic steatosis. Glucocorticoid-induced lipolysis requires the phosphorylation of cytosolic hormone-sensitive lipase (HSL) and perilipin 1 (Plin1) in the lipid droplet by protein kinase A (PKA). We previously identified Pik3r1 (also called p85α) as a glucocorticoid receptor target gene. Here, we found that glucocorticoids increased HSL phosphorylation, but not Plin1 phosphorylation, in adipose tissue-specific Pik3r1-null (AKO) mice. Furthermore, in lipid droplets, the phosphorylation of HSL and Plin1 and the levels of catalytic and regulatory subunits of PKA were increased by glucocorticoids in wild-type mice. However, these effects were attenuated in AKO mice. In agreement with reduced WAT lipolysis, glucocorticoid- initiated hepatic steatosis and hypertriglyceridemia were improved in AKO mice. Our data demonstrated a novel role of Pik3r1 that was independent of the regulatory function of phosphoinositide 3-kinase in mediating the metabolic action of glucocorticoids. Thus, the inhibition of Pik3r1 in adipocytes could alleviate lipid disorders caused by excess glucocorticoid exposure

The ATLAS 5.5 GHz survey of the Extended Chandra Deep Field South: Catalogue, Source Counts and Spectral Indices

Star forming galaxies are thought to dominate the sub-mJy radio population, but recent work has shown that low luminosity AGN can still make a significant contribution to the faint radio source population. Spectral indices are an important tool for understanding the emission mechanism of the faint radio sources. We have observed the extended Chandra Deep Field South at 5.5 GHz using a mosaic of 42 pointings with the Australia Telescope Compact Array (ATCA). Our image reaches an almost uniform sensitivity of ~12 microJy rms over 0.25 deg^2 with a restoring beam of 4.9 x 2.0 arcsec, making it one of the deepest 6cm surveys to date. We present the 5.5 GHz catalogue and source counts from this field. We take advantage of the large amounts of ancillary data in this field to study the 1.4 to 5.5 GHz spectral indices of the sub-mJy population. For the full 5.5 GHz selected sample we find a flat median spectral index, alpha_med = -0.40, which is consistent with previous results. However, the spectral index appears to steepen at the faintest flux density levels (S_{5.5 GHz} < 0.1 mJy), where alpha_med = -0.68. We performed stacking analysis of the faint 1.4 GHz selected sample (40 < S_{1.4 GHz} < 200 microJy) and also find a steep average spectral index, alpha = -0.8, consistent with synchrotron emission. We find a weak trend of steepening spectral index with redshift. Several young AGN candidates are identified using spectral indices, suggesting Gigahertz Peaked Spectrum (GPS) sources are as common in the mJy population as they are at Jy levels.Comment: 18 pages, 16 figures, accepted for publication in MNRA

Unary Pushdown Automata and Straight-Line Programs

We consider decision problems for deterministic pushdown automata over a unary alphabet (udpda, for short). Udpda are a simple computation model that accept exactly the unary regular languages, but can be exponentially more succinct than finite-state automata. We complete the complexity landscape for udpda by showing that emptiness (and thus universality) is P-hard, equivalence and compressed membership problems are P-complete, and inclusion is coNP-complete. Our upper bounds are based on a translation theorem between udpda and straight-line programs over the binary alphabet (SLPs). We show that the characteristic sequence of any udpda can be represented as a pair of SLPs---one for the prefix, one for the lasso---that have size linear in the size of the udpda and can be computed in polynomial time. Hence, decision problems on udpda are reduced to decision problems on SLPs. Conversely, any SLP can be converted in logarithmic space into a udpda, and this forms the basis for our lower bound proofs. We show coNP-hardness of the ordered matching problem for SLPs, from which we derive coNP-hardness for inclusion. In addition, we complete the complexity landscape for unary nondeterministic pushdown automata by showing that the universality problem is $\Pi_2 \mathrm P$-hard, using a new class of integer expressions. Our techniques have applications beyond udpda. We show that our results imply $\Pi_2 \mathrm P$-completeness for a natural fragment of Presburger arithmetic and coNP lower bounds for compressed matching problems with one-character wildcards