Stability and nonlinear adjustment of vortices in Keplerian flows

We investigate the stability, nonlinear development and equilibrium structure of vortices in a background shearing Keplerian flow. We make use of high-resolution global two-dimensional compressible hydrodynamic simulations. We introduce the concept of nonlinear adjustment to describe the transition of unbalanced vortical fields to a long-lived configuration. We discuss the conditions under which vortical perturbations evolve into long-lived persistent structures and we describe the properties of these equilibrium vortices. The properties of equilibrium vortices appear to be independent from the initial conditions and depend only on the local disk parameters. In particular we find that the ratio of the vortex size to the local disk scale height increases with the decrease of the sound speed, reaching values well above the unity. The process of spiral density wave generation by the vortex, discussed in our previous work, appear to maintain its efficiency also at nonlinear amplitudes and we observe the formation of spiral shocks attached to the vortex. The shocks may have important consequences on the long term vortex evolution and possibly on the global disk dynamics. Our study strengthens the arguments in favor of anticyclonic vortices as the candidates for the promotion of planetary formation. Hydrodynamic shocks that are an intrinsic property of persistent vortices in compressible Keplerian flows are an important contributor to the overall balance. These shocks support vortices against viscous dissipation by generating local potential vorticity and should be responsible for the eventual fate of the persistent anticyclonic vortices. Numerical codes have be able to resolve shock waves to describe the vortex dynamics correctly.Comment: 12 pages, 10 figure

Performance of organically grown tomato cultivars under greenhouse conditions

A agricultura orgânica no Brasil cresce a taxas superiores a 30% ao ano, devido principalmente à maior conscientização dos consumidores que buscam alimentos saudáveis, livres de resíduos químicos e biológicos. Dentre as hortaliças cultivadas em sistema orgânico, o tomate constitui grande desafio para os produtores devido à inexistência de recomendações de manejo cultural e de cultivares desenvolvidas específicas para esse sistema de cultivo. Diante disso, o presente trabalho teve como objetivo avaliar o desempenho de cultivares de tomate sob sistema orgânico, em ambiente protegido. O experimento foi conduzido de maio a outubro de 2004 em campo, no município de Araraquara-SP. O delineamento experimental adotado foi blocos ao acaso, com quatro repetições e oito tratamentos (cultivares Avalon, Colibri, HTX-5415, HTX-8027, Sahel, San Marzano, San Vito e Jane). As plantas foram conduzidas em fileiras duplas, com duas hastes por planta no espaçamento de 0,8 m entre linhas e 0,6 m entre plantas (cerca de 20.000 plantas ha-1), sem poda apical. O híbrido Sahel destacou-se com o melhor desempenho para rendimento comercial. A traça-do-tomateiro se revelou como fator limitante à produção de tomate em sistema orgânico, sendo responsável, em média, por 17% de danos nos frutos colhidos das oito cultivares que foram avaliadas.Organic agriculture in Brazil has been increasing about 30% per year over the last few years, since consumers are seeking for healthier foods, i.e. nutritious and free of pesticide residues. Among organically grown vegetable crops, tomato is an attractive economic opportunity for growers. However, the lack of information about management practices and adapted cultivars to organic production systems under protected cultivation are pointed out as important constraints that prevents this activity to expand. This work aimed at evaluating the performance of indeterminate tomato cultivars in organic management systems in unheated plastic greenhouse. In both experiments tomato plants were staked. Plant spacing was 1.5 m between rows and 0.35 m between plants. They were planted in double line and spaced 0.8 m between lines and 0.6 m between plants (about 20,000 plants ha-1). The experiment was set up in a randomized complete block design, with four replications and eight treatments (cultivars: Avalon, Colibri, HTX-5415, HTX-8027, Sahel, San Marzano, San Vito, and Jane). Sahel hybrid exhibited an outstanding performance for marketable yield under organic cultivation. Tomato pinworm (Tuta absoluta) was a serious limiting pest for organically grown tomatoes, responding for 17% of damage in the fruits harvested from the evaluated cultivars

Presbyvestibulopathy, Comorbidities, and Perception of Disability: A Cross-Sectional Study

Objective: To assess the perception of disability in patients with presbyvestibulopathy and to determine the factors (demographic, balance test scores, and comorbidities) that determine higher levels of disability. Material and Methods: This was a cross-sectional study conducted in a tertiary university hospital. There were 103 patients who fulfilled the diagnostic criteria for presbyvestibulopathy and were included. Dizziness Handicap Inventory (DHI) score was the main variable used to quantify disability. Influence on DHI score, sex, age, time of evolution, equilibriometric parameters (posturographic scores and timed up and go test), history of falls, comorbidities (high blood pressure, diabetes, and dyslipidemia), psychotropic drug use, tobacco or alcohol use, living environment (urban or rural), and active lifestyle were analyzed. Results: Most of the DHI scores showed a moderate (46 patients, 44.7%) or severe (39 participants, 37.9%) handicap. DHI scores were higher in women (59.8 vs. 36.1, p < 0.001), patients with obesity (58.92 vs. 48.68; p = 0.019), benzodiazepine (59.9 vs. 49.1, p = 0.008) or other psychotropic drug (60.7 vs. 49.2, p = 0.017) users, and fallers (57.1 vs. 47.3, p = 0.048). There was also a significant positive correlation between DHI score, time (Rho coefficient: 0.371, p < 0.001), and steps (Rho coefficient: 0.284, p = 0.004) used in the TUG and with the short FES-I questionnaire (a shortened version of the Falls Efficacy Scale-International) score (Rho coefficient: 0.695, p < 0.001). DHI scores were lower in alcohol consumers than in non-drinkers (46.6 vs. 56, p = 0.048). No significant correlation was found between DHI scores and age, time of evolution, posturographic scores, comorbidities, environment (rural or urban), or active lifestyle. Conclusion: Most patients with presbyvestibulopathy show an important subjective perception of disability in relation to their symptoms. This perception is substantially higher in women than in men. The most influential factors are difficulties in walking, fear of falling, and obesity. Unique Identifier: NCT03034655, www.clinicaltrials.gov

Modified Timed Up and Go Test for Tendency to Fall and Balance Assessment in Elderly Patients With Gait Instability

Objective: To compare the results from the modified Timed Up and Go Test (TUG) with posturographic variables, the subjective perception of disability due to gait instability, and the number of falls in a sample of the elderly population with imbalance, to confirm that the TUG Test is a useful clinical instrument to assess the tendency to fall in individuals of this age group. Materials and Methods: Cross-sectional study conducted in a tertiary university hospital, in 174 people aged 65 years or older with gait instability. Modified TUG Test was performed; time, step count and the need for support during the test were the analyzed variables. They were compared with the number of falls, Computerized Dynamic Posturography scores, and questionnaires scores (Dizziness Handicap Inventory and a shortened version of the Falls Efficacy Scale-International). Results: The average time to complete the TUG Test was 21.24 +/- 8.18 s, and the average step count was 27.36 +/- 7.93. One hundred two patients (58.6%) required no support to complete the test, whereas the other 72 (41.4%) used supports. The time taken to complete the Test was significantly related with having or not having fallen in the previous year, with the scores of the questionnaires, and with various parameters of dynamic posturography. A higher percentage of patients who took more than 15 s had fallen in the previous year than those who took up to 15 s to complete the test [P = 0.012; OR = 2.378; 95% CI (1.183, 4.780)]. No significant correlation was found between the step count and the number of falls in the previous year, with falling during the test or not, or with being a single or a frequent faller. No relation was found between the need for supports and the number of falls, with having or not having fallen in the previous year, or with being a single or frequent faller. Conclusion: The modified TUG Test is in relation with the presence or absence of falls. Time is the essential parameter for analyzing the risk of falling and the 15-s threshold is a good value to differentiate elderly patients at high risk of falling. Unique Identifier: NCT03034655, www.clinicaltrials.gov

Elastic scattering, inelastic excitation, and neutron transfer for Li 7 + Sn 120 at energies around the Coulomb barrier

Experimental angular distributions for the 7 Li + 120 Sn elastic and inelastic (projectile and target excitations) scattering, and for the neutron stripping reaction, have been obtained at E LAB = 20, 22, 24, and 26 MeV, covering an energy range around the Coulomb barrier ( V (LAB) B ≈ 21 . 4 MeV). Coupled channel and coupled reaction channel calculations were performed and both describe satisfactorily the experimental data sets. The 1 2 − state 7 Li inelastic excitation (using a rotational model), as well as the projectile coupling to the continuum ( α plus a tritium particle) play a fundamental role on the proper description of elastic, inelastic, and transfer channels. Couplings to the one-neutron stripping channel do not significantly affect the theoretical elastic scattering angular distributions. The spectroscopic amplitudes of the transfer channel were obtained through a shell model calculation. The theoretical angular distributions for the one-neutron stripping reaction agreed with the experimental data

Adventive hydrothermal circulation on Stromboli volcano (Aeolian Islands, Italy) revealed by geophysical and geochemical approaches: Implications for general fluid flow models on volcanoes

International audienceOn March 15th 2007 a paroxysmal explosion occurred at the Stromboli volcano. This event generated a large amount of products, mostly lithic blocks, some of which impacted the ground as far as down to 200 m a.s.l., about 1.5 km far away from the active vents. Two days after the explosion, a new vapour emission was discovered on the north-eastern flank of the volcanic edifice, at 560 m a.s.l., just above the area called "Nel Cannestrà". This new vapour emission was due to a block impact. In order to investigate the block impact area to understand the appearance of the vapour emission, we conducted on May 2008 a multidisciplinary study involving Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), Self-Potential (SP), CO2 soil diffuse degassing and soil temperature surveys. This complementary data set revealed the presence of an anomalous conductive body, probably related to a shallow hydrothermal level, at about 10-15 m depth, more or less parallel to the topography. It is the first time that such a hydrothermal fluid flow, with a temperature close to the water boiling point (76 °C) has been evidenced at Stromboli at this low elevation on the flank of the edifice. The ERT results suggest a possible link between (1) the main central hydrothermal system of Stromboli, located just above the plumbing system feeding the active vents, with a maximum of subsurface soil temperature close to 90 °C and limited by the NeoStromboli summit crater boundary and (2) the investigated area of Nel Cannestrà, at ~ 500 m a.s.l., a buried eruptive fissure active 9 ka ago. In parallel, SP and CO2 soil diffuse degassing measurements suggest in this sector at slightly lower elevation from the block impact crater a magmatic and hydrothermal fluid rising system along the N41° regional fault. A complementary ERT profile, on May 2009, carried out from the NeoStromboli crater boundary down to the block impact crater displayed a flank fluid flow apparently connected to a deeper system. The concept of shallow hydrothermal level have been compared to similar ERT results recently obtained on Mount Etna and La Fossa cone of Vulcano. This information needs to be taken into account in general fluid flow models on volcanoes. In particular, peripheral thermal waters (as those bordering the north-eastern coast of Stromboli) could be contaminated by hydrothermal and magmatic fluids coming from regional faults but also from the summit