The fully kinetic Biermann battery and associated generation of pressure anisotropy

The dynamical evolution of a fully kinetic, collisionless system with imposed background density and temperature gradients is investigated analytically. The temperature gradient leads to the generation of temperature anisotropy, with the temperature along the gradient becoming larger than that in the direction perpendicular to it. This causes the system to become unstable to pressure anisotropy driven instabilities, dominantly to electron Weibel. When both density and temperature gradients are present and non-parallel to each other, we obtain a Biermann-like linear in time magnetic field growth. Accompanying particle in cell numerical simulations are shown to confirm our analytical results.Comment: 5 pages, 2 figures, + Supplementary materials (4 pages, 2 figures

Gender Matters! Analyzing Global Cultural Gender Preferences for Venues Using Social Sensing

Gender differences is a phenomenon around the world actively researched by social scientists. Traditionally, the data used to support such studies is manually obtained, often through surveys with volunteers. However, due to their inherent high costs because of manual steps, such traditional methods do not quickly scale to large-size studies. We here investigate a particular aspect of gender differences: preferences for venues. To that end we explore the use of check-in data collected from Foursquare to estimate cultural gender preferences for venues in the physical world. For that, we first demonstrate that by analyzing the check-in data in various regions of the world we can find significant differences in preferences for specific venues between gender groups. Some of these significant differences reflect well-known cultural patterns. Moreover, we also gathered evidence that our methodology offers useful information about gender preference for venues in a given region in the real world. This suggests that gender and venue preferences observed may not be independent. Our results suggests that our proposed methodology could be a promising tool to support studies on gender preferences for venues at different spatial granularities around the world, being faster and cheaper than traditional methods, besides quickly capturing changes in the real world

Exploring drivers of psychology well-being at music festivals

The aim of the current study is to analyze tourist engagement with music festivals and their psychological well-being is achieved through surprise consumption, positive affect, arousal delight and satisfaction. A sample of 394 usable questionnaires allow us to understand that surprising consumption, arousal, positive affect and satisfaction are very important drivers to engage visitors to music festivals. Engaged tourists are more willing to reach a positive psychological well-being.info:eu-repo/semantics/acceptedVersio

Fatigue behaviour of AA6082-T6 MIG welded butt joints improved by friction stir processing

Friction Stir Processing (FSP) was based on the principles of Friction Stir Welding (FSW), a solid-state joining process originally developed for aluminium alloys. It is an emerging metalworking technique which can provide localized modification and control of microstructures in near-surface layers of processed metallic components. In this research, FSP appears as an alternative to traditional methods for fatigue strength improvement of weld joints, such as re-melting, hammering and blasting. This technique was applied on Metal Inert Gas (MIG) butt welds with and without reinforcement, performed on AA6082-T6 alloy plates. The potential benefits of post-processing MIG welds by FSP were studied using microstructure analysis, hardness measurement, tensile strength, residual stress measurement, and fatigue testing. Fatigue tests were carried out under constant amplitude loading with the stress ratio R set to 0. Friction stir processing of MIG welds does not change the hardness and mechanical strength of the weld substantially, but the fatigue strength was increased, due to the geometry modification in the weld toe, reduction of weld defects and grain refinement of the microstructure

Influence of physical exercise and protein supplementation in quality of life (SF36) in seniors to live in the community

info:eu-repo/semantics/publishedVersio

Recomendação de Baveno VI Sobre Evicção da Endoscopia de Rastreio em Doentes com Cirrose: Já Lá Estamos?

INTRODUCTION: Recent studies assessed the predictive value of liver transient elastography, combined or not with platelet count, for the presence of esophageal varices in patients with liver cirrhosis, and multiple cutoffs have been proposed. The Baveno VI consensus states that patients with compensated advanced chronic liver disease, liver stiffness 150,000 have a very low risk of having varices requiring treatment and can avoid screening endoscopy. We aimed to validate this recommendation in a cohort of cirrhotic patients. METHODS: Retrospective analysis of all patients evaluated at the Gastroenterology Department (Centro Hospitalar de Lisboa Central) between September 2009 and October 2015 with a liver stiffness (FibroScan®) compatible with liver cirrhosis as well as upper endoscopy and blood tests within 12 months from elastography. Patients on propranolol ≥80 mg/day or carvedilol ≥12.5 mg/day, as well as those with previous variceal bleeding, variceal endoscopic treatments, or cirrhosis decompensations were excluded. We validated the new Baveno VI recommendation and explored alternative cutoffs. RESULTS: Ninety-seven patients were analyzed, 76.3% (74/97) male, mean age 54.3 ± 11.2 years. Most patients (55.7%) had no varices and 14.4% had varices requiring treatment. Most patients (78.4%) had cirrhosis related to chronic hepatitis C. If the new Baveno VI recommendation had been applied to this cohort, upper endoscopy would have been avoided in 11.3% (11/97) of patients, none of them with esophageal varices requiring treatment: specificity 100%, sensitivity 13.3%, positive predictive value 100%, and negative predictive value 16.3% for absence of varices requiring treatment. If screening endoscopy had been avoided in those patients with liver stiffness <30 kPa and platelet count ≥120,000, endoscopy would have been avoided in 27.8% (27/97) of patients, none of whom with esophageal varices requiring treatment: specificity 100%, sensitivity 32.5%, positive predictive value 100%, and negative predictive value 20% for absence of varices requiring treatment. CONCLUSIONS: The new Baveno VI criteria identified compensated cirrhotic patients without varices requiring treatment in whom screening endoscopy could have been avoided safely. Further studies are needed to confirm these findings and potentially explore more ambitious but still safe cutoffs for those criteria.info:eu-repo/semantics/publishedVersio

Magnetic-field generation and amplification in an expanding plasma

WOS:000335816700013Particle-cell simulations are used to investigate the formation of magnetic fields B in plasmas with perpendicular electron density and temperature gradients. For system sizes L comparable to the ion skin depth d(i), it is shown that B similar to i/L, consistent with the Biermann battery effect. However, for large L/d(i), it is found that the Weibel instability (due to electron temperature anisotropy) supersedes the Biermann battery as the main producer of B. The Weibel-produced fields saturate at a finite amplitude (plasma beta approximate to 100), independent of L. The magnetic energy spectra below the electron Larmor radius scale are well fitted by the power law with slope -16/3, as predicted by Schekochihin et al

The generation of magnetic fields by the Biermann battery and the interplay with the Weibel instability

An investigation of magnetic fields generated in an expanding bubble of plasma with misaligned temperature and density gradients (driving the Biermann battery mechanism) is performed. With gradient scales L, large-scale magnetic fields are generated by the Biermann battery mechanism with plasma 1, as long as L is comparable to the ion inertial length di. For larger system sizes, L/de 100 (where deis the electron inertial length), the Weibel instability generates magnetic fields of similar magnitude but with wavenumber kde0.2. In both cases, the growth and saturation of these fields have a weak dependence on mass ratio mi/me, indicating electron mediated physics. A scan in system size is performed at mi/me= 2000, showing agreement with previous results with mi/me= 25. In addition, the instability found at large system sizes is quantitatively demonstrated to be the Weibel instability. Furthermore, magnetic and electric energy spectra at scales below the electron Larmor radius are found to exhibit power law behavior with spectral indices -16/3 and -4/3, respectively

Anorectal Complications in Patients with Haematological Malignancies

Background: Anorectal complications are common in patients with haematological malignancies. Objectives: The objectives are to characterize anorectal complications in these patients, identify risk factors and shed light on treatment, morbidity and mortality rates. Patients and methods: A retrospective, observational study that included 83 inpatients with haematological malignancies and proctological symptoms from January 2010 to September 2015 was conducted. Clinical outcomes were obtained through a detailed review of medical records. Results: The median age was 56 years, and 52 (62.7%) patients were men. Fifty-six (67.5%) patients had nonseptic anorectal complications and 27 (32.5%) patients had septic anorectal complications. Risks factors: Patients with septic anorectal complications were more commonly male, older, and had lower absolute neutrophil counts, but the differences were not statistically significant (P=0.79, 0.67 and 0.89, respectively). In positive blood cultures [23/70 (32.9%)], Enterococcus faecium, Klebsiella pneumonia, and Escherichia coli were the most common isolated agents. Treatment: In nonseptic anorectal complications, conservative treatments/minor proctological procedures were adopted, and patients with septic anorectal complications were treated with antibiotics±major proctological procedures and/or surgical drainage/debridement. Results of treatment: Forty-eight (85.7%) patients in the nonseptic complications group improved compared with 23 (85.2%) patients in the septic complications group. The overall mortality rate was 2.4% (n=2), with one (1.2%) death related to perianal sepsis. Conclusion: Enterococcus spp. were more commonly identified in this study and can be increasing in this specific population. In contrast to other reports, we did not identify an association between septic anorectal complications and possible risk factors such as male sex, younger age or a low absolute neutrophil count. Most patients had nonseptic anorectal complications. A major proctological procedure/surgical debridement should always be applied in septic complications, which have better prognoses now than in the past.info:eu-repo/semantics/publishedVersio