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The Role of the Brain in the Pathogenesis and Physiology of Polycystic Ovary Syndrome (PCOS).
Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder, affecting at least 10% of women of reproductive age. PCOS is typically characterized by the presence of at least two of the three cardinal features of hyperandrogenemia (high circulating androgen levels), oligo- or anovulation, and cystic ovaries. Hyperandrogenemia increases the severity of the condition and is driven by increased luteinizing hormone (LH) pulse secretion from the pituitary. Indeed, PCOS women display both elevated mean LH levels, as well as an elevated frequency of LH pulsatile secretion. The abnormally high LH pulse frequency, reflective of a hyperactive gonadotropin-releasing hormone (GnRH) neural circuit, suggests a neuroendocrine basis to either the etiology or phenotype of PCOS. Several studies in preclinical animal models of PCOS have demonstrated alterations in GnRH neurons and their upstream afferent neuronal circuits. Some rodent PCOS models have demonstrated an increase in GnRH neuron activity that correlates with an increase in stimulatory GABAergic innervation and postsynaptic currents onto GnRH neurons. Additional studies have identified robust increases in hypothalamic levels of kisspeptin, another potent stimulator of GnRH neurons. This review outlines the different brain and neuroendocrine changes in the reproductive axis observed in PCOS animal models, discusses how they might contribute to either the etiology or adult phenotype of PCOS, and considers parallel findings in PCOS women
An efficient prescription to find the eigenfunctions of point interactions Hamiltonians
A prescription invented a long time ago by Case and Danilov is used to get
the wave function of point interactions in two and three dimensions.Comment: 6 page
Bounds on from 3-3-1 model at the LHC energies
The Large Hadron Collider will restart with higher energy and luminosity in
2015. This achievement opens the possibility of discovering new phenomena
hardly described by the Standard Model, that is based on two neutral gauge
bosons: the photon and the . This perspective imposes a deep and systematic
study of models that predicts the existence of new neutral gauge bosons. One of
such models is based on the gauge group
called 3-3-1 model for short.
In this paper we perform a study with predicted in two versions of
the 3-3-1 model and compare the signature of this resonance in each model
version. By considering the present and future LHC energy regimes, we obtain
some distributions and the total cross section for the process . Additionally, we derive lower bounds
on mass from the latest LHC results. Finally we analyze the LHC
potential for discovering this neutral gauge boson at 14 TeV center-of-mass
energy.Comment: 6 pages, 9 figures, 2 table
Dirac's hole theory versus quantum field theory
Dirac's hole theory and quantum field theory are usually considered
equivalent to each other. For models of a certain type, however, the
equivalence may not hold as we discuss in this Letter. This problem is closely
related to the validity of the Pauli principle in intermediate states of
perturbation theory.Comment: No figure
Fermion masses in a model for spontaneous parity breaking
In this paper we discuss a left-right symmetric model for elementary
particles and their connection with the mass spectrum of elementary fermions.
The model is based on the group . New
mirror fermions and a minimal set of Higgs particles that breaks the symmetry
down to are proposed. The model can accommodate a consistent
pattern for charged and neutral fermion masses as well as neutrino
oscillations. An important consequence of the model is that the connection
between the left and right sectors can be done by the neutral vector gauge
bosons Z and a new heavy Z'.Comment: 7 pages, 3 figures. Accepted in Eur. Phys. J.
Two definitions of the electric polarizability of a bound system in relativistic quantum theory
For the electric polarizability of a bound system in relativistic quantum
theory, there are two definitions that have appeared in the literature. They
differ depending on whether or not the vacuum background is included in the
system. A recent confusion in this connection is clarified
Validity of Feynman's prescription of disregarding the Pauli principle in intermediate states
Regarding the Pauli principle in quantum field theory and in many-body
quantum mechanics, Feynman advocated that Pauli's exclusion principle can be
completely ignored in intermediate states of perturbation theory. He observed
that all virtual processes (of the same order) that violate the Pauli principle
cancel out. Feynman accordingly introduced a prescription, which is to
disregard the Pauli principle in all intermediate processes. This ingeneous
trick is of crucial importance in the Feynman diagram technique. We show,
however, an example in which Feynman's prescription fails. This casts doubts on
the general validity of Feynman's prescription
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