Polarized thermal emission by thin metal wires

We report new measurements of the linear polarization of thermal radiation emitted by incandescent thin tungsten wires, with thicknesses ranging from five to hundred microns. Our data show very good agreement with theoretical predictions, based on Drude-type fits to measured optical properties of tungsten.Comment: 12 pages, 4 encapsulated figures. This new version matches the one published in New. J. Phys.. Improved presentation, more references added, and one new figure include

Laser induced fluorescence for axion dark matter detection: a feasibility study in YLiF4_4:Er3+^{3+}

We present a detection scheme to search for QCD axion dark matter, that is based on a direct interaction between axions and electrons explicitly predicted by DFSZ axion models. The local axion dark matter field shall drive transitions between Zeeman-split atomic levels separated by the axion rest mass energy $m_a c^2$. Axion-related excitations are then detected with an upconversion scheme involving a pump laser that converts the absorbed axion energy ($\sim$ hundreds of $\mu$eV) to visible or infrared photons, where single photon detection is an established technique. The proposed scheme involves rare-earth ions doped into solid-state crystalline materials, and the optical transitions take place between energy levels of $4f^N$ electron configuration. Beyond discussing theoretical aspects and requirements to achieve a cosmologically relevant sensitivity, especially in terms of spectroscopic material properties, we experimentally investigate backgrounds due to the pump laser at temperatures in the range $1.9-4.2$ K. Our results rule out excitation of the upper Zeeman component of the ground state by laser-related heating effects, and are of some help in optimizing activated material parameters to suppress the multiphonon-assisted Stokes fluorescence.Comment: 8 pages, 5 figure

Inflation in Multidimensional Quantum Cosmology

We extend to multidimensional cosmology Vilenkin's prescription of tunnelling from nothing for the quantum origin of the observable Universe. Our model consists of a $D+4$-dimensional spacetime of topology ${\cal R}\times {\cal S}^3 \times{\cal S}^D$, with a scalar field (``chaotic inflaton'') for the matter component. Einstein gravity and Casimir compactification are assumed. The resulting minisuperspace is 3--dimensional. Patchwise we find an approximate analytic solution of the Wheeler--DeWitt equation through which we discuss the tunnelling picture and the probability of nucleation of the classical Universe with compactifying extra dimensions. Our conclusion is that the most likely initial conditions, although they do not lead to the compactification of the internal space, still yield (power-law) inflation for the outer space. The scenario is physically acceptable because the inner space growth is limited to $\sim 10^{11}$ in 100 e-foldings of inflation, starting from the Planck scale.Comment: RevTeX, 30 pages, 4 figures available via fax on request to [email protected], submitted to Phys. Rev.

Testing the neutrality of matter by acoustic means in a spherical resonator

New measurements to test the neutrality of matter by acoustic means are reported. The apparatus is based on a spherical capacitor filled with gaseous SF$_6$ excited by an oscillating electric field. The apparatus has been calibrated measuring the electric polarizability. Assuming charge conservation in the $\beta$ decay of the neutron, the experiment gives a limit of $\epsilon_\text{p-e}\lesssim1\cdot10^{-21}$ for the electron-proton charge difference, the same limit holding for the charge of the neutron. Previous measurements are critically reviewed and found incorrect: the present result is the best limit obtained with this technique

Measurement of the Casimir force between parallel metallic surfaces

We report on the measurement of the Casimir force between conducting surfaces in a parallel configuration. The force is exerted between a silicon cantilever coated with chromium and a similar rigid surface and is detected looking at the shifts induced in the cantilever frequency when the latter is approached. The scaling of the force with the distance between the surfaces was tested in the 0.5 - 3.0 $\mu$m range, and the related force coefficient was determined at the 15% precision level.Comment: 4 Figure

Infrared emission spectrum and potentials of 0u+0_u^+ and 0g+0_g^+ states of Xe2_2 excimers produced by electron impact

We present an investigation of the Xe$_{2}$ excimer emission spectrum observed in the near infrared range about 7800 cm$^{-1}$ in pure Xe gas and in an Ar (90%) --Xe (10%) mixture and obtained by exciting the gas with energetic electrons. The Franck--Condon simulation of the spectrum shape suggests that emission stems from a bound--free molecular transition never studied before. The states involved are assigned as the bound $(3)0_{u}^{+}$ state with $6p [1/2]_{0}$ atomic limit and the dissociative $(1)0_{g}^{+}$ state with $6s [3/2]_{1}$ limit. Comparison with the spectrum simulated by using theoretical potentials shows that the dissociative one does not reproduce correctly the spectrum features.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let

Cascade Birth of Universes in Multidimensional Spaces

The formation mechanism of universes with distinctly different properties is considered within the framework of pure gravity in a space of D > 4 dimensions. The emergence of the Planck scale and its relationship to the inflaton mass are discussed.Comment: 10 p., minor correction

Hysteroscopy in the management of endometrial hyperplasia and cancer in reproductive aged women: new developments and current perspectives

Over the last twenty years, the incidence of early endometrial cancer (EC) and atypical endometrial hyperplasia (AEH) among women of reproductive age is increasing rapidly, likely due to a combination of factors including increased prevalence of obesity and delayed of childbirths. Regarding preoperative diagnosis of endometrial neoplasia, it is still debated which is the most accurate and reliable method to obtain endometrial histopathological samples with fractional dilatation and curettage (D&C) having been considered, for a long time, as the method of choice. Nowadays, the advent of in-office endometrial biopsy with or without hysteroscopy has radically changed the approach, giving the opportunity to perform the endometrial biopsy under direct visualization. However, the lack of agreement about its diagnostic accuracy is still relevant. Since a significant number of women with AEH and/or EC are of childbearing age, a fertility-sparing diagnostic and therapeutic approach should be considered in all cases. The feasibility, safety and efficacy of fertility-sparing strategies involving hysteroscopic focal resections in conjunction with hormonal therapies have been evaluated and beneficial effects have been confirmed in several studies and one meta-analysis. Both local and systemic administration of hormonal therapies are currently used. Oral progestin, including medroxyprogesterone acetate (MPA) and megestrol acetate, are the most commonly used therapies. Nowadays, new therapeutic approaches, such as levonorgestrel intrauterine systems (LNG-IUS), gonadotropin-releasing hormone (GnRH) agonists, combined megestrol acetate and metformin, and other combinations of therapies are also used as first line therapies or after the hysteroscopic resection of the lesion. However, it is still unclear which approach provides higher clinical response with lower relapse rate, in addition to preserving fertility in women desiring to conceive. The aim of this narrative review is to summarize the available evidence regarding the evaluation and management with fertility-sparing treatments options of women with AEC and EC

Proposal to produce long-lived mesoscopic superpositions through an atom-driven field interaction

We present a proposal for the production of longer-lived mesoscopic superpositions which relies on two requirements: parametric amplification and squeezed vacuum reservoir for cavity-field states. Our proposal involves the interaction of a two-level atom with a cavity field which is simultaneously subjected to amplification processes.Comment: 12 pages, title changed, text improved and refences adde