Thermal evolution of hybrid stars within the framework of a nonlocal Nambu--Jona-Lasinio model

We study the thermal evolution of neutron stars containing deconfined quark matter in their core. Such objects are generally referred to as quark-hybrid stars. The confined hadronic matter in their core is described in the framework of non-linear relativistic nuclear field theory. For the quark phase we use a non-local extension of the SU(3) Nambu Jona-Lasinio model with vector interactions. The Gibbs condition is used to model phase equilibrium between confined hadronic matter and deconfined quark matter. Our study indicates that high-mass neutron stars may contain between 35 and 40 % deconfined quark-hybrid matter in their cores. Neutron stars with canonical masses of around $1.4\, M_\odot$ would not contain deconfined quark matter. The central proton fractions of the stars are found to be high, enabling them to cool rapidly. Very good agreement with the temperature evolution established for the neutron star in Cassiopeia A (Cas A) is obtained for one of our models (based on the popular NL3 nuclear parametrization), if the protons in the core of our stellar models are strongly paired, the repulsion among the quarks is mildly repulsive, and the mass of Cas A has a canonical value of $1.4\, M_\odot$.Comment: 10 pages, 7 figure

Effect of aluminium sheet surface conditions on feasibility and quality of resistance spot welding

A study investigating the effect of sheet surface condition on resistance spot welding (RSW) of aluminium has been carried out. This concentrates on two automotive aluminium alloys; AA5754 and AA6111, used for structural and closure applications respectively. The results show the marked effect that surface condition can have on the RSW process. For AA5754 sheet incomplete removal of a ‘disrupted surface layer’ prior to surface pretreatment is shown to have a detrimental effect on the RSW process. The solid wax lubricant used to assist metal forming leads to unpredictable changes in contact resistance, and consequently affects the process stability. For AA6111 closures the final surface topography can influence the RSW process. Standard ‘mill’ and electro-discharge textured (EDT) finish sheet surfaces were examined and preliminary results suggest that both are suitable for welding. The successful application of RSW of aluminium sheet requires careful consideration of the sheet surface condition. This requires close collaboration between material suppliers and automotive manufacturers

A step forward in disclosing the secret of stradivari's varnish by NMR spectroscopy

It is commonly thought that the varnishes used by the great violin-maker Antonio Stradivari may have a role in determining not only the esthetical features but also the acoustic properties of his instruments, and the idea of a "lost secret" is still widespread among musicians and violin-makers. Previous scientific researches on varnish samples of Stradivari's instruments revealed that they were generally made by a mix of linseed oil with and colophony or metal rosinates in different ratios ranging between 75/25 (oil/resin) and 60/40 (oil/rosinate). However, it is still not clear whether the mixture composition can be related to any structural and/or functional feature of the resulting varnish. To investigate this aspect, we prepared varnishes with different linseed oil/colophony (w/w) ratios and applied NMR techniques to achieve information about their chemical-physical characteristics. Here, we show that the two components strongly interact in the solid state and that only the varnish prepared from 75/25 (w/w) linseed oil/colophony mixture displays unique properties in terms of dynamic homogeneity unlike coatings with other compositions. Our results suggest that the so-called "secret" of Stradivari's finish could not be related to unknown ingredient(s) but to a specific oil/resin composition that provides the best performance

Effects of pathogen reduction technology and storage duration on the ability of cryoprecipitate to rescue induced coagulopathies in vitro

BACKGROUND: Fibrinogen concentrates and cryoprecipitate are currently used for fibrinogen supplementation in bleeding patients with dysfibrinogenemia. Both products provide an abundant source of fibrinogen but take greater than 10 min to prepare for administration. Fibrinogen concentrates lack coagulation factors (i.e., factor VIII [FVIII], factor XIII [FXIII], von Willebrand factor [VWF]) important for robust hemostatic function. Cryoprecipitate products contain these factors but have short shelf lives (\u3c6 h). Pathogen reduction (PR) of cryoprecipitate would provide a shelf-stable immediately available adjunct containing factors important for rescuing hemostatic dysfunction. STUDY DESIGN AND METHODS: Hemostatic adjunct study products were psoralen-treated PR-cryoprecipitated fibrinogen complex (PR-Cryo FC), cryoprecipitate (Cryo), and fibrinogen concentrates (FibCon). PR-Cryo FC and Cryo were stored for 10 days at 20-24°C. Adjuncts were added to coagulopathies (dilutional, 3:7 whole blood [WB]:normal saline; or lytic, WB + 75 ng/ml tissue plasminogen activator), and hemostatic function was assessed by rotational thromboelastometry and thrombin generation. RESULTS: PR of cryoprecipitate did not reduce levels of FVIII, FXIII, or VWF. PR-Cryo FC rescued dilutional coagulopathy similarly to Cryo, while generating significantly more thrombin than FibCon, which also rescued dilutional coagulopathy. Storage out to 10 days at 20-24°C did not diminish the hemostatic function of PR-Cryo FC. DISCUSSION: PR-Cryo FC provides similar and/or improved hemostatic rescue compared to FibCon in dilutional coagulopathies, and this rescue ability is stable over 10 days of storage. In hemorrhaging patients, where every minute delay is associated with a 5% increase in mortality, the immediate availability of PR-Cryo FC has the potential to improve outcomes

Clinical evaluation of creatine kinase and aspartate aminotransferase for monitoring muscle effort in working dogs in different simulated fieldworks

The clinical profiles of muscle biomarkers (Creatine Kinase–CK-and Aspartate Aminotransferase–AST) performed during training may help in determining the fitness level of dogs and their potentiality to perform specific activities. This study investigated the potential variations of physiological parameters and muscular biomarkers in trained search and rescue dogs during search activity in two different areas. The aim was to verify the absence of any muscular enzymes after 20 min of search activity. The variations of physiological parameters (pulse rate; respiratory rate; rectal body temperature) and skeletal muscular biomarkers (CK and AST) were evaluated before and after search activity. Twenty-three trained dogs met the inclusion criteria and were divided into two groups. One group experienced search activity in a well-known area, while the second one in a similar, but unknown, area. The results for physiological parameters and skeletal muscular biomarkers values showed no significant differences between the two groups (p > 0.05), confirming that an effective conditioning protects against enzymatic alteration during a 20 min duration of submaximal activity

Neutrino emissivity in the quark-hadron mixed phase of neutron stars

Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (≲ 109K) and quark fractions (≲30%) , and that contributions due to lattice vibrations are insignificant compared to static-lattice contributions.Instituto de Física La Plat