Quantum Brayton cycle with coupled systems as working substance

We explore the quantum version of Brayton cycle with a composite system as the working substance. The actual Brayton cycle consists of two adiabatic and two isobaric processes. Two pressures can be defined in our isobaric process, one corresponds to the external magnetic field (characterized by $F_x$) exerted on the system, while the other corresponds to the coupling constant between the subsystems (characterized by $F_y$). As a consequence, we can define two types of quantum Brayton cycle for the composite system. We find that the subsystem experiences a quantum Brayton cycle in one quantum Brayton cycle (characterized by $F_x$), whereas the subsystem's cycle is of quantum Otto in another Brayton cycle (characterized by $F_y$). The efficiency for the composite system equals to that for the subsystem in both cases, but the work done by the total system are usually larger than the sum of work done by the two subsystems. The other interesting finding is that for the cycle characterized by $F_y$, the subsystem can be a refrigerator while the total system is a heat engine. The result in the paper can be generalized to a quantum Brayton cycle with a general coupled system as the working substance.Comment: 7 pages, 3 figures, accepted by Phys. Rev.

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

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

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 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

Search for new resonant states in 10C and 11C and their impact on the cosmological lithium problem

The observed primordial 7Li abundance in metal-poor halo stars is found to be lower than its Big-Bang nucleosynthesis (BBN) calculated value by a factor of approximately three. Some recent works suggested the possibility that this discrepancy originates from missing resonant reactions which would destroy the 7Be, parent of 7Li. The most promising candidate resonances which were found include a possibly missed 1- or 2- narrow state around 15 MeV in the compound nucleus 10C formed by 7Be+3He and a state close to 7.8 MeV in the compound nucleus 11C formed by 7Be+4He. In this work, we studied the high excitation energy region of 10C and the low excitation energy region in 11C via the reactions 10B(3He,t)10C and 11B(3He,t)11C, respectively, at the incident energy of 35 MeV. Our results for 10C do not support 7Be+3He as a possible solution for the 7Li problem. Concerning 11C results, the data show no new resonances in the excitation energy region of interest and this excludes 7Be+4He reaction channel as an explanation for the 7Li deficit.Comment: Accepted for publication in Phys. Rev. C (Rapid Communication

On the local birth place of Geminga

Using estimates of the distance and proper motion of Geminga and the constraints on its radial velocity posed by the shape of its bow shock, we investigate its birth place by tracing its space motion backwards in time. Our results exclude the lambda Ori association as the origin site because of the large distance between both objects at any time. Our simulations place the birth region at approximately 90-240 pc from the Sun, between 197 degrees and 199 degrees in Galactic longitude and -16 degrees and -8 degrees in latitude, most probably inside the Cas-Tau OB association or the Ori OB1a association. We discard the possibility of the progenitor being a massive field star. The association of Geminga with either stellar association implies an upper limit of M = 15 Msun for the mass of its progenitor. We also propose new members for the Cas-Tau and Ori OB1 associations.Comment: 6 pages, 5 figures. Accepted for publication in Astronomy & Astrophysic

Measurement of forward neutral pion transverse momentum spectra for s\sqrt{s} = 7TeV proton-proton collisions at LHC

The inclusive production rate of neutral pions in the rapidity range greater than $y=8.9$ has been measured by the Large Hadron Collider forward (LHCf) experiment during LHC $\sqrt{s}=7$\,TeV proton-proton collision operation in early 2010. This paper presents the transverse momentum spectra of the neutral pions. The spectra from two independent LHCf detectors are consistent with each other and serve as a cross check of the data. The transverse momentum spectra are also compared with the predictions of several hadronic interaction models that are often used for high energy particle physics and for modeling ultra-high-energy cosmic-ray showers.Comment: 18 Pages, 10 figures, submitted to Phys. Rev.