883 resultados para Bert Call
Resumo:
An adolescent and young adult (AYA) cancer patient is defined as an individual of 15 to 39 years of age at the time of initial cancer diagnosis.1,2 The number of AYA cancer survivors has dramatically increased over the past decades due to availability of novel therapeutics, with the 5-year overall survival rate among adolescents aged 15 to 19 years old exceeds 80% for most cancers.3 AYA cancer survivors, however, often experience a myriad of treatment-related chronic and late toxicities that can lead to functional impairment at great economic, emotional and social cost.4 As the cure rates of AYA cancers continue to improve and survivors live longer, post-treatment health issues in these survivors are becoming increasingly relevant, and more in-depth research is needed in this group of patients...
Resumo:
Low-frequency sounds are advantageous for long-range acoustic signal transmission, but for small animals they constitute a challenge for signal detection and localization. The efficient detection of sound in insects is enhanced by mechanical resonance either in the tracheal or tympanal system before subsequent neuronal amplification. Making small structures resonant at low sound frequencies poses challenges for insects and has not been adequately studied. Similarly, detecting the direction of long-wavelength sound using interaural signal amplitude and/or phase differences is difficult for small animals. Pseudophylline bushcrickets predominantly call at high, often ultrasonic frequencies, but a few paleotropical species use lower frequencies. We investigated the mechanical frequency tuning of the tympana of one such species, Onomarchus uninotatus, a large bushcricket that produces a narrow bandwidth call at an unusually low carrier frequency of 3.2. kHz. Onomarchus uninotatus, like most bushcrickets, has two large tympanal membranes on each fore-tibia. We found that both these membranes vibrate like hinged flaps anchored at the dorsal wall and do not show higher modes of vibration in the frequency range investigated (1.5-20. kHz). The anterior tympanal membrane acts as a low-pass filter, attenuating sounds at frequencies above 3.5. kHz, in contrast to the high-pass filter characteristic of other bushcricket tympana. Responses to higher frequencies are partitioned to the posterior tympanal membrane, which shows maximal sensitivity at several broad frequency ranges, peaking at 3.1, 7.4 and 14.4. kHz. This partitioning between the two tympanal membranes constitutes an unusual feature of peripheral auditory processing in insects. The complex tracheal shape of O. uninotatus also deviates from the known tube or horn shapes associated with simple band-pass or high-pass amplification of tracheal input to the tympana. Interestingly, while the anterior tympanal membrane shows directional sensitivity at conspecific call frequencies, the posterior tympanal membrane is not directional at conspecific frequencies and instead shows directionality at higher frequencies.
Resumo:
Acoustic signal variation and female preference for different signal components constitute the prerequisite framework to study the mechanisms of sexual selection that shape acoustic communication. Despite several studies of acoustic communication in crickets, information on both male calling song variation in the field and female preference in the same system is lacking for most species. Previous studies on acoustic signal variation either were carried out on populations maintained in the laboratory or did not investigate signal repeatability. We therefore used repeatability analysis to quantify variation in the spectral, temporal and amplitudinal characteristics of the male calling song of the field cricket Plebeiogryllus guttiventris in a wild population, at two temporal scales, within and across nights. Carrier frequency (CF) was the most repeatable character across nights, whereas chirp period (CP) had low repeatability across nights. We investigated whether female preferences were more likely to be based on features with high (CF) or low (CP) repeatability. Females showed no consistent preferences for CF but were significantly more attracted towards signals with short CPs. The attractiveness of lower CP calls disappeared, however, when traded off with sound pressure level (SPL). SPL was the only acoustic feature that was significantly positively correlated with male body size. Since relative SPL affects female phonotaxis strongly and can vary unpredictably based on male spacing, our results suggest that even strong female preferences for acoustic features may not necessarily translate into greater advantage for males possessing these features in the field. (C) 2013 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
Resumo:
用云纹干涉法,研究了单向增强CALL混杂复合材料在纤维方向和垂直于纤维方向的弯曲特征。
Resumo:
The bending behavior and damage characteristics of CALL (Carbon fiber/epoxy/AL Laminate) hybrid composites have been studied by moire interferometry. The shear strain distribution along the cross-section and the forms of damage of bending beams are obtained. The results show that the magnitude of the shear strain in a carbon/epoxy layer is obviously larger than that in a corresponding aluminum layer and the shear strain distribution of a CFRP layer along the cross-section conforms basically to a parabolic distribution curve, as for the shear strain distribution in aluminum layers along the cross-section. Shear damage, either in the interfaces or in carbon-fiber/epoxy laminae, and tensile failure of CFRP laminae in the tension surface represent, respectively, the damage forms of the longitudinal and transverse bending specimen.
Resumo:
Revised: 2006-06
Resumo:
Escritores/as pós-coloniais têm se engajado em denunciar o doloroso legado da escravidão e do colonialismo, através da recuperação de histórias previamente apropriadas e distorcidas por narrativas mestras. A investigação e a narrativização do passado esquecido de ex-colônias têm sido uma estratégia empregada no sentido de se reconstruir identidades que foram fragmentadas devido às múltiplas opressões sofridas ou testemunhadas por autores. Michelle Cliff é uma romancista, poeta, e ensaísta diaspórica, nascida na Jamaica e que vive nos Estados Unidos. Ela é uma das muitas vozes pós-coloniais comprometidas com uma literatura de resistência que luta pela descolonização cultural e encoraja o sentimento de pertencimento. O objetivo dessa dissertação é analisar os romances de cunho autobiográfico de Cliff, Abeng (1984) e No Telephone to Heaven (1987), que lidam com questões relacionadas às práticas coloniais e pós-coloniais. Os dois romances retratam a saga da protagonista Clare Savage, através da qual Cliff revela o impacto da colonização no Caribe, denuncia as configurações de poder geradas a partir dos imbricamentos entre raça, gênero e classe, e critica a maneira deturpada como a história da Jamaica é transmitida e disseminada através da educação colonial à qual os Jamaicanos são submetidos. A autora também explora os efeitos que as diásporas exercem no processo de construção identitária e o movimento de resgate e recriação de uma história própria por parte dos sujeitos diaspóricos