4,399 research outputs found
X-29A forward-swept-wing flight research program status
The X-29A aircraft is a fascinating combination of integrated technologies incorporated into a unique research aircraft. The X-29A program is multiple agency program with management and other responsibilities divided among NASA, DARPA, the U.S. Air Force, and the Grumman Corporation. An overview of the recently completed X-29A flight research program, objectives achieved, and a discussion of its future is presented. Also discussed are the flight test approach expanding the envelope, typical flight maneuvers performed, X-29A program accomplishments, lessons learned for the Number One aircraft, and future plans with the Number Two aircraft. A schedule for both aircraft is presented. A description of the unique technologies incorporated into the X-29A aircraft is given, along with descriptions of the onboard instrumentation system. The X-29A aircraft research program has proven highly successful. Using high fly rates from a very reliable experimental aircraft, the program has consistently met or exceeded its design and research goals
Syntheses of (+)-30-epi-, (-)-6-epi-, (±)-6,30-epi-13,14-didehydroxyisogarcinol and (±)-6,30-epi-garcimultiflorone A utilizing highly diastereoselective, Lewis acid-controlled cyclizations
The first syntheses of 13,14-didehydroxyisogarcinol (6) and garcimultiflorone A (5) stereoisomers are reported in six steps from a commercially available phloroglucinol. Lewis acid-controlled, diastereoselective cationic oxycyclizations enabled asymmetric syntheses of (-)-6-epi-6 and (+)-30-epi-6. A similar strategy enabled production of the meso-dervied isomers (±)-6,30-epi-6 and (±)-6,30-epi-5. Finally, a convenient strategy for gram scale synthesis was developed utilizing diastereomer separation at a later stage in the synthesis that minimized the number of necessary synthetic operations to access all possible stereoisomers.R01 GM073855 - NIGMS NIH HHS; R24 GM111625 - NIGMS NIH HHS; R35 GM118173 - NIGMS NIH HH
Comparison of The Kois Dento-Facial Analyzer System with an Earbow for Mounting a Maxillary Cast
Statement of problem: The Kois Dento-Facial Analyzer System (KDFA) is used by clinicians to mount maxillary casts and evaluate and treat patients. Limited information is available for understanding whether the KDFA should be considered as an alternative to an earbow.
Purpose: The purpose of this study was to evaluate maxillary casts mounted using the KDFA with casts mounted using Panadent\u27s Pana-Mount Facebow (PMF). Both articulation methods were compared against a lateral cephalometric radiograph.
Material and methods: Fifteen dried human skulls were used. Lateral cephalometric radiographs and 2 maxillary impressions were made of each skull. One cast from each skull was mounted on an articulator by means of the KDFA and the other by using the PMF. A standardized photograph of each articulation was made, and the distance from the articular center to the incisal edge position and the occlusal plane angle were measured. The distance from condylar center to the incisal edge and the occlusal plane angle were measured from cephalometric radiographs. Finally, the 3-dimensional position of each articulation was determined with a Panadent CPI-III. A randomized complete block design analysis of variance (RCBD) and post hoc tests (Tukey-Kramer HSD) (α=.05) were used to evaluate the occlusal plane angle and axis-central incisor distance. A paired 2-sample t test for means (α=.05) was used to compare the X, Y, and Z distance at the right and left condyle.
Results: The KDFA and PMF mounted the maxillary cast in a position that was not statistically different from the skull when comparing the occlusal plane angle (P=.165). Both the KDFA and the PMF located the maxillary central incisor edge position in a significantly different position compared with the skull (P=.001) but were not significantly different from each other. The 3-dimensional location of the maxillary casts varied at the condyles by approximately 9 to 10.3 mm.
Conclusion: The KDFA mounted the maxillary cast in a position that was not statistically different from the PMF when comparing the incisal edge position and the occlusal plane angle. Both the KDFA and the PMF located the maxillary incisal edge position in a significantly different position compared with the anatomic position on dried human skulls
General No-Scale Supergravity: An - Tale
We study the grand unification model flipped with additional
vector-like particle multiplets, or - for short, in the
framework of General No-Scale Supergravity. In our analysis we allow the
supersymmetry (SUSY) breaking soft terms to be generically non-zero, thereby
extending the phenomenologically viable parameter space beyond the highly
constrained one-parameter version of -. In this initial
inquiry, the mSUGRA/CMSSM SUSY breaking terms are implemented. We find this
easing away from the vanishing SUSY breaking terms enables a more broad mass
range of vector-like particles, dubbed flippons, including flippons less than 1
TeV that could presently be observed at the LHC2, as well as a lighter gluino
mass and SUSY spectrum overall. This presents heightened odds that the General
No-Scale - viable parameter space can be probed at the LHC2.
The phenomenology comprises both bino and higgsino dark matter, including a
Higgs funnel region. Particle states emerging from the SUSY cascade decays are
presented to experimentally distinguish amongst the diverse phenomenological
regions.Comment: 8 pages, 4 figures, 4 tables; Version accepted for publication in
Physics Letters
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The impact of liquidity on the valuation of European real estate securities
Purpose: The purpose of this paper is to test the hypothesis that the valuations of European real estate securities are, in part, determined by the relative liquidity in the companies’ shares.
Design/methodology/approach: Six groups are derived for our sample of European listed real estate companies. They are split between the UK and Europe, and then both sets are categorised by liquidity as large, medium or small. These are then tested for market depth, market tightness and difference in valuations over the cycle 2002-2012. Intuitively, it can be expected that the stock market valuation premium for companies with greater liquidity increases post the global financial crisis.
Findings: The key discriminating variable that drives companies’ liquidity and valuations is market capitalisation. For both the UK and Europe, the valuation premium of larger companies vs small companies has increased significantly since 2008 (by 20-40 per cent), which can be attributed to the increased value placed on liquidity post GFC.
Research limitations/implications: The sample size is relatively small, and subject to individual company influences on stock market valuation.
Practical implications: The key implications from the findings are the cost and quantum of new equity capital available to companies with superior liquidity, and the possibility of exclusion from portfolios for companies with low liquidity.
Originality/value: Previous studies have focussed on returns for measuring a liquidity premium. This study focusses on relative valuations and how the liquidity premium changes throughout the cycle
HiMAT flight program: Test results and program assessment overview
The Highly Manueverable Aircraft Technology (HiMAT) program consisted of design, fabrication of two subscale remotely piloted research vehicles (RPRVs), and flight test. This technical memorandum describes the vehicles and test approach. An overview of the flight test results and comparisons with the design predictions are presented. These comparisons are made on a single-discipline basis, so that aerodynamics, structures, flight controls, and propulsion controls are examined one by one. The interactions between the disciplines are then examined, with the conclusions that the integration of the various technologies contributed to total vehicle performance gains. An assessment is made of the subscale RPRV approach from the standpoint of research data quality and quantity, unmanned effects as compared with manned vehicles, complexity, and cost. It is concluded that the RPRV technique, as adopted in this program, resulted in a more complex and costly vehicle than expected but is reasonable when compared with alternate ways of obtaining comparable results
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Liquidity in global real estate securities markets
Purpose: The purpose of this paper is to test the relationship between liquidity in listed real estate markets, company size and geography during different market cycles, specifically pre-crisis (2002-2006) and post-crisis (2010-2014). Further, the study analyses the impact of stock liquidity on stock performance. In a previous study the authors examined the impact of liquidity on the valuation of European real estate shares. The result showed that there is a strong relationship between liquidity, valuation and market capitalisation post the Global Financial Crisis.
Design/methodology/approach: The paper studies the linkages between regional market liquidity and company size for 60 listed real estate companies globally and determines the key drivers of company stock market liquidity pre- and post-crisis as well as the impact on stock performance. Analysis of variance is used to test cross-sectional independence in market liquidity combined with the Tukey’s post hoc test. The selected test indicators of liquidity to capture market depth and market tightness are daily stock turnover as percentage of market capitalisation and daily bid-ask spreads.
Findings: Findings confirm previous studies that market liquidity factors are correlated globally over time indicating markets interdependence. However, sample groups by company size and geography form independent samples with different sample means, thus specific liquidity levels in each market may be different. First, stock turnover levels have not recovered post-crisis to pre-crisis levels in the majority of markets while spreads have continued moving downward to nearly insignificant levels in line with the rest of the equity market. Second, with regards to stock performance, the European bias previously detected is not apparent in the USA, and there is no evidence of the small cap vs large cap effect of small companies achieving superior returns, although smaller companies have outperformed in Europe and Asia in each of the last three years (2012-2014).
Practical implications: The key implication is that although spread levels for smaller companies are higher, implying a slight risk premium when investing in small companies, this did not manifest into consistent superior stock market returns in the periods studied. In a mature market such as the USA or UK, liquidity levels in terms of stock turnover are higher and spreads are lower thus reducing trading costs, making them more attractive for investors.
Originality/value: This research brings together previous analysis on stock market liquidity and stock performance on a global market level. It further tests the dependence of market liquidity on two key indicators, namely, geography and company size and analyses market changes with respect to liquidity pre- and post-crisi
Inspiration from Intersecting D-branes: General Supersymmetry Breaking Soft Terms in No-Scale -
Motivated by D-brane model building, we evaluate the - model
with additional vector-like particle multiplets, referred to as flippons,
within the framework of No-Scale Supergravity with non-vanishing general
supersymmetry breaking soft terms at the string scale. The viable phenomenology
is uncovered by applying all current experimental constraints, including but
not limited to the correct light Higgs boson mass, WMAP and Planck relic
density measurements, and several LHC constraints on supersymmetric particle
spectra. Four interesting regions of the parameter space arise, as well as
mixed scenarios, given by: (i) light stop coannihilation; (ii) pure Higgsino
dark matter; (iii) Higgs funnel; and (iv) light stau coannihilation. All
regions can generate the observed value of the relic density commensurate with
a 125 GeV light Higgs boson mass, with the exception of the relatively small
relic density value for the pure Higgsino lightest supersymmetric particle
(LSP). This work is concluded by gauging the model against present LHC search
constraints and derivation of the final states observable at the LHC for each
of these scenarios.Comment: 13 pages, 4 Figures, 4 Table
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