638 research outputs found
Developmentally regulated multisensory integration for prey localization in the medicinal leech
Medicinal leeches, like many aquatic animals, use water disturbances to localize their prey, so they need to be able to determine if a wave disturbance is created by prey or by another source. Many aquatic predators perform this separation by responding only to those wave frequencies representing their prey. As leeches' prey preference changes over the course of their development, we examined their responses at three different life stages. We found that juveniles more readily localize wave sources of lower frequencies (2 Hz) than their adult counterparts (8–12 Hz), and that adolescents exhibited elements of both juvenile and adult behavior, readily localizing sources of both frequencies. Leeches are known to be able to localize the source of waves through the use of either mechanical or visual information. We separately characterized their ability to localize various frequencies of stimuli using unimodal cues. Within a single modality, the frequency–response curves of adults and juveniles were virtually indistinguishable. However, the differences between the responses for each modality (visual and mechanosensory) were striking. The optimal visual stimulus had a much lower frequency (2 Hz) than the optimal mechanical stimulus (12 Hz). These frequencies matched, respectively, the juvenile and the adult preferred frequency for multimodally sensed waves. This suggests that, in the multimodal condition, adult behavior is driven more by mechanosensory information and juvenile behavior more by visual. Indeed, when stimuli of the two modalities were placed in conflict with one another, adult leeches, unlike juveniles, were attracted to the mechanical stimulus much more strongly than to the visual stimulus
Long-Duration Human Habitation Beyond Low-Earth Orbit: Why is the Near Future Critical?
For more than a decade, habitation systems capable of comfortable human occupation and effective operations beyond low-Earth orbit (LEO) for more than a few weeks have been a priority recommendation to NASA. This capability is a lynch pin for human exploration beyond the Earth-Moon system. Here we describe briefly some relevant concepts and discuss justifications in the current political and financial environment for why near-term human habitation systems beyond LEO is an imperative
Constitutional Convention
Billings Gazette special issue about the Montana Constitutional Convention and government information articles pertaining to the subject. Included is a list of 1972 delegates.https://digitalcommons.mtech.edu/crucible_materials/1007/thumbnail.jp
Potential Science Missions Enabled by NASA's Planned Ares V
NASA s planned Ares V cargo vehicle with its 10 meter diameter fairing and ~60,000 kg payload mass to L2 offers the potential to launch entirely new classes of space science missions such as 8-meter monolithic aperture telescopes, 12-meter aperture x-ray telescopes, 16 to 24 meter segmented telescopes and highly capable outer planet missions. The paper will summarize the current Ares V baseline performance capabilities and review potential mission concepts enabled by these capabilities
Potential Astrophysics Science Missions Enabled by NASA's Planned Ares V
NASA s planned Ares V cargo vehicle with its 10 meter diameter fairing and ~60,000 kg payload mass to L2 offers the potential to launch entirely new classes of space science missions such as 8-meter monolithic aperture telescopes, 12- meter aperture x-ray telescopes, 16 to 24 meter segmented telescopes and highly capable outer planet missions. The paper will summarize the current Ares V baseline performance capabilities and review potential mission concepts enabled by these capabilities
Timing of UHT metamorphism at Mather Peninsula in Rauer Islands: Zircon and monazite U-Th-Pb and rare earth elements chemistry constraints
第6回極域科学シンポジウム[OG] 地圏11月16日(月) 国立極地研究所3階セミナー
Going Beyond Gadgets: The Importance of Scalability for Analogue Quantum Simulators
We propose a theoretical framework for analogue quantum simulation to capture
the full scope of experimentally realisable simulators, motivated by a set of
fundamental criteria first introduced by Cirac and Zoller. Our framework is
consistent with Hamiltonian encodings used in complexity theory, is stable
under noise, and encompasses a range of possibilities for experiment, such as
the simulation of open quantum systems and overhead reduction using
Lieb-Robinson bounds. We discuss the requirement of scalability in analogue
quantum simulation, and in particular argue that simulation should not involve
interaction strengths that grow with the size of the system. We develop a
general framework for gadgets used in Hamiltonian complexity theory, which may
be of interest independently of analogue simulation, and in particular prove
that size-dependent scalings are unavoidable in Hamiltonian locality reduction.
However, if one allows for an additional resource of engineered dissipation, we
demonstrate a scheme that circumvents the locality reduction no-go theorem
using the quantum Zeno effect. Our gadget framework opens the door to formalise
and resolve long-standing open questions about gadgets. We conclude with a
discussion on universality results in analogue quantum simulation.Comment: 52 pages, 12 figures; revised proof of proposition 16 and slightly
strengthened result, typos corrected, references added, minor edits to
abstract and main tex
Ares V and Future Very Large Launch Vehicles to Enable Major Astronomical Missions
The current NASA architecture intended to return humans to the lunar surface includes the Ares V cargo launch vehicle, which is planned to be available within a decade. The capabilities designed for Ares V would permit an 8.8-m diameter, 55 mT payload to be carried to Sun-Earth L1,2 locations. That is, this vehicle could launch very large optical systems to achieve major scientific goals that would otherwise be very difficult. For example, an 8-m monolith UV/visual/IR telescope appears able to be launched to a Sun-Earth L2 location. Even larger apertures that are deployed or assembled seem possible. Alternatively, multiple elements of a spatial array or two or three astronomical observatories might be launched simultaneously. Over the years, scientists and engineers have been evaluating concepts for astronomical observatories that use future large launch vehicles. In this presentation, we report on results of a recent workshop held at NASA Ames Research Center that have improved understanding of the science goals that can be achieved using Ares V. While such a vehicle uniquely enables few of the observatory concepts considered at the workshop, most have a baseline mission that can be flown on existing or near-future vehicles. However, the performance of the Ares V permits design concepts (e.g., large monolithic mirrors) that reduce complexity and risk
FJ44 Turbofan Engine Test at NASA Glenn Research Center's Aero-Acoustic Propulsion Laboratory
A Williams International FJ44-3A 3000-lb thrust class turbofan engine was tested in the NASA Glenn Research Center s Aero-Acoustic Propulsion Laboratory. This report presents the test set-up and documents the test conditions. Farfield directivity, in-duct unsteady pressures, duct mode data, and phased-array data were taken and are reported separately
- …