Search results for "FAS"
showing 10 items of 2015 documents
Testing the assumptions of conditional handicap theory: costs and condition dependence of a sexually selected trait
2000
Conditional handicap models of sexual selection predict that sexual traits are reliable signals of male quality because they are (a) condition dependent and (b) costly to produce or maintain. In this study, my objective was to experimentally investigate whether the drumming of male Hygrolycosa rubrofasciata wolf spiders is a condition-dependent costly trait. Males court females by drumming dry leaves with their abdomen and females preferentially mate with males drumming at higher rates. I manipulated male phenotypic condition and drumming rate simultaneously by keeping males on three different food rations and either introducing or not introducing them to a female. Food ration treatment aff…
Attività motoria e sportiva in età evolutiva
2017
Large retroperitoneal abscess extended to the inferior right limb secondary to a perforated ileal Crohn’s disease: the importance of the multidiscipl…
2016
The typical complications of Crohn's disease concerns small and large bowel. The full thickness inflammation of the intestinal wall develops in strictures, fistulas and abdominal abscesses. Nowadays the most accepted therapeutic for intra-abdominal abscess option is antibiotic therapy and, in case of need, percutaneous drainage of the abscess. If the abscess passes through the pelvic foramen the abscess can involve the inferior limbs. We report a case a perforation of terminal ileum in Crohn's disease complicated by a large abscess of the right iliac fossa reaching the spaces between the anterior lateral muscles of the right thigh as far as the anterior lateral pre-tibial region. We discuss…
Frequency-dependent response and dynamic disorder
1991
Abstract This paper discusses selected aspects of the application of dynamic percolation models to ionic transport in mixed-ion superionic conductors. The discussion is based on an AB lattice gas model with hard-core repulsions and a ratio of τ, 0 ⩽ τ ⩽ ∞, between the transition rates of particles A and B. The frequency-dependent conductivity for a tracer particle is calculated within an effective-medium theory. The motion of the background B-particles is regarded as providing a fluctuating disordered environment for the tracer particles A. A crossover frequency separating high-frequency and low-frequency response is found which scales with τ as ω c ∼ τ 1 2 . The results for the dc limit ar…
Radiation defects in undoped and Nd‐doped LaGaO 3 crystals
2005
Radiation induced defects have been studied in undoped and Nd-doped (6 mol% and 12 mol%) LaGaO3 crystals. Wide absorption band (2.2–2.8 eV) was observed after crystal irradiation with X-rays at 300 K. Induced defects have been annealed in air at ∼450 K. Similar absorption band was observed in transient absorption spectra after ns-pulsed electron beam excitation. The radiation defect creation efficiency is higher in undoped LaGaO3 crystal. It is shown that small concentration of Nd-doping increases the LaGaO3 crystal radiation hardness. In transient absorption spectra along with 2.7 eV band the absorption bands at 1.5 eV and 2.2 eV were observed. The decay process of transient absorption has…
Decoupling the artificial special pair to slow down the rate of singlet energy transfer
2012
Trimer 2, composed of a cofacial heterobismacrocycle, octamethyl-porphyrin zinc(II) and bisarylporphyrin zinc(II) held by an anthracenyl spacer, and a flanking acceptor, bisarylporphyrin free-base ( Ar = -3,5-(t Bu )2 C 6 H 3), has been studied by means of absorption spectroscopy, "steady state and time-resolved fluorescence" and fs transient absorption spectroscopy, and density functional theory (DFT) in order to assess the effect of decoupling the chromophores' low energy MOs on the rate of the singlet, S1, energy transfer, k ET , compared to a recently reported work on a heavily coupled trimeric system, Trimer 1, [biphenylenebis(n-nonyl)porphyrin zinc(II)]-bisarylporphyrin free-base ( A…
Transient absorption spectra and relaxation kinetics in Nb-doped PbWO4 scintillating crystals
2001
Abstract The spectra and relaxation kinetics of absorption induced by a pulsed electron beam were studied for undoped and Nb-doped PbWO 4 single crystals. A significant influence of Nb doping on transient absorption was found. The influence of Nb doping on the relaxation kinetics is proposed to be due to an oxygen vacancy involving electron–hole recombination. A delay was observed (35– 50 ns ) between the growth of F-centers and the irradiation pulse. A large portion of the F-centers decays within ∼16 μs due to recombination with mobile holes. The prolonged recombination processes are responsible for the decrease of the scintillation yield in PbWO 4 : Nb crystals.