11,738 research outputs found
The increasing-returns-to-scale/sticky- price approach to monetary analysis
Economies of scale ; Monetary theory
Sidereal time analysis as a toll for the study of the space distribution of sources of gravitational waves
Gravitational wave (GW) detectors operating on a long time range can be used
for the study of space distribution of sources of GW bursts or to put strong
upper limits on the GW signal of a wide class of source candidates. For this
purpose we propose here a sidereal time analysis to analyze the output signal
of GW detectors. Using the characteristics of some existing detectors, we
demonstrate the capability of the sidereal time analysis to give a clear
signature of different localizations of GW sources: the Galactic Center, the
Galactic Plane, the Supergalactic plane, the Great Attractor. On the contrary,
a homogeneous 3D-distribution of GW sources gives a signal without features. In
this paper we consider tensor gravitational waves with randomly oriented
polarization. We consider GW detectors at fixed positions on the Earth, and a
fixed orientation of the antenna.Comment: 7 pages, 6 figure
Female impersonation as an alternative reproductive strategy in giant cuttlefish
Out of all the animals, cephalopods possess an unrivalled ability to change their shape and body patterns. Our observations of giant cuttlefish (Sepia apama) suggest this ability has allowed them to evolve alternative mating strategies in which males can switch between the appearance of a female and that of a male in order to foil the guarding attempts of larger males. At a mass breeding aggregation in South Australia, we repeatedly observed single small males accompanying mating pairs. While doing so, the small male assumed the body shape and patterns of a female. Such males were never attacked by the larger mate-guarding male. On more than 20 occasions, when the larger male was distracted by another male intruder, these small males, previously indistinguishable from a female, were observed to change body pattern and behaviour to that of a male in mating display. These small males then attempted to mate with the female, often with success. This potential for dynamic sexual mimicry may have played a part in driving the evolution of the remarkable powers of colour and shape transformation which characterize the cephalopods
Dissociation of CH4 by electron impact: Production of metastable hydrogen and carbon fragments
Metastable fragments produced by electron impact excitation of CH4 have been investigated for incident electron energies from threshold to 300 eV. Only metastable hydrogen and carbon atoms were observed. Onset energies for the production of metastable hydrogen atoms were observed at electron impact energies of 22.0 + or - .5 eV, 25.5 + or - .6 eV, 36.7 + or - .6 eV and 66 + or - 3 eV, and at 26.6 + or - .6 eV for the production of metastable carbon atoms. Most of the fragments appear to have been formed in high-lying Rydberg states. The total metastable hydrogen cross section reaches a maximum value of approximately 1 X 10 to the minus 18th power sq cm at 100 eV. At the same energy, the metastable carbon cross section is 2 x 10 to the minus 19th power sq cm
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S-Geranylgeranyl-L-glutathione is a ligand for human B cell-confinement receptor P2RY8.
Germinal centres are important sites for antibody diversification and affinity maturation, and are also a common origin of B cell malignancies. Despite being made up of motile cells, germinal centres are tightly confined within B cell follicles. The cues that promote this confinement are incompletely understood. P2RY8 is a Gα13-coupled receptor that mediates the inhibition of migration and regulates the growth of B cells in lymphoid tissues1,2. P2RY8 is frequently mutated in germinal-centre B cell-like diffuse large B cell lymphoma (GCB-DLBCL) and Burkitt lymphoma1,3-6, and the ligand for this receptor has not yet been identified. Here we perform a search for P2RY8 ligands and find P2RY8 bioactivity in bile and in culture supernatants of several mouse and human cell lines. Using a seven-step biochemical fractionation procedure and a drop-out mass spectrometry approach, we show that a previously undescribed biomolecule, S-geranylgeranyl-L-glutathione (GGG), is a potent P2RY8 ligand that is detectable in lymphoid tissues at the nanomolar level. GGG inhibited the chemokine-mediated migration of human germinal-centre B cells and T follicular helper cells, and antagonized the induction of phosphorylated AKT in germinal-centre B cells. We also found that the enzyme gamma-glutamyltransferase-5 (GGT5), which was highly expressed by follicular dendritic cells, metabolized GGG to a form that did not activate the receptor. Overexpression of GGT5 disrupted the ability of P2RY8 to promote B cell confinement to germinal centres, which indicates that GGT5 establishes a GGG gradient in lymphoid tissues. This work defines GGG as an intercellular signalling molecule that is involved in organizing and controlling germinal-centre responses. As the P2RY8 locus is modified in several other types of cancer in addition to GCB-DLBCL and Burkitt lymphoma, we speculate that GGG might have organizing and growth-regulatory roles in multiple human tissues
Swift Pointing and the Association Between Gamma-Ray Bursts and Gravitational-Wave Bursts
The currently accepted model for gamma-ray burst phenomena involves the
violent formation of a rapidly rotating solar mass black hole. Gravitational
waves should be associated with the black-hole formation, and their detection
would permit this model to be tested, the black hole progenitor (e.g.,
coalescing binary or collapsing stellar core) identified, and the origin of the
gamma rays (within the expanding relativistic fireball or at the point of
impact on the interstellar medium) located. Even upper limits on the
gravitational-wave strength associated with gamma-ray bursts could constrain
the gamma-ray burst model. To do any of these requires joint observations of
gamma-ray burst events with gravitational and gamma-ray detectors. Here we
examine how the quality of an upper limit on the gravitational-wave strength
associated with gamma-ray burst observations depends on the relative
orientation of the gamma-ray-burst and gravitational-wave detectors, and apply
our results to the particular case of the Swift Burst-Alert Telescope (BAT) and
the LIGO gravitational-wave detectors. A result of this investigation is a
science-based ``figure of merit'' that can be used, together with other mission
constraints, to optimize the pointing of the Swift telescope for the detection
of gravitational waves associated with gamma-ray bursts.Comment: aastex, 14 pages, 2 figure
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