5,851 research outputs found
Space market model space industry input-output model
The goal of the Space Market Model (SMM) is to develop an information resource for the space industry. The SMM is intended to contain information appropriate for decision making in the space industry. The objectives of the SMM are to: (1) assemble information related to the development of the space business; (2) construct an adequate description of the emerging space market; (3) disseminate the information on the space market to forecasts and planners in government agencies and private corporations; and (4) provide timely analyses and forecasts of critical elements of the space market. An Input-Output model of market activity is proposed which are capable of transforming raw data into useful information for decision makers and policy makers dealing with the space sector
Cluster and field elliptical galaxies at z~1.3. The marginal role of the environment and the relevance of the galaxy central regions
We compared the properties of 56 elliptical galaxies selected from three
clusters at with those of field galaxies in the GOODS-S (~30),
COSMOS (~180) and CANDELS (~220) fields. We studied the relationships among
effective radius, surface brightness, stellar mass, stellar mass density
and central mass density within 1 kpc radius. We
find that cluster ellipticals do not differ from field ellipticals: they share
the same structural parameters at fixed mass and the same scaling relations. On
the other hand, the population of field ellipticals at shows a
significant lack of massive ( M) and large (R kpc) ellipticals with respect to the cluster. Nonetheless, at
M, the two populations are similar. The size-mass
relation of ellipticals at z~1.3 defines two different regimes, above and below
a transition mass M: at lower masses the
relation is nearly flat (R), the mean radius is
constant at ~1 kpc and while, at larger masses,
the relation is R. The transition mass marks the
mass at which galaxies reach the maximum . Also the
-mass relation follows two different regimes,
, defining a transition mass
density M pc. The mass density
does not correlate with mass, dense/compact galaxies can be
assembled over a wide mass regime, independently of the environment. The
central mass density, , besides to be correlated with the mass,
is correlated to the age of the stellar population: the higher the central
stellar mass density, the higher the mass, the older the age of the stellar
population. [Abridged]Comment: Accepted for publication in A&A; 20 pages, 13 figures (replaced to
match the A&A version
Four Loop Result in Lattice Gauge Theory by a Stochastic Method: Lattice Correction to the Condensate
We describe a stochastic technique which allows one to compute numerically
the coefficients of the weak coupling perturbative expansion of any observable
in Lattice Gauge Theory. The idea is to insert the exponential representation
of the link variables into the
Langevin algorithm and the observables and to perform the expansion in
\beta^{-1/2}. The Langevin algorithm is converted into an infinite hierarchy of
maps which can be exactly truncated at any order. We give the result for the
simple plaquette of SU(3) up to fourth loop order (\beta^{-4}) which extends by
one loop the previously known series.Comment: 9 pages. + 5 figures (postscript) appended at the end, (University of
Parma, Dept.of Physics, report uprf-397-1994
Age, metallicity and star formation history of spheroidal galaxies in cluster at z~1.2
We present the analysis, based on spectra collected at the Large Binocular
Telescope, of the stellar populations in seven spheroidal galaxies in the
cluster XLSSJ0223 at 1.22. The aim is to constrain the epoch of their
formation and their star formation history. Using absorption line strenghts and
full spectral fitting, we derive for the stellar populations of the seven
spheroids a median age =2.40.6 Gyr, corresponding to a median
formation redshift $\sim2.6_{-0.5}^{+0.7}$ (lookback time =
11$_{-1.0}^{+0.6}$ Gyr). We find a significant scatter in age, showing that
massive spheroids, at least in our targeted cluster, are not coeval. The median
metallicity is [Z/H]=0.09$\pm$0.16, as for early-types in clusters at
0$<z<<\sigma_e_{dyn}\Sigma_e_{dyn}\Sigma_e_{dyn}\Sigma_ez\sim1.3$, i.e.
more massive spheroids are more metal rich, have lower stellar mass density and
tend to be older than lower-mass galaxies.Comment: 16 pages, 6 figures, 6 tables, published on MNRA
Additional Soft Jets in Production at the Tevatron \pp Collider
A large fraction of top quark events in \pp collisions at 1.8\ \TeV will
contain additional soft hadronic jets from gluon bremsstrahlung off the quarks
and gluons in the hard processes \qq, gg \to \tt \to \bb \ww. These extra
jets can cause complications when attempting to reconstruct from the
invariant mass of combinations of final-state quarks and leptons. We show how
such soft radiation cannot be unambiguously associated with either
initial-state radiation or or with final-state radiation off the quarks.
The top quarks can radiate too, and in fact the pattern of radiation has a very
rich structure, which depends on the orientation of the final-state particles
with respect to each other and with respect to the beam. We calculate the full
radiation pattern of soft jets in the soft gluon approximation and compare with
several approximate forms which are characteristic of parton shower Monte
Carlos. The implications for top mass measurements are discussed.Comment: plain LaTeX, 13 pages plus 9 figures included as a separate uuencoded
file (or avail. from authors); DTP/94/60, UR-136
The Sources of b-Quarks at the Tevatron and their Correlations
The leading-log order QCD hard scattering Monte-Carlo models of HERWIG,
ISAJET, and PYTHIA are used to study the sources of b-quarks at the Tevatron.
The reactions responsible for producing b and bbar quarks are separated into
three categories; flavor creation, flavor excitation, and
parton-shower/fragmentation. Flavor creation corresponds to the production of a
b-bbar pair by gluon fusion or by annihilation of light quarks, while flavor
excitation corresponds to a b or bbar quark being knocked out of the
initial-state by a gluon or a light quark or antiquark. The third source occurs
when a b-bbar pair is produced within a parton shower or during the
fragmentation process of a gluon or a light quark or antiquark (includes gluon
splitting). The QCD Monte-Carlo models indicate that all three sources of
b-quarks are important at the Tevatron and when combined they qualitatively
describe the inclusive cross-section data. Correlations between the b and bbar
quark are very different for the three sources and can be used to isolate the
individual contributions.Comment: RevTex4, 14 pages, 20 figures, submitted to Phys. Rev.
Non-susceptible landslide areas in Italy and in the Mediterranean region
Abstract. We used landslide information for 13 study areas in Italy and morphometric information obtained from the 3-arcseconds shuttle radar topography mission digital elevation model (SRTM DEM) to determine areas where landslide susceptibility is expected to be negligible in Italy and in the landmasses surrounding the Mediterranean Sea. The morphometric information consisted of the local terrain slope which was computed in a square 3 × 3-cell moving window, and in the regional relative relief computed in a circular 15 × 15-cell moving window. We tested three different models to classify the "non-susceptible" landslide areas, including a linear model (LNR), a quantile linear model (QLR), and a quantile, non-linear model (QNL). We tested the performance of the three models using independent landslide information presented by the Italian Landslide Inventory (Inventario Fenomeni Franosi in Italia – IFFI). Best results were obtained using the QNL model. The corresponding zonation of non-susceptible landslide areas was intersected in a geographic information system (GIS) with geographical census data for Italy. The result determined that 57.5% of the population of Italy (in 2001) was located in areas where landslide susceptibility is expected to be negligible. We applied the QNL model to the landmasses surrounding the Mediterranean Sea, and we tested the synoptic non-susceptibility zonation using independent landslide information for three study areas in Spain. Results showed that the QNL model was capable of determining where landslide susceptibility is expected to be negligible in the validation areas in Spain. We expect our results to be applicable in similar study areas, facilitating the identification of non-susceptible landslide areas, at the synoptic scale
Charge asymmetry in hadroproduction of heavy quarks
A sizeable difference in the differential production cross section of top and
antitop quarks, respectively, is predicted for hadronically produced heavy
quarks. It is of order and arises from the interference between
charge odd and even amplitudes respectively. For the TEVATRON it amounts to
approximately 5-10% in the region where the cross section is large and could
therefore be measured in the next round of experiments. At the LHC the
asymmetry can be studied by selecting appropriately chosen kinematical regions.Comment: LaTeX, 5pp, 5 figures, uses revtex. The complete paper, including
figures, is also available via anonymous ftp at
ftp://ttpux2.physik.uni-karlsruhe.de/ , or via www at
http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints/ Final version as
published in Phys.Rev.Let
Statistical hadronization and hadronic microcanonical ensemble I
We present a full treatment of the microcanonical ensemble of the ideal
hadron-resonance gas in a quantum-mechanical framework which is appropriate for
the statistical model of hadronization. By using a suitable transition operator
for hadronization we are able to recover the results of the statistical theory,
particularly the expressions of the rates of different channels. Explicit
formulae are obtained for the phase space volume or density of states of the
ideal relativistic gas in quantum statistics which, for large volumes, turn to
a cluster decomposition whose terms beyond the leading one account for
Bose-Einstein and Fermi-Dirac correlations. The problem of the computation of
the microcanonical ensemble and its comparison with the canonical one, which
will be the main subject of a forthcoming paper, is addressed.Comment: 15 pages, LaTeX macros svjour.cls and svepj.clo needed, revised
version to be published in Eur. Phys. J.
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