1,474 research outputs found
Ultrahigh Energy Nuclei in the Galactic Magnetic Field
Observations are consistent with a significant fraction of heavy nuclei in
the cosmic ray flux above a few times 10^19 eV. Such nuclei can be deflected
considerably in the Galactic magnetic field, with important implications for
the search of their sources. We perform detailed simulations of heavy nuclei
propagation within recent Galactic magnetic field models. While such models are
not yet sufficiently constrained to predict deflection maps in detail, we find
general features of the distribution of (de-) magnified flux from sources.
Since in most theoretical models sources of heavy nuclei are located in the
local large scale structure of galaxies, we show examples of images of several
nearby galaxy clusters and of the supergalactic plane. Such general features
may be useful to develop efficient methods for source reconstruction from
observed ultrahigh energy cosmic ray arrival directions.Comment: 17 pages, 11 figures. Published in JCA
Pulmonary hypertension in patients with chronic myeloproliferative disorders
Pulmonary hypertension (PH) is a major complication of several haematological disorders. Chronic myeloproliferative diseases (CMPDs) associated with pulmonary hypertension have been included in group five of the clinical classification for pulmonary hypertension, corresponding to pulmonary hypertension for which the aetiology is unclear and/or multifactorial. The aim of this review is to discuss the epidemiology, pathogenic mechanism and treatment approaches of the more common forms of pulmonary hypertension in the context of CMPD\u2019s: chronic thromboembolic pulmonary hypertension, precapillary pulmonary hypertension and drug-induced PH
Cosmic String Spacetime in Dilaton Gravity and Flat Rotation Curves
In dilaton gravity theories, we consider a string-like topological defect
formed during U(1) gauge symmetry-breaking phase transition in the early
Universe, and far from the cosmic string we have vacuum solutions of the
generalized Einstein equation. We discuss how they can be related to the
flatness of galactic rotation curves.Comment: 9 pages, RevTeX4 fil
Spontaneous childbirth-related mental images among pregnant women: a mixed-method study.
Mental imagery may reflect the present, past or future. Childbirth is often anticipated with joy but also in some cases with fear, which may negatively impact on the childbirth experience. So far, research on birth-related mental imagery in pregnancy is lacking. This study aimed to investigate in detail the phenomenology of spontaneous childbirth-related mental images and the association between main imagery characteristics (valence, positive/negative percentage ratio and impact on behaviour and decision-making) and fear of childbirth.
A concurrent triangulation mixed methods design was employed. Thirty-seven nulliparous, French-speaking women, aged ≥ 18 years in their third trimester of pregnancy completed self-report questionnaires assessing fear of childbirth, spontaneous use of mental imagery, prenatal depression and trait anxiety, and participated in a mental imagery interview to assess spontaneous childbirth-related mental images. Women with a prenatal diagnosis of malformation were excluded.
All participants reported having spontaneous mental images of their impending childbirth. The images captured were rich in detail and included a variety of sensory modalities. More positive mental images were associated with less fear of childbirth (r = -0.533, p = .008) and women who had a higher proportion of negative mental images had a higher fear of childbirth (r = 0.428, p = .005). The impact of the most negative mental images on behaviour and decision-making was positively correlated with fear of childbirth (r = 0.342, p = .038).
Our results indicate that negative spontaneous childbirth-related imagery is associated with fear of childbirth. Intervention techniques could be developed that focus on enhancing positive childbirth-related mental images during pregnancy and thus fostering a more positive childbirth experience
A_4 Symmetry and Lepton Masses and Mixing
Stimulated by Ma's idea which explains the tribimaximal neutrino mixing by
assuming an A_4 flavor symmetry, a lepton mass matrix model is investigated. A
Frogatt-Nielsen type model is assumed, and the flavor structures of the masses
and mixing are caused by the VEVs of SU(2)_L-singlet scalars \phi_i^u and
\phi_i^d (i=1,2,3), which are assigned to {\bf 3} and ({\bf 1}, {\bf 1}',{\bf
1}'') of A_4, respectively.Comment: 13 pages including 1 table, errors in Sec.7 correcte
Seesaw Mass Matrix Model of Quarks and Leptons with Flavor-Triplet Higgs Scalars
In a seesaw mass matrix model M_f = m_L M_F^{-1} m_R^\dagger with a universal
structure of m_L \propto m_R, as the origin of m_L (m_R) for quarks and eptons,
flavor-triplet Higgs scalars whose vacuum expectation values v_i are
proportional to the square roots of the charged lepton masses m_{ei}, i.e. v_i
\propto \sqrt{m_{ei}}, are assumed. Then, it is investigated whether such a
model can explain the observed neutrino masses and mixings (and also quark
masses and mixings) or not.Comment: version accepted by EPJ
Neutrino Large Mixing in Universal Yukawa Coupling Model with Small Violation
We have analyzed the possibility that the universal Yukawa coupling
(democratic mass matrix) with small violations of Dirac and Majorana neutrinos
can induce the large mixing of neutrinos through the seesaw mechanism. The
possibility can be achieved by the condition that the violation parameters of
Majorana neutrinos are sufficiently smaller than the violation parameters of
Dirac neutrinos. Allowed regions of the violation parameters producing the
observed neutrino mass hierarchy and large neutrino mixing are not so
restricted at present in contrast to the violation parameters for quark sector.Comment: 14 pages, 4figure
Interaction of global and local monopoles
We study the direct interaction between global and local monopoles. While in
two previous papers, the coupling between the two sectors was only indirect
through the coupling to gravity, we here introduce a new term in the potential
that couples the Goldstone field and the Higgs field directly. We investigate
the influence of this term in curved space and compare it to the results
obtained previously.Comment: 9 Revtex pages, 4 ps-figure
Percolation on the average and spontaneous magnetization for q-states Potts model on graph
We prove that the q-states Potts model on graph is spontaneously magnetized
at finite temperature if and only if the graph presents percolation on the
average. Percolation on the average is a combinatorial problem defined by
averaging over all the sites of the graph the probability of belonging to a
cluster of a given size. In the paper we obtain an inequality between this
average probability and the average magnetization, which is a typical extensive
function describing the thermodynamic behaviour of the model
Universal Seesaw Mass Matrix Model with an S_3 Symmetry
Stimulated by the phenomenological success of the universal seesaw mass
matrix model, where the mass terms for quarks and leptons f_i (i=1,2,3) and
hypothetical super-heavy fermions F_i are given by \bar{f}_L m_L F_R +\bar{F}_L
m_R f_R + \bar{F}_L M_F F_R + h.c. and the form of M_F is democratic on the
bases on which m_L and m_R are diagonal, the following model is discussed: The
mass terms M_F are invariant under the permutation symmetry S_3, and the mass
terms m_L and m_R are generated by breaking the S_3 symmetry spontaneously. The
model leads to an interesting relation for the charged lepton masses.Comment: 8 pages + 1 table, latex, no figures, references adde
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