411 research outputs found
The measurement of rotary shaft seal film thickness.
SIGLEAvailable from British Library Document Supply Centre- DSC:D95582 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Relativistic theory of tidal Love numbers
In Newtonian gravitational theory, a tidal Love number relates the mass
multipole moment created by tidal forces on a spherical body to the applied
tidal field. The Love number is dimensionless, and it encodes information about
the body's internal structure. We present a relativistic theory of Love
numbers, which applies to compact bodies with strong internal gravities; the
theory extends and completes a recent work by Flanagan and Hinderer, which
revealed that the tidal Love number of a neutron star can be measured by
Earth-based gravitational-wave detectors. We consider a spherical body deformed
by an external tidal field, and provide precise and meaningful definitions for
electric-type and magnetic-type Love numbers; and these are computed for
polytropic equations of state. The theory applies to black holes as well, and
we find that the relativistic Love numbers of a nonrotating black hole are all
zero.Comment: 25 pages, 8 figures, many tables; final version to be published in
Physical Review
Defensive landscape architecture in modern public spaces
By 2030, we should have universal access to safe, inclusive, and accessible green and public places, especially for women and children, the elderly, and people with disabilities, according to the Sustainable Development Goals. However, the increasing privatisation of land and gentrification of the urban landscape is putting a limit on the amount of public space available for people to express themselves and use the city as they desire. This paper investigates and reviews the literature on defensive architecture, as well as its historical foundations, definitions, implementation, and reason for existence. The findings provide a clear reflection on the growing awareness of extreme defensive landscape architecture typologies such as spikes and other aggressive measures. Finally, the paper offers worldwide best-practice examples and recommendations for ensuring inclusion and safety in public spaces. We argue that in order to design sustainable public spaces, a holistic approach that considers both intangible values and social inclusion is required
Tidal torque induced by orbital decay in compact object binaries
As we observe in the moon-earth system, tidal interactions in binary systems
can lead to angular momentum exchange. The presence of viscosity is generally
regarded as the condition for such transfer to happen. In this paper, we show
how the orbital evolution can cause a persistent torque between the binary
components, even for inviscid bodies. This preferentially occurs at the final
stage of coalescence of compact binaries, when the orbit shrinks successively
by gravitational waves and plunging on a timescale shorter than the viscous
timescale. The total orbital energy transferred to the secondary by this torque
is ~0.01 of its binding energy. We further show that this persistent torque
induces a differentially rotating quadrupole perturbation. Specializing to the
case of a secondary neutron star, we find that this non equilibrium state has
an associated free energy of 10^47-10^48 erg, just prior to coalescence. This
energy is likely stored in internal fluid motions, with a sizable amount of
differential rotation. By tapping this free energy reservoir, a preexisting
weak magnetic field could be amplified up to a strength of ~10^15 Gauss. Such a
dynamically driven tidal torque can thus recycle an old neutron star into a
highly magnetized neutron star, with possible observational consequences at
merger.Comment: 14 pages, 8 figures, new sections added, accepted on Sept.19,
published on MNRA
Relativistic tidal properties of neutron stars
We study the various linear responses of neutron stars to external
relativistic tidal fields. We focus on three different tidal responses,
associated to three different tidal coefficients: (i) a gravito-electric-type
coefficient G\mu_\ell=[length]^{2\ell+1} measuring the \ell^{th}-order mass
multipolar moment GM_{a_1... a_\ell} induced in a star by an external
\ell^{th}-order gravito-electric tidal field G_{a_1... a_\ell}; (ii) a
gravito-magnetic-type coefficient G\sigma_\ell=[length]^{2\ell+1} measuring the
\ell^{th} spin multipole moment G S_{a_1... a_\ell} induced in a star by an
external \ell^{th}-order gravito-magnetic tidal field H_{a_1... a_\ell}; and
(iii) a dimensionless ``shape'' Love number h_\ell measuring the distortion of
the shape of the surface of a star by an external \ell^{th}-order
gravito-electric tidal field. All the dimensionless tidal coefficients
G\mu_\ell/R^{2\ell+1}, G\sigma_\l/R^{2\ell+1} and h_\ell (where R is the radius
of the star) are found to have a strong sensitivity to the value of the star's
``compactness'' c\equiv GM/(c_0^2 R) (where we indicate by c_0 the speed of
light). In particular, G\mu_\l/R^{2\l+1}\sim k_\ell is found to strongly
decrease, as c increases, down to a zero value as c is formally extended to the
``black-hole (BH) limit'' c^{BH}=1/2. The shape Love number h_\ell is also
found to significantly decrease as c increases, though it does not vanish in
the formal limit c\to c^{BH}. The formal vanishing of \mu_\ell and \sigma_\ell
as c\to c^{BH} is a consequence of the no-hair properties of black holes; this
suggests, but in no way proves, that the effective action describing the
gravitational interactions of black holes may not need to be augmented by
nonminimal worldline couplings.Comment: 21 pages, 10 figures. Matches the published versio
Evidence for D1 Dopamine Receptor Activation by a Paracrine Signal of Dopamine in Tick Salivary Glands
Ticks that feed on vertebrate hosts use their salivary secretion, which contains various bioactive components, to manipulate the host's responses. The mechanisms controlling the tick salivary gland in this dynamic process are not well understood. We identified the tick D1 receptor activated by dopamine, a potent inducer of the salivary secretion of ticks. Temporal and spatial expression patterns examined by immunohistochemistry and reverse transcription polymerase chain reaction suggest that the dopamine produced in the basal cells of salivary gland acini is secreted into the lumen and activates the D1 receptors on the luminal surface of the cells lining the acini. Therefore, we propose a paracrine function of dopamine that is mediated by the D1 receptor in the salivary gland at an early phase of feeding. The molecular and pharmacological characterization of the D1 receptor in this study provides the foundation for understanding the functions of dopamine in the blood-feeding of ticks
Spin and quadrupole contributions to the motion of astrophysical binaries
Compact objects in general relativity approximately move along geodesics of
spacetime. It is shown that the corrections to geodesic motion due to spin
(dipole), quadrupole, and higher multipoles can be modeled by an extension of
the point mass action. The quadrupole contributions are discussed in detail for
astrophysical objects like neutron stars or black holes. Implications for
binaries are analyzed for a small mass ratio situation. There quadrupole
effects can encode information about the internal structure of the compact
object, e.g., in principle they allow a distinction between black holes and
neutron stars, and also different equations of state for the latter.
Furthermore, a connection between the relativistic oscillation modes of the
object and a dynamical quadrupole evolution is established.Comment: 43 pages. Proceedings of the 524. WE-Heraeus-Seminar "Equations of
Motion in Relativistic Gravity". v2: fixed reference. v3: corrected typos in
eqs. (1), (57), (85
Shiga Toxin Binding to Glycolipids and Glycans
Background: Immunologically distinct forms of Shiga toxin (Stx1 and Stx2) display different potencies and disease outcomes, likely due to differences in host cell binding. The glycolipid globotriaosylceramide (Gb3) has been reported to be the receptor for both toxins. While there is considerable data to suggest that Gb3 can bind Stx1, binding of Stx2 to Gb3 is variable. Methodology: We used isothermal titration calorimetry (ITC) and enzyme-linked immunosorbent assay (ELISA) to examine binding of Stx1 and Stx2 to various glycans, glycosphingolipids, and glycosphingolipid mixtures in the presence or absence of membrane components, phosphatidylcholine, and cholesterol. We have also assessed the ability of glycolipids mixtures to neutralize Stx-mediated inhibition of protein synthesis in Vero kidney cells. Results: By ITC, Stx1 bound both Pk (the trisaccharide on Gb3) and P (the tetrasaccharide on globotetraosylceramide, Gb4), while Stx2 did not bind to either glycan. Binding to neutral glycolipids individually and in combination was assessed by ELISA. Stx1 bound to glycolipids Gb3 and Gb4, and Gb3 mixed with other neural glycolipids, while Stx2 only bound to Gb3 mixtures. In the presence of phosphatidylcholine and cholesterol, both Stx1 and Stx2 bound well to Gb3 or Gb4 alone or mixed with other neutral glycolipids. Pre-incubation with Gb3 in the presence of phosphatidylcholine and cholesterol neutralized Stx1, but not Stx2 toxicity to Vero cells
Risk to human health related to the presence of perfluoroalkyl substances in food
Acknowledgements: The Panel wishes to thank the following for their support provided to this scientific output as Hearing experts: Klaus Abraham, Esben Budtz-Jørgensen, Tony Fletcher, Philippe Grandjean, Hans Mielke and Hans Rumke and EFSA staff members: Davide Arcella, Marco Binaglia, Petra Gergelova, Elena Rovesti and Marijke Schutte. The Panel wishes to acknowledge all European competent institutions, Member State bodies and other organisations that provided data for this scientific output. The Panel would also like to thank the following authors and co-authors for providing additional information in relation to their respective studies: Berit Granum, Margie M Peden-Adams, Thomas Webster.Peer reviewedPublisher PD
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