A new method for estimating the pattern speed of spiral structure in the Milky Way

In the last few decades many efforts have been made to understand the effect of spiral arms on the gas and stellar dynamics in the Milky Way disc. One of the fundamental parameters of the spiral structure is its angular velocity, or pattern speed $\Omega_p$, which determines the location of resonances in the disc and the spirals' radial extent. The most direct method for estimating the pattern speed relies on backward integration techniques, trying to locate the stellar birthplace of open clusters. Here we propose a new method based on the interaction between the spiral arms and the stars in the disc. Using a sample of around 500 open clusters from the {\it New Catalogue of Optically Visible Open Clusters and Candidates}, and a sample of 500 giant stars observed by APOGEE, we find $\Omega_p = 23.0\pm0.5$ km s$^{-1}$ kpc$^{-1}$, for a local standard of rest rotation $V_0=220$~km s$^{-1}$ and solar radius $R_0=8.0$~kpc. Exploring a range in $V_0$ and $R_0$ within the acceptable values, 200-240 km s$^{-1}$ and 7.5-8.5 kpc, respectively, results only in a small change in our estimate of $\Omega_p$, that is within the error. Our result is in close agreement with a number of studies which suggest values in the range 20-25 km s$^{-1}$ kpc$^{-1}$. An advantage of our method is that we do not need knowledge of the stellar age, unlike in the case of the birthplace method, which allows us to use data from large Galactic surveys. The precision of our method will be improved once larger samples of disk stars with spectroscopic information will become available thanks to future surveys such as 4MOST.Comment: 10 pages, 6 figures, 4 tables, accepted for publication in MNRA

Hepatitis C virus (HCV): ever in reliable partnerships?

Hepatitis C virus (HCV) is a parenterally transmitted hepatotropic pathogen. HCV infection is a major health problem worldwide, frequently causing cirrhosis and liver cancer. There is no preventive vaccine against HCV and treatment, consisting of interferon alpha plus Ribavirin, is generally effective in less than 50% of cases. HCV has evolved mechanisms for surviving in the host. Infection with multiple different HCV variants, as well as interaction with concurrent pathogens, might be successful strategies for viral persistence. The present review illustrates the current status of HCV co-infection with highly relevant pathogens. Issues regarding tropism, disease progression and antiviral treatment response, among other aspects, are discussed. Data accumulated reveal that HCV co-infection should not be considered the mere sum of several independent infections. Some significant questions are still unanswered. Therefore, nowadays, it might be more reasonable to face HCV co-infections as a new biological, clinical and even predominant epidemiological entit

Wave Equation for Sound in Fluids with Vorticity

We use Clebsch potentials and an action principle to derive a closed system of gauge invariant equations for sound superposed on a general background flow. Our system reduces to the Unruh (1981) and Pierce (1990) wave equations when the flow is irrotational, or slowly varying. We illustrate our formalism by applying it to waves propagating in a uniformly rotating fluid where the sound modes hybridize with inertial waves.Comment: RevTeX, 27page

Capim-elefante como biomassa para produção de energia.

bitstream/item/142629/1/capim-elefante-biomassa-energia.pd

An Analytic Equation of State for Ising-like Models

Using an Environmentally Friendly Renormalization we derive, from an underlying field theory representation, a formal expression for the equation of state, $y=f(x)$, that exhibits all desired asymptotic and analyticity properties in the three limits $x\to 0$, $x\to \infty$ and $x\to -1$. The only necessary inputs are the Wilson functions $\gamma_\lambda$, $\gamma_\phi$ and $\gamma_{\phi^2}$, associated with a renormalization of the transverse vertex functions. These Wilson functions exhibit a crossover between the Wilson-Fisher fixed point and the fixed point that controls the coexistence curve. Restricting to the case N=1, we derive a one-loop equation of state for $2< d<4$ naturally parameterized by a ratio of non-linear scaling fields. For $d=3$ we show that a non-parameterized analytic form can be deduced. Various asymptotic amplitudes are calculated directly from the equation of state in all three asymptotic limits of interest and comparison made with known results. By positing a scaling form for the equation of state inspired by the one-loop result, but adjusted to fit the known values of the critical exponents, we obtain better agreement with known asymptotic amplitudes.Comment: 10 pages, 2 figure

The role of temperature in the magnetic irreversibility of type-I Pb superconductors

Evidence of how temperature takes part in the magnetic irreversibility in the intermediate state of a cylinder and various disks of pure type-I superconducting lead is presented. Isothermal measurements of first magnetization curves and magnetic hysteresis cycles are analyzed in a reduced representation that defines an equilibrium state for flux penetration in all the samples and reveals that flux expulsion depends on temperature in the disks but not in the cylinder. The magnetic field at which irreversibility sets in along the descending branch of the hysteresis cycle and the remnant magnetization at zero field are found to decrease with temperature in the disks. The contributions to irreversibility of the geometrical barrier and the energy minima associated to stress defects that act as pinning centers on normal-superconductor interfaces are discussed. The differences observed among the disks are ascribed to the diverse nature of the stress defects in each sample. The pinning barriers are suggested to decrease with the magnetic field to account for these results

Moiré flat bands in strongly coupled atomic arrays

Moiré effects arise from stacking periodic structures with a specific geometrical mismatch and promise unique possibilities. However, their full potential for photonic applications has yet to be explored. Here, we investigate the photonic band structure for an atomic stack of strongly coupled linear arrays in the dipolar regime. A moiré parameter θ is used to parameterize a relative lattice constant mismatch between the two arrays that plays the role of a 1D twist angle. The system’s interaction matrix is analytically diagonalized and reveals the presence of localized excitations which strongly enhance the density of optical states in spectral regions that can be controlled via the moiré parameter. We also confirm our findings by numerical simulations of finite systems. Our work provides a better understanding of photonic moiré effects and their potential use in photonic devices such as optical sensors and light traps

Technologies in the cruise tourism services: A systematic and bibliometric approach

COVID-19 and the faster evolution of emerging technologies forced companies to create new business models and become more digital. Therefore, companies worldwide have adopted different digital technologies such as online stores, digital assistants, digital panels, or robotic services. This trend has also impacted the cruise industry, with new cruise ships using digital technologies onboard such as: Artificial Intelligence (AI): ⎼ ZOE digital assistance is used in the latest MSC Cruise Ships. ⎼ Virtual Concierge app used on the newest Celebrity Cruises Ships. ⎼ Robotic bartender at the Bionic Bar on Royal Caribbean Cruise Lines. ⎼ Pepper, the humanoid robot at Costa Cruise Line ships. ⎼ Rob the first humanoid robot bartender at MSC Cruise ships. Virtual Reality (VR): ⎼ Shore excursions ⎼ Culinary dining Despite the strong adoption of new technologies in cruise ships, existing studies related to the use of AI, VR, or robots in smart tourism are mostly limited to restaurants, hotels, or airports. Opening an opportunity to develop a systematic and bibliometric review on this topic - Technologies in the cruise tourism services.info:eu-repo/semantics/publishedVersio

The perception of tactile feeling and corresponding textile attributes worldwide

The textile industry has been exploring sensory analysis as means to evaluate different products as a strategy to improve product comfort. The sensory analysis uses a set of attributes standardized for sensory evaluation: the lexicons. This paper compares three lexicons developed to assess the sensory comfort of textile fabrics, by researchers from France, Portugal and Brazil. Quantitative Descriptive Analysis was conducted for the development of these lexicons. The study showed that France and Portugal have thirteen attributes in common and seven attributes are common in France, Portugal and Brazil: Light-Heavy, Gross-Fine, Fresh-Hot, Soft, Plushy, Elasticity and Falling.This work was supported by FEDER funds through the Competitivity Factors Operational Program COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136

Implementação de um plano de amostragem seqüencial para Oebalus spp. em arroz irrigado.

Com base em estudos da distribuição populacional e espacial dos percevejos do grão realizados em 29 campos de arroz irrigado nos municípios de Formoso do Araguaia (TO) e São Miguel do Araguaia (GO), foi desenvolvido um plano de amostragem seqüencial para auxiliar no manejo dessas espécies.Resumo ID:1938-1