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Forest fires can cause direct mortality to wildlife, and the associated habitat damage can reduce carrying capacity and population densities. However, little is known about long-term responses of animals to fire in the wet tropics. From 2000-2015, we examined siamang ranging patterns in habitat damaged by fire to assess the effects on these arboreal frugivores. We mapped home ranges (HR) of seven siamang groups inhabiting contiguous HR 3-5, 10-12, and 17–18 years post-fire. We predicted that if habitat connectivity or quality improved over time in burned areas, HR should become larger and centroid locations should shift toward recovering areas. Since territoriality constrains siamang ranging, we examined effects of social and habitat factors on ranging. By 18 years post-fire, tree density in the burned area had returned to the 1997 baseline, but composite LandSat images indicated that tree species composition differed in burned and unburned forest. Our data and the associated models indicated that HR sizes in burned forest increased over time whereas those in unburned forest did not. Centroid locations moved little (15.5 ± 6.9 m y-1) and their movement appeared to be predominantly influenced by social factors, although HR centroids in burned habitat shifted further into the burned area while those in adjacent unburned forest did not. In a large burned area unused by siamangs before 2012, two new groups were observed 15-17 years post-fire, although one subsequently disappeared. This is the first study of the long-term effects of fire on small ape habitat use. By 18 years post-fire, siamangs had incorporated some burned areas into their HR, but did not use heavily damaged areas. Reduced frugivore densities in burned areas may inhibit forest regeneration by disrupting seed dispersal.

Audience effects on sexual behavior, including changes in copulation frequency and duration in the presence of conspecifics, have been reported in multimale–multifemale groups of several primate species. We examined the interaction of male sexual behavior with group composition and within-group mating pattern in a population of siamangs (Symphalangus syndactylus) containing unimale–unifemale groups and multimale–unifemale groups using mixed models. Aggression in a sexual context was never observed. As predicted, however, copulation rates were lower and copulations were significantly shorter in duration in two-male groups than in unimale groups, even if copulations involving subordinate males were excluded. Dominant males monopolized copulations with the group female in most groups, but copulations were shared among males in three stable two-male groups. When both resident males copulated with the group’s female, there was no evidence that copulating pairs moved to secluded areas, and the duration of copulations did not differ between males. These results are consistent with the hypothesis that male–male tolerance in multimale siamang groups is facilitated by adjustments to sexual behavior in the presence of a sexual competitor.

The authors, reviewing the international literature with their clinical experience developed in reconstructive surgery of acetabular defects due to aseptic loosening of acetabular cups, suggest their guidelines to the right use of acetabular reinforcement rings.

The aseptic loosening of the femoral stem may require different treatments due to the complex problems related to the bone resorption (qualitatively and quantitatively): a minimum bone stock loss may result in a periprosthetic resorption that is so severe to make the fixation of the revision prosthesis extremely difficult. The revision surgery of a loosened hip prosthesis is often characterized by a complex reconstruction due to such severe loss of femoral bone tissue. We illustrate our experience with MP-Link modular stem (Waldemar Link, Hamburg, Germany) in cases of severe bone loss of the metaphyseal area and of the proximal third of the femoral shaft, assessing the technological developments (materials and design) over the years and examining the pros and cons of cementless distalfixation modular stems versus the traditional Wagner's stem.

This paper addresses the problem of limit-cycle taming, which is defined in this paper as the use of nonlinear control laws to ensure that the limit-cycle behaviour of the system beyond the stability boundary is of a benign rather than a destructive nature. Specifically, we consider a one-parameter (denoted by λ) autonomous dynamic system having algebraic nonlinearities. We assume that the system has a stable solution, x = 0, for λ < λ0, and experiences a Hopf bifurcation at λ = λ0. Using a singular perturbation analysis about the stability boundary, it is shown that, using a simple nonlinear control law, limit-cycle taming is always possible in the neighbourhood of a Hopf bifurcation. The control system proposed for limit-cycle taming is fully nonlinear, and therefore does not affect the linear behaviour of the system (in particular its stability characteristics). Hence, limit-cycle taming may be used in conjunction with a standard linear active control (e.g. use of linear active control to increase the stability boundary). Applications of the theory to the problem of flutter are presented.

In this paper a method for the evaluation of pressure and velocity fields for a horizontal-axis wind turbine in the presence of yaw is presented. The flow is assumed to be potential and incompressible. The formulation used is general and is applicable to unsteady incompressible potential flows around wind turbines, as well as aircraft and ship propellers. In order to assess the importance of the wake geometry a free-wake analysis is included in this paper. Comparisons with experimental results are also included.

Frontal analysis was used to study the removal of soluble SiO 2 from water by strong-base, or mixed functionality, anion-exchange resins. It was found that if the total concentration of the anions in the influent water exceeds values corresponding to the solubility of SiO 2 (of the order of 2 meq/l under the conditions of this work), then part of the SiO 2 retained by the resin is found in the non-ionic form. This phenomenon is amplified by high SiO 2 content and is reduced in the presence of HCO 3 − ions. Mixed functionality acrylic resins show this phenomenon to a lesser extent. Regeneration of non-ionic silica becomes a solubilization phenomenon rather than ion exchange. Implications on co- and counter-current regeneration are discussed.

The problem addressed in this work consists of prediction of the acoustic field generated by the aerodynamic interaction between propeller and fuselage of a general aviation aircraft. We focus on the analysis of the acoustic field generate by a propeller-fuselage configuration (no wing), where the wake of the propeller remains separated from the surface of the fuselage. Three differen methodologies are applied. The first is based on the potential function and consists in a unified approach for aerodynamic and aeroacoustic analysis. The second is a Kirchhoff approach applied to the fuselage surface in order to determine the scattered pressure in the field once the pressure on the propeller is known. The third is the integration of the FWH equation which determines the pressure field once the pressure on both propeller and fuselage is given. Numerical results are shown for a simple, but realistic, configuration, with the analysis of fuselage effects and the comparison among the considered formulations.

This work presents a boundary-integral-equation methodology for the aerodynamic analysis of unsteady, subsonic, compressible, potential flows around N bodies, each having arbitrary shape and motion, with applications to rotor-fuselage configurations. Starting from the differential problem, the unknown is expressed in terms of a boundary integral representation, which is given by the sum of integrals over the surfaces of the N bodies. The novelty is that each contribution is expressed in a frame of reference rigidly connected to the corresponding body. This fact simplifies considerably both the derivation of the formulation and the evaluation of the surface integrals (since in this case one deals with integrals over time-independent surfaces). In this paper, first we present the boundary integral formulation for N surfaces including one that surrounds the wake and is rigidly-connected to the undisturbed air.

In the present work we present a third-order boundary element method for the prediction of sound scattered by rigid or elastic shells impinged by planar pressure waves. The so-called Fictitious Eigenvalues Difficulty introduced by the boundary element method approach (that consists of the existence of spurious resonances for the frequencies of related interior problem) is overcome by the CONDOR technique by Burton and Miller which corresponds to the use of a suitable linear combination of the KirchhofFHelmoltz equation with that obtained by taking its normal derivative. The resulting boundary integral equation is here solved by a piecewise bicubic discretization. Numerical results obtained for radiation and scattering problems are presented, and validated through comparison with analytical solutions. Numerical analysis shows that the convergence rate is of order h3 (h being the typical size of the elements), indicating that this is a true third-order method.

We report a patient with thalassemia intermedia who developed a mediastinal syndrome due to the growth of paravertebral hematopoietic masses in the posterior mediastinum. Because the patient did not receive blood transfusions due to alloimmunization, she was first treated with human recombinant erythropoietin (escalating low-moderate doses) to recover hemoglobin levels, then in association with radiotherapy to prevent a worsening of her anemia. The mean Hb level dramatically increased and peaked at week 11, to 83 g/l, and remained unchanged before and after radiotherapy (81 versus 78 g/l). Immediately after radiotherapy extramedullary hematopoiesis volume decreased by 16.4%.

The paper persents recent developments in a singular perturbation method, known as the “Lie transformation method” for the analysis of nonlinear dynamical systems having chaotic behavior. A general approximate solution for a system of first-order differential equations having algebraic nonlinearities is introduced. Past applications to simple dynamical nonlinear models have shown that this method yields highly accurate solutions of the systems. In the present paper the capability of this method is extended to the analysis of dynamical systems having chaotic behavior: indeed, the presence of “small divisors” in the general expression of the solution suggests a modification of the method that is necessary in order to analyze nonlinear systems having chaotic behavior (indeed, even non-simple-harmonic behavior). For the case of Hamiltonian systems this is consistent with the KAM (Kolmogorov-Arnold-Moser) theory, which gives the limits of integrability for such systems; in contrast to the KAM theory, the present formulation is not limited to conservative systems. Applications to a classic aeroelastic problem (panel flutter) are also included.

A vorticity-only formulation is used in order to study the behavior of the solutions of the Navier-Stokes equations for two-dimensional incompressible flows as the Reynolds number is increased. This approach allows for the confinement of the numerical-solution domain to the vortical region of the flow, and a consequent reduction of the state variables of the system. The vorticity-only formulation is obtained from a vorticity-stream function formulation by inverting the Poisson equation relating the vorticity to the stream function and substituting the expression for the velocity in the vorticity-transport equation. The vorticity at the solid boundary is determined from the boundary conditions. The resulting dynamical system consists of a set of first-order ordinary differential equations having only quadratic nonlinearities. This system is then used to address the behavior of the solution beyond the stability boundary, within the context of the theory of dynamical systems. This part of the paper is very general and is based on the use of a singular-perturbation technique, known as the method of multiple time scales; formulae for the nonlinear analysis near a Hopf bifurcation are given explicitly in terms of the coefficients of the dynamical system. Preliminary numerical results for the validation of the formulation are presented for the case of two-dimensional flows around a circular cylinder. These results include the steady-state solution with varying μ, the eigenvalues and the eigenvectors of the related stability matrix, and the characteristics of the corresponding limit cycle.

In recent years there has been an increasing interest in integrated optimal design methods as a rational approach to the design problem ([1]). In these methods, objective and constraint functions are assigned and the system analysis is performed by integrating several disciplines (e.g., aerodynamics, structural dynamics, control etc.) in a common optimization procedure. If a formal optimization is used, gradients of the objective and constraint functions with respect to the design variables of interest are required. This in turn implies the computation of the so called sensitivities coefficients, i.e., the derivatives of certain key quantities describing the system with respect to the design variables. In the field of computational structural mechanics, the subject of sensitivity analysis is relatively mature, and the references that are available are extensive. In the field of aerodynamics, there exist a limited number of studies and research continues to be active on this subject ([2]). The present work is based on Arsuffi, [3], to which the reader is referred for an extensive review of the subject, as well as details on the mathematical formulation and on the numerical results.

Several mechanical or aeroelastic systems can be reduced to a standard dynamical system, i.e., a system of ODEs, using spectral methods. The resulting ordinary differential equations with constant coefficients can be either integrated numerically directly or, if the nonlinearities are sufficiently weak, can be analyzed by a singular perturbation approach. In the present paper an extension of the Lie transformation method is used in combination with suitable numerical-integration schemes in order to enhance the efficiency of the solution of the equation governing dynamical systems having chaotic behavior. The extension of the Lie transformation method gives a general procedure to obtain the simplest equations necessary to describe the phenomenon. Aeroelastic applications have been included.

A unified methodology for the analysis of potential and viscous flows is reviewed. The viscous-flow formulation is based on the decomposition of the velocity field into two terms: the first (vortical velocity) is due to the vorticity in the field, whereas the second is irrotational. The specific decomposition used is characterized by the fact that the vortical velocity vanishes in a region 𝓥 0, which comprises most of the irrotational region. As a consequence, the additional field sources in the equation for the potential also vanish in 𝓥0, even for unsteady compressible flows. This is a major advantage for boundary integral formulations. In addition, it is shown how in the limit, as the thickness of the vortical region goes to zero, the viscous-flow formulation reduces continuously to the potential-flow formulation. Also, the methodology is general in that it is applicable for the solution of unsteady compressible flows around complex configurations. The extent of the validation of the numerical implementation is reported : the validation for the potential-flow formulation is extensive (recent applications include unsteady transonic three-dimensional flows around isolated wings and subsonic flows around isolated helicopter rotors in forward flight), whereas the validation of the viscous-flow formulation is limited in the impulsive start of airfoils in two-dimensional incompressible flows.

The objective of this work is to review some recent advances in a boundary-integral-equation method developed by the authors and their collaborators for the aerodynamic analysis of unsteady, potential, subsonic flows around bodies having arbitrary motion, with applications to helicopter rotors in hover and forward flight.