9,639 research outputs found
X-Ray Emission from the Warm Hot Intergalactic Medium
The number of detected baryons in the Universe at z<0.5 is much smaller than
predicted by standard big bang nucleosynthesis and by the detailed observation
of the Lyman alpha forest at red-shift z=2. Hydrodynamical simulations indicate
that a large fraction of the baryons today is expected to be in a ``warm-hot''
(10^5-10^7K) filamentary gas, distributed in the intergalactic medium. This
gas, if it exists, should be observable only in the soft X-ray and UV bands.
Using the predictions of a particular hydrodynamic model, we simulated the
expected X-ray flux as a function of energy in the 0.1-2 keV band due to the
Warm-Hot Intergalactic Medium (WHIM), and compared it with the flux from local
and high red-shift diffuse components. Our results show that as much as 20% of
the total diffuse X-ray background (DXB) in the energy range 0.37-0.925keV
could be due to X-ray flux from the WHIM, 70% of which comes from filaments at
redshift z between 0.1 and 0.6. Simulations done using a FOV of 3', comparable
with that of Suzaku and Constellation-X, show that in more than 20% of the
observations we expect the WHIM flux to contribute to more than 20% of the DXB.
These simulations also show that in about 10% of all the observations a single
bright filament in the FOV accounts, alone, for more than 20% of the DXB flux.
Red-shifted oxygen lines should be clearly visible in these observations.Comment: 19 pages, 6 figure
Rhythmic Motion of a Droplet under a DC Electric Field
The effect of a stationary electric field on a water droplet with a diameter
of several tens micrometers in oil was examined. Such a droplet exhibits
repetitive translational motion between the electrodes in a spontaneous manner.
The state diagram of this oscillatory motion was deduced; at 0-20 V the droplet
is fixed at the surface of the electrode, at 20-70 V the droplet exhibits
small-amplitude oscillatory motion between the electrodes, and at 70-100 V the
droplet shows large-amplitude periodic motion between the electrodes. The
observed rhythmic motion is explained in a semi-quantitative manner by using
differential equations, which includes the effect of charging the droplet under
an electric field. We also found that twin droplets exhibit synchronized
rhythmic motion between the electrodes
Ownership Structure, Investment Behavior and Firm Performance in Japanese Manufacturing Industries
Using data spanning the 1996-1998 fiscal years of 247 of Japan's largest manufacturers, we empirically evaluate the extent to which a firm's investment behavior and financial performance is influenced by its ownership structure. To do so, we examine six distinct categories of Japanese shareholders: foreign investors, investment funds, pen sion funds, banks and insurance companies, affiliated companies and insiders. Our findings strongly indicate that the relationship between the equity stakes of a particular category of investor and a firm's financial performance and investment behavior is highly idiosyncratic. Such a result emphasizes the importance of making finely grained and contextually relevant distinctions when modeling and evaluating corporate governance relations.corporate governance;performance;Japan;investment behaviour;ownership
Muon capture in the front end of the IDS neutrino factory
We discuss the design of the muon capture front end of the neutrino factory
International Design Study. In the front end, a proton bunch on a target
creates secondary pions that drift into a capture transport channel, decaying
into muons. A sequence of rf cavities forms the resulting muon beams into
strings of bunches of differing energies, aligns the bunches to (nearly) equal
central energies, and initiates ionization cooling. The muons are then
accelerated to high energy where their decays provide neutrino beams. For the
International Design Study (IDS), a baseline design must be developed and
optimized for an engineering and cost study. We present a baseline design that
can be used to establish the scope of a future neutrino Factory facility.Comment: 3 pp. 1st International Particle Accelerator Conference: IPAC'10,
23-28 May 2010: Kyoto, Japa
On the dynamical structure of the Trojan group of asteroids
Using a semi-analytical approach, domains of possible motion for Trojan asteroids were established. It is shown that stable librating motion is possible for both high inclination and high eccentricity. Frequency distributions were also produced for real Trojan asteroids, against differing libration amplitudes and libration periods
Holographic storage of multiple coherence gratings in a Bose-Einstein condensate
We demonstrate superradiant conversion between a two-mode collective atomic
state and a single-mode light field in an elongated cloud of Bose-condensed
atoms. Two off-resonant write beams induce superradiant Raman scattering,
producing two independent coherence gratings with a different wave vector in
the cloud. By applying phase-matched read beams after a controllable delay, the
gratings can be selectively converted into the light field also in a
superradiant way. Due to the large cooperativity parameter and the small
velocity width of the condensate, a high conversion efficiency of % and
a long storage time of s were achieved.Comment: 5 pages, 4 figure
Why is the condensed phase of DNA preferred at higher temperature? DNA compaction in the presence of a multivalent cation
Upon the addition of multivalent cations, a giant DNA chain exhibits a large
discrete transition from an elongated coil into a folded compact state. We
performed single-chain observation of long DNAs in the presence of a
tetravalent cation (spermine), at various temperatures and monovalent salt
concentrations. We confirmed that the compact state is preferred at higher
temperatures and at lower monovalent salt concentrations. This result is
interpreted in terms of an increase in the net translational entropy of small
ions due to ionic exchange between higher and lower valence ions.Comment: 4pages,3figure
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