5,832 research outputs found
Xanthogranulomatous endometritis
Xanthogranulomatous inflammatory changes of the endometrium are rare and appear to be related to obstructive changes in the endocervical canal. An elderly patient with an advanced squamous carcinoma of the cervix uteri presented with this condition. Other similar cases are discussed in relation to aetiology and pathogenesis.peer-reviewe
Depósitos de glaciares rocosos en Sierra Nevada (Granada)
En las cumbres de Sierra Nevada aparecen depósitos de morfologia
acordonada que están constituidos por acumulaciones de cantos
angulosos de gran tamaño y una pequeña o nula proporción en matriz.
Estos han sido interpretados como depósitos de glaciares rocosos,
generados en una última crisis climatica acontecida entre los 13.000
y 10.000 años B.PAmong the variety of deposits in the high mountain zone of Sierra
Nevada, some coarse-grained detritic acumulations are worthy to remark.
These appear related to glacial scarps and have been interpreted
as ancien rock glaciers deposits. Two types have been distinguished:
the first has a string-like morfology, the matrix is very scarce and hollow
can be found between the pebbles; the second tends to show lobulate
forms and higher contents of matrix. In both cases the pebbles
are extremely angular and heterometric. The mechanism which probably
originated these depositional forms has been gravitational displacing
of a rock fragments mass with interstitial ice, wich confered
a plastic behaviour to the assemblage. The age for these processes
is estimate between 13.000 and 10.000 years B.
The star-forming environment of a ULX in NGC 4559: an optical study
We have studied the candidate optical counterparts and the stellar population
in the star-forming complex around a bright ULX in NGC4559, using HST/WFPC2,
XMM-Newton/OM, and ground-based data. We find that the ULX is located near a
small group of OB stars. The brightest point source in the Chandra error circle
is consistent with a single blue supergiant of mass ~ 20 M_sun and age ~ 10
Myr. A few other stars are resolved inside the error circle: mostly blue and
red supergiants with masses ~ 10-15 M_sun and ages ~ 20 Myr. This is consistent
with the interpretation of this ULX as a black hole (BH) accreting from a
high-mass donor star in its supergiant phase, via Roche-lobe overflow. The
observed optical colors and the blue-to-red supergiant ratio suggest a low
metal abundance: 0.2 <~ Z/Z_sun <~ 0.4 (Padua tracks), or 0.05 <~ Z/Z_sun <~
0.2 (Geneva tracks). The age of the star-forming complex is <~ 30 Myr. H-alpha
images show that this region has a ring-like appearance. We propose that it is
an expanding wave of star formation, triggered by an initial density
perturbation, in a region where the gas was only marginally stable to
gravitational collapse. A possible trigger was the collision with a satellite
dwarf galaxy, visible a few arcsec north-west of the complex, going through the
gas-rich outer disk of NGC4559. The X-ray data favour a BH more massive (M > 50
M_sun) than typical Milky Way BH candidates. The optical data favour a
``young'' BH originating in the recent episode of massive star formation;
however, they also rule out an association with young massive star clusters. We
speculate that other mechanisms may lead to the formation of relatively massive
BHs (~ 50-100 M_sun) from stellar evolution processes in low-metallicity
environments, or when star formation is triggered by galactic collisions.Comment: MNRAS accepted, 19 pages. Contact the first author for
full-resolution picture
Internal energy fluctuations of a granular gas under steady uniform shear flow
The stochastic properties of the total internal energy of a dilute granular
gas in the steady uniform shear flow state are investigated. A recent theory
formulated for fluctuations about the homogeneous cooling state is extended by
analogy with molecular systems. The theoretical predictions are compared with
molecular dynamics simulation results. Good agreement is found in the limit of
weak inelasticity, while systematic and relevant discrepancies are observed
when the inelasticity increases. The origin of this behavior is discussed
The Enskog equation for confined elastic hard spheres
A kinetic equation for a system of elastic hard spheres or disks confined by
a hard wall of arbitrary shape is derived. It is a generalization of the
modified Enskog equation in which the effects of the confinement are taken into
account and it is supposed to be valid up to moderate densities. From the
equation, balance equations for the hydrodynamic fields are derived,
identifying the collisional transfer contributions to the pressure tensor and
heat flux. A Lyapunov functional, , is identified. For any
solution of the kinetic equation, decays monotonically in time
until the system reaches the inhomogeneous equilibrium distribution, that is a
Maxwellian distribution with a the density field consistent with equilibrium
statistical mechanics
International Evidence on Stochastic and Deterministic Monetary Neutrality.
We analyze the issue of the impact of multiple breaks on monetary neutrality results, using a long annual international data set. We empirically verify whether neutrality propositions remain addressable (and if so, whether they hold or not), when unit root tests are carried out allowing for multiple structural breaks in the long-run trend function of the variables. It is found that conclusions on neutrality are sensitive to the number and location of breaks. In order to interpret the evidence for structural breaks, we introduce a notion of deterministic monetary neutrality, which naturally arises in the absence of permanent stochastic shocks to the variables.Deterministic and Stochastic Neutrality and Superneutrality of Money, Unit Roots, Structural Breaks, Resampling Methods
Rheological effects in the linear response and spontaneous fluctuations of a sheared granular gas
The decay of a small homogeneous perturbation of the temperature of a dilute
granular gas in the steady uniform shear flow state is investigated. Using
kinetic theory based on the inelastic Boltzmann equation, a closed equation for
the decay of the perturbation is derived. The equation involves the generalized
shear viscosity of the gas in the time-dependent shear flow state, and
therefore it predicts relevant rheological effects beyond the quasi-elastic
limit. A good agreement is found when comparing the theory with molecular
dynamics simulation results. Moreover, the Onsager postulate on the regression
of fluctuations is fulfilled
- …