515 research outputs found
Test of Einstein Equivalence Principle for 0-spin and half-integer-spin atoms: Search for spin-gravity coupling effects
We report on a conceptually new test of the equivalence principle performed
by measuring the acceleration in Earth's gravity field of two isotopes of
strontium atoms, namely, the bosonic Sr isotope which has no spin vs the
fermionic Sr isotope which has a half-integer spin. The effect of
gravity upon the two atomic species has been probed by means of a precision
differential measurement of the Bloch frequency for the two atomic matter waves
in a vertical optical lattice. We obtain the values for the E\"otv\"os parameter and
for the coupling between nuclear spin and gravity.
This is the first reported experimental test of the equivalence principle for
bosonic and fermionic particles and opens a new way to the search for the
predicted spin-gravity coupling effects.Comment: 5 pages, 4 figures. New spin-gravtity coupling analysis on the data
added to the manuscrip
Botulinum toxin treatment in glaucomatous patients: a pilot study
PURPOSE: The purpose was to evaluate the efficacy of the treatment of iatrogenic entropion (IE), in patients affected by primary open angle glaucoma (POAG), by botulinum toxin injections (BTI). PATIENTS AND METHODS: 20 patients of the "Glaucoma Center" of the Hospital "Umberto I" (Rome) were examined. These patients had POAG and used prostaglandin analogues (PA). Mean age was 75.5 years old (range 68-83); they had been suffering from PAOG since 10 years and were not affected by other relevant systemic diseases. One to three BTI were made into the lower orbicularis muscle using a 0.3 G needle (0.025 to 0.05 units for each injection site). RESULTS: The results were particularly significant in 18 out of 20 patients. Two patients showed slight improvements. A rating scale ranging from 0 to 6 points (0 corresponded to 'no effect' and 6 to the 'complete' resolution of the entropion) was used to evaluate the goals of the treatment. The average rating was 5.37 points. CONCLUSIONS: The entropion due to glaucoma therapy with PA can be successfully treated with BTI in the orbicularis muscle, despite offering temporary therapeutic effects
An accurate approach for computational pKa determination of phenolic compounds
Computational chemistry is a valuable tool, as it allows for in silico prediction of key parameters of novel compounds, such as pKa. In the framework of computational pKa determination, the literature offers several approaches based on different level of theories, functionals and continuum solvation models. However, correction factors are often used to provide reliable models that adequately predict pKa. In this work, an accurate protocol based on a direct approach is proposed for computing phenols pKa. Importantly, this methodology does not require the use of correction factors or mathematical fitting, making it highly practical, easy to use and fast. Above all, DFT calculations performed in the presence two explicit water molecules using CAM-B3LYP functional with 6-311G+dp basis set and a solvation model based on density (SMD) led to accurate pKa values. In particular, calculations performed on a series of 13 differently substituted phenols provided reliable results, with a mean absolute error of 0.3. Furthermore, the model achieves accurate results with -CN and -NO2 substituents, which are usually excluded from computational pKa studies, enabling easy and reliable pKa determination in a wide range of phenols
Prolyl 3âhydroxylase 2 is a molecular player of angiogenesis
Prolyl 3âhydroxylase 2 (P3H2) catalyzes the postâtranslational formation of 3â hydroxyproline on collagens, mainly on type IV. Its activity has never been directly associated to angiogenesis. Here, we identified P3H2 gene through a deepâsequencing transcriptome analysis of human umbilical vein endothelial cells (HUVECs) stimulated with vascular endothelial growth factor A (VEGFâA). Differently from many previous studies we carried out the stimulation not on starved HUVECs, but on cells grown to maintain the best condition for their in vitro survival and propagation. We showed that P3H2 is induced by VEGFâA in two primary human endothelial cell lines and that its transcription is modulated by VEGFâA/VEGF receptor 2 (VEGFRâ2) signaling pathway through p38 mitogenâactivated protein kinase (MAPK). Then, we demonstrated that P3H2, through its activity on type IV Collagen, is essential for angiogenesis properties of endothelial cells in vitro by performing experiments of gainâ and lossâofâfunction. Immunofluorescence studies showed that the overexpression of P3H2 induced a more condensed status of Collagen IV, accompanied by an alignment of the cells along the Collagen IV bundles, so towards an evident proâangiogenic status. Finally, we found that P3h2 knockdown prevents pathological angiogenesis in vivo, in the model of laserâinduced choroid neovascularization. Together these findings reveal that P3H2 is a new molecular player involved in new vessels formation and could be considered as a potential target for antiâangiogenesis therapy
Study of a constrained finite element elbow prosthesis: the influence of the implant placement
Background: The functional results of total elbow arthroplasty (TEA) are controversial and the medium- to long-term revision rates are relatively high. The aim of the present study was to analyze the stresses of TEA in its classic configuration, identify the areas of greatest stress in the prosthesisâboneâcement interface, and evaluate the most wearing working conditions. Materials and methods: By means of a reverse engineering process and using a 3D laser scanner, CAD (computer-aided drafting) models of a constrained elbow prosthesis were acquired. These CAD models were developed and their elastic properties, resistance, and stresses were studied through finite element analysis (finite element methodâFEM). The obtained 3D elbow-prosthesis model was then evaluated in cyclic flexionâextension movements (> 10 million cycles). We highlighted the configuration of the angle at which the highest stresses and the areas most at risk of implant mobilization develop. Finally, we performed a quantitative study of the stress state after varying the positioning of the stem of the ulnar component in the sagittal plane by ± 3°. Results: The greatest von Mises stress state in the bone component for the 90° working configuration was 3.1635 MPa, which occurred in the most proximal portion of the humeral blade and in the proximal middle third of the shaft. At the ulnar level, peaks of 4.1763 MPa were recorded at the proximal coronoid/metaepiphysis level. The minimum elastic resistance and therefore the greatest stress states were recorded in the bone region at the apex of the ulnar stem (0.001967 MPa). The results of the analysis for the working configurations at 0° and 145° showed significant reductions in the stress states for both prosthetic components; similarly, varying the positioning of the ulnar component at 90° (â 3° in the sagittal plane, 0° in the frontal plane) resulted in better working conditions with a greater resulting developed force and a lower stress peak in the ulnar cement. Conclusion: The areas of greatest stress occur in specific regions of the ulnar and humeral components at the boneâcementâprosthesis interface. The heaviest configuration in terms of stresses was when the elbow was flexed at 90°. Variations in the positioning in the sagittal plane can mechanically affect the movement, possibly resulting in longer survival of the implant. Level of evidence:
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