2,844 research outputs found
Ultrasonographic appearance of early embryonic mortality in buffalo (Bubalus bubalis)
Embryonic mortality is one of the main causes responsible of the decline in fertility that occurs in buffaloes during periods of increasing daylight length (out sexual breeding season). Transrectal ultrasonography for pregnancy diagnosis offers some advantages over palpation per rectum: earlier diagnosis of pregnancy/non-pregnancy, determination of embryo/fetus viability, reduction of misdiagnosis, and reduction of .potential. iatrogenic embryo/fetal attrition. Non pregnant buffaloes on Day 25 after AI showed higher Resistive Index (RI) (P<0.05) and Pulsatility Index (P=0.07) values, registered on CL on Days 10 after AI, compared to pregnant buffaloes. RI values were significantly higher (P=0.02) in non pregnant buffaloes also on Day 45 after AI. Colour Doppler sonography could be used to gain specific information relating to the ovarian blood flow in predicting early embryonic loss and to describe the ultrasonographic features of early embryonic death in buffaloes
Two-neutron transfer in nuclei close to the dripline
We investigate the two-neutron transfer modes induced by (t,p) reactions in
neutron-rich oxygen isotopes. The nuclear response to the pair transfer is
calculated in the framework of continuum-Quasiparticle Random Phase
Approximation (cQRPA). The cQRPA allows a consistent determination of the
residual interaction and an exact treatment of the continuum coupling. The
(t,p) cross sections are calculated within the DWBA approach and the form
factors are evaluated by different methods : macroscopically, following the
Bayman and Kallio method, and fully microscopically. The largest cross section
corresponds to a high-lying collective mode built entirely upon continuum
quasiparticle states.Comment: 12 pages, 7 figure
A Two-Threshold Model for Scaling Laws of Non-Interacting Snow Avalanches
The sizes of snow slab failure that trigger snow avalanches are power-law
distributed. Such a power-law probability distribution function has also been
proposed to characterize different landslide types. In order to understand this
scaling for gravity driven systems, we introduce a two-threshold 2-d cellular
automaton, in which failure occurs irreversibly. Taking snow slab avalanches as
a model system, we find that the sizes of the largest avalanches just
preceeding the lattice system breakdown are power law distributed. By tuning
the maximum value of the ratio of the two failure thresholds our model
reproduces the range of power law exponents observed for land-, rock- or snow
avalanches. We suggest this control parameter represents the material cohesion
anisotropy.Comment: accepted PR
Hamiltonian formulation and analysis of a collisionless fluid reconnection model
The Hamiltonian formulation of a plasma four-field fluid model that describes
collisionless reconnection is presented. The formulation is noncanonical with a
corresponding Lie-Poisson bracket. The bracket is used to obtain new
independent families of invariants, so-called Casimir invariants, three of
which are directly related to Lagrangian invariants of the system. The Casimirs
are used to obtain a variational principle for equilibrium equations that
generalize the Grad-Shafranov equation to include flow. Dipole and homogeneous
equilibria are constructed. The linear dynamics of the latter is treated in
detail in a Hamiltonian context: canonically conjugate variables are obtained;
the dispersion relation is analyzed and exact thresholds for spectral stability
are obtained; the canonical transformation to normal form is described; an
unambiguous definition of negative energy modes is given; and thresholds
sufficient for energy-Casimir stability are obtained. The Hamiltonian
formulation also is used to obtain an expression for the collisionless
conductivity and it is further used to describe the linear growth and nonlinear
saturation of the collisionless tearing mode.Comment: 4 figure
Radiative Neutrino Decay in Media
In this letter we introduce a new method to determine the radiative neutrino
decay rate in the presence of a medium. Our approach is based on the
generalisation of the optical theorem at finite temperature and density.
Differently from previous works on this subject, our method allows to account
for dispersive and dissipative electromagnetic properties of the medium. Some
inconsistencies that are present in the literature are pointed-out and
corrected here. We shortly discuss the relevance of our results for neutrino
evolution in the early universe.Comment: 11 pages, 3 encapsulated figure
Nuclear structure in strong magnetic fields: nuclei in the crust of a magnetar
Covariant density functional theory is used to study the effect of strong
magnetic fields, up to the limit predicted for neutron stars (for magnetars G), on nuclear structure. All new terms in the equation of
motion resulting from time reversal symmetry breaking by the magnetic field and
the induced currents, as well as axial deformation, are taken into account in a
self-consistent fashion. For nuclei in the iron region of the nuclear chart it
is found that fields in the order of magnitude of G significantly
affect bulk properties like masses and radii.Comment: 9 pages, 6 figure
Preliminary archaeometric analysis on a marble bas-relief of unknown origin
This paper addresses an archaeometric study of a marble bas-relief seized by the Cosenza Carabinieri Unit for the Protection of Cultural Heritage and Anti-Counterfeiting (Calabria, Italy). The research aimed to collect data on the authenticity of the artwork, providing indications about the compositional features of the sampled materials. An analytical approach based on the use of SEM-EDX and FT-IR techniques along with a stylistic evaluation of the artwork, allowed us to answer the requests posed by the institutions and to set the work in a different historical context from the Roman production
Constrained Simulations of the Magnetic Field in the Local Universe and the Propagation of UHECRs
We use simulations of LSS formation to study the build-up of magnetic fields
(MFs) in the ICM. Our basic assumption is that cosmological MFs grow in a MHD
amplification process driven by structure formation out of a seed MF present at
high z. Our LCDM initial conditions for the density fluctuations have been
statistically constrained by the observed galaxies, based on the IRAS 1.2-Jy
all-sky redshift survey. As a result, prominent galaxy clusters in our
simulation coincide closely with their real counterparts. We find excellent
agreement between RMs of our simulated clusters and observational data. The
improved resolution compared to previous work also allows us to study the MF in
large-scale filaments, sheets and voids. By tracing the propagation of UHE
protons in the simulated MF we construct full-sky maps of expected deflection
angles of protons with arrival energies E=1e20eV and 4e19eV, respectively.
Strong deflections are only produced if UHE protons cross clusters, however
covering only a small area on the sky. Multiple crossings of sheets and
filaments over larger distances may give rise to noticeable deflections,
depending on the model adopted for the magnetic seed field. Based on our
results we argue that over a large fraction of the sky the deflections are
likely to remain smaller than the present experimental angular sensitivity.
Therefore, we conclude that forthcoming air shower experiments should be able
to locate sources of UHE protons and shed more light on the nature of
cosmological MFs.Comment: 3revised version, JCAP, accepte
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