A first-order purely frame-formulation of General Relativity

In the gauge natural bundle framework a new space is introduced and a first-order purely frame-formulation of General Relativity is obtained.Comment: 9 Pages, Submitted to Classical and Quantum Gravit

Critical exact solutions for self-gravitating Dirac fields

We consider the Einstein-Dirac field equations describing a self-gravitating massive neutrino, looking for axially-symmetric exact solutions; in the search of general solutions, we find some that are specific and which have critical features, such as the fact that the space-time curvature turns out to be flat and the spinor field gives rise to a vanishing bi-linear scalar $\overline{\psi}\psi=0$ with non-vanishing bi-linear pseudo-scalar $i\overline{\psi}\gamma^5\psi\not=0$: because in quantum field theory general computational methods are built on plane-wave solutions, for which bi-linear pseudo-scalar vanishes while the bi-linear scalar does not vanish, then the solutions we found cannot be treated with the usual machinery of quantum field theory. This means that for the Einstein-Dirac system there exist admissible solutions which nevertheless cannot be quantized with the common prescriptions; we regard this situation as yet another issue of tension between Einstein gravity and quantum principles. Possible ways to quench this tension can be seen either in enlarging the validity of quantum field theory or by restricting the space of the solutions of the Einstein-Dirac system of field equations.Comment: 12 page

Exact solutions for Weyl fermions with gravity

We consider the single-handed spinor field in interaction with its own gravitational field described by the set of field equations given by Weyl field equations written in terms of derivatives that are covariant with respect to the gravitational connection plus Einstein field equations soured with the energy tensor of the spinor: for the Weyl spinor and the ensuing spacetime of Weyl-Lewis-Papapetrou structure, we will find all exact solutions. The obtained solution for the metric tensor is that of a PP-wave spacetime while the spinor field is a flag-dipole.Comment: 12 page

Integrability of Dirac equations in static spherical space-times

We consider the Dirac equations in static spherically-symmetric space-times, and we present a type of spinor field whose structure allows the separation of elevation angle and radial coordinate in very general situations. We demonstrate that after such a separation of variables the Dirac equations reduce to two equations that can always be integrated, at least in principle. To prove that ours is a fully-working method, we find an explicit exact solution in the special case of the de Sitter universe.Comment: 10 page

Non minimally coupled condensate cosmologies: matching observational data with phase space

We compare theoretical predictions with observations for a class of cosmological models in which the dark energy component is modeled as a fermionic condensate, non-minimally coupled with the gravitational eld and characterized by some specic selfinteraction potentials. Our analysis is based on the Markov Chain Monte Carlo Method (MCMC) and employs dierent data sets. It turns out that with an appropriate choice of parameters our models are fully compatible with several observed data. We combine these parameter values with phase space analysis to deduce the features of the entire cosmic history of the considered models

Dirac spinors in Bianchi-I f(R)-cosmology with torsion

We study Dirac spinors in Bianchi type-I cosmological models, within the framework of torsional $f(R)$-gravity. We find four types of results: the resulting dynamic behavior of the universe depends on the particular choice of function $f(R)$; some $f(R)$ models do not isotropize and have no Einstein limit, so that they have no physical significance, whereas for other $f(R)$ models isotropization and Einsteinization occur, and so they are physically acceptable, suggesting that phenomenological arguments may select $f(R)$ models that are physically meaningful; the singularity problem can be avoided, due to the presence of torsion; the general conservation laws holding for $f(R)$-gravity with torsion ensure the preservation of the Hamiltonian constraint, so proving that the initial value problem is well-formulated for these models.Comment: 25 pages, 1 figur

Inhibition mechanism of urease by Au(III) compounds unveiled by x-ray diffraction analysis

The nickel-dependent enzyme urease is a virulence factor for a large number of critical human pathogens, making this enzyme a potential target of therapeutics for the treatment of resistant bacterial infections. In the search for novel urease inhibitors, five selected coordination and organometallic Au(III) compounds containing N∧N or C∧N and C∧N∧N ligands were tested for their inhibitory effects against Canavalia ensiformis (jack bean) urease. The results showed potent inhibition effects with IC50 values in the nanomolar range. The 2.14 Å resolution crystal structure of Sporosarcina pasteurii urease inhibited by the most effective Au(III) compound [Au(PbImMe)Cl2]PF6 (PbImMe = 1-methyl-2-(pyridin-2-yl)-benzimidazole) reveals the presence of two Au ions bound to the conserved triad αCys322/αHis323/αMet367. The binding of the Au ions to these residues blocks the movement of a flap, located at the edge of the active site channel and essential for enzyme catalysis, completely obliterating the catalytic activity of urease. Overall, the obtained results constitute the basis for the design of new gold complexes as selective urease inhibitors with future antibacterial applications

Retrospective descriptive analysis of the physiological kinetics of prostate-specific antigen in men older than 75 years.

Several studies have compared prostate-specific antigen (PSA) kinetics in men with and without cancer, but there has been no adequate analysis of the longitudinal variation in PSA. The aim of this study was to assess the fluctuations in PSA in a cohort of elderly men in an attempt to define a physiological pattern of PSA kinetics. We searched a specific cohort of patients aged > 75 years and with PSA value < 2.0 ng mL(-1). A history of all PSA values over the past 10 years was compiled for each patient to create a database of patients fitting the following criteria: (1) minimum of five PSA measurements, (2) over at least 5 years. Exclusion criteria were: (1) PSA < 0.2 ng mL(-1) at each measurement and (2) having had more than one PSA test per year. In all, 1 327 patients (mean age: 78.52 years) fit the inclusion criteria. The mean variation from the first to the last PSA test was 0.05 +/- 0.43, with a mean follow-up of 6.79 +/- 1.71 years. Over the same period, the mean fluctuation from the lowest to the highest PSA value was 0.04 +/- 0.55 (P = 0.925). The mean annual PSA velocity (PSAV) was calculated by dividing the mean variation from the first to the last PSA test by the number of years of observation for each patient and was set at 0.0104 +/- 0.1050. Concluding, in a large-scale cohort of elderly individuals considered healthy and evaluated for a considerable follow-up, the average annual PSAV as well as the average fluctuation from the lowest to the highest PSA value are insignificant

Senhance robotic platform for ovarian borderline tumor treatment: minimally invasive robotic approach for conservative adnexal surgery

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Stapled hemorrhoidopexy: no more a new technique

Haemorrhoidal disease affect between 4.4% and 36.4% of the general population. The common symptoms are: bleeding, prolapse, pain, discharge, itching and hampered anal hygiene. There is no correlation between specific symptoms and anatomic grading. Apparently severe looking haemorrhoids can cause relatively few symptoms. Open haemorrhoidectomy, as described by Milligan, has been accepted worldwide as the best choice for treatment of symptomatic haemorrhoids. In 1998, Longo proposed a procedure for haemorrhoidectomy with minimal postoperative pain, no perianal wound requiring postoperative wound care and a relatively short operative time. His technique presented a new notion for treating haemorrhoids as he proposed circumferential rectal mucosectomy that results in mucosal lifting (anopexy). His aim was not excision of the haemorrhoidal tissue but rather restoring anatomical and physiological aspects of the haemorrhoidal plexus. The grading system described by Goligher, is the most commonly used and is based on objective findings and patient history. Stapled hemorrhoidopexy is performed for grade III and IV, for grade II in case of major bleeding. In lithotomy position and spinal anesthesia and after taking all aseptic precautions, the procedure of stapled hemorrhoidectomy was performed according to Longo’s technique. After this surgical procedure, the need to manually reduce prolapse will have been cured in approximately 90% of patients and the overall preoperative symptoms will be much reduced in the great majority. There should be no anal pain. Bowel habits should have returned to a normal pattern without urgency. One year follow-up or longer 11% of patients had remaining or recurrent prolapse, the reintervention rate is about 10%