7,905 research outputs found
Reefing system
A mechanical device for receiving a cable and controlling the motion of the cable is described. The cable moves freely in one direction and movement is resisted in the opposite direction until the forces exerted on the cable exceed a predetermined amount. Exceeding the minimum amount of force permits the cable to move in the opposite direction. Diagrams of the device are included
Binocular device for displaying numerical information in field of view
An apparatus is described for superimposing numerical information on the field of view of binoculars. The invention has application in the flying of radio-controlled model airplanes. Information such as airspeed and angle of attack are sensed on a model airplane and transmitted back to earth where this information is changed into numerical form. Optical means are attached to the binoculars that a pilot is using to track the model air plane for displaying the numerical information in the field of view of the binoculars. The device includes means for focusing the numerical information at infinity whereby the user of the binoculars can see both the field of view and the numerical information without refocusing his eyes
Late-time vacuum phase transitions: Connecting sub-eV scale physics with cosmological structure formation
We show that a particular class of postrecombination phase transitions in the
vacuum can lead to localized overdense regions on relatively small scales,
roughly 10^6 to 10^10 M_sun, potentially interesting for the origin of large
black hole seeds and for dwarf galaxy evolution. Our study suggests that this
mechanism could operate over a range of conditions which are consistent with
current cosmological and laboratory bounds. One byproduct of phase transition
bubble-wall decay may be extra radiation energy density. This could provide an
avenue for constraint, but it could also help reconcile the discordant values
of the present Hubble parameter (H_0) and sigma_8 obtained by cosmic microwave
background (CMB) fits and direct observational estimates. We also suggest ways
in which future probes, including CMB considerations (e.g., early dark energy
limits), 21-cm observations, and gravitational radiation limits, could provide
more stringent constraints on this mechanism and the sub-eV scale
beyond-standard-model physics, perhaps in the neutrino sector, on which it
could be based. Late phase transitions associated with sterile neutrino mass
and mixing may provide a way to reconcile cosmological limits and laboratory
data, should a future disagreement arise.Comment: 17 pages, 18 figures. v2: includes additional references and minor
corrections/clarifications. v3: includes additional text, figures, and
references (matches published version
Effect of afterbody geometry and sting diameter on the aerodynamic characteristics of slender bodies at mach numbers from 1.57 to 2.86
Afterbody geometry and sting diameter effect on aerodynamics of slender bodies at supersonic spee
Neutrino Flavor Evolution in Neutron Star Mergers
We examine the flavor evolution of neutrinos emitted from the disk-like
remnant (hereafter called \lq\lq neutrino disk\rq\rq) of a binary neutron star
(BNS) merger. We specifically follow the neutrinos emitted from the center of
the disk, along the polar axis perpendicular to the equatorial plane. We
carried out two-flavor simulations using a variety of different possible
initial neutrino luminosities and energy spectra, and for comparison,
three-flavor simulations in specific cases. In all simulations, the normal
neutrino mass hierarchy was used. The flavor evolution was found to be highly
dependent on the initial neutrino luminosities and energy spectra; in
particular, we found two broad classes of results depending on the sign of the
initial net electron neutrino lepton number (i.e., the number of neutrinos
minus the number of antineutrinos). In the antineutrino dominated case, we
found that the Matter-Neutrino Resonance (MNR) effect dominates, consistent
with previous results, whereas in the neutrino dominated case, a bipolar
spectral swap develops. The neutrino dominated conditions required for this
latter result have been realized, e.g, in a BNS merger simulation that employs
the \lq\lq DD2\rq\rq\ equation of state for neutron star matter[Phys. Rev. D
93, 044019 (2016)]. For this case, in addition to the swap at low energies, a
collective Mikheyev-Smirnov-Wolfenstein (MSW) mechanism generates a high-energy
electron neutrino tail. The enhanced population of high-energy electron
neutrinos in this scenario could have implications for the prospects of
-process nucleosynthesis in the material ejected outside the plane of the
neutrino disk.Comment: Version published in Physical Review D. 22 pages, 16 figures, 9
tables. For movies see Ancillary files in version
Description of a landing site indicator (LASI) for light aircraft operation
An experimental cockpit mounted head-up type display system was developed and evaluated by LaRC pilots during the landing phase of light aircraft operations. The Landing Site Indicator (LASI) system display consists of angle of attack, angle of sideslip, and indicated airspeed images superimposed on the pilot's view through the windshield. The information is made visible to the pilot by means of a partially reflective viewing screen which is suspended directly in frot of the pilot's eyes. Synchro transmitters are operated by vanes, located at the left wing tip, which sense angle of attack and sideslip angle. Information is presented near the center of the display in the form of a moving index on a fixed grid. The airspeed is sensed by a pitot-static pressure transducer and is presented in numerical form at the top center of the display
The effects of day and night temperature on Chrysanthemum morifolium: investigating the safe limits for temperature integration
The impact of day and night temperatures on pot chrysanthemum (cultivars ‘Covington’ and ‘Irvine’) was assessed by exposing cuttings, stuck in weeks 39, 44, and 49, to different temperature regimes in short-days. Glasshouse heating setpoints of 12°, 15°, 18°, and 21°C, were used during the day, with venting at 2°C above these set-points. Night temperatures were then automatically manipulated to ensure that all of the treatments achieved similar mean diurnal temperatures. Plants were grown according to commercial practice and the experiment was repeated over 2 years. Increasing the day temperature from approx. 19°C to 21°C, and compensating by reducing the night temperature, did not have a significant impact on flowering time, although plant height was increased.This suggests that a temperature integration strategy which involves higher vent temperatures, and exploiting solar gain to give higher than normal day temperatures, should have minimal impact on crop scheduling. However, lowering the day-time temperature to approx. 16°C, and compensating with a warmer night, delayed flowering by up to 2 weeks. Therefore, a strategy whereby, in Winter, more heat is added at night under a thermally-efficient blackout screen may result in flowering delays.Transfers between the temperature regimes showed that the flowering delays were proportional to the amount of time spent in a low day-time temperature regime. Plants flowered at the same time, irrespective of whether they were transferred on a 1-, 2-, or 4-week cycle
Understanding the cognitive aspects of human error will increase the usability of user interfaces.
Understanding the cognitive aspects of human error will increase the usability of user interfaces. It is important to study the cognitive aspects of human error because many disasters have been attributed to operator errors. Creating usable interfaces that reduce the likelihood of error will save industries a great deal of money and may even save human lives. A greater understanding of human errors can be obtained by examining the psychological basis of errors, the methods used to study errors, some of the problems associated with studying errors and different types of errors. Next, the current research findings can then be applied to user interfaces to reduce the probability of user errors. Then, a web survey system, phpESP, will be analyzed based on the guidelines for reducing human error in user interfaces. The analysis of the survey system can server as a guide to help designers reduce potential user errors
DExD/H box RNA helicases: multifunctional proteins with important roles in transcriptional regulation
The DExD/H box family of proteins includes a large number of proteins that play important roles in RNA metabolism. Members of this family have been shown to act as RNA helicases or unwindases, using the energy from ATP hydrolysis to unwind RNA structures or dissociate RNA–protein complexes in cellular processes that require modulation of RNA structures. However, it is clear that several members of this family are multifunctional and, in addition to acting as RNA helicases in processes such as pre-mRNA processing, play important roles in transcriptional regulation. In this review I shall concentrate on RNA helicase A (Dhx9), DP103 (Ddx20), p68 (Ddx5) and p72 (Ddx17), proteins for which there is a strong body of evidence showing that they play important roles in transcription, often as coactivators or corepressors through their interaction with key components of the transcriptional machinery, such as CREB-binding protein, p300, RNA polymerase II and histone deacetylases
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Business Models and Modelling
International audienceThe business model topic has generated a lot of discussion since the phrase first gained currency in academic articles the late 1990s (Zott, Amit & Massa, 2011). This growing attention culminated in the 2010 Long Range Planning Special Issue that brought the field’s leading scholars together to answer questions about what the business model was and what was its purpose. A key point that emerged was that a business model is more than a statement of how “value is created and captured”; it is a ‘model’ - and, like many other kinds of models - can appear in many guises and serve many purposes. These include being a ‘manipulable device’ that can be used to help academics or managers understand the linkages between value creation and value capture more clearly; as well as being an artefact that can be used to convey knowledge about a business and its status to others (see for instance, Morgan and Morrison, 1999; Teece, 2010, Baden-Fuller & Morgan, 2010)
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