15,584 research outputs found
CHARTS FOR EQUILIBRIUM FLOW PROPERTIES OF AIR IN HYPERVELOCITY NOZZLES
Charts for equilibrium flow properties of air in hypervelocity nozzle
Reflection positive affine actions and stochastic processes
In this note we continue our investigations of the representation theoretic
aspects of reflection positivity, also called Osterwalder--Schrader positivity.
We explain how this concept relates to affine isometric actions on real Hilbert
spaces and how this is connected with Gaussian processes with stationary
increments
Effects of Tariffication: Tariffs, Quotas and VERs under Monopolistic Competition
Recent rounds of GATT and later WTO have advocated widespread tariffication, meaning that existing non-tariff barriers be converted into import equivalent tariffs. From an economic point of view, the effects of such tariffication are not entirely clear. The paper presents a general equilibrium model with monopolistic competition to examine the welfare effects of tariffication. The ranking of pre- and post-tariffication welfare depends crucially on the nature of the initial trade barrier and the tariff tool applied. Tariffication using a specific (an ad valorem) tariff results in the same (a reduced) welfare level compared to an initial quota, whereas welfare is increased (the same) compared to an initial VER.Trade policy, tariffication, specific tariff, ad valorem tariff, quota, VER
Tariffs and Firm-Level Heterogeneous Fixed Export Costs
Recent literature on the workhorse model of intra-industry trade has explored heterogeneous cost structures at the firm level. These approaches have proven to add realism and predictive power. This note shows, however, that this added realism also implies that there may exist a positive bilateral tariff that maximizes national and world welfare. Applying one of the simplest specifications possible, namely a symmetric two-country intra-industry trade model with fixed export costs that are heterogeneous across firms, we find that the reciprocal reduction of small tariffs reduces welfare.Optimal tariff; Welfare; Intra-industry trade; Monopolistic competition; Protectionism
The Possible z=0.83 Precursors of z=0 M* Early-type Cluster Galaxies
We examine the distribution of stellar masses of galaxies in MS 1054-03 and
RX J0152.7-1357, two X-ray selected clusters of galaxies at z=0.83. Our stellar
mass estimates, from spectral energy distribution fitting, reproduce the
dynamical masses as measured from velocity dispersions and half-light radii
with a scatter of 0.2 dex in the mass for early-type galaxies. When we restrict
our sample of members to high stellar masses, > 1e11.1 Msun (M* in the
Schechter mass function for cluster galaxies), we find that the fraction of
early-type galaxies is 79 +/- 6% at z=0.83 and 87 +/- 6% at z=0.023 for the
Coma cluster, consistent with no evolution. Previous work with
luminosity-selected samples finds that the early-type fraction in rich clusters
declines from =~80% at z=0 to =~60% at z=0.8. The observed evolution in the
early-type fraction from luminosity-selected samples must predominately occur
among sub-M* galaxies. As M* for field and group galaxies, especially
late-types, is below M* for clusters galaxies, infall could explain most of the
recent early-type fraction growth. Future surveys could determine the
morphological distributions of lower mass systems which will confirm or refute
this explanation.Comment: 5 pages in emulate ApJ format with three color figures. Accepted for
publication in ApJ Letters, v642n2. Updated to correct grammatical and
typographic errors found by the journa
Asymptotic Behavior of Ext functors for modules of finite complete intersection dimension
Let be a local ring, and let and be finitely generated
-modules such that has finite complete intersection dimension. In this
paper we define and study, under certain conditions, a pairing using the
modules \Ext_R^i(M,N) which generalizes Buchweitz's notion of the Herbrand
diference. We exploit this pairing to examine the number of consecutive
vanishing of \Ext_R^i(M,N) needed to ensure that \Ext_R^i(M,N)=0 for all
. Our results recover and improve on most of the known bounds in the
literature, especially when has dimension at most two
Synthesis and Stoichiometry of MgB2
The system MgxB2 has been investigated to investigate possible
nonstoichiometry in MgB2. When synthesized at 850oC, MgB2 is a line compound
with a possible Mg vacancy content of about 1%. Small changes in lattice
constants as a function of starting composition result from grain interaction
stresses, whose character is different in the Mg-rich, near-stoichiometric, and
Mg-deficient regimes. A small linear decrease of the superconducting transition
temperature, Tc, in the Mg-rich regime results from accidental impurity doping.Comment: Accepted for publication in Physica C. 24 pages, 7 figure
On The Linearity of The Black Hole - Bulge Mass Relation in Active and in Nearby Galaxies
Analysis of PG quasar observations suggests a nonlinear relation between the
black hole mass, M_BH, and the bulge mass, M_bulge, although a linear relation,
as proposed for nearby galaxies, cannot be ruled out. New M_BH values for
nearby galaxies from Gebhardt et al., and L_bulge measurements for Seyfert 1
galaxies from Virani et al., are used here to obtain a more accurate value for
the slope of the M_BH-M_bulge relation. The combined sample of 40 active and
non-active galaxies suggests a significantly nonlinear relation, M_BH\propto
M_bulge^{1.53\pm 0.14}. Further support for a nonlinear relation is provided by
the slope of the M_BH-stellar velocity dispersion relation found recently, and
by the low M_BH found in late type spiral galaxies. The mean M_BH/M_bulge ratio
is therefore not a universal constant, but rather drops from ~0.5% in bright
(M_V ~ -22) ellipticals, to ~0.05% in low luminosity (M_V ~ -18) bulges. Hubble
Space Telescope determinations of M_BH in late type spirals, and of the bulge
magnitude in narrow line Seyfert 1 galaxies (both predicted to have low M_BH),
can further test the validity of the nonlinear M_BH-M_bulge relation.Comment: Accepted for publication in ApJ, 9 pages inc. 2 figure
A statistical study of the global structure of the ring current
[1] In this paper we derive the average configuration of the ring current as a function of the state of the magnetosphere as indicated by the Dst index. We sort magnetic field data from the Combined Release and Radiation Effects Satellite (CRRES) by spatial location and by the Dst index in order to produce magnetic field maps. From these maps we calculate local current systems by taking the curl of the magnetic field. We find both the westward (outer) and the eastward (inner) components of the ring current. We find that the ring current intensity varies linearly with Dst as expected and that the ring current is asymmetric for all Dst values. The azimuthal peak of the ring current is located in the afternoon sector for quiet conditions and near midnight for disturbed conditions. The ring current also moves closer to the Earth during disturbed conditions. We attempt to recreate the Dst index by integrating the magnetic perturbations caused by the ring current. We find that we need to multiply our computed disturbance by a factor of 1.88 ± 0.27 and add an offset of 3.84 ± 4.33 nT in order to get optimal agreement with Dst. When taking into account a tail current contribution of roughly 25%, this agrees well with our expectation of a factor of 1.3 to 1.5 based on a partially conducting Earth. The offset that we have to add does not agree well with an expected offset of approximately 20 nT based on solar wind pressure
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