342,372 research outputs found
Enhanced Supernova Axion Emission and Its Implications
No full textWe calculate the axion emission rate from reactions involving thermal pions in matter encountered in supernovae and neutron star mergers, identify unique spectral features, and explore their implications for astrophysics and particle physics. We find that it is about 2-5 times larger than nucleon-nucleon bremsstrahlung, which in past studies was considered to be the dominant process. The axion spectrum is also found be much harder. Together, the larger rates and higher axion energies imply a stronger bound on the mass of the QCD axion and better prospects for direct detection in a large underground neutrino detector from a nearby galactic supernova
Biodynamics of the seated human body with dual-axis excitation: nonlinearity and cross-axis coupling
No full textThe apparent mass of the seated human body and the transmissibility to the upper-body (i.e., the spine and the pelvis) during vertical vibration excitation have been reported to have resonance frequencies around 5 Hz. With fore-and-aft excitation the apparent mass shows a first peak around 1 Hz and second mode around 2 to 3 Hz. Little is known about how the motion of the upper-body during excitation in one direction is affected by the addition of vibration in an orthogonal direction (i.e., the cross-axis coupling). The principal objective of the research reported in this thesis was to identify how the resonances in the apparent mass and transmissibility, and their association, depends on the magnitude of the inline vibration excitation and the addition of an orthogonal vibration excitation. The research was also designed to investigate the characteristics necessary in mathematical models that represent the cross-axis coupling and nonlinearity evident in the biodynamic responses of the human body.The movement of the body (over the first, fifth and twelfth thoracic vertebrae, the third lumbar vertebra, and the pelvis) in the fore-and-aft and vertical directions (and in pitch at the pelvis) was measured in 12 seated male subjects during random vertical vibration excitation (over the range 0.25 to 20 Hz) at three vibration magnitudes (0.25, 0.5 and 1.0 ms-2 r.m.s.) and during fore-and-aft vibration excitation over the same frequency range and at the same three vibration magnitudes. At the highest magnitude of vertical excitation the effect of adding fore-aft excitation (at 0.25, 0.5, and 1.0 ms-2 r.m.s.) was investigated. Similarly, at the highest magnitude of fore-and-aft excitation the effect of adding vertical vibration (at 0.25, 0.5, and 1.0 ms-2 r.m.s.) was investigated. The forces in the fore-and-aft and vertical directions on the seat surface were also measured so as to calculate apparent masses. The subjects adopted a normal upright posture, an erect posture, and a slouched posture. Resonance frequencies in the apparent mass and transmissibility during vertical excitation decreased with increasing magnitude of vertical excitation and with the addition of fore-and-aft excitation. The modulus of the first peak in the apparent mass and transmissibility during fore-and-aft excitation decreased with increasing magnitude of fore-and-aft excitation and with the addition of vertical excitation. Complex vibration modes in the upper-body appear to be responsible for the resonances in both the vertical and the fore-and-aft apparent masses. Compared to the normal upright posture, the erect posture tended to increase the resonance frequency in the apparent mass and transmissibility associated with vertical excitation but decrease the resonance frequency in the apparent mass and transmissibility associated with fore-and-aft excitation. The association between resonances in the transmissibility to the upper body and the resonance in the apparent mass varied with vertical excitation but not with fore-aft excitation.A seven degree-of-freedom multi-body model indicated that the resonance frequency in the vertical apparent mass on the seat and the vertical transmissibility to the upper-body with either vertical or dual-axis excitation is sensitive to the vertical stiffness of tissues beneath the pelvis and closely related to the vertical motion of the upper body. It has also been shown that the first mode of the fore-and-aft apparent mass and the fore-and-aft transmissibility can be attributed to the fore-and-aft movement of the upper-body due to the pelvis pitch, while the second mode can be attributed to the fore-and-aft movement of the upper-body caused by shear deformation of the pelvis tissue. It is suggested that a mathematical model developed with single-axis excitation can represent the biodynamic response with dual-axis excitation by changing these sensitive parameters (e.g., the stiffness of the tissue beneath the pelvis).A finite element human body model with flexible bodies representing the tissue beneath the pelvis and thighs and rigid bodies representing other body segments provided sensible prediction of the first resonance frequencies and the associated modulus in the vertical inline and fore-and-aft cross-axis apparent mass on the seat and the transmissibility to the lumbar spine, as well as the pressure distribution on the seat surface. With the flexible bodies assigned the material properties of nonlinear low density foam, the model was allowed to reflect the softening effect (i.e., a reduce in the resonance frequency of the vertical apparent mass) when the when the magnitude of the vertical excitation was increased
fore hook
No full textfore- prefixWell sometimes perhaps we wouldn't batten out,we'd only have three bend[s] - fore hook,midship bend an' after hook,we used to call 'em.YesDNE-citJ. D. A. WIDDOWSON JUL 1973Not usedNot usedWithdrawnStamped but not use
Observable signatures of enhanced axion emission from protoneutron stars
No full textWe perform general relativistic one-dimensional supernova (SN) simulations to identify observable signatures of enhanced axion emission from the pion-induced reaction π-+p→n+a inside a newly born protoneutron star (PNS). We focus on the early evolution after the onset of the supernova explosion to predict the temporal and spectral features of the neutrino and axion emission during the first 10 s. Pions are included as explicit new degrees of freedom in hot and dense matter. Their thermal population and their role in axion production are both determined consistently to include effects due to their interactions with nucleons. For a wide range of ambient conditions encountered inside a PNS, we find that the pion-induced axion production dominates over nucleon-nucleon bremsstrahlung processes. By consistently including the role of pions on the dense matter equation of state and on the energy loss, our simulations predict robust discernible features of neutrino and axion emission from a galactic supernova that can be observed in terrestrial detectors. For axion couplings that are compatible with current bounds, we find a significant suppression with time of the neutrino luminosity during the first 10 s. This suggests that current bounds derived from the neutrino signal from SN 1987A can be improved and that future galactic supernovae may provide significantly more stringent constraints
Cash holding or Net Debt, What is Relevant for Indonesian Firms?
No full textPaper investigates the firm level determinants of cash holdings by Indonesian firms. It also examines net debt as substitute measure for cash holding in firm’s financial policies. Sample comprises of 483 Indonesian companies listed on Indonesia stock exchange. Study finds that firms with robust cash flows, and higher cost of capital hold more cash. Firms holding greater noncash liquid assets have moderate cash holdings. Cash holding is most relevant for financially constrained firms, and growth firms. Net debt appears to be most relevant element for low growth firms. No hedging firms are indifferent about their cash holdings and net debt
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Nocturnal Emissions piece on the Fore Street sports bar, Fore Play.
No full textNocturnal Emissions piece on the Fore Street sports bar, Fore Play
Binocular coordination in fore/aft motion
No full textStabilization of images on the fovea during either fore/aft translation of a subject or fore/aft movement of a visual target in front of a stationary observer imposes complex geometrical requirements that depend upon the eccentricity of the object of interest with respect to the eyes. Each eye needs to be rotated independently with varying proportions of conjugate (version) and disconjugate (vergence) eye movements to maintain fixation of the target. Here, we describe binocular coordination in the early response to translational movements of normal subjects along their naso-occipital axis. We recorded the responses evoked by small (about 4 cm), abrupt (about 0.7 g), fore/aft translations in four normal subjects while they viewed a near target. In the for-ward and backward starting positions the target was 15 or 10.5 cm away, respectively. Each subject was tested with the target centered between the eyes, aligned on the right eye, and placed to the right of the right eye by ∼3 cm. The three conditions differed only in the lateral eccentricity of the target, yet the geometrical requirements for image stabilization are very different: pure vergence, one eye still, or mostly version. We found that the eye-movement responses closely matched what was needed for visual stabilization of the target, though responses to stimuli calling for divergence were less accurate than those for convergence. The latency of these responses ranged from 40 to 65 ms and achieved about 80% of the ideal response by 90 to 100 ms after the onset of the stimulus. Next, we asked whether these eye movements were generated by the vestibular system or by high-level strategies for image stabilization, such as pursuit. Thus, in a second set of experiments we used the mean profile of fore\aft body motion computed for each subject to drive a small visual target across the same distances and in the same eccentricities used during body translations. We found that visually driven responses had longer latencies (by at least 80 ms, ranging from 144 to 155 ms) and slower dynamics (with significantly lower peak eye velocities), highlighting the different subsystems producing the two types of responses. Saccades were also an important component of the response to both visual and vestibular stimuli, less frequent during the centered-target configuration and more frequent during viewing of eccentric targets. Visual stimuli evoked saccadic corrections more often and at shorter latencies than did vestibular stimuli. Both smooth and saccadic eye movements were appropriately disconjugate and their pattern depended on whether the eyes were converging or diverging. © 2005 New York Academy of Sciences
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