1,357 research outputs found

    Traffic scenario generation technique for piloted simulation studies

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    Piloted simulation studies of cockpit traffic display concepts require the development of representative traffic scenarios. With the exception of specific aircraft interaction issues, most research questions can be addressed using traffic scenarios consisting of prerecorded aircraft movements merged together to form a desired traffic pattern. Prerecorded traffic scenarios have distinct research advantages, allowing control of traffic encounters with repeatability of scenarios between different test subjects. A technique is described for generation of prerecorded jet transport traffic scenarios suitable for use in piloted simulation studies. Individual flight profiles for the aircraft in the scenario are created interactively with a computer program designed specifically for this purpose. The profiles are then time-correlated and merged into a complete scenario. This technique was used to create traffic scenarios for the Denver, Colorado area with operations centered at Stapleton International Airport. Traffic scenarios for other areas may also be created using this technique, with appropriate modifications made to the navigation fix locations contained in the flight profile generation program

    Applications of Hilbert Module Approach to Multivariable Operator Theory

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    A commuting nn-tuple (T1,…,Tn)(T_1, \ldots, T_n) of bounded linear operators on a Hilbert space \clh associate a Hilbert module H\mathcal{H} over C[z1,…,zn]\mathbb{C}[z_1, \ldots, z_n] in the following sense: C[z1,…,zn]×H→H,(p,h)↦p(T1,…,Tn)h,\mathbb{C}[z_1, \ldots, z_n] \times \mathcal{H} \rightarrow \mathcal{H}, \quad \quad (p, h) \mapsto p(T_1, \ldots, T_n)h,where p∈C[z1,…,zn]p \in \mathbb{C}[z_1, \ldots, z_n] and h∈Hh \in \mathcal{H}. A companion survey provides an introduction to the theory of Hilbert modules and some (Hilbert) module point of view to multivariable operator theory. The purpose of this survey is to emphasize algebraic and geometric aspects of Hilbert module approach to operator theory and to survey several applications of the theory of Hilbert modules in multivariable operator theory. The topics which are studied include: generalized canonical models and Cowen-Douglas class, dilations and factorization of reproducing kernel Hilbert spaces, a class of simple submodules and quotient modules of the Hardy modules over polydisc, commutant lifting theorem, similarity and free Hilbert modules, left invertible multipliers, inner resolutions, essentially normal Hilbert modules, localizations of free resolutions and rigidity phenomenon. This article is a companion paper to "An Introduction to Hilbert Module Approach to Multivariable Operator Theory".Comment: 46 pages. This is a companion paper to arXiv:1308.6103. To appear in Handbook of Operator Theory, Springe

    A photometricity and extinction monitor at the Apache Point Observatory

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    An unsupervised software ``robot'' that automatically and robustly reduces and analyzes CCD observations of photometric standard stars is described. The robot measures extinction coefficients and other photometric parameters in real time and, more carefully, on the next day. It also reduces and analyzes data from an all-sky 10μm10 \mu m camera to detect clouds; photometric data taken during cloudy periods are automatically rejected. The robot reports its findings back to observers and data analysts via the World-Wide Web. It can be used to assess photometricity, and to build data on site conditions. The robot's automated and uniform site monitoring represents a minimum standard for any observing site with queue scheduling, a public data archive, or likely participation in any future National Virtual Observatory.Comment: accepted for publication in A

    Evaluation of Potential Protective Factors Against Metabolic Syndrome in Bottlenose Dolphins: Feeding and Activity Patterns of Dolphins in Sarasota Bay, Florida

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    Free-ranging bottlenose dolphins (Tursiops truncatus) living in Sarasota Bay, Florida appear to have a lower risk of developing insulin resistance and metabolic syndrome compared to a group of dolphins managed under human care. Similar to humans, differences in diet and activity cycles between these groups may explain why Sarasota dolphins have lower insulin, glucose, and lipids. To identify potential protective factors against metabolic syndrome, existing and new data were incorporated to describe feeding and activity patterns of the Sarasota Bay wild dolphin community. Sarasota dolphins eat a wide variety of live fish and spend 10–20% of daylight hours foraging and feeding. Feeding occurs throughout the day, with the dolphins eating small proportions of their total daily intake in brief bouts. The natural pattern of wild dolphins is to feed as necessary and possible at any time of the day or night. Wild dolphins rarely eat dead fish or consume large amounts of prey in concentrated time periods. Wild dolphins are active throughout the day and night; they may engage in bouts of each key activity category at any time during daytime. Dive patterns of radio-tagged dolphins varied only slightly with time of day. Travel rates may be slightly lower at night, suggesting a diurnal rhythm, albeit not one involving complete, extended rest. In comparison, the managed dolphins are older; often fed a smaller variety of frozen-thawed fish types; fed fish species not in their natural diet; feedings and engaged activities are often during the day; and they are fed larger but fewer meals. In summary, potential protective factors against metabolic syndrome in dolphins may include young age, activity, and small meals fed throughout the day and night, and specific fish nutrients. These protective factors against insulin resistance and type 2 diabetes are similar to those reported in humans. Further studies may benefit humans and dolphins

    The Isolation and Partial Characterization of Two Novel Sphingolipids from Neurospora crassa: Di(Inositolphosphoryl)ceramide and [(gal)_3glu]ceramide

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    Neurospora crassa strains labeled uniformly with ^(32)P_i and [^3H]inositol exhibit at least six phospholipid components containing ^3H when separated by paper chromatography. One of the major components is phosphatidylinositol. Other components, which account for 40 to 60% of the lipid-extractable ^3H in various strains, are stable to mild alkaline methanolysis and appear to be sphingolipids with equivalent amounts of inositol and phosphorus. The major phosphosphingolipid was purified by means of differential solubility and by column chromatography on porous silica beads. This substance contains equivalent amounts of hydroxysphinganine and hydroxytetracosanoic acid and 2 eq each of myoinositol, phosphorus, and sodium. Alkaline degradation yielded 2 eq of inositol monophosphate and periodate degradation gave a C-15 fragment. The elemental composition of this compound also fits the formulation, (inositol-P)_2-ceramide. A [^3H]inositol pulse-chase experiment carried out with an inositol-requiring mutant in exponential growth shows labeled inositol accumulating in the sphingolipid accompanied by decreased labeling in phosphatidylinositol and the acid-soluble fraction. These changes also occur when the chase is carried out during inositol starvation suggesting that degradation of phosphatidylinositol and formation of sphingolipid occurs in the absence of growth. A neutral glycosphingolipid was also obtained as a by-product of the phospholipid purification. This substance is provisionally formulated as the ceramide tetrahexoside: [(gal)_3glu]-N-hydroxytetracosonyl-hydroxysphinganine

    Embedding Flipped SU(5) into SO(10)

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    We embed the flipped SU(5) models into the SO(10) models. After the SO(10) gauge symmetry is broken down to the flipped SU(5) \times U(1)_X gauge symmetry, we can split the five/one-plets and ten-plets in the spinor \mathbf{16} and \mathbf{\bar{16}} Higgs fields via the stable sliding singlet mechanism. As in the flipped SU(5) models, these ten-plet Higgs fields can break the flipped SU(5) gauge symmetry down to the Standard Model gauge symmetry. The doublet-triplet splitting problem can be solved naturally by the missing partner mechanism, and the Higgsino-exchange mediated proton decay can be suppressed elegantly. Moreover, we show that there exists one pair of the light Higgs doublets for the electroweak gauge symmetry breaking. Because there exist two pairs of additional vector-like particles with similar intermediate-scale masses, the SU(5) and U(1)_X gauge couplings can be unified at the GUT scale which is reasonably (about one or two orders) higher than the SU(2)_L \times SU(3)_C unification scale. Furthermore, we briefly discuss the simplest SO(10) model with flipped SU(5) embedding, and point out that it can not work without fine-tuning.Comment: RevTex4, 28 pages, 3 figures, typos correcte

    'Surely the most natural scenario in the world’: Representations of ‘Family’ in BBC Pre-school Television

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    Historically, the majority of work on British children’s television has adopted either an institutional or an audience focus, with the texts themselves often overlooked. This neglect has meant that questions of representation in British children’s television – including issues such as family, gender, class or ethnicity - have been infrequently analysed in the UK context. In this article, we adopt a primarily qualitative methodology and analyse the various textual manifestations of ‘family’, group, or community as represented in a selected number of BBC pre-school programmes. In doing so, we question the (limited amount of) international work that has examined representations of the family in children’s television, and argue that nuclear family structures do not predominate in this sphere

    Paleomagnetism of Middle Tertiary Volcanic-Rocks from the Western Cascade Series, Northern California

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    The Western Cascade Series (WCS) is a 3.5-km-thick, crudely homoclinal (east dipping) calcalkaline volcanic sequence of mid-Oligocene to early Miocene age that crops out near the southern tip of the Cascade Range in northern California. The mean direction of remanent magnetization in the WCS is D, 4.9°; I, 57.6° (N, 53; k, 14.4; α95 , 5.3°). When compared to a reference direction for the North American cration, the WCS direction indicates that the southern Cascade Range has rotated 14.0° +/- 9.0° since the WCS accumulated. A difference in mean direction between the lower and upper halves of the WCS suggests that much of this rotation occurred during the late Oligocene. Six other paleomagnetic studies of rock units of an age roughly comparable to the WCS also are available from western Oregon, northwestern California, and southwestern Washington. All show statistically significant clockwise rotation (inclination of all but one are concordant). Comparison of directions indicates that the Pacific Northwest did not rotate as a rigid body, but neither did it behave as a collection of small, independently rotating domains. The amount of rotation found throughout the area increases to the west or northwest, suggesting a driving force for rotation operating at the continental margin

    Surveying Standard Model Flux Vacua on T6/Z2×Z2T^6/Z_2\times Z_2

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    We consider the SU(2)LxSU(2)R Standard Model brane embedding in an orientifold of T6/Z2xZ2. Within defined limits, we construct all such Standard Model brane embeddings and determine the relative number of flux vacua for each construction. Supersymmetry preserving brane recombination in the hidden sector enables us to identify many solutions with high flux. We discuss in detail the phenomenology of one model which is likely to dominate the counting of vacua. While Kahler moduli stabilization remains to be fully understood, we define the criteria necessary for generic constructions to have fixed moduli.Comment: 30 pages, LaTeX, v2: added reference
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