Adolescent Perceptions of Fathers' Authority and Adolescent Behavioral Autonomy

Peterson (1986) examined the direct relationships between bases of fathers' authority and adolescent behavioral autonomy. The current study examines the direct and indirect relationships between adolescent perceptions of fathers' legitimate, expert, reward, coercive, and referent authority (French & Raven, 1959) using structural equations modeling and adolescent behavioral autonomy. A convenience sample was obtained consisting of 97 boys and 93 girls with a mean age of 16.0. The measurement model supported the dimensions identified by Peterson using exploratory factor analysis. The structural equations model required respecification which yielded ?2 = 30.8, p < .00; RMSEA = .15; RFI = .63 for the boys' model and ?2 = 25.2, p < .00; RMSEA = .13; RFI = .78 for the girls model. Significant relationships were found at p < .05 between expert, reward, and coercive authority and behavioral autonomy for boy and girl adolescents and referent authority and behavioral autonomy for boys only. Expert, reward, and referent authority mediated the relationship between legitimate authority and behavioral autonomy for boy and girl adolescents.Department of Human Development and Family Scienc

Deeply penetrating in vivo photoacoustic imaging using a clinical ultrasound array system

Using a hand-held photoacoustic probe integrated with a clinical ultrasound array system, we successfully imaged objects deeply positioned in biological tissues. The optical contrasts were enhanced by methylene blue with a concentration of ~30 mM. The penetration depth reached ~5.2 cm in chicken breast tissue by using 650-nm wavelength, which is ~4.7 times the 1/e optical penetration depth. This imaging depth was achieved using a laser fluence on the tissue surface of only 3 mJ/cm2, which is 1/7 of the American National Standards Institute (ANSI) safety limit (20 mJ/cm2). The noise equivalent sensitivity at this depth was ~11 mM. Further, after intradermal injection of methylene blue in a rat, a sentinel lymph node was easily detected in vivo, beneath a 2-cm thick layer of chicken breast. Also, blood located 3.5 cm deep in the rat was clearly imaged with intrinsic contrast. We have photoacoustically guided insertion of a needle into a rat sentinel lymph node with accumulated methylene blue. These results highlight the clinical potential of photoacoustic image-guided identification and needle biopsy of sentinel lymph nodes for axillary staging in breast cancer patients

Modelling and characterisation of a ultrasound-actuated needle for improved visibility in ultrasound-guided regional anaesthesia and tissue biopsy

AbstractClear needle visualisation is recognised as an unmet need for ultrasound guided percutaneous needle procedures including regional anaesthesia and tissue biopsy. With inadequate needle visibility, these procedures may result in serious complications or a failed operation. This paper reports analysis of the modal behaviour of a previously proposed ultrasound-actuated needle configuration, which may overcome this problem by improving needle visibility in colour Doppler imaging. It uses a piezoelectric transducer to actuate longitudinal resonant modes in needles (outer diameter 0.8–1.2mm, length>65mm). The factors that affect the needle’s vibration mode are identified, including the needle length, the transducer’s resonance frequency and the gripping position. Their effects are investigated using finite element modelling, with the conclusions validated experimentally. The actuated needle was inserted into porcine tissue up to 30mm depth and its visibility was observed under colour Doppler imaging. The piezoelectric transducer is able to generate longitudinal vibration with peak-to-peak amplitude up to 4μm at the needle tip with an actuating voltage of 20Vpp. Actuated in longitudinal vibration modes (distal mode at 27.6kHz and transducer mode at 42.2kHz) with a drive amplitude of 12–14Vpp, a 120mm needle is delineated as a coloured line in colour Doppler images, with both needle tip and shaft visualised. The improved needle visibility is maintained while the needle is advanced into the tissue, thus allowing tracking of the needle position in real time. Moreover, the needle tip is highlighted by strong coloured artefacts around the actuated needle generated by its flexural vibration. A limitation of the technique is that the transducer mode requires needles of specific lengths so that the needle’s resonance frequency matches the transducer. This may restrict the choice of needle lengths in clinical applications