Dielectric spectroscopy study of thermally-aged extruded model power cables

“Model” extruded power cables, having a much reduced geometry but using the same extrusion techniques and materials as full-sized cables, have been examined using dielectric spectroscopy techniques to study their thermal ageing effects. Cables insulated with homo-polymer XLPE and co-polymer of XLPE with micron-sized ethylene-butyl-acrylate (EBA) islands were studied by both frequency-domain and time-domain dielectric spectroscopy techniques after accelerated thermal ageing under 135°C for 60 days. In the frequency domain, a frequency response analyzer (FRA) was used to measure the frequency range from 10-4Hz to 1Hz at temperatures from 20°C to 80°C. In the time domain, a special charging/discharging current measurement system was developed to measure the frequencies from 10-1Hz to 102Hz. These techniques were chosen to cope with the extremely low dielectric losses of the model cables. The results are compared with those from new model power cables that were degassed at 80°C for 5 days. Thermal ageing was found to increase the low-frequency conductivity, permittivity and the discharging current. Both homo- and co-polymer cables have substantial increase of dielectric loss after ageing

First direct observation of two protons in the decay of 45^{45}Fe with a TPC

The decay of the ground-state two-proton emitter 45Fe was studied with a time-projection chamber and the emission of two protons was unambiguously identified. The total decay energy and the half-life measured in this work agree with the results from previous experiments. The present result constitutes the first direct observation of the individual protons in the two-proton decay of a long-lived ground-state emitter. In parallel, we identified for the first time directly two-proton emission from 43Cr, a known beta-delayed two-proton emitter. The technique developped in the present work opens the way to a detailed study of the mechanism of ground-state as well as beta-delayed two-proton radioactivity.Comment: 4 pages, 5 figure

The Equation of State and the Hugoniot of Laser Shock-Compressed Deuterium

The equation of state and the shock Hugoniot of deuterium are calculated using a first-principles approach, for the conditions of the recent shock experiments. We use density functional theory within a classical mapping of the quantum fluids [ Phys. Rev. Letters, {\bf 84}, 959 (2000) ]. The calculated Hugoniot is close to the Path-Integral Monte Carlo (PIMC) result. We also consider the {\it quasi-equilibrium} two-temperature case where the Deuterons are hotter than the electrons; the resulting quasi-equilibrium Hugoniot mimics the laser-shock data. The increased compressibility arises from hot $D^+-e$ pairs occuring close to the zero of the electron chemical potential.Comment: Four pages; One Revtex manuscript, two postscipt figures; submitted to PR

Line-field confocal optical coherence tomography: a new tool for non-invasive differential diagnosis of pustular skin disorders

Background The spectrum of pustular skin disorders (PSD) is large and particularly challenging, including inflammatory, infectious and amicrobial diseases. Moreover, although pustules represent the unifying clinical feature, they can be absent or not fully developed in the early stage of the disease. The line-field confocal optical coherence tomography (LC-OCT) is a recently developed imaging technique able to perform a non-invasive, in vivo, examination of the epidermis and upper dermis, reaching very high image resolution and virtual histology. Objectives We aimed to investigate the potentialities of LC-OCT in the non-invasive differential diagnosis of a series of 11 PSD with different aetiology, microscopic features, body location and incidence rates. Materials and Methods Complete LC-OCT imaging (i.e. 2D/3D frames, videos) was performed on a total of 19 patients (10 females and 9 males) aged between 35 and 79 years. Images were blindly evaluated and compared with corresponding histopathologic findings. Results The LC-OCT imaging was able to detect with high accuracy the pustule structure including shape, margins, morphology and cellular content, along with peculiar epidermal and adnexal alterations in each condition, including: Acute Generalized Exanthematous Pustulosis, Generalized pustular psoriasis, Generalized pustular figurate erythema, Subcorneal Pustular Dermatosis, Intraepidermal IgA pustulosis, Palmoplantar pustulosis, Palmoplantar pustular psoriasis. Herpetic whitlow, Acrodermatitis continua of Hallopeau, Vesicopustular Sweet syndrome and Vesicopustular Eosinophilic cellulitis, with pustular appearance, were also compared. Conclusions The new LC-OCT can represent a rapid, non-invasive and painless tool which can help differentiating among PSD of different aetiology and microscopic morphology in clinical mimickers in daily practice

Perioperative mortality and major cardio-pulmonary complications after lung surgery for non-small cell carcinoma

Objectives: A database of patients operated of lung cancer was analyzed to evaluate the predictive risk factors of operative deaths and life-threatening cardiopulmonary complications. Methods: From 1990 to 1997, data were collected concerning 634 consecutive patients undergoing lung resection for non-small cell carcinoma in an academic medical centre and a regional hospital. Operations were managed by a team of experienced surgeons, anaesthesiologists and chest physicians. Operative mortality was defined as death within 30 days of operation and/or intra-hospital death. Respiratory failure, myocardial infarct, heart failure, pulmonary embolism and stroke were considered as major non-fatal complications. Preoperative risk factors, extent of surgery, pTNM staging, perioperative mortality and major cardiopulmonary complications were recorded and evaluated using chi-square statistics and multivariate logistic regression. Results: Complete data were obtained in 621 cases. The overall operative mortality was 3.2% (n=19). Cardiovascular complications (n=10), haemorrhage (n=4) and sepsis or acute lung injury (n=5) were incriminated as the main causative factors. In addition, there were 13 life-threatening complications (2.1%) consisting in strokes (n=4), myocardial infarcts (n=5), pulmonary embolisms (n=1), acute lung injury (n=1) and respiratory failure (n=2). Four independent predictors of operative death were identified: pneumonectomy, evidence of coronary artery disease (CAD), ASA class 3 or 4 and period 1990-93. In addition, the risk of major complications was increased in hypertensive patients and in those belonging to ASA class 3 or 4. A trend towards improved outcome was observed during the second period, from 1994 to 97. Conclusion: Our data demonstrate that perioperative mortality is mainly dependent on the extent of surgery, the presence of CAD and provision of adequate medical and nursing care. Preoperative testing and interventions to reduce the cardiovascular risk factors may help to further improve perioperative outcom

The Path Integral Monte Carlo Calculation of Electronic Forces

We describe a method to evaluate electronic forces by Path Integral Monte Carlo (PIMC). Electronic correlations, as well as thermal effects, are included naturally in this method. For fermions, a restricted approach is used to avoid the ``sign'' problem. The PIMC force estimator is local and has a finite variance. We applied this method to determine the bond length of H$_2$ and the chemical reaction barrier of H+H$_2\longrightarrow$H$_2$+H. At low temperature, good agreement is obtained with ground state calculations. We studied the proton-proton interaction in an electron gas as a simple model for hydrogen impurities in metals. We calculated the force between the two protons at two electronic densities corresponding to Na ($r_s=3.93$) and Al ($r_s=2.07$) using a supercell with 38 electrons. The result is compared to previous calculations. We also studied the effect of temperature on the proton-proton interaction. At very high temperature, our result agrees with the Debye screening of electrons. As temperature decreases, the Debye theory fails both because of the strong degeneracy of electrons and most importantly, the formation of electronic bound states around the protons.Comment: 18 pages, 10 figure

The 2-D electron gas at arbitrary spin polarizations and arbitrary coupling strengths: Exchange-correlation energies, distribution functions and spin-polarized phases

We use a recent approach [Phys. Rev. Letters, {\bf 84}, 959 (2000)] for including Coulomb interactions in quantum systems via a classical mapping of the pair-distribution functions (PDFs) for a study of the 2-D electron gas. As in the 3-D case, the ``quantum temperature'' T_q of a classical 2-D Coulomb fluid which has the same correlation energy as the quantum fluid is determined as a function of the density parameter r_s. Spin-dependent exchange-correlation energies are reported. Comparisons of the spin-dependent pair-distributions and other calculated properties with any available 2-D quantum Monte Carlo (QMC) results show excellent agreement, strongly favouring more recent QMC data. The interesting novel physics brought to light by this study are: (a) the independently determined quantum-temperatures for 3-D and 2-D are found to be approximately the same, (i.e, universal) function of the classical coupling constant Gamma. (b) the coupling constant Gamma increases rapidly with r_s in 2-D, making it comparatively more coupled than in 3-D; the stronger coupling in 2-D requires bridge corrections to the hyper- netted-chain method which is adequate in 3-D; (c) the Helmholtz free energy of spin-polarized and unpolarized phases have been calculated. The existence of a spin-polarized 2-D liquid near r_s = 30, is found to be a marginal possibility. These results pertain to clean uniform 2-D electron systems.Comment: This paper replaces the cond-mat/0109228 submision; the new version include s more accurate numerical evaluation of the Helmholtz energies of the para- and ferromagentic 2D fluides at finite temperatures. (Paper accepted for publication in Phys. Rev. Lett.

The gravitational mass of Proxima Centauri measured with SPHERE from a microlensing event

Proxima Centauri, our closest stellar neighbour, is a low-mass M5 dwarf orbiting in a triple system. An Earth-mass planet with an 11 day period has been discovered around this star. The star's mass has been estimated only indirectly using a mass-luminosity relation, meaning that large uncertainties affect our knowledge of its properties. To refine the mass estimate, an independent method has been proposed: gravitational microlensing. By taking advantage of the close passage of Proxima Cen in front of two background stars, it is possible to measure the astrometric shift caused by the microlensing effect due to these close encounters and estimate the gravitational mass of the lens (Proxima Cen). Microlensing events occurred in 2014 and 2016 with impact parameters, the closest approach of Proxima Cen to the background star, of 1\farcs6 $\pm$ 0\farcs1 and 0\farcs5 $\pm$ 0\farcs1, respectively. Accurate measurements of the positions of the background stars during the last two years have been obtained with HST/WFC3, and with VLT/SPHERE from the ground. The SPHERE campaign started on March 2015, and continued for more than two years, covering 9 epochs. The parameters of Proxima Centauri's motion on the sky, along with the pixel scale, true North, and centering of the instrument detector were readjusted for each epoch using the background stars visible in the IRDIS field of view. The experiment has been successful and the astrometric shift caused by the microlensing effect has been measured for the second event in 2016. We used this measurement to derive a mass of 0.150$^{\textrm{+}0.062}_{-0.051}$ (an error of $\sim$ 40\%) \MSun for Proxima Centauri acting as a lens. This is the first and the only currently possible measurement of the gravitational mass of Proxima Centauri.Comment: 10 pages, 6 figures, accepted by MNRA

Minimal work principle: proof and counterexamples

The minimal work principle states that work done on a thermally isolated equilibrium system is minimal for adiabatically slow (reversible) realization of a given process. This principle, one of the formulations of the second law, is studied here for finite (possibly large) quantum systems interacting with macroscopic sources of work. It is shown to be valid as long as the adiabatic energy levels do not cross. If level crossing does occur, counter examples are discussed, showing that the minimal work principle can be violated and that optimal processes are neither adiabatically slow nor reversible. The results are corroborated by an exactly solvable model.Comment: 13 pages, revtex, 2 eps figure

UVA-1 phototherapy as adjuvant treatment for eosinophilic fasciitis: in vitro and in vivo functional characterization

Introduction: Eosinophilic fasciitis (EF) is a rare autoimmune disease causing progressive induration of dermal, hypodermal, and muscularis fascia. The exact pathogenesis is yet to be fully understood, and a validated therapy protocol still lacks. We here aimed to realize a clinical–functional characterization of these patients. Materials and methods: A total of eight patients (five males, 45 years average) were treated with adjuvant high-dose UVA-1 phototherapy (90 J/cm), after having received the standard systemic immunosuppressive protocol (oral methylprednisolone switched to methotrexate). Body lesion mapping, Localized Scleroderma Assessment Tool (LoSCAT), Dermatology Life Quality Index (DLQI), High-Resolution Ultrasound (HRUS) (13-17MHz), and ultra HRUS (55–70 MHz) were performed at each examination time taking specific anatomical points. Gene expression analysis at a molecular level and in vitro UVA-1 irradiation was realized on lesional fibroblasts primary cultures. Results: The LoSCAT and the DLQI showed to decrease significantly starting from the last UVA-1 session. A significant reduction in muscularis fascia thickness (−50% on average) was estimated starting from 3 months after the last UVA-1 session and maintained up to 12 months follow-up. Tissues was detected by HRUS. The UVA-1 in vitro irradiation of lesional skin sites cells appeared not to affect their viability. Molecular genes analysis revealed a significant reduction of IL-1ß and of TGF-ß genes after phototherapy, while MMPs 1,2,9 gene expression was enhanced. Comment: These preliminary in vivo and in vitro findings suggest that UVA-1 phototherapy is a safe and useful adjuvant therapy able to elicit anti-inflammatory effects and stimulate tissue matrix digestion and remodeling at lesional sites