Approximation of the acoustic radiation impedance of a cylindrical pipe

Useful approximation formulae for radiation impedance are given for the reflection coefficients of both infinitely flanged and unflanged rigid-walled cylindrical ducts. The expressions guarantee that simple but necessary physical and mathematical principles are met, like hermitian symmetry for the reflection coefficient (identical behaviour of positive and negative frequencies) and causality for the impulse response. A non causal but more accurate expression is also proposed that is suitable for frequency-domain applications. The formulae are obtained by analytical and numerical fitting to reference results from Levine & Schwinger for the unflanged case and extracted from the radiation impedance matrix given by Zorumski for the infinite flanged case.Comment: Journal of Sound and Vibration (2008) accepte

Tourism And Urbanization: Environmental Problem Of The Araruai Lagoon, State Of Rio De Janeiro, Brazil

The Araruama Lagoon (Rio de Janeiro) is known for its scenic beauty and natural resources, factors that have led to the economic expansion of the region. In recent decades, tourism and property speculation have been key to the urban development of the municipalities surrounding this Lagoon. Using secondary data and a theoretical framework based on Political Ecology and Critical Environmental Education, this article seeks to analyze the correlations between the development processes of the towns surrounding the Lagoon and the impact of these processes on the environmental quality of its ecosystem. In recent years, the evolution of parameters studied revealed that the imbalance in terms of the sustainable development of the region has damaged the health of this body of water. Large quantities of fresh water, as well as domestic and industrial effluents discharged without appropriate treatment in the Lagoon, have overloaded the ecological system, with negative effects for the entire economy in the surrounding area.194598

Reciprocal preening and food sharing in colour-polymorphic nestling barn owls.

Barn owl (Tyto alba) siblings preen and offer food items to one another, behaviours that can be considered prosocial because they benefit a conspecific by relieving distress or need. In experimental broods, we analysed whether such behaviours were reciprocated, preferentially exchanged between specific phenotypes, performed to avoid harassment and food theft or signals of hierarchy status. Three of the results are consistent with the hypothesis of direct reciprocity. First, food sharing was reciprocated in three-chick broods but not in pairs of siblings, that is when nestlings could choose a partner with whom to develop a reciprocating interaction. Second, a nestling was more likely to give a prey item to its sibling if the latter individual had preened the former. Third, siblings matched their investment in preening each other. Manipulation of age hierarchy showed that food stealing was directed towards older siblings but was not performed to compensate for a low level of cooperation received. Social behaviours were related to melanin-based coloration, suggesting that animals may signal their propensity to interact socially. The most prosocial phenotype (darker reddish) was also the phenotype that stole more food, and the effect of coloration on prosocial behaviour depended upon rank and sex, suggesting that colour-related prosociality is state dependent

Development of dried probiotic apple cubes incorporated with Lactobacillus casei NRRL B-442

[EN] This work presents the development of a probiotic dried apple snack consisting of dried apple cubes impregnated with Lactobacillus casei NRRL B-442. Apple cubes were impregnated with probiotic microorganisms and dried under different temperatures (10-60 degrees C), with or without application of ultrasound. The viability of Lactobacillus casei in the dried apple snack was evaluated studying the effects of drying conditions and ultrasound application (as a drying enhancing technology). A mathematical model was developed to predict the drying kinetics and the inactivation of Lactobacillus casei. Drying and microorganism inactivation rates increased with increasing process temperature and with ultrasound application. The concentration of probiotics in the apple snacks was similar to the concentration of microorganisms in commercial probiotic dairy products when the apples were dried at 60 degrees C or when ultrasound-assisted air-drying was applied, thus proving that the production of dried probiotic apple snacks is possible and technically viable.The authors acknowledge the financial support of Generalitat Valenciana (PROMETEOII/2014/005) from Spain, and the financial support and the award of a scholarship of CNPq from Brazil.Rodrigues, S.; Silva, LCA.; Mulet Pons, A.; Carcel Carrión, JA.; Fernandes, FA. (2018). Development of dried probiotic apple cubes incorporated with Lactobacillus casei NRRL B-442. Journal of Functional Foods. 41:48-54. https://doi.org/10.1016/j.jff.2017.12.042S48544

Therapeutic and Prophylactic Potential of Vitamin D for Multiple Sclerosis

A plethora of investigations demonstrated that vitamin D (VitD) has a broad immunomodulatory potential. It induces tolerogenic dendritic cells in vitro leading to the development of regulatory T cells that have a key role in immunomodulation of autoimmune diseases including multiple sclerosis (MS). Studies showed that many MS patients present lower serum levels of VitD than healthy subjects. In addition, VitD supplementation has been associated with a reduced relative risk of developing MS. Considering the alterations in VitD levels in patients and also the immunomodulatory properties of VitD, it would be interesting to evaluate VitD potential as a tolerogenic adjuvant in experimental models of MS. In this context, our research team has been investigating strategies employing VitD to establish an in vivo tolerance state toward central nervous system antigens in experimental autoimmune encephalomyelitis (EAE). We observed that the association between a myelin peptide and VitD determined both therapeutic and prophylactic effects on EAE development

Chemical and spectroscopic characterization of humic acids extracted from the bottom sediments of a Brazilian subtropical microbasin

International audienceHumic substances (HS) perform a fundamental role in aquatic environments, exhibiting different levels of reactivity in retaining metal ions and organic pollutants. Also, they control the primary production of these ecosystems and act in the carbon sequestering process. In order to improve our understanding vis-à-vis the structural and functional features of HS from aquatic systems, this study aimed to chemically and spectroscopically characterize humic acids (HA) isolated from bottom sediment samples of a stream in a Brazilian subtropical microbasin by elemental analysis, and infrared (FT-IR), ultraviolet and visible (UV-Vis) and solid-state 13C nuclear magnetic resonance (CP-MAS 13C NMR) spectroscopies, thermogravimetry (TG), and scanning electron microscopy (SEM). Although all samples originated from the same environment, the data showed that the HA have distinct chemical and spectroscopic properties, and that the location and characteristics of the sampling points from which the sediments were collected played an important role in the differences observed. Furthermore, vascular plant matter is probably the main contributor to these samples

ANÁLISE DA CURVA DE CRESCIMENTO DA CIRCUNFERÊNCIA ESCROTAL DE TOUROS DA RAÇA CANCHIM E DO GRUPO GENÉTICO MA

O objetivo deste trabalho foi ajustar diferentes curvas de crescimento para circunferência escrotal (CE) em função da idade, em touros da raça Canchim e do grupo genético MA mediante a utilização de modelos não lineares. Na análise foram empregadas 27.363 medidas da circunferência escrotal, provenientes de 5.520 touros da Raça Canchim e, 8.892 medidas de circunferência escrotal oriundas de 1.450 touros do grupo genético MA. Os resultados obtidos demonstram que o modelo Gompertz foi o que melhor descreveu o crescimento da CE nos touros da raça Canchim e o Logístico foi o mais adequado para descrever o crescimento da CE no grupo genético MA. O modelo Brody apresentou pouca utilidade no ajustamento da CE em função da idade. Growth curves of Scrotal circunference in Canchim and MA bulls Abstract The objective of this study was to adjust different growth curves of scrotal circumference (SC) by age. The data consisted of records on Canchim bulls and bulls of the MA genetic group wich were fit by no linear models. Were considered 27.363 measures on 5.520 Canchim bulls and 8.892 measures on 1.450 bulls of the MA genetic group. The results showed that the Gompertz model was the best to describe the growth of SC in the Canchim bulls and the Logistic model was the most appropriate to describe the growth of SC in the MA genetic group. The Brody model presented little usefulness in the adjustment of SC by age

Convergence of the critical attractor of dissipative maps: Log-periodic oscillations, fractality and nonextensivity

For a family of logistic-like maps, we investigate the rate of convergence to the critical attractor when an ensemble of initial conditions is uniformly spread over the entire phase space. We found that the phase space volume occupied by the ensemble W(t) depicts a power-law decay with log-periodic oscillations reflecting the multifractal character of the critical attractor. We explore the parametric dependence of the power-law exponent and the amplitude of the log-periodic oscillations with the attractor's fractal dimension governed by the inflexion of the map near its extremal point. Further, we investigate the temporal evolution of W(t) for the circle map whose critical attractor is dense. In this case, we found W(t) to exhibit a rich pattern with a slow logarithmic decay of the lower bounds. These results are discussed in the context of nonextensive Tsallis entropies.Comment: 8 pages and 8 fig

Universality and scaling study of the critical behavior of the two-dimensional Blume-Capel model in short-time dynamics

In this paper we study the short-time behavior of the Blume-Capel model at the tricritical point as well as along the second order critical line. Dynamic and static exponents are estimated by exploring scaling relations for the magnetization and its moments at early stage of the dynamic evolution. Our estimates for the dynamic exponents, at the tricritical point, are $z= 2.215(2)$ and $\theta= -0.53(2)$.Comment: 12 pages, 9 figure