Relationship, through geologic time, of days per lunar month to growth increments in fossil and recent molluscan shells Semiannual status report, 14 Sep. 1967 - 14 Mar. 1968

Relationship of geologic time and days per lunar month to growth patterns in fossil and recent molluscan shell

Rapid fluctuations in the high-energy X-ray flux from a source in Crux

Balloonborne X ray telescopic observations of two point sources in Cru

Detection of high-energy X-ray flare from a source in Crux

Balloonborne X ray telescopic observation of point source in Cru

Continual variations in the high energy X-ray flux from Sco X-1

Balloon X ray observations of intensity fluctuations in Sco X-

Problems in cow evaluation and current use of cow index report of a working group on cow evaluation

International audienc

XMM-Newton observation of 4U 1543-475: the X-ray spectrum of a stellar-mass black-hole at low luminosity

We report the results of an observation of the galactic black-hole binary 4U 1543-475 performed by XMM-Newton on 2002 August 18, about two months after the start of an outburst detected by Rossi-XTE. Despite the relatively low flux of the source, corresponding to a luminosity Lx ~ 4x10^34 erg/s (i.e. about 10^(-5) times the Eddington luminosity), we could obtain a good quality spectrum thanks to the high throughput of the XMM-Newton EPIC instrument. The spectrum is well fit by a power law with photon index 1.9-2 without any evidence for iron emission lines or for thermal emission from an accretion disk. We could estimate an upper-limit on the disk bolometric luminosity as a function of the colour temperature: it is always lower than ~10^33 erg/s, i.e. less than 10 % of the source total luminosity. Finally, we evaluated that the disk colour temperature must satisy the condition kTcol<0.25 keV in order to obtain an acceptable value for the disk inner radius.Comment: 4 pages, 3 figures, 2 tables. Accepted for publication by Astronomy & Astrophysics Letter

A Model for Emission from Jets in X-ray Binaries: Consequences of a Single Acceleration Episode

There are strong evidence for powerful jets in the low/hard state of black-hole X-ray binaries (BHXRBs). Here, we present a model in which electrons are accelerated once at the base of the jet, and are cooled by synchrotron emission and possible adiabatic energy losses. The accelerated electrons assume a Maxwellian distribution at low energies and possible energetic power law tail. These assumptions yield to a wealth of spectra, which we study in details. We identify critical values of the magnetic field, and five transition frequencies in the spectra. In particular, we show that: (I) the decay of the magnetic field along the jet enables, for wide jets, production of flat radio spectra without the need for electrons re-acceleration along the jet. (II) An increase of the magnetic field above a critical value of ~10^5 G leads to a sharp decrease in the flux at the radio band, while the flux at higher frequencies saturates to a constant value. (III) For strong magnetic field, the flux decays in the optical/UV band as F_nu ~ nu^{-1/2}, irrespective of the electrons initial distribution. (IV) For B_0 ~ 10^4 G, the X-ray flux gradually steepens. (V) With adiabatic energy losses, flat spectrum can be obtained only at a limited frequency range, and under certain conditions (VI) For narrow jets, r(x) ~ x^{alpha} with alpha < 1/2, flat radio spectrum cannot be obtained. We provide full description of the spectrum in the different scenarios, and show that our model is consistent with the key observed properties of BHXRBs.Comment: Slightly shortened; references added; accepted for publication in Ap

Processing of Body Odor Signals by the Human Brain

Brain development in mammals has been proposed to be promoted by successful adaptations to the social complexity as well as to the social and non-social chemical environment. Therefore, the communication via chemosensory signals might have been and might still be a phylogenetically ancient communication channel transmitting evolutionary significant information. In humans, the neuronal underpinnings of the processing of social chemosignals have been investigated in relation to kin recognition, mate choice, the reproductive state and emotional contagion. These studies reveal that human chemosignals are probably not processed within olfactory brain areas but through neuronal relays responsible for the processing of social information. It is concluded that the processing of human social chemosignals resembles the processing of social signals originating from other modalities, except that human social chemosignals are usually communicated without the allocation of attentional resources, that is below the threshold of consciousness. Deviances in the processing of human social chemosignals might be related to the development and maintenance of mental disorders